bluuebunny/crossref_metadata_2025 huggingface dataset:
Comment on “Supersonic regime of the Hall-magnetohydrodynamics resistive tearing instability” [Phys. Plasmas 19, 072519 (2012)]
Authors: Vekstein G. , Kusano K.
Published: February 2013

Ahedo and Ramos [Phys. Plasmas 19, 072519 (2012)] revisited what they called the supersonic regime of the Hall-mediated resistive tearing instability and arrived to results that disagree with the previously known ones (Fruchtman and Strauss [Phys. Fluids B 5, 1408 (1993)], Bian and Vekstein [Phys. Plasmas 14, 072107 (2007)]). The present Comment aims to clarify the origin of this disagreement and to confirm in this way the validity of the earlier findings.
Response to “Comment on ‘Supersonic regime of the Hall-magnetohydrodynamics resistive tearing instability’” [Phys. Plasmas 20, 014703 (2013)]
Authors: Ramos J. J. , Ahedo E.
Published: February 2013

The Comment by Vekstein and Kusano repeats conclusions of Bian and Vekstein [Phys. Plasmas 14, 072107 (2007)] which were inferred from order of magnitude estimates and missed crucial fine details of the problem. The Comment does not show any actual solution to substantiate them, therefore we do not deem that it provides a valid clarification or counterargument to our mathematically proven result, which covers a parametric range down to β=0.
Experimental observation of left polarized wave absorption near electron cyclotron resonance frequency in helicon antenna produced plasma
Authors: Barada Kshitish K. , Chattopadhyay P. K. , Ghosh J. , Kumar Sunil , Saxena Y. C.
Published: February 2013

Asymmetry in density peaks on either side of an m = +1 half helical antenna is observed both in terms of peak position and its magnitude with respect to magnetic field variation in a linear helicon plasma device [Barada et al., Rev. Sci. Instrum. 83, 063501 (2012)]. The plasma is produced by powering the m = +1 half helical antenna with a 2.5 kW, 13.56 MHz radio frequency source. During low magnetic field (B < 100 G) operation, plasma density peaks are observed at critical magnetic fields on either side of the antenna. However, the density peaks occurred at different critical magnetic fields on both sides of antenna. Depending upon the direction of the magnetic field, in the m = +1 propagation side, the main density peak has been observed around 30 G of magnetic field. On this side, the density peak around 5 G corresponding to electron cyclotron resonance (ECR) is not very pronounced, whereas in the m = −1 propagation side, very pronounced ECR peak has been observed around 5 G. Another prominent density peak around 12 G has also been observed in m = −1 side. However, no peak has been observed around 30 G on this m = −1 side. This asymmetry in the results on both sides is explained on the basis of polarization reversal of left hand polarized waves to right hand polarized waves and vice versa in a bounded plasma system. The density peaking phenomena are likely to be caused by obliquely propagating helicon waves at the resonance cone boundary.
Chemical speciation at buried interfaces in high-temperature processed polycrystalline silicon thin-film solar cells on ZnO:Al
Authors: Becker Christiane , Pagels Marcel , Zachäus Carolin , Pollakowski Beatrix , Beckhoff Burkhard , Kanngießer Birgit , Rech Bernd
Published: February 2013

The combination of polycrystalline silicon (poly-Si) thin films with aluminum doped zinc oxide layers (ZnO:Al) as transparent conductive oxide enables the design of appealing optoelectronic devices at low costs, namely in the field of photovoltaics. The fabrication of both thin-film materials requires high-temperature treatments, which are highly desired for obtaining a high electrical material quality. Annealing procedures are typically applied during crystallization and defect-healing processes for silicon and can boost the carrier mobility and conductivity of ZnO:Al layers. In a combined poly-Si/ZnO:Al layer system, an in-depth knowledge of the interaction of both layers and the control of interface reactions upon thermal treatments is crucial. Therefore, we analyze the influence of rapid thermal treatments up to 1050 °C on solid phase crystallized poly-Si thin-film solar cells on ZnO:Al-coated glass, focusing on chemical interface reactions and modifications of the poly-Si absorber material quality. The presence of a ZnO:Al layer in the solar cell stack was found to limit the poly-Si solar cell performance with open circuit voltages only below 390 mV (compared to 435 mV without ZnO film), even if a silicon nitride (SiN) diffusion barrier was included. A considerable amount of diffused zinc inside the silicon was observed. By grazing-incidence X-ray fluorescence spectrometry, a depth-resolving analysis of the elemental composition close to the poly-Si/(SiN)/ZnO:Al interface was carried out. Temperatures above 1000 °C were found to promote the formation of new chemical compounds within about 10 nm of interface, such as zinc silicates (Zn2SiO4) and aluminium oxide (AlxOy). These results give valuable insights about the temperature-limitations of Si/ZnO thin-film solar cell fabrication and the formation of high-mobility ZnO-layers by thermal anneal.
Theory of magnetic field line random walk in noisy reduced magnetohydrodynamic turbulence
Authors: Ruffolo D. , Matthaeus W. H.
Published: February 2013

