bluuebunny/crossref_metadata_2025 huggingface dataset:
Coincident-Current Nondestructive Readout from Thin Magnetic Films
Authors: Oakland Lewis J. , Rossing Thomas D.
Published: March 2008

By using cores which consist of two-vacuum-deposited ferromagnetic films it is possible to build memory arrays from which data can be read out nondestructively by use of coincident-current selection. It is thus possible to eliminate the external selection matrices commonly associated with nondestructive readout memories. This system promises to be inexpensive, reliable, and fast, especially in a memory in which read operations occur more frequently than write operations.

Three different devices are described which fulfill the criterion of coincident-current nondestructive readout. Good signal to noise has been achieved with each of these.
Reversible Component of Magnetization
Authors: McKay R. W.
Published: March 2008

A method of nondestructive sensing of a ferrite-core memory has been suggested which depends on the variation of the reversible component of magnetization with the state of the core. In the work reported here, measurements of this reversible component were made for two types of cores. It was found that the reversible component varies nearly three to one between the remanent state and the demagnetized state. The effects of finite core-wall thickness and of flux-leakage are discussed.
Hysteresis and Eddy Losses in Silicon Iron as a Function of Sheet Thickness
Authors: Neurath P. W.
Published: March 2008

Pry and Bean have calculated energy losses in magnetic sheet materials using a simple domain model. A quantitative verification of these results for (110) [001] oriented 3.2% Si-Fe, varied in thickness from 13 to 2 mils, have been attempted. Domain wall spacings were measured visually from static Bitter patterns and calculated from measured 60 cy and dc hysteresis losses. It is pointed out that the calculated spacing must be the spacing between simultaneously moving walls and that this is several times as large as the visually observed one for the thin gauge sheets. At the thicker gauges, probably due to the skin effect, the discrepancy decreases.
Current-induced magnetic instability in SrRuO3
Authors: Feigenson Michael , Reiner James W. , Klein Lior
Published: March 2008

Current pulses injected into a fully magnetized region of the itinerant ferromagnet SrRuO3 destabilize the uniform state and induce the formation of a domain structure when the current density exceeds a certain threshold. We study the temperature and field dependence of the destabilizing current (Ids) and compare the results with the temperature and field dependence exhibited by the current required for depinning domain walls in the same region (Idp). We find a qualitative difference between Ids and Idp and suggest that Ids may be related to current-induced nucleation.
Valence orbital response to pseudorotation of tetrahydrofuran: A snapshot using dual space analysis
Authors: Duffy Patrick , Sordo José A. , Wang Feng
Published: March 2008

The pseudorotation of tetrahydrofuran (THF) (C4H8O) has been studied using density functional theory, with respect to the valence orbital responses to the ionization potentials and to orbital electron and momentum distributions. Three conformations of THF, the global minimumstructure Cs, local minimum structure C2, and a transition state structure C1, which arecharacteristic configurations on the potential energy surface, are examined using the SAOP∕et-pVQZ//B3LYP∕6-311++G** models with the aforementioned dual space analysis. It is noted in the ionization energy spectra that the minimum structures Cs and C2 are not directly connected by pseudorotation, but through the transition state structure C1. As a result, some orbitals of the Cs conformer are able to “correlate” to orbitals of the C2 conformer without a strict symmetry constraint, i.e., orbital 7a′ of the Cs conformer is correlated to orbital 5b of the C2 conformer. It is also noted that although the valence orbital ionization potentials are not significantly altered by the pseudorotation of THF, their spectra (mainly due to excitation) are quite different indeed. Detailed orbital analysis based on dual space analysis is given. The valence orbital behavior of the conformations is orbital dependent. It can be approximately divided into three groups: the “signature group” is associated with orbitals experiencing significant changes. The frontier orbitals are in this group. The “nearly identical group” includes orbitals without apparent changes across the conformations. Most of the orbitals showing a certain degree of distortion during the pseudorotation process belong to the third group. The present study demonstrates that a comprehensive understanding of the pseudorotation of THF and its dynamics requires multidimensional information and that the information gained from momentum space is complementary to that from the more familiar coordinate space.
Interference and quantization in semiclassical response functions
Authors: Gruenbaum Scott M. , Loring Roger F.
Published: March 2008

Application of the Herman–Kluk semiclassical propagator to the calculation of spectroscopic response functions for anharmonic oscillators has demonstrated the quantitative accuracy of these approximate dynamics. In this approach, spectroscopic response functions are expressed as multiple phase-space integrals over pairs of classical trajectories and their associated stability matrices. Here we analyze the Herman–Kluk semiclassical approximation to a linear response function and determine the origin of the capacity of this method to reproduce quantum effects in a response function from classical dynamical information. Our analysis identifies those classical trajectories that contribute most significantly to the response function on different time scales. This finding motivates a procedure for computing the linear response function in which the interference between pairs of classical trajectories is treated approximately, resulting in an integral over a single average trajectory, as in a purely classical calculation.
Heat kernel estimates and spectral properties of a pseudorelativistic operator with magnetic field
Authors: Jakubassa-Amundsen D. H.
Published: March 2008

