bluuebunny/crossref_metadata_2025 huggingface dataset:
Terrestrial foreshock Langmuir waves: STEREO observations, theoretical modeling, and quasi‐linear simulations
Authors: Malaspina David M. , Li Bo , Cairns Iver H. , Robinson Peter A. , Kuncic Zdenka , Ergun Robert E.
Published: December 2009

Langmuir waves in the terrestrial electron foreshock are investigated using observations from the STEREO spacecraft, theoretical modeling, and quasi‐linear simulations. Emphases are placed on spatial variations of Langmuir field strength with distance between the spacecraft and the tangent point and on the effects of ambient density fluctuations on these variations. The STEREO mission provides new observations of foreshock Langmuir waves at distances more than twice as far from Earth as previously observed. Based on established geometric properties of the foreshock region, two methods are developed for separating Langmuir waves of foreshock origin from those of solar and/or heliospheric origins. The observed maximum foreshock Langmuir field strength falls with distance via a power law with an exponent −1.01 ± 0.12. The theory and simulations predict field strengths and power law spatial variations in field strengths that are consistent with the observations when scattering of Langmuir waves by density fluctuations is included. The power law exponents predicted by both theory and simulations fall within the uncertainty of the observations for the typical solar wind conditions observed but differ by a factor of ≈1.5 from simulations that assume density homogeneity. This indicates that density fluctuations play an important role in the beam‐Langmuir wave dynamics in the foreshock.
Steep, transient density gradients in the Martian ionosphere similar to the ionopause at Venus
Authors: Duru F. , Gurnett D. A. , Frahm R. A. , Winningham J. D. , Morgan D. D. , Howes G. G.
Published: December 2009

With the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on the Mars Express (MEX) spacecraft, the electron density can be measured by two methods: from the excitation of local plasma oscillations and from remote sounding. A study of the local electron density versus time for 1664 orbits revealed that in 132 orbits very sharp gradients in the electron density occurred that are similar to the ionopause boundary commonly observed at Venus. In 40 of these cases, remote sounding data have also confirmed identical locations of steep ionopause‐like density gradients. Measurements from the Analyzer of Space Plasma and Energetic Atoms (ASPERA‐3) electron spectrometer and ion mass analyzer instruments (also on Mars Express) verify that these sharp decreases in the electron density occur somewhere between the end of the region where ionospheric photoelectrons are dominant and the magnetosheath. Combined studies of the two experiments reveal that the steep density gradients define a boundary where the magnetic fields change from open to closed. This study shows that, although the individual cases are from a wide range of altitudes, the average altitude of the boundary as a function of solar zenith angle is almost constant. The average altitude is approximately 500 km up to solar zenith angles of 60°, after which it shows a slight increase. The average thickness of the boundary is about 22 km according to remote sounding measurements. The altitude of the steep gradients shows an increase at locations with strong crustal magnetic fields.
The use of PARAFAC modeling to trace terrestrial dissolved organic matter and fingerprint water masses in coastal Canadian Arctic surface waters
Authors: Walker Sally A. , Amon Rainer M. W. , Stedmon Colin , Duan Shuiwang , Louchouarn Patrick
Published: December 2009

The optical properties of chromophoric dissolved organic matter (CDOM) were investigated in the Canadian Archipelago and coastal Beaufort Sea surface waters using fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC). Environmental dynamics of individual components were evaluated and compared to salinity, in situ fluorescence, absorption at 312 nm (a312), dissolved organic carbon, and lignin phenol concentrations. A positive linear relationship between four fluorescent components and lignin phenols suggests a terrestrial origin, whereas two components were unrelated to a river source, suggesting an autochthonous source. Elevated concentrations of terrestrial components were observed in the Mackenzie River plume near the coast of Alaska and decreased as water was transported to the Canadian Archipelago. The two nonterrestrial components exhibited only background levels in concentrations along the transect, suggesting minimal productivity within plume and archipelago surface waters. The relative abundance of terrestrial components in relation to nonterrestrial components allowed us to distinguish water masses including Atlantic, Archipelago, and Mackenzie River plume, respectively. This study illustrates the usefulness of PARAFAC to fingerprint water masses based on the optical characteristics of CDOM and shows promise to improve our understanding of upper Arctic Ocean ventilation.
Chloride ion transport and mass balance in a metropolitan area using road salt
Authors: Novotny Eric V. , Sander Andrew R. , Mohseni Omid , Stefan Heinz G.
Published: December 2009