When a magnetic field consists of a mean part and fluctuations, the stochastic wandering of its field lines is often treated as a diffusive process. Under suitable conditions, a stable value is found for the mean square transverse displacement per unit parallel displacement relative to the mean field. Here, we compute the associated field line diffusion coefficient for a highly anisotropic “noisy” reduced magnetohydrodynamic model of the magnetic field, which is useful in describing low frequency turbulence in the presence of a strong applied DC mean magnetic field, as may be found, for example, in the solar corona, or in certain laboratory devices. Our approach is nonperturbative, based on Corrsin's independence hypothesis, and makes use of recent advances in understanding factors that control decorrelation over a range of parameters described by the Kubo number. Both Bohm and quasilinear regimes are identified.
What does a first-order reversal curve diagram really mean? A study case: Array of ferromagnetic nanowires
Authors: Dobrotă Costin-Ionuţ , Stancu Alexandru
Published: February 2013

The magnetic characterization technique of hysteretic materials based on the measurement of the first-order reversal curves (FORC) is one of the most appealing methods recently introduced in hundreds of new laboratories, but due to the complexity of the FORC data analysis, it is not always properly used. This method originated in identification procedures for the classical Preisach model and consequently often the FORC distribution is interpreted as a slightly distorted Preisach distribution. In this paper, we discuss this idea from two points of view derived from the basic assumptions used in the Preisach model. One is that the interaction field is equivalent with a shift of the rectangular hysteron along the applied field axis without changing the intrinsic coercivity. The other is the direct use of switching fields as coordinates, in fact, the ones defining the Preisach plane. We discuss the compatibility between the experimental FORC distribution and the Preisach model developed on the interaction field hypothesis. As a “toy model,” we are using a system of ferromagnetic nanowires, explaining from the physical point of view the complex FORC diagrams as they are obtained in experiments. This explanation gives a fundament for the correct interpretation of the FORC diagram in order to get “Preisach type” information about the system, mainly about the distributions of coercive and interaction fields within the sample. These results are relevant for many ferromagnetic systems and give a valuable guide for understanding the FORC technique and its fundamental link with the Preisach model.
Emittance of positron beams produced in intense laser plasma interaction
Authors: Chen Hui , Sheppard J. C. , Meyerhofer D. D. , Hazi A. , Link A. , Anderson S. , Baldis H. A. , Fedosejev R. , Gronberg J. , Izumi N. , Kerr S. , Marley E. , Park J. , Tommasini R. , Wilks S. , Williams G. J.
Published: February 2013

The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm·mrad, comparable to the positron sources used at existing accelerators. With 1010-1012 positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5–20 MeV, may be useful as an alternative positron source for future accelerators.
Perspective: Flicking with flow: Can microfluidics revolutionize the cancer research?
Authors: Das Tamal , Chakraborty Suman
Published: February 2013

According to the World Health Organization, cancer is one of the leading causes of death worldwide. Cancer research, in its all facets, is truly interdisciplinary in nature, cutting across the fields of fundamental and applied sciences, as well as biomedical engineering. In recent years, microfluidics has been applied successfully in cancer research. There remain, however, many elusive features of this disease, where microfluidic systems could throw new lights. In addition, some inherent features of microfluidic systems remain unexploited in cancer research. In this article, we first briefly review the advancement of microfluidics in cancer biology. We then describe the biophysical aspects of cancer and outline how microfluidic system could be useful in developing a deeper understanding on the underlying mechanisms. We next illustrate the effects of the confined environment of microchannel on cellular dynamics and argue that the tissue microconfinement could be a crucial facet in tumor development. Lastly, we attempt to highlight some of the most important problems in cancer biology, to inspire next level of microfluidic applications in cancer research.
A wide range of energy spin-filtering in a Rashba quantum ring using S-matrix method
Authors: Naeimi Azadeh S. , Eslami Leila , Esmaeilzadeh Mahdi
Published: February 2013

In this paper, spin-filtering properties of transmitted electrons through a quantum ring in the presence of Rashba spin-orbit interaction and magnetic flux are studied. To investigate the effects of coupling between the leads and ring on the spin-filtering, the S-matrix method is used. It is shown that by tuning the Rashba spin-orbit strength and the magnetic flux, the quantum ring can act as a perfect spin-filter with high efficiency. The spin-filtering can be changed from spin up to spin down and vice versa by changing the Rashba strength when the magnetic flux is held constant or by changing the magnetic flux when the Rashba strength is held constant. In addition, the effect of the angle between the leads on spin-filtering properties is taken into account and the angles at which the spin-filtering can occur are determined. The spin-filtering can take place in narrow ranges of electron energy for weak coupling, while for strong coupling it can take place in a wide range of electron energy.
Impact of conducting nonmagnetic layers on the magnetization dynamics in thin-film magnetic nanostructures
Authors: Maksymov Ivan S. , Kostylev M.
Published: February 2013