Based on the Mehler heat kernel of the Schrödinger operator for a free electron in a constant magnetic field, an estimate for the kernel of EA=∣α(p−eA)+βm∣ is derived, where EA represents the kinetic energy of a Dirac electron within the pseudorelativistic no-pair Brown–Ravenhall model. This estimate is used to provide the bottom of the essential spectrum for the two-particle Brown–Ravenhall operator, describing the motion of the electrons in a central Coulomb field and a constant magnetic field, if the central charge is restricted to Z⩽86.
Poisson-transformed density fitting in relativistic four-component Dirac–Kohn–Sham theory
Authors: Belpassi Leonardo , Tarantelli Francesco , Sgamellotti Antonio , Quiney Harry M.
Published: March 2008

We present recent developments in the implementation of the density fitting approach for the Coulomb interaction within the four-component formulation of relativistic density functional theory [Belpassi et al., J. Chem. Phys. 124, 124104 (2006)]. In particular, we make use of the Poisson equation to generate suitable auxiliary basis sets and simplify the electron repulsion integrals [Manby and Knowles, Phys. Rev. Lett. 87, 163001 (2001)]. We propose a particularly simple and efficient method for the generation of accurate Poisson auxiliary basis sets, based on already available standard Coulomb fitting sets. Just as is found in the nonrelativistic case, we show that the number of standard auxiliary fitting functions that need to be added to the Poisson-generated functions in order to achieve a fitting accuracy equal or, in some cases, better than that of the standard procedure is remarkably small. The efficiency of the present implementation is demonstrated in a detailed study of the spectroscopic properties and energetics of several gold containing systems, including the Au dimer and the CsAu molecule. The extraction reaction of a H2O molecule from a Au(H2O)9+ cluster is also calculated as an example of mixed heavy-light-atom molecular systems. The scaling behavior of the algorithm implemented is illustrated for some closed shell gold clusters up to Au5+. The increased sparsity of the Coulomb matrices involved in the Poisson fitting is identified, as are potential computational applications and the use of the Poisson fitting for the relativistic exchange-correlation problem.
Er
3
+
luminescence and cooperative upconversion in ErxY2−xSiO5 nanocrystal aggregates fabricated using Si nanowires
Authors: Suh Kiseok , Shin Jung H. , Seo Seok-Jun , Bae Byeong-Soo
Published: March 2008

Er 3 + luminescence and cooperative upconversion in ErxY2−xSiO5 nanocrystal aggregates fabricated using Si nanowires is investigated. X-ray diffraction and photoluminescence spectroscopy indicate that the composition of the final nanocrystals can be varied continuously from pure Y2SiO5 to pure Er2SiO5 while keeping the crystal structure the same. Analysis of concentration and pump-power dependence of the Er3+ photoluminescence intensity and decay time shows that while cooperative upconversion occurs at high Er concentrations, the cooperative upconversion coefficient is only (2.2±1.1)×10−18cm3∕s at a Er concentration of 1.2×1021cm−3. This is nearly ten times lower at more than ten times higher Er concentration than that reported from Er-doped silica and demonstrates the viability of using such silicates for compact, high-gain Si-based optical material for Si photonics.
Iron-carbon interactions at high temperatures and pressures
Authors: Rouquette J. , Dolejš D. , Kantor I. Yu. , McCammon C. A. , Frost D. J. , Prakapenka V. B. , Dubrovinsky L. S.
Published: March 2008

We have performed experiments in the Fe–C system at 2200–3400K and 25–70GPa using a multianvil press and laser-heated diamond anvil cell in order to constrain the stability of Fe3C. Iron carbide was observed experimentally as a stable phase using both experimental methods and independently confirmed by thermodynamic calculations. Our results imply that pure iron and carbon cannot coexist in a stable equilibrium at high pressure and high temperature. The high reactivity between metallic iron and the diamond requires a careful design of diamond anvil cell experiments in order to avoid carbon transport to the sample.
Ab initio potential energy surfaces and nonadiabatic interactions in the H++NO collision system
Authors: Amaran Saieswari , Kumar Sanjay , Köppel H.
Published: March 2008

Ab initio calculations on the H++NO system have been carried out in Jacobi coordinates at the multireference configuration interaction level employing Dunning’s correlation-consistent polarized valence triple zeta basis set to analyze the role of low-lying electronic excited states in influencing the collision dynamics relevant to the experimental collision energy range of 9.5–30eV. The lowest two adiabatic potential energy surfaces, asymptotically correlating to H++NO(XΠ2) and H(S2)+NO+(XΣ+1), have been obtained. Using ab initio procedures, the (radial) nonadiabatic couplings and the mixing angle between the lowest two electronic states (1A′2 and 2A′2) have been obtained to yield the corresponding quasidiabatic potential energy matrix. The strengths of the computed vibrational coupling matrix elements reflect a similar trend, as has been observed experimentally in the magnitudes of the state-to-state transition probability for the inelastic vibrational excitations [J. Krutein and F. Linder, J. Chem. Phys. 71, 559 (1979); F. A. Gianturco et al., J. Phys. B 14, 667 (1981)].
Magnetic strip patterns induced by focused ion beam irradiation
Authors: Makarov D. , Tibus S. , Rettner C. T. , Thomson T. , Terris B. D. , Schrefl T. , Albrecht M.
Published: March 2008