In the Twin Cities metropolitan area (TCMA) of Minneapolis/St. Paul, Minnesota, an estimated 317,000 metric tons (t) of road salt were used annually for road deicing between 2000 and 2005. To determine the annual retention of road salt, a chloride budget was conducted for a 4150 km2 watershed encompassing the populated areas of the TCMA. In addition to inflows and outflows in the major rivers of the TCMA, multiple sources of chloride were examined, but only road salt and wastewater treatment plant (WWTP) effluents were large enough to be included in the analysis. According to the chloride budget, 235,000 t of chloride entered the TCMA annually with the Mississippi and Minnesota rivers, and 355,000 t exited through the Mississippi River. Of the 120,000 t of chloride added annually to the rivers inside the TCMA watershed boundaries, 87,000 t came from WWTPs and 33,000 t came from road salt. Of the 142,000 t of chloride applied annually in the TCMA watershed as road salt (241,000 t NaCl), only 23% (33,000 t) were exported through the Mississippi River and 109,000 t or 77% were retained in the TCMA watershed. Chloride budgets for 10 subwatersheds within the TCMA analyzed in a similar way, gave an average chloride retention rate of 72%. The retention is occurring in the soils, surface waters (numerous lakes, wetlands, and ponds) and in the groundwater. Chloride concentrations in many of these urban water bodies are now considerably higher than the presettlement background levels of less than 3 mg/L with concentrations as high as 2000 mg/L in shallow groundwater wells. The continued accumulation of chloride in the groundwater and surface waters is a cause for concern.
Do Hotel Customers use a Multi-Expectation Framework in the Evaluation of Services? A Study in Cappadocia, Turkey
Authors: Yilmaz Ibrahim
Published: December 2009

This study investigates whether hotel customers use a multi-expectation framework as a comparison standard in the evaluation of hotel services. The study sample consisted of two-star, three-star, four-star, and five-star hotels in Nevşehir, one of the major provinces of Cappadocia, Turkey. The evaluations of 241 respondents demonstrated that hotel customers use two types of expectations (desired and adequate) as a comparison standard in evaluating hotel services. The results also suggest that, in general, hotel customers have a narrow zone of tolerance between these expectations. Hotel customers have the narrowest zone of tolerance on the ‘empathy’ dimension. It is concluded therefore that hotel customers are not likely to accept heterogeneity in hotel services, particularly in the area of ‘empathy’.
Research on the transport and deposition of nanoparticles in a rotating curved pipe
Authors: Lin Jianzhong , Lin Peifeng , Chen Huajun
Published: December 2009

A finite-volume code and the SIMPLE scheme are used to study the transport and deposition of nanoparticles in a rotating curved pipe for different angular velocities, Dean numbers, and Schmidt numbers. The results show that when the Schmidt number is small, the nanoparticle distributions are mostly determined by the axial velocity. When the Schmidt number is many orders of magnitude larger than 1, the secondary flow will dominate the nanoparticle distribution. When the pipe corotates, the distribution of nanoparticle mass fraction is similar to that for the stationary case. There is a “hot spot” deposition region near the outside edge of bend. When the pipe counter-rotates, the Coriolis force pushes the region with high value of nanoparticle mass fraction toward inside edge of the bend. The hot spot deposition region appears inside the edge. The particle deposition over the whole edge of the bend becomes uniform as the Dean number increases. The corotation of pipe makes the particle deposition efficiency a reduction, while high counter-rotation of pipe only slightly affects the deposition efficiency. When two kinds of secondary flows are coexisting, the relative deposition efficiency is larger than that for the stationary case.
Infinite integrals of Whittaker and Bessel functions with respect to their indices
Authors: Becker Peter A.
Published: December 2009

We obtain several new closed-form expressions for the evaluation of a family of infinite-domain integrals of the Whittaker functions Wκ,μ(x) and Mκ,μ(x) and the modified Bessel functions Iμ(x) and Kμ(x) with respect to the index μ. The new family of definite integrals is useful in a variety of contexts in mathematical physics. In particular, the integral involving Kμ(x) represents a new example of the Kontorovich–Lebedev transform. We discuss the relationship between the results derived here and the previously known integrals of Whittaker and Bessel functions. In some cases, we obtain entirely new expressions, and in other cases, we generalize previously known results. An application to time-dependent radiation transport theory is also discussed.
The effect of hydrogen charging on Ln-based amorphous materials
Authors: Chuang C. P. , Huang J. H. , Dmowski W. , Liaw P. K. , Li R. , Zhang T. , Ren Y.
Published: December 2009