Through rigorous numerical simulations with an improved finite-difference time-domain algorithm consistent with a linearized Landau-Lifshitz-Gilbert equation and Hoffmann interlayer exchange boundary conditions, we investigate theoretically broadband ferromagnetic resonance response of single-layer and bilayer magnetic film nanostructures closely contacting with nonmagnetic metal layers. We show that the nonmagnetic capping/seed layers decrease the nonuniformity of the magnetic field inside the magnetic films, which decreases the effect of dominating first higher-order standing spin-wave mode observable in broadband ferromagnetic resonance spectrometry. We also demonstrate that the conductivity of a microstrip line inducing a microwave Oersted field in the magnetic films insignificantly affects the frequency and linewidth of the resonances. However, it exerts a shielding effect on the magnetic field and thus reduces the amplitude of the resonance peaks. Finally, we argue that in experiments involving spin wave detection in insulating magnetic films via the inverse spin-Hall effect voltage, the platinum electrode should be placed away from the microstrip line. Our findings will be useful for the design and optimization of spintronic devices for spin-based data-storage and processing.
Dynamics of laser ablated colliding plumes
Authors: Gupta Shyam L. , Pandey Pramod K. , Thareja Raj K.
Published: February 2013

We report the dynamics of single and two collinearly colliding laser ablated plumes of ZnO studied using fast imaging and the spectroscopic measurements. Two dimensional imaging of expanding plume and temporal evolution of various species in interacting zones of plumes are used to calculate plume front velocity, electron temperature, and density of plasma. The two expanding plumes interact with each other at early stage of expansion (∼20 ns) resulting in an interaction zone that propagates further leading to the formation of stagnation layer at later times (>150 ns) at the lateral collision front of two plumes. Colliding plumes have larger concentration of higher ionic species, higher temperature, and increased electron density in the stagnation region. A one-to-one correlation between the imaging and optical emission spectroscopic observations in interaction zone of the colliding plumes is reported.
Discrete kinetic eigenmode spectra of electron plasma oscillations in weakly collisional plasma: A numerical study
Authors: Black Carrie , Germaschewski Kai , Bhattacharjee Amitava , Ng C. S.
Published: February 2013

It has been demonstrated that in the presence of weak collisions, described by the Lenard-Bernstein (LB) collision operator, the Landau-damped solutions become true eigenmodes of the system and constitute a complete set [C.-S. Ng et al., Phys. Rev. Lett. 83, 1974 (1999) and C. S. Ng et al., Phys. Rev. Lett. 96, 065002 (2004)]. We present numerical results from an Eulerian Vlasov code that incorporates the Lenard-Bernstein collision operator [A. Lenard and I. B. Bernstein, Phys. Rev. 112, 1456 (1958)]. The effect of collisions on the numerical recursion phenomenon seen in Vlasov codes is discussed. The code is benchmarked against exact linear eigenmode solutions in the presence of weak collisions, and a spectrum of Landau-damped solutions is determined within the limits of numerical resolution. Tests of the orthogonality and the completeness relation are presented.
Shape-anisotropic heterogeneous nucleation and magnetic Gibbs-Thomson effect in itinerant-electron metamagnetic transition of La(Fe0.88Si0.12)13 magnetocaloric compound
Authors: Fujita A. , Kondo T. , Kano M. , Yako H.
Published: February 2013

Macroscopic anisotropy of spatial selectivity in magnetic nucleation and growth was clarified for itinerant-electron metamagnetic transition of La(Fe0.88Si0.12)13 by the time-dependent Ginzburg-Landau model combined with the Maxwell electromagnetic equation. Spontaneous generation of voltage supports symmetric growth in the longitudinal direction of the specimen as predicted by the simulation. The difference between nucleation-growth behaviors in thermally induced transition and those in field-induced transition is also elucidated. Electrical resistivity measurements also detect anisotropic growth of the induced phase. These results imply that the magnetic-dipole version of Gibbs-Thomson effect governs growth behavior.
Systematic structural and chemical characterization of the transition layer at the interface of NO-annealed 4H-SiC/SiO2 metal-oxide-semiconductor field-effect transistors
Authors: Taillon Joshua A. , Hyuk Yang Joon , Ahyi Claude A. , Rozen John , Williams John R. , Feldman Leonard C. , Zheleva Tsvetanka S. , Lelis Aivars J. , Salamanca-Riba Lourdes G.
Published: February 2013

We present a systematic characterization of the transition layer at the 4H-SiC/SiO2 interface as a function of nitric oxide (NO) post-annealing time, using high-resolution transmission electron microscopy for structural characterization and spatially resolved electron energy-loss spectroscopy for chemical analysis. We propose a systematic method for determining transition layer width by measuring the monotonic chemical shift of the Si-L2,3 edge across the interface, and compare its efficacy to traditional measures from the literature, revealing the proposed method to be most reliable. A gradual shift in the Si-L2,3 edge onset energy suggests mixed Si-C/Si-O bonding in the transition layer. We confirm an inverse relationship between NO-anneal time and transition layer width, which correlates with improved channel mobility, enhanced N density at the interface, and decreased interface trap density. No excess C was noted in the interfacial region.
A 2-inch, large-size deep ultraviolet light-emitting device using dynamically controlled micro-plasma-excited AlGaN
Authors: Aoyagi Y. , Kurose N.
Published: February 2013