Focused ion beam exposure was used to locally alter the magnetic properties of a continuous Co∕Pd multilayer film with perpendicular magnetic anisotropy. The saturation magnetization, coercivity, and magnetic anisotropy of the films can be tuned by Ga irradiation depending on exposure dose. As a result, a periodic strip pattern consisting of 80nm wide exposed strips which are magnetically soft, separated by 170nm wide magnetically hard, unexposed areas was created. Due to strong magnetostatic coupling between the strips, a number of magnetic domain configurations could be stabilized and these have been observed by magnetic force microscopy and magneto-optic Kerr effect measurements. The magnetic domain configurations and their reversal behavior were investigated by micromagnetic simulations as a function of exposure dose and strip period.
Electrical transport properties of a nanorod GaN p-n homojunction grown by molecular-beam epitaxy
Authors: Park Young S. , Park Chang M. , Lee J. W. , Cho H. Y. , Kang T. W. , Yoo Kyung-Hwa , Son Min-Soo , Han Myung-Soo
Published: March 2008

We investigated the electrical properties of a GaN nanorod p-n junction diode patterned on a SiO2 substrate using e-beam lithography. The electron transport mechanisms were characterized by temperature-dependence and current-voltage measurements. At a low temperature, the current-voltage curves showed that the current slowly increased with a given voltage for the forward bias and hardly changed for the reverse bias, indicating the tunneling current dominates through the deep trap barrier. At a high temperature, however, the current-voltage curves exhibited strong temperature dependence suggesting that thermionic emission with an activation energy of 19.1meV over a barrier dominated.
The environment of graphene probed by electrostatic force microscopy
Authors: Moser J. , Verdaguer A. , Jiménez D. , Barreiro A. , Bachtold A.
Published: March 2008

We employ electrostatic force microscopy to study the electrostatic environment of graphene sheets prepared with the micromechanical exfoliation technique. We detect the electric dipole of residues left from the adhesive tape during graphene preparation, as well as the dipole of water molecules adsorbed on top of graphene. Water molecules form a dipole layer that can generate an electric field as large as ∼109Vm−1. We expect that water molecules can significantly modify the electrical properties of graphene devices.
Surface reconstruction evolution and anatase formation in the process of oxidation of titanium nitride film
Authors: Wu S. X. , Liu Y. J. , Xing X. J. , Yu X. L. , Xu L. M. , Yu Y. P. , Li S. W.
Published: March 2008

Titanium nitride film was grown on MgO(001) substrate by plasma-assisted molecular beam epitaxy and then oxidized by oxygen plasma. Reflection high-energy electron diffraction (RHEED) was employed to in situ monitor the process of growth and oxidation. After the TiN film was oxidized for a moment, spots among main streaks were observed in RHEED pattern, which should be attributed to the isolated surface reconstruction domains disorderedly distributing on flat surface. Subsequently, the spots gradually evolved to streaks so that more clear RHEED patterns of (2×1) surface reconstruction were observed. It was argued that the disordered and isolated reconstruction domains congregated to large domains or even perfect reconstruction surface with oxidation time evolving. After oxidation, a series of characterization methods were applied to study the TiO2 phase, which consistently confirmed that the phase of oxidized titanium nitride is anatase but not rutile.
Transition from drift to interchange instabilities in an open magnetic field line configuration
Authors: Poli F. M. , Ricci P. , Fasoli A. , Podestà M.
Published: March 2008

The transition from a regime dominated by drift instabilities to a regime dominated by pure interchange instabilities is investigated and characterized in the simple magnetized toroidal device TORPEX [TORoidal Plasma EXperiment, A. Fasoli et al., Phys. of Plasmas 13, 055906 (2006)]. The magnetic field lines are helical, with a dominant toroidal component and a smaller vertical component. Instabilities with a drift character are observed in the favorable curvature region, on the high field side with respect to the maximum of the background density profile. For a limited range of values of the vertical field they coexist with interchange instabilities in the unfavorable curvature region, on the plasma low field side. With increasing vertical magnetic field magnitude, a gradual transition between the two regimes is observed on the low field side, controlled by the value of the field line connection length. The observed transition follows the predictions of a two-fluid linear model.
Electromigration effects upon the Sn∕Ni–7wt%V interfacial reactions
Authors: Chen Chih-chi , Chen Sinn-wen , Chang Chih-horng
Published: March 2008

The electromigration effects upon the Sn∕Ni–7wt%V interfacial reactions are examined. A ternary T phase was formed in the Sn∕Ni–7wt%V couple reacted at 200°C in the early stage. The reaction phases became T∕Ni3Sn4 and an interesting T∕Ni3Sn4∕T∕Ni3Sn4 alternating layer structure with longer reaction time. The passage of electric current of 500A∕cm2 density through the couple alters the reaction rates and the phase progression time. At the interface with electrons flow concurrently to the diffusion of Sn atoms, the reaction rates are enhanced.
Intrafacet migration effects in InGaN∕GaN structures grown on triangular GaN ridges studied by submicron beam x-ray diffraction
Authors: Bonanno P. L. , O’Malley S. M. , Sirenko A. A. , Kazimirov A. , Cai Z.-H. , Wunderer T. , Brückner P. , Scholz F.
Published: March 2008