In present work, the effects of hydrogen charging on Ln-based (Ln=La,Ce) bulk-metallic glasses (BMG) are studied. The (La0.5Ce0.5)65Al10Co25 were charged with hydrogen by an electrochemical method in an alkali solution. The hydrogen concentration in the sample after a 36 h charge can reach as high as 1286 w-ppm. With the presence of hydrogen atoms, the hardness of specimen increased by 80% compared to the as-cast samples. The structural evolution of the amorphous matrix due to the hydrogen-uptake process was investigated by the high-energy x-ray scattering technique. The sample surface was crystallized after hydrogen charging. X-ray diffraction measurements revealed broad crystalline peaks superimposed on an amorphous-scattering pattern. The crystalline phase grew from the surface to at least one hundred microns deep into the amorphous matrix. The atomic arrangements of both amorphous and crystalline phases were characterized by the atomic pair-distribution function.
Toughness scale from first principles
Authors: Ogata Shigenobu , Li Ju
Published: December 2009

We correlate the experimentally measured fracture toughness of 24 metals and ceramics to their quantum mechanically calculated brittleness parameter. The brittleness parameter is defined as the ratio of the elastic energy density needed to spontaneously break bonds in shear versus in tension, and is a primitive-cell property. Under 300 GPa hydrostatic pressure, the model predicts that diamond has smaller brittleness than molybdenum at zero pressure, and thus should deform plastically without cracking at room temperature.
On non-Abelian Toda A2(1) model and related hierarchies
Authors: Demskoi Dmitry K. , Lee Jyh-Hao
Published: December 2009

We study limiting cases of the two known integrable chiral-type models with three-dimensional configuration space. One of the initial models is the non-Abelian Toda A2(1) model and the other was found by means of the symmetry approach by Meshkov and Demskoi [Theor. Math. Phys. 134, 351 (2003)]. The C-integrability of the reduced models is established by constructing their complete sets of integrals and general solutions. A description of the generalized symmetry algebras of these models is given in terms of operator mapping integrals into symmetries. The integrals of the Liouville-type systems are known to define Miura-type transformations for their generalized symmetries. This fact allowed us to find a few new systems of the Yajima–Oikawa type. We present a recursion operator for one them.
Gate induced crossover between Fabry–Pérot and quantum dot behavior in a single walled carbon nanotube hole transistor
Authors: Kamimura T. , Matsumoto K.
Published: December 2009

Gate induced crossover between Fabry–Pérot and quantum dot behavior in a single walled carbon nanotube (SWCNT) hole transistor is observed. The SWCNT transistor that can operate as a resonant tunneling transistor (RTT) and also as a single-hole transistor (SHT) using SWCNT as channel is fabricated. When negatively high voltage is applied to the gate electrode, the SWCNT transistor shows RTT characteristic, e.g., Fabry–Pérot quantum interference pattern. While, when negatively low voltage is applied to the gate electrode, the SWCNT transistor shows SHT characteristic, e.g., Coulomb diamond characteristic. The transition between RTT and SHT is achieved by modulating the coupling strength between the electrode and the quantum island using gate voltage change. Schottky barriers at the contact between the SWCNT and the electrodes act as tunneling barriers. The thicknesses of the tunneling barriers are modulated by the gate voltage change, and the strength of the coupling between the electrode and quantum island is also changed. The characteristics of the convertible transistor can be observed up to 100K. Moreover, the channel length dependence is observed.
The initial oxidation of Al–Mg alloys: Depth-resolved quantitative analysis by angle-resolved x-ray photoelectron spectroscopy and real-time in situ ellipsometry
Authors: Panda E. , Jeurgens L. P. H. , Mittemeijer E. J.
Published: December 2009

Real-time in situ spectroscopic ellipsometry and in situ, angle-resolved x-ray photoelectron spectroscopy (AR-XPS) have been applied to establish the relationships between the growth kinetics and the developing microstructure of ultrathin (<3 nm) oxide films grown on clean Al–1.12 at. % Mg alloy surfaces by thermal oxidation in the temperature range T=300–485 K. To this end, procedures for the depth-resolved quantitative AR-XPS analysis of ultrathin, multiple-element, and/or multiphase oxide overgrowths on binary alloy surfaces were developed. As a result, the relationships between the relative depth distributions of Al and Mg in the developing oxide films, the oxide-film growth kinetics, and the oxidation-induced compositional changes in the AlMg alloy substrate could be established as a function of the oxidation conditions.
Photoacoustic detection of gases using microcantilevers
Authors: Adamson Brian D. , Sader John E. , Bieske Evan J.
Published: December 2009