A dynamically controlled micro-plasma-excited (MIPE) aluminum gallium nitride deep ultraviolet (DUV) light-emitting device is demonstrated. This device provides high-power DUV emission at any desired wavelength and allows enlargement of emission areas like plasma display panels for easy, low-cost fabrication. Neither p-n junctions nor electrode contacts are required for device fabrication. We fabricated 2-in. diameter wafer-size MIPE emitters of DUV light at specific wavelengths from AlGaN quantum wells with 50 mW average output power. We can also fabricate 6-in. diameter DUV emitters using sapphire wafers and 1 m × 5 m panel-type DUV emitters.
Doubly excited states of the hydrogen negative ion and helium atom in astrophysical plasmas
Authors: Jiang Pinghui , Kar Sabyasachi , Zhou Y.
Published: February 2013

The nonthermal effects on the doubly excited resonance states of the hydrogen negative ion and helium atom are investigated in Lorentzian astrophysical plasma environments using highly correlated Hylleraas-type wave functions in the framework of the stabilization method. Resonance parameters (resonance position and width) are reported for the first time as functions of the spectral index and plasma parameter. The screening effects are more pronounced in the stronger screening region.
Quantum spin Hall effect induced by electric field in silicene
Authors: An Xing-Tao , Zhang Yan-Yang , Liu Jian-Jun , Li Shu-Shen
Published: February 2013

We investigate the transport properties in a zigzag silicene nanoribbon in the presence of an external electric field. The staggered sublattice potential and two kinds of Rashba spin-orbit couplings can be induced by the external electric field due to the buckled structure of the silicene. A bulk gap is opened by the staggered potential and gapless edge states appear in the gap by tuning the two kinds of Rashba spin-orbit couplings properly. Furthermore, the gapless edge states are spin-filtered and are insensitive to the non-magnetic disorder. These results prove that the quantum spin Hall effect can be induced by an external electric field in silicene, which may have certain practical significance in applications for future spintronics device.
Novel pressure-induced phase transitions in Co3O4
Authors: Hirai Shigeto , Mao Wendy L.
Published: February 2013

Co3O4 represents an intriguing strongly correlated system since it is a spin liquid originating from A-site magnetic frustration. We conducted in-situ high pressure synchrotron x-ray diffraction experiments on Co3O4, and found two new monoclinic phases with the P121/c1 and C12/m1 structures. These high pressure phases are distinct from the high pressure structures that were previously reported for other 3d transition metal spinel oxides. The charge transfer does not drive the normal spinel to transform into a symmetry equivalent inverse spinel, and instead we observe transformations into the new monoclinic phases which have two distinct Co2+ and Co3+ octahedral sites.
Body-Shape Adaptation Cannot Be Explained by Adaptation to Narrow and Wide Rectangles
Authors: Hummel Dennis , Grabhorn Ralph , Mohr Harald M
Published: February 2013

Visual adaptation to certain body shapes alters visual perception of subsequently presented pictures of bodies. We investigated whether these effects can be explained by adaptation to low-level visual objects, ie narrow and wide rectangles. Participants ( n = 29) adapted to manipulated photographs of their own bodies, depicting them either unrealistically thin or fat. The perceived shapes of their own bodies were subsequently assessed by an interleaved staircase paradigm. A second experiment ( n = 29) used the same design to test for adaptation effects evoked by narrow and wide bars. After adapting to a thin picture of own body, participants also judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. Importantly, this effect could not be replicated by adaptation to narrow and wide bars, demonstrating that the body-shape aftereffect cannot be explained by adaptation to low-level properties. The results support the existence of a perceptual body-shape aftereffect, resulting from a specific adaptation to thin and fat body shapes.
More Rapid and Stronger Vection in Elementary School Children Compared with Adults
Authors: Shirai Nobu , Seno Takeharu , Morohashi Sachie
Published: February 2013

We compared vection (visually induced illusory self-motion perception) among elementary school children and adults by measuring latency to onset, cumulative duration, and estimated strength of vection. Significantly stronger vection with shorter latency was observed in children compared with adults. Several possible causes (eg size-difference of the effective visual field) of the age-related differences are discussed.
Characteristics of Eye Movements in 3-D Object Learning: Comparison between Within-Modal and Cross-Modal Object Recognition
Authors: Ueda Yoshiyuki , Saiki Jun
Published: February 2013

Recent studies have indicated that the object representation acquired during visual learning depends on the encoding modality during the test phase. However, the nature of the differences between within-modal learning (eg visual learning-visual recognition) and cross-modal learning (eg visual learning – haptic recognition) remains unknown. To address this issue, we utilised eye movement data and investigated object learning strategies during the learning phase of a cross-modal object recognition experiment. Observers informed of the test modality studied an unfamiliar visually presented 3-D object. Quantitative analyses showed that recognition performance was consistent regardless of rotation in the cross-modal condition, but was reduced when objects were rotated in the within-modal condition. In addition, eye movements during learning significantly differed between within-modal and cross-modal learning. Fixations were more diffused for cross-modal learning than in within-modal learning. Moreover, over the course of the trial, fixation durations became longer in cross-modal learning than in within-modal learning. These results suggest that the object learning strategies employed during the learning phase differ according to the modality of the test phase, and that this difference leads to different recognition performances.
Some Insights into Why the Perception of Mach Bands is Strong for Luminance Ramps and Weak or Vanishing for Luminance Steps
Authors: Bakshi Ashish , Ghosh Kuntal
Published: February 2013