Synchrotron radiation has been utilized for x-ray diffraction and reciprocal space mapping of InGaN∕GaN multiple-quantum-well (MQW) structures grown on the sidewalls of 10-μm-wide triangular GaN ridges with {1−1.1} facets. Samples were produced by lateral overgrowth through a patterned dielectric mask by using metal-organic vapor-phase epitaxy. Global MQW strain, period, and the tilt of the (00.1) crystallographic planes have been measured across the sidewall facets using a 240nm x-ray beam. Results of this study are interpreted in terms of suppressed intrafacet migration of In and Ga precursors during the MQW growth.
Three-dimensional phase-field simulation of domain structures in ferroelectric islands
Authors: Zhang J. X. , Wu R. , Choudhury S. , Li Y. L. , Hu S. Y. , Chen L. Q.
Published: March 2008

A three-dimensional phase-field model was developed for studying domain structures in ferroelectric islands attached onto a substrate. It simultaneously takes into account the long-range electric and elastic interactions, substrate constraint, as well as the stress relaxation caused by the surfaces of an island. The phase-field simulations demonstrated that the domain structures of ferroelectric islands could be dramatically different from those of continuous thin films due to the change of stress state. The stress distribution inside islands is highly dependent on the aspect ratio of the islands. It provides us an effective way for engineering the domain structures of ferroelectric materials.
Enhanced light output of GaN-based light-emitting diodes with ZnO nanorod arrays
Authors: An Sung Jin , Chae Jee Hae , Yi Gyu-Chul , Park Gil H.
Published: March 2008

We report enhanced light output of GaN-based light-emitting diodes (LEDs) with vertically aligned ZnO nanorod arrays. The ZnO nanorod arrays were prepared on the top layer of GaN LEDs using catalyst-free metalorganic vapor phase epitaxy. Compared to conventional GaN LEDs, light output of GaN LEDs with the ZnO nanorod arrays increased up to 50% and 100% at applied currents of 20 and 50mA, respectively. The source of the enhanced light output is also discussed.
Cutting carbon nanotubes for solar cell application
Authors: Kalita Golap , Adhikari Sudip , Aryal Hare Ram , Umeno Masayoshi , Afre Rakesh , Soga Tetsuo , Sharon Maheshwar
Published: March 2008

This paper presents the application of cutting multiwalled carbon nanotubes (cut-MWNTs) in solar cell. Cutting of MWNTs is performed by plasma fluorination and followed by defluorination. Cut-MWNTs with lengths of 50–200nm are incorporated in a poly(3-octylthiophene)∕n-Si heterojunction solar cell. We found that a device fabricated with cut-MWNTs shows much better performance than that of a device with pristine MWNTs. The device with cut-MWNTs shows short circuit current density, open circuit voltage, fill factor, and power conversion efficiency as 7.65mA∕cm2, 0.23V, 31%, and 0.54%, respectively. Here, we proposed that cut-MWNTs provide efficient hole transportation having a few nanometer transportation path, hence suppressing recombination. Cut-MWNTs can be the solution to the shorting and shunting effects generally observed in the MWNT solar cell.
Pedestrian Environments, Transit Path Choice, and Transfer Penalties: Understanding Land-Use Impacts on Transit Travel
Authors: Guo Zhan , Ferreira Joseph
Published: March 2008

This paper investigates the impact of pedestrian environments on walking behavior, and the related choice of travel path for transit riders. Activity logs from trip surveys combined with transit-route and land-use information are used to fit discrete-choice models of how riders choose among multiple paths to downtown destinations. The work illustrates (1) how the quality of pedestrian environments along transit egress paths affects transfers inside a transit system, and (2) how the impedance of transferring affects egress walking path choices. The use of GIS techniques for path-based spatial analysis is key to understanding the impact of pedestrian environments on walking behavior at the street level. The results show that desirable pedestrian environments encourage transit riders to choose paths that are ‘friendlier’, even if they involve more walking after leaving transit. Policy implications for land-use planning and transit service planning are discussed.
The Relationship between the Capacity of the Spanish Central Government to Retain Tax-Revenue Shares and Interregional Inequality
Authors: Mora Toni
Published: March 2008

I examine the relationship between the dynamics of the size of the Spanish central government, by looking at central government tax-revenue-retention shares in different domestic regions, and regional-income heterogeneity. Annual data correspond to the 1986–2001 period. In addition to interregional inequality, other factors, such as per capita transfers from the central government, regional saving rates, and years in which there is a change in the party leading the central government, also contribute to the decreasing dynamics of revenues that are retained by the Spanish central government.
The Performativity of Scale: The Social Construction of Scale Effects in Narva, Estonia
Authors: Kaiser Robert , Nikiforova Elena
Published: March 2008