We describe a new technique for measuring the infrared absorption spectra of gases using atomic force microscope microcantilevers. This photoacoustic system is demonstrated for a dilute acetylene/helium mixture by recording the acetylene ν1+ν3 infrared overtone transitions using a wavelength modulated tunable diode laser as the infrared light source. The technique presents significant advantages over existing methods in terms of size, simplicity, speed and insensitivity to ambient vibrations. The maximum achievable signal-to-noise for resonant and non-resonant photoacoustic excitation of the microcantilever is examined and is found to be limited by the microcantilever’s Brownian noise.
Metal organic vapor phase epitaxy growth of single crystalline GaN on planar Si(211) substrates
Authors: Ravash Roghaiyeh , Bläsing Jürgen , Hempel Thomas , Noltemeyer Martin , Dadgar Armin , Christen Jürgen , Krost Alois
Published: December 2009

We present metal organic vapor phase epitaxy growth of polarization reduced, wurtzitic gallium nitride layers with an 18° inclination of the c-axis to the surface normal on planar Si(211) substrates. The growth of this layer is performed as c-axis oriented growth on the naturally occurring Si(111) planes of the Si(211) substrate. Cathodoluminescence measurements on a ∼1.2 μm thick structure reveals that it has a low concentration of basal plane stacking faults and no prismatic stacking fault luminescence.
Stimulated emission of near-infrared radiation by current injection into silicon (100) quantum well
Authors: Saito S. , Suwa Y. , Arimoto H. , Sakuma N. , Hisamoto D. , Uchiyama H. , Yamamoto J. , Sakamizu T. , Mine T. , Kimura S. , Sugawara T. , Aoki M.
Published: December 2009

We describe the observation of stimulated emissions by current injections into a silicon quantum well. The device consists of a free standing membrane with a distributed feedback resonant cavity fabricated by state-of-the-art silicon processes. The emission spectra have multimode structures peaked in the near-infrared region above the submilliampere threshold currents at room temperatures. Consequently, electronics and photonics should be able to be converged on chips by using silicon quantum well laser diodes.
Ferroelectric polymer/silver nanocomposites with high dielectric constant and high thermal conductivity
Authors: Huang Xingyi , Jiang Pingkai , Xie Liyuan
Published: December 2009

Ferroelectric polymer nanocomposites with silver (Ag) nanoparticles as inclusions were prepared and the dielectric properties and thermal conductivity were studied. The results showed that the nanocomposites have high dielectric constant and high thermal conductivity. When the loading level of Ag nanoparticles is 20.0 vol %, the dielectric constant and thermal conductivity of the nanocomposites were 120 at 103 Hz and 6.5 W/mK, respectively. Our results also showed that there is no percolation in the nanocomposites when Ag loading range is within 20.0%.
Self-organized quantum dot arrays: Kinetic mapping of adatom capture
Authors: Levchenko I. , Ostrikov K.
Published: December 2009

Deterministic synthesis of self-organized quantum dot arrays for renewable energy, biomedical, and optoelectronic applications requires control over adatom capture zones, which are presently mapped using unphysical geometric tessellation. In contrast, the proposed kinetic mapping is based on simulated two-dimensional adatom fluxes in the array and includes the effects of nucleation, dissolution, coalescence, and process parameters such as surface temperature and deposition rate. This approach is generic and can be used to control the nanoarray development in various practical applications.
Extreme sensitivity displayed by single crystal diamond deep ultraviolet photoconductive devices
Authors: Bevilacqua Mose , Jackman Richard B
Published: December 2009

Deep UV detection using a single crystal diamond (SCD) substrate without a homoepitaxial layer has been demonstrated using a defect passivation treatment. Despite evidence of surface damage on the SCD, the treatments lead to highly effective photoconductive devices, displaying six-orders of discrimination between deep UV and visible light and a responsivity as high as 100 A/W, equivalent to an external quantum efficiency of 700, similar to the best values for devices based on high quality homoepitaxial layers. Impedance spectroscopic investigations suggest that the treatment used reduces the impact of less resistive surface material, most likely defects left from substrate polishing.
Study of temporal current stability and fluctuations of field emitted electrons from ZnO nanostructure films
Authors: Uppireddi Kishore , Yang Boqian , Feng Peter Xian , Morell Gerardo
Published: December 2009

Stable field emission currents and low fluctuations are important feasibility requirements for the application of materials in field emission devices and displays, more than the low turn on fields that are generally considered. The current stability and current fluctuations of field emitted electrons from ZnO nanostructures were investigated over the period of 2, 12, and 24 h. The films with nanoneedle structure having density around ten/μm2 showed better short and long-term (temporal) stability over a period of 24 h. The short- and long-term stability and the current fluctuations of the nanostructures are reported and the causes for the degradation of the emission current are discussed.
In-situ characterization of rapid crystallization of amorphous CoFeB electrodes in CoFeB/MgO/CoFeB junctions during thermal annealing
Authors: Wang W. G. , Jordan-sweet J. , Miao G. X. , Ni C. , Rumaiz A. K. , Shah L. R. , Fan X. , Parsons P. , Stearrett R. , Nowak E. R. , Moodera J. S. , Xiao J. Q.
Published: December 2009