In this paper we present some demonstrations concerning the width of Mach bands and henceforth hypothesize certain relations. We show that it is the variation in width of Mach bands in relation to luminance gradients which is responsible for Mach bands being strong for luminance ramps and weak or vanishing for luminance steps. We present the results of the experiments carried out by us using some of these demonstrations to provide support for our claims.
Shaping our workforce: a Tasmanian development program
Authors: Shannon Elizabeth A. , Burchill T. Alice
Published: February 2013

The Tasmanian Department of Health and Human Services management and leadership development program consists of a foundation program for frontline and aspiring managers, with additional program streams for graduate trainees, senior nurses and allied health professionals, clinical leaders and senior executive management teams. An academic pathway has also been developed in partnership with the University of Tasmania. Some elements of the management and leadership program were developed with a great deal of specificity and structure, while others have been left free to respond to expressed need as it arises. This case study describes the development and delivery, challenges and achievements of the program, focusing on the more structured elements: the foundation, graduate trainee and academic streams. In particular, it illustrates the strengths and weakness of a program that depends upon the goodwill and commitment of organisational partners and middle and senior managers, during a time of fiscal constraint. This article will be of interest to other jurisdictions and sectors seeking to strengthen staff management and leadership skills.
Does Australia have the appropriate health reform agenda to close the gap in Indigenous health?
Authors: Donato Ronald , Segal Leonie
Published: February 2013

This paper provides an analysis of the national Indigenous reform strategy – known as Closing the Gap – in the context of broader health system reforms underway to assess whether current attempts at addressing Indigenous disadvantage are likely to be successful. Drawing upon economic theory and empirical evidence, the paper analyses key structural features necessary for securing system performance gains capable of reducing health disparities. Conceptual and empirical attention is given to the features of comprehensive primary healthcare, which encompasses the social determinants impacting on Indigenous health. An important structural prerequisite for securing genuine improvements in health outcomes is the unifying of all funding and policy responsibilities for comprehensive primary healthcare for Indigenous Australians within a single jurisdictional framework. This would provide the basis for implementing several key mutually reinforcing components necessary for enhancing primary healthcare system performance. The announcement to introduce a long-term health equality plan in partnership with Aboriginal people represents a promising development and may provide the window of opportunity needed for implementing structural reforms to primary healthcare.

What is known about the topic?
Notwithstanding the intention of previous policies, considerable health disparity exists between Indigenous and non-Indigenous Australians. Australia has now embarked on its most ambitious national Indigenous health reform strategy, but there has been little academic analysis of whether such reforms are capable of eliminating health disadvantage for Aboriginal people.

What does the paper add?
This paper provides a critical analysis of Indigenous health reforms to assess whether such policy initiatives are likely to be successful and outlines key structural changes to primary healthcare system arrangements that are necessary to secure genuine system performance gains and improve health outcomes for Indigenous Australians.

What are the implications for practitioners?
For policymakers, the need to establish genuine partnership and engagement between Aboriginal people and the Australian government in pursuing a national Indigenous reform agenda is of critical importance. The establishment of the National Congress of Australia’s First Peoples provides the opportunity for policymakers to give special status to Indigenous Australians in health policy development and create the institutional breakthrough necessary for effecting primary healthcare system change.
Elevated reporting of unprotected anal intercourse and injecting drug use but no difference in HIV prevalence among Indigenous Australian men who have sex with men compared with their Anglo-Australian peers
Authors: Lea Toby , Costello Michael , Mao Limin , Prestage Garrett , Zablotska Iryna , Ward James , Kaldor John , de Wit John , Holt Martin
Published: February 2013

Background Although half of the HIV notifications among Aboriginal and Torres Strait Islander people (‘Indigenous Australians’) are attributed to homosexual transmission, there has been little research examining sexual and drug use risk practices among Indigenous Australian men who have sex with men (MSM). Methods: Respondents were Indigenous Australian (n = 1278) and Anglo-Australian men (n = 24 002) participating in the routine cross-sectional Gay Community Periodic Surveys conducted in Australia from 2007 to 2011. Sociodemographic characteristics, sexual risk practices, drug use, HIV testing and HIV status of Indigenous and Anglo-Australian men were compared and evaluated to discover whether Indigenous status was independently associated with HIV risk practices. Results: Although an equivalent proportion of Indigenous and Anglo-Australian men reported being HIV-positive (9.6%), Indigenous MSM were more likely to report unprotected anal intercourse with casual partners in the previous 6 months (27.9% v. 21.5%; Adjusted odds ratio (AOR) = 1.29, 95% confidence interval (CI): 1.11–1.49). Indigenous men were more likely than Anglo-Australian men to report use of several specific drugs and twice as likely to report injecting drug use in the previous 6 months (8.8% v. 4.5%; AOR = 1.43, 95% CI: 1.11–1.86). Conclusions: Despite a higher proportion of Indigenous men reporting sexual and drug use practices that increase the risk of HIV transmission, there were no differences in the HIV status of Indigenous and Anglo-Australian men. However, the elevated rates of risk practices suggest that Indigenous MSM should remain a focus for HIV prevention, care and support.
Preferences for rapid point-of-care HIV testing in Nova Scotia, Canada
Authors: Lewis Nathaniel M. , Gahagan Jacqueline C. , Stein Carlye
Published: February 2013