In their recent critique of the politics of scale literature, Marston, Jones, and Woodward (2005, “Human geography without scale” Transactions of the Institute of British Geographers, New Series30 416–432) argue against the continued use of scale in human geography. While acknowledging that there are significant problems with scale as it has been conceptualized and operationalized in human geography, we argue that more, rather than less, attention needs to be paid to the political genealogy of scale ontologies, defined here as the historically contextualized analysis of the social production of scaled knowledge. As a first step in this direction, we develop a poststructural reframing using performativity, as an approach that explores the reiterative and citational practices through which scale effects are socially produced. We are especially concerned in this paper to examine the ways in which scale effects are produced and deployed as discursive devices that create timespace conjunctures and ruptures between place and identity. Using sites of memory as our analytical lens, we trace the citational practices that have naturalized and sedimented a series of scale effects in Narva, Estonia, and explore the consequences of these discursive rescalings for the articulation of place and identity.
Out of Rubble: Natural Disaster and the Materiality of the House
Authors: Wilford Justin
Published: March 2008

Studies of the cultural dimensions of natural disasters have largely opposed the social world to the physical world. In such studies, the social world of humans constructs meaning against the implacable force of nature. In this paper, following the theoretical lead of ‘new materialists’ such as Bruno Latour and Daniel Miller, I argue that the physical world plays an integral role in the construction of meaning out of natural disasters. By focusing on the various cultural narratives surrounding Hurricane Katrina as well as the particular material genre of the house, I analyze the ways the human and physical worlds participate in the production of meaning. The specific materiality of the house in New Orleans is explored through three key stages of the Katrina disaster: the initial landfall and flooding, the first week of ostensible chaos, and the return of residents to their houses.
The Technological Metaphysics of Planetary Space: Being in the Age of Globalization
Authors: Joronen Mikko
Published: March 2008

In this paper I look at globalization in terms of the metaphysical event of being, arguing that in order to discuss the issue of globalization the ontological conditions of possibility for its historical appearance need to be prioritized. Using the philosophy of Martin Heidegger allows us to see how globalization belongs to the modern calculable understanding of space, and therefore to the particular metaphysical event of technological existence. Through an acknowledgment of the metaphysics of gigantic growth and totalitarian magnitude, globalization is seen as a planetary consummation of the kind of technological disclosure of being. This is a period in which the entire globe stands at the service of complete and manipulative calculability. In this paper I argue that in globalization the world is ontologically understood as a picture in which everything becomes gathered together as a reserve to be ordered and challenged by anthropocentric will and value-creation.
Biodiversity and conservation of freshwater fishes in selected rivers on Choiseul Island, Solomon Islands
Authors: Boseto David , Morrison Clare , Pikacha Patrick , Pitakia Tikai
Published: March 2008

During a terrestrial biodiversity survey of Choiseul Island, we conducted freshwater fish surveys in seven sites between July 2005 and August 2006. We found 32 fish species from 15 families (38% of known Solomon Island freshwater fish). Most species were uncommon with the exception of Kuhlia marginata (6/7 sites), K. rupestris (5/7 sites) and Glossogobius sp. 1 (5/7 sites). No introduced species were found in any of the sites. Species richness ranged from 2-14 species per site and was highest in Lumutu River and Kolombangara River. This difference between sites is partially attributed to substrate type (higher richness in sites with gravel substrates than mud) and distance from the coast (higher richness near the coast than inland). The results of this survey in conjunction with a previous survey bring the total number of freshwater fish species on Choiseul Island to 41. This diversity is threatened by habitat degradation through sedimentation and over harvesting of some species. We recommend a number of activities to ameliorate these threats including seasonal banning of fish harvest during breeding periods and mass juvenile migrations, discouraging the practice of streamside agriculture, and education of locals on the negative impacts of logging on watershed health and productivity.
Susceptibility of six tomato cultivars to the root-knot nematode, Meloidogyne incognita
Authors: Singh Sunil K. , Khurma Uma R.
Published: March 2008

Six tomato cultivars Moneymaker, Beefsteak, Roma, Summertaste, Mini Roma and Smallfry were tested for their susceptibility to root- knot nematodes at inoculum levels of 200, 400, 600 Juveniles (J2) per pot. All were found to be susceptible to varying degrees as egg masses were present in all with Moneymaker and Roma being the most susceptible and Mini Roma, the least susceptible. The inoculum levels had a significant effect (p<0.05) on the number of galls and plant weights. The gall numbers and plant weights was negatively correlated, with the highest gall numbers and lowest plant weights recorded at the highest inoculum level in all cultivars except in Mini Roma in which there was little variation in gall numbers and plant weights.
Culturing of human peripheral blood cells reveals unsuspected lymphocyte responses relevant to HIV disease
Authors: Sahaf Bita , Atkuri Kondala , Heydari Kartoosh , Malipatlolla Meena , Rappaport Jay , Regulier Emmanuel , Herzenberg Leonard A. , Herzenberg Leonore A.
Published: March 2008