Rapid point-of-care (POC) testing for HIV has been shown to increase the uptake of testing, rates of clients receiving test results, numbers of individuals aware of their status and timely access to care for those who test positive. In addition, several studies have shown that rapid POC testing for HIV is highly acceptable to clients in a variety of clinical and community-based health care settings. Most acceptability studies conducted in North America, however, have been conducted in large, urban environments where concentrations of HIV testing sites and testing innovations are greatest. Using a survey of client preferences at a sexual health clinic in Halifax, Nova Scotia, we suggest that HIV test seekers living in a region outside of Canada’s major urban HIV epicentres find rapid POC testing highly acceptable. We compare the results of the Halifax survey with existing acceptability studies of rapid POC HIV testing in North America and suggest ways in which it might be of particular benefit to testing clients and potential clients in Nova Scotia and other regions of Canada that currently have few opportunities for anonymous or rapid testing. Overall, we found that rapid POC HIV testing was highly desirable at this study site and may serve to overcome many of the challenges associated with HIV prevention and testing outside of well-resourced metropolitan environments.
Independent Estimates of Catch by Private and Public Access Fishers Avoid Between‐Group Sources of Error in a Recreational Fishing Survey
Authors: Ashford Julian R. , Jones Cynthia M. , Fegley Lynn
Published: February 2013

Many recreational fishing surveys assume that fishers who use private or public property to gain access to the fishery behave similarly, but divergent behavior may result in bias and excessive error due to between‐group variation. In a 2002 survey of the recreational catch of blue crab Callinectes sapidus in Maryland, we interviewed waterfront property households by telephone and sampled public access boat ramps to obtain independent estimates of private and public access catch and effort. Waterfront property households caught more crabs than fishers from public boat ramps but achieved this only by using effort over an order of magnitude larger. They maintained a consistent catch from July to September, whereas catch from public access sites showed a well‐defined peak in August. Estimating catch independently for private and public access avoided bias and between‐group error generated by such differences. As a result, independent estimation of catch by private and public access users is a useful option for marine recreational surveys, under the conditions of significant and exclusive private access, large public access bias, and low correlation between effort and catch.
The Effects of Total Dissolved Gas on Chum Salmon Fry Survival, Growth, Gas Bubble Disease, and Seawater Tolerance
Authors: Geist David R. , Linley Timothy J. , Cullinan Valerie , Deng Zhiqun
Published: February 2013

Chum Salmon Oncorhynchus keta alevins developing in gravel downstream of Bonneville Dam on the Columbia River are exposed to elevated total dissolved gas (TDG) when water is spilled to move migrating salmon smolts to the ocean. We studied whether alevins that were exposed to six levels of dissolved gas ranging from 100% to 130% TDG at three development periods between hatch and emergence (hereafter, early, middle, and late stages) experienced differential mortality, growth, gas bubble disease, or seawater tolerance. Each life stage was exposed for 49 d (early stage), 28 d (middle stage), or 15 d (late stage) beginning at 13, 34, and 47 d posthatch, respectively, through emergence. Mortality for all stages was estimated to be 8% (95% confidence interval [CI] = 4–12%) when dissolved gas levels were less than 117% TDG. Mortality increased as dissolved gas levels rose above 117% TDG; the lethal concentration producing 50% mortality was 128.7% TDG (95% CI = 127.2–130.3% TDG) in the early and middle stages. There was no evidence that gas exposure affected growth. The proportion of fish with gas bubble disease increased with increasing gas concentrations, and bubbles occurred most commonly in the nares and gastrointestinal tract. Early stage fish exhibited higher ratios of filamental to lamellar gill chloride cells than late-stage fish, and these ratios increased and decreased for early and late-stage fish, respectively, as gas levels increased; however, there were no significant differences in mortality between life stages after 96 h in seawater. The study results suggest that water quality guidelines for dissolved gas (≤105% TDG) offer a conservative level of protection to Chum Salmon alevins incubating in gravel habitat downstream of Bonneville Dam.

Received June 1, 2012; accepted November 13, 2012
Dilations of semigroup crossed products as crossed products of dilations
Authors: Larsen Nadia , Li Xin
Published: February 2013

Laca constructed a minimal automorphic dilation for every semigroup dynamical system arising from an action of an Ore semigroup by injective endomorphisms of a unital

C
∗

C^*

-algebra. Here we show that the semigroup crossed product with its action by inner endomorphisms given by the implementing isometries has as minimal automorphic dilation the group crossed product of the original dilation. Applications include recent examples studied by Cuntz and the second-named author.
Using Notches to Uncover Optimization Frictions and Structural Elasticities: Theory and Evidence from Pakistan
*
Authors: Kleven Henrik J. , Waseem Mazhar
Published: February 2013