Recombinant HIV-Tat (Tat) induces extensive apoptosis in peripheral blood mononuclear cells (PBMCs) cultured in typical CO
2
incubators, which are equilibrated with air (21% O
2
). However, as we show here, Tat apoptosis induction fails in PBMCs cultured at physiological oxygen levels (5% O
2
). Under these conditions, Tat induces PBMCs to divide, efficiently primes them for HIV infection, and supports virus production by the infected cells. Furthermore, Tat takes only 2 h to prime PBMCs under these conditions. In contrast, PHA/IL-2, which is widely used to prime cells for HIV infection, takes 2–3 days. These findings strongly recommend culturing primary cells at physiological oxygen levels. In addition, they suggest HIV-Tat as a key regulator of HIV disease progression.
The prevalence of methamphetamine and amphetamine abuse in North America: a review of the indicators, 1992–2007
Authors: MAXWELL JANE CARLISLE , RUTKOWSKI BETH A.
Published: March 2008

Introduction. This paper reviews epidemiological information about methamphetamine production and use in North America. Methods. Information is drawn from a range of sources, including, but not limited to, historical accounts, peer‐reviewed papers, population surveys and large national databases. Results. Methamphetamine and amphetamine use in North America is characterised by geographic variations, with different types of the drug, different routes of administration and different types of users at various times. Unlike some other drug use patterns in North America, the nature of methamphetamine use in Canada, Mexico and the United States has been linked closely in terms of production and supply of the drug. According to their national household surveys, the annual prevalence for ‘speed’ use in Canada was 0.8% in 2004, 0.3% for ‘anfetaminas’ and 0.1% for ‘metanfetaminas’ in Mexico in 2002, and 1.4% for ‘stimulants’ in the United States in 2006. Discussion. Although the data sources in the three North American countries are not consistent in methodology, terminology or frequency of reporting, all show similar trends. The type of stimulant most used has shifted from non‐medical use of pharmaceutical amphetamine to use of powder methamphetamine and then to use of ‘ice’. The indicators show the problem is greatest in the western parts of the countries and is moving eastward, but the decreased availability of pseudoephedrine may have a significant impact on the nature of the epidemic in the future. Nevertheless, use of methamphetamine poses a number of risks for users and specialised treatment resources for these various populations are needed.
Characteristics and harms associated with injecting versus smoking methamphetamine among methamphetamine treatment entrants
Authors: McKETIN REBECCA , ROSS JOANNE , KELLY ERIN , BAKER AMANDA , LEE NICOLE , LUBMAN DAN I. , MATTICK RICHARD
Published: March 2008

Introduction and Aims. To compare the characteristics and harms associated with injecting and smoking methamphetamine among methamphetamine treatment entrants. Method and design. A structured face‐to‐face interview was used to assess demographics, drug use patterns and harms [physical and mental health, psychological distress, psychotic symptoms, crime and human immunodeficiency virus (HIV) risk behaviour] among 400 methamphetamine treatment entrants in Sydney and Brisbane, Australia. Participants who had injected but not smoked methamphetamine in the month before treatment (n = 195, injectors) were compared to participants who had either: (a) injected and smoked (n = 90, injectors who smoke), or (b) smoked but not injected (n = 73, smokers), during this time. Results. In comparison with injectors, smokers were primarily non‐injecting drug users, who were younger, more likely to be female and use ecstasy rather than heroin. After adjusting for these differences smokers were less dependent on methamphetamine than injectors, but they took the drug as often and had similarly high levels of psychological distress, poor physical and mental health, psychotic symptoms, sexual risk behaviour and criminal involvement. Injectors who smoked had a similar demographic and clinical profile to injectors, including comparable levels of needle sharing, but they used methamphetamine more often and had greater criminal involvement. Conclusion. Within this treatment sample, smoking methamphetamine occurred among both long‐standing injecting drug users and a comparatively younger group of non‐injecting drug users. It was associated with less severe methamphetamine dependence than injecting, but more intense use patterns and similar levels of other harms.
The epidemiology of methamphetamine use and harm in Australia
Authors: DEGENHARDT LOUISA , ROXBURGH AMANDA , BLACK EMMA , BRUNO RAIMONDO , CAMPBELL GABRIELLE , KINNER STUART , FETHERSTON JAMES
Published: March 2008

Introduction and aims. There has been considerable media attention recently upon possible increases in methamphetamine use in Australia. Much of this debate has focused upon extreme cases of problematic crystal methamphetamine use, without reference to the broader population context. This paper provides data on methamphetamine use in Australia, and documents trends in methamphetamine‐related harms. Design and Methods. Data used were from: (1) Australian Customs Service drug detections; (2) Australian Crime Commission drug seizure, arrest and clandestine laboratory detections data; (3) National Drug Strategy Household Survey (NDSHS) and Australian Secondary Student Alcohol and Drug Survey (ASSADS); (4) data from the Illicit Drug Reporting System (IDRS) and Ecstasy and related Drug Reporting System (EDRS); and (5) data from NSW Emergency Department Information System, National Hospital Morbidity Database and Australian Bureau of Statistics causes of death databases. Results. There appears to have been an increase in both importation and local manufacture of meth/amphetamine. Population data show that meth/amphetamine use remains low and stable. However, clear increases in crystal methamphetamine use have occurred among sentinel groups of regular drug users. Frequent crystal use among regular injecting drug users is associated with earlier initiation to injecting, greater injection risk behaviours and more extensive criminal activity. In recent years, indicators of meth/amphetamine‐related harm have stabilised, following steady increases in earlier years. Discussion and Conclusions. Some methamphetamine users experience significant problems related to their use; harms are particularly prevalent among regular IDU. Methamphetamine users, however, are a diverse group, and strategies need to be appropriately targeted towards different kinds of users.
Variance-based selection may explain general mating patterns in social insects
Authors: Rueppell Olav , Johnson Nels , Rychtář Jan
Published: March 2008

Female mating frequency is one of the key parameters of social insect evolution. Several hypotheses have been suggested to explain multiple mating and considerable empirical research has led to conflicting results. Building on several earlier analyses, we present a simple general model that links the number of queen matings to variance in colony performance and this variance to average colony fitness. The model predicts selection for multiple mating if the average colony succeeds in a focal task, and selection for single mating if the average colony fails, irrespective of the proximate mechanism that links genetic diversity to colony fitness. Empirical support comes from interspecific comparisons, e.g. between the bee generaApisandBombus,and from data on several ant species, but more comprehensive empirical tests are needed.
New dyrosaurid crocodylomorph and evidences for faunal turnover at the K–P transition in Brazil
Authors: Barbosa José Antonio , Kellner Alexander Wilhelm Armin , Viana Maria Somália Sales
Published: March 2008

The discovery of a new dyrosaurid crocodylomorph from the well-dated Palaeocene deposits of northeastern Brazil sheds new light on the evolutionary history of this extinct group of marine crocodylomorphs that have survived the Cretaceous–Palaeogene (K–P) extinction crisis.Guarinisuchus munizi, the most complete member of this group collected in South America so far, is closely related to the African forms, and this fact suggests that dyrosaurids had crossed the Atlantic Ocean before the K–P boundary and dispersed from there to North America and other parts of South America. This discovery also suggests that on the coast of northeastern Brazil, dyrosaurids replaced the pre-existing Late Cretaceous fauna of diversified mosasaurs, a group of marine lizards, after the K–P extinction event, becoming the main predators, together with sharks, in shallow marine Palaeocene environments. More detailed stratigraphic records and detailed dating of the deposits with dyrosaurids are necessary to correlate this particular pattern found in the ancient northeastern Brazilian coast within the evolution of the group, especially in Africa.
Mode of Inheritance of Primary Metabolic Traits in Tomato
Authors: Schauer Nicolas , Semel Yaniv , Balbo Ilse , Steinfath Matthias , Repsilber Dirk , Selbig Joachim , Pleban Tzili , Zamir Dani , Fernie Alisdair R.
Published: March 2008

To evaluate components of fruit metabolic composition, we have previously metabolically phenotyped tomato (Solanum lycopersicum) introgression lines containing segmental substitutions of wild species chromosome in the genetic background of a cultivated variety. Here, we studied the hereditability of the fruit metabolome by analyzing an additional year's harvest and evaluating the metabolite profiles of lines heterozygous for the introgression (ILHs), allowing the evaluation of putative quantitative trait locus (QTL) mode of inheritance. These studies revealed that most of the metabolic QTL (174 of 332) were dominantly inherited, with relatively high proportions of additively (61 of 332) or recessively (80 of 332) inherited QTL and a negligible number displaying the characteristics of overdominant inheritance. Comparison of the mode of inheritance of QTL revealed that several metabolite pairs displayed a similar mode of inheritance of QTL at the same chromosomal loci. Evaluation of the association between morphological and metabolic traits in the ILHs revealed that this correlation was far less prominent, due to a reduced variance in the harvest index within this population. These data are discussed in the context of genomics-assisted breeding for crop improvement, with particular focus on the exploitation of wide biodiversity.
A muscle transcriptome analysis identifies positional candidate genes for a complex trait in pig
Authors: Lobjois V. , Liaubet L. , SanCristobal M. , Glénisson J. , Fève K. , Rallières J. , Le Roy P. , Milan D. , Cherel P. , Hatey F.
Published: March 2008

Muscle tenderness is an important complex trait for meat quality and thus for genetic improvement through animal breeding. However, the physiological or genetic control of tenderness development in muscle is still poorly understood. In this work, using transcriptome analysis, we found a relationship between gene expression variability and tenderness. Muscle (longissimus dorsi) samples from 30 F2 pigs were characterized by Warner–Bratzler Shear Force (WBSF) on cooked meat as a measurement of muscle tenderness. Gene expression levels were measured using microarrays for 17 muscle samples selected to represent a range of WBSF values. Using a linear regression model, we determined that samples with WBSF values above 30 N could be effectively analysed for genes exhibiting a significant association of their expression level on shear force (false discovery rate <0.05). These genes were shown to be involved in three functional networks: cell cycle, energy metabolism and muscle development. Twenty‐two genes were mapped on the pig genome and 12 were found to be located in regions previously reported to contain quantitative trait loci (QTL) affecting pig meat tenderness (chromosomes 2, 6 and 13). Some genes appear therefore as positional candidate genes for QTL.
Using molecular markers and multivariate methods to study the genetic diversity of local European and Asian chicken breeds
Authors: Berthouly C. , Bed'Hom B. , Tixier‐Boichard M. , Chen C. F. , Lee Y. P. , Laloë D. , Legros H. , Verrier E. , Rognon X.
Published: March 2008