We develop a framework for nonparametrically identifying optimization frictions and structural elasticities using notches—discontinuities in the choice sets of agents—introduced by tax and transfer policies. Notches create excess bunching on the low-tax side and missing mass on the high-tax side of a cutoff, and they are often associated with a region of strictly dominated choice that would have zero mass in a frictionless world. By combining excess bunching (observed response attenuated by frictions) with missing mass in the dominated region (frictions), it is possible to uncover the structural elasticity that would govern behavior in the absence of frictions and arguably capture long-run behavior. We apply our framework to tax notches in Pakistan using rich administrative data. While observed bunching is large and sharp, optimization frictions are also very large as the majority of taxpayers in dominated ranges are unresponsive to tax incentives. The combination of large observed bunching and large frictions implies that the frictionless behavioral response to notches is extremely large, but the underlying structural elasticity driving this response is nevertheless modest. This highlights the inefficiency of notches: by creating extremely strong price distortions, they induce large behavioral responses even when structural elasticities are small.
Forebrain HCN1 Channels Contribute to Hypnotic Actions of Ketamine
Authors: Zhou Cheng , Douglas Jennifer E. , Kumar Natasha N. , Shu Shaofang , Bayliss Douglas A. , Chen Xiangdong
Published: February 2013

Background:

Ketamine is a commonly used anesthetic, but the mechanistic basis for its clinically relevant actions remains to be determined. The authors previously showed that HCN1 channels are inhibited by ketamine and demonstrated that global HCN1 knockout mice are twofold less sensitive to hypnotic actions of ketamine. Although that work identified HCN1 channels as a viable molecular target for ketamine, it did not determine the relevant neural substrate.

Methods:

To localize the brain region responsible for HCN1-mediated hypnotic actions of ketamine, the authors used a conditional knockout strategy to delete HCN1 channels selectively in excitatory cells of the mouse forebrain. A combination of molecular, immunohistochemical, and cellular electrophysiologic approaches was used to verify conditional HCN1 deletion; a loss-of-righting reflex assay served to ascertain effects of forebrain HCN1 channel ablation on hypnotic actions of ketamine.

Results:

In conditional knockout mice, HCN1 channels were selectively deleted in cortex and hippocampus, with expression retained in cerebellum. In cortical pyramidal neurons from forebrain-selective HCN1 knockout mice, effects of ketamine on HCN1-dependent membrane properties were absent; notably, ketamine was unable to evoke membrane hyperpolarization or enhance synaptic inputs. Finally, the EC50 for ketamine-induced loss-of-righting reflex was shifted to significantly higher concentrations (by approximately 31%).

Conclusions:

These data indicate that forebrain principal cells represent a relevant neural substrate for HCN1-mediated hypnotic actions of ketamine. The authors suggest that ketamine inhibition of HCN1 shifts cortical neuron electroresponsive properties to contribute to ketamine-induced hypnosis.
Effects of Intratracheal Mesenchymal Stromal Cell Therapy during Recovery and Resolution after Ventilator-induced Lung Injury
Authors: Curley Gerard F. , Ansari Bilal , Hayes Mairead , Devaney James , Masterson Claire , Ryan Aideen , Barry Frank , O’Brien Timothy , Toole Daniel O’ , Laffey John G.
Published: February 2013

Background:

Mesenchymal stromal cells (MSCs) have been demonstrated to attenuate acute lung injury when delivered by intravenous or intratracheal routes. The authors aimed to determine the efficacy of and mechanism of action of intratracheal MSC therapy and to compare their efficacy in enhancing lung repair after ventilation-induced lung injury with intravenous MSC therapy.

Methods:

After induction of anesthesia, rats were orotracheally intubated and subjected to ventilation-induced lung injury (respiratory rate 18 min−1, P
insp 35 cm H2O,) to produce severe lung injury. After recovery, animals were randomized to receive: (1) no therapy, n = 4; (2) intratracheal vehicle (phosphate-buffered saline, 300 µl, n = 8); (3) intratracheal fibroblasts (4 × 106 cells, n = 8); (4) intratracheal MSCs (4 × 106 cells, n = 8); (5) intratracheal conditioned medium (300 µl, n = 8); or (6) intravenous MSCs (4 × 106 cells, n = 4). The extent of recovery after acute lung injury and the inflammatory response was assessed after 48 h.

Results:

Intratracheal MSC therapy enhanced repair after ventilation-induced lung injury, improving arterial oxygenation (mean ± SD, 146 ± 3.9 vs. 110.8 ± 21.5 mmHg), restoring lung compliance (1.04 ± 0.11 vs. 0.83 ± 0.06 ml·cm H2O−1), reducing total lung water, and decreasing lung inflammation and histologic injury compared with control. Intratracheal MSC therapy attenuated alveolar tumor necrosis factor-α (130 ± 43 vs. 488 ± 211 pg·ml−1) and interleukin-6 concentrations (138 ± 18 vs. 260 ± 82 pg·ml−1). The efficacy of intratracheal MSCs was comparable with intravenous MSC therapy. Intratracheal MSCs seemed to act via a paracine mechanism, with conditioned MSC medium also enhancing lung repair after injury.