French and Asian subsets of chicken breeds were first analysed using 22 microsatellites and then compared to the AVIANDIV European set using 14 loci. Positive correlations were observed between FIT or FST and typological values or variance of markers using the multivariate analysis mcoa. The first axis of the multivariate representation separated Asian from European breeds, revealing breeds with Asian ancestor. Using all or 14 loci, correct assignation rate was always higher than 93%. The Weitzman index and the aggregate diversity D were calculated using 22 loci within French and Asian breeds. The French breed Coucou de Rennes and the Hua‐Tung breed seemed to contribute the most to the global diversity of each subset. This approach on French‐only breeds and then on French with AVIANDIV domestic breeds (14 loci) showed that the Marans breed contributed the most. The AVIANDIV framework could be useful to evaluate the genetic diversity of local breeds and to help in connecting national and regional conservation policies.
How helpers help: disentangling ecological confounds from the benefits of cooperative breeding
Authors: WRIGHT JONATHAN , RUSSELL ANDREW F.
Published: March 2008

Evolutionary explanations for helping in cooperative breeding systems usually require a positive effect of helping on the fitness of the breeders being assisted. However, such helper effects have proven surprisingly difficult to quantify. Cockburn et al. (this issue) apply detailed statistical analyses to long‐term field data on the enigmatic superb fairy‐wren. They show that it is possible to disentangle the complex web of ecological and evolutionary interactions that confound so many studies. Whilst fairy‐wren helpers may not increase nest productivity, they do increase future survival of breeding females. This study points the way for future statistical explorations of long‐term data in other cooperative birds and mammals.
Pleistocene climatic cycling and diversification of the Andean treefrog, Hypsiboas andinus
Authors: KOSCINSKI DARIA , HANDFORD PAUL , TUBARO PABLO L. , SHARP SARAH , LOUGHEED STEPHEN C.
Published: March 2008

Our understanding of the causes of diversification of Neotropical organisms lags behind that of Northern Hemisphere biota, especially for montane and temperate regions of southern South America. We investigated the mitochondrial DNA genealogical patterns in 262 individuals of the frog Hypsiboas andinus from 26 sites across the eastern ranges of the Andes Mountains in Argentina and Bolivia. Our phylogenetic analyses indicate at least three distinct lineages: one representing H. andinus from Northwestern Argentina and southern Bolivia, at least one H. andinus lineage from northern Bolivia, and one clade containing both H. andinus (from the southern portion of the species range) and its putative sister taxon Hypsiboas riojanus. Hypsiboas andinus samples from northern Bolivia are well differentiated and may represent distinct species. The northern Argentine H. andinus lineage and southern H. andinus /H. riojanus lineage likely diverged between 2 and 6 million years ago; their current sympatry may be the result of secondary contact due to range expansion after isolation during Andean uplift or may reflect cryptic species. Within the geographically extensive northern H. andinus clade, we found significant geographical structuring consistent with historical fragmentation and subsequent range expansion. The timing of this fragmentation and range expansion coincide with the Pleistocene, a time of extensive climatic cycling and vegetational shifts. Average divergence among clades is lower than those found for other Neotropical taxa, highlighting the potential importance of recent climatic history in diversification in the southern Andes.
Host and vector movement affects genetic diversity and spatial structure of Buggy Creek virus (Togaviridae)
Authors: BROWN CHARLES R. , BROWN MARY BOMBERGER , PADHI ABINASH , FOSTER JEROME E. , MOORE AMY T. , PFEFFER MARTIN , KOMAR NICHOLAS
Published: March 2008

Determining the degree of genetic variability and spatial structure of arthropod‐borne viruses (arboviruses) may help in identifying where strains that potentially cause epidemics or epizootics occur. Genetic diversity in arboviruses is assumed to reflect relative mobility of their vertebrate hosts (and invertebrate vectors), with highly mobile hosts such as birds leading to genetic similarity of viruses over large areas. There are no empirical studies that have directly related host or vector movement to virus genetic diversity and spatial structure. Using the entire E2 glycoprotein‐coding region of 377 Buggy Creek virus isolates taken from cimicid swallow bugs (Oeciacus vicarius), the principal invertebrate vector for this virus, we show that genetic diversity between sampling sites could be predicted by the extent of movement by transient cliff swallows (Petrochelidon pyrrhonota) between nesting colonies where the virus and vectors occur. PairwiseFSTvalues between colony sites declined significantly with increasing likelihood of a swallow moving between those sites per 2‐day interval during the summer nesting season. Sites with more bird movement between them had virus more similar genetically than did pairs of sites with limited or no bird movement. For one virus lineage, Buggy Creek virus showed greater haplotype and nucleotide diversity at sites that had high probabilities of birds moving into or through them during the summer; these sites likely accumulated haplotypes by virtue of frequent virus introductions by birds. Cliff swallows probably move Buggy Creek virus by transporting infected bugs on their feet. The results provide the first empirical demonstration that genetic structure of an arbovirus is strongly associated with host/vector movement, and suggest caution in assuming that bird‐dispersed arboviruses always have low genetic differentiation across different sites.