Conclusions:

Intratracheal MSC therapy enhanced recovery after ventilation-induced lung injury via a paracrine mechanism, and was as effective as intravenous MSC therapy.
Increased mitochondrial mutation frequency after an island colonization: positive selection or accumulation of slightly deleterious mutations?
Authors: Hardouin Emilie A. , Tautz Diethard
Published: February 2013

Island colonizations are excellent models for studying early processes of evolution. We found in a previous study on mice that had colonized the sub-Antarctic Kerguelen Archipelago about 200 years ago that they were derived from a single founder lineage and that this showed an unexpectedly large number of new mutations in the mitochondrial D-loop. To assess whether positive selection has played a role in the emergence of these variants, we have obtained 16 full mitochondrial genome sequences from these mice. For comparison, we have compiled 57 mitochondrial genome sequences from laboratory inbred lines that became established about 100 years ago, also starting from a single founder lineage. We find that the island mice and the laboratory lines show very similar mutation frequencies and patterns. None of the patterns in the Kerguelen mice provides evidence for positive selection. We conclude that nearly neutral evolutionary processes that assume the presence of slightly deleterious variants can fully explain the patterns. This supports the notion of time-dependency of molecular evolution and provides a new calibration point. Based on the observed mutation frequency, we calculate an average evolutionary rate of 0.23 substitutions per site per Myr for the earliest time frame of divergence, which is about six times higher than the long-term rate of 0.037 substitutions per site per Myr.
A comparison of bats and rodents as reservoirs of zoonotic viruses: are bats special?
Authors: Luis Angela D. , Hayman David T. S. , O'Shea Thomas J. , Cryan Paul M. , Gilbert Amy T. , Pulliam Juliet R. C. , Mills James N. , Timonin Mary E. , Willis Craig K. R. , Cunningham Andrew A. , Fooks Anthony R. , Rupprecht Charles E. , Wood James L. N. , Webb Colleen T.
Published: February 2013

Bats are the natural reservoirs of a number of high-impact viral zoonoses. We present a quantitative analysis to address the hypothesis that bats are unique in their propensity to host zoonotic viruses based on a comparison with rodents, another important host order. We found that bats indeed host more zoonotic viruses per species than rodents, and we identified life-history and ecological factors that promote zoonotic viral richness. More zoonotic viruses are hosted by species whose distributions overlap with a greater number of other species in the same taxonomic order (sympatry). Specifically in bats, there was evidence for increased zoonotic viral richness in species with smaller litters (one young), greater longevity and more litters per year. Furthermore, our results point to a new hypothesis to explain in part why bats host more zoonotic viruses per species: the stronger effect of sympatry in bats and more viruses shared between bat species suggests that interspecific transmission is more prevalent among bats than among rodents. Although bats host more zoonotic viruses per species, the total number of zoonotic viruses identified in bats (61) was lower than in rodents (68), a result of there being approximately twice the number of rodent species as bat species. Therefore, rodents should still be a serious concern as reservoirs of emerging viruses. These findings shed light on disease emergence and perpetuation mechanisms and may help lead to a predictive framework for identifying future emerging infectious virus reservoirs.
Whole-Cell In Vivo Patch-Clamp Recordings in the Drosophila Brain
Authors: Murthy Mala , Turner Glenn
Published: February 2013

Whole-cell patch-clamp recordings provide exceptional access to spiking and synaptic neural activity. This method has been applied to neurons in the central nervous system of Drosophila and allows researchers the opportunity to study the function of their neurons of interest within the context of native circuits in a genetically tractable model system. In this protocol, we describe the technique for in vivo whole-cell patch-clamp recordings in a preparation which exposes neurons in the fly brain. We also offer technical suggestions and discuss some of the challenges encountered in recording from single neurons in the fly brain. Neurons are patched following routine recording protocols for whole-cell patch clamp. At the physiology rig, additional cleaning of the brain is performed to allow easy access to the neurons, and the cells can be filled with a diffusible dye during recordings, to examine the morphology of the recorded cell post hoc. In the electrophysiology rig used for Drosophila patch-clamp recordings, the microscope stage has been removed, so that the recording platform instead rests on a ring stand support that is magnetically fixed to the table. Manipulators and stimulus delivery are also in fixed locations, whereas the microscope sits on an x–y translation stage.
The Primer Extension Assay
Authors: Carey Michael F. , Peterson Craig L. , Smale Stephen T.
Published: February 2013

In the primer extension assay, the transcription start site for a gene is determined experimentally by identifying the 5′ end of the encoded messenger RNA (mRNA). The protocol begins with a primer, usually a synthetic oligonucleotide of about 20 residues, that is complementary to an mRNA sequence ∼50–150 nucleotides downstream of the anticipated 5′ end. The primer is 5′-end-labeled using [γ-32P]ATP and T4 polynucleotide kinase and is annealed to the specific mRNA molecules within an RNA sample. Reverse transcriptase (RT), deoxyribonucleoside triphosphates, and appropriate buffer components are added to the primer–mRNA hybrids to catalyze elongation of the primer to the 5′ end of the mRNA. The resulting radiolabeled complementary DNA (cDNA) products are analyzed by denaturing polyacrylamide gel electrophoresis, followed by autoradiography. The sizes of the bands detected on the gel, as compared to an adjacent sequencing ladder or molecular weight standards, provide a measure of the distance from the 5′ end of the synthetic oligonucleotide to the beginning of the mRNA transcripts. In theory, the 3′ end of the cDNA will coincide with the 5′ end of the mRNA. Thus, the size of the radiolabeled cDNAs should represent the distance from the labeled 5′ end of the primer to the 5′ end of the mRNA (i.e., the 3′ end of the cDNA). If the labeled cDNA products are within the resolution range of the gel, the transcription start site can be determined with an accuracy of plus or minus one nucleotide.