We report the crystallization study of CoFeB/MgO/CoFeB magnetic tunnel junctions using in-situ, time-resolved synchrotron-based x-ray diffraction and transmission electron microscopy. It was found that the crystallization of amorphous CoFeB electrodes occurs on a time scale of seconds during the postgrowth high temperature annealing. The crystallization can be well fit by the Johnson–Mehl–Avrami model and the effective activation energy of the process was determined to be 150 kJ/mol. The solid-state epitaxy mode of CoFeB was found to involve separate crystallization at different locations followed by subsequent merging of small grains, instead of layer-by-layer growth of CoFeB film along the MgO template.
Selenium and tellurium: Elemental catalysts for conversion of graphite to diamond under high pressure and temperature
Authors: Lv S. J. , Hong S. M. , Yuan C. S. , Hu Y.
Published: December 2009

The behavior of six systems of graphite with Sn, Pb, Sb, Bi, Se, and Te was investigated under high-pressure of around 9.0–9.6 GPa and high-temperature 1600–1850 °C. The results showed that the selenium and tellurium have obvious catalytic effects on spontaneous nucleation and crystal growth of diamond under pressure at 9.6 GPa, and at temperatures of 1800 and 1850 °C. The outer shell electron configuration analogous to oxygen and sulfur may play an important role in converting graphite to diamond under the high-pressure and high-temperature.
Time dependent thermoelectric performance of a bundle of silicon nanowires for on-chip cooler applications
Authors: Zhang Gang , Zhang Qing-Xin , Kavitha Devi , Lo Guo-Qiang
Published: December 2009

With finite element simulation, the time dependent thermoelectric performance of silicon nanowires (SiNWs) is studied systematically. Short response time has been observed in SiNW cooler which decreases with increasing of the number of SiNWs. Moreover, the impacts of inhomogeneous thermal conductivity distribution in one bundle on the cooling temperature have been studied. The cooling temperature decreases due to the existing of unexpected high thermal conductivity SiNW. This impact can be suppressed in large system. Our results provide a comprehensive performance analysis of SiNWs for on-chip thermoelectric cooler applications.
Influence of metal work function on the position of the Dirac point of graphene field-effect transistors
Authors: Park Noejung , Kim Bum-Kyu , Lee Jeong-O , Kim Ju-Jin
Published: December 2009

We studied the effect of metal contact on the position of the Dirac point by means of transport measurements. To determine the sole effect of metal contact, we prepared more than 100 graphene devices following the same fabrication procedure and with a device layout that differed only in the type of metal electrode used. By measuring the peak position of the resistance, the Dirac points (VgDirac) were recorded in the gate response. The work function of metal-graphene complex was found to be a fair phenomenological indicator of the location of VgDirac in the transfer response.
The annual effective dose due to natural radionuclides in the reservoir and tap water in Yaoundé area, Cameroon
Authors: Lydie R. Marie , Nemba R. Martin
Published: December 2009

The average concentrations of radionuclides of reservoir and tap water in the Yaoundé area, with a population of 1.5 million inhabitants were estimated from measurements of mean specific activity using a well calibrated Canberra NaI(Tl) detector system. Water samples were collected from reservoirs and taps during the dry and the rainy seasons respectively in December 2002 and July 2003. The radionuclides observed with regularity belonged to the decay series naturally occurring radionuclides headed by 238U and 232Th as well as the non-series nuclide 40K. The average specific activity values obtained for 40K, 226Ra and 228Ra, respectively were for reservoir water 70 ± 11 BqL–1; 8.7 ± 3.5 BqL–1; 0.6 ± 0.2 BqL–1 during the dry season, and 50 ± 9 BqL–1; 8.5 ± 3.7 BqL–1; 0.6 ± 0.2 BqL–1 during the rainy season and for tap water, we have respectively 111 ± 17 BqL–1; 11.4 ± 3.7 BqL–1; 1 ± 0.3 BqL–1 during the dry season, and 51 ± 10 BqL–1; 9 ± 3.5 BqL–1; 0.7 ± 0.2 BqL–1 during the rainy season. The annual effective dose received by Yaoundé adult population as a result of ingestion of this drinking water is respectively 0.925 mSv for the reservoir water and 1.052 mSv for the tap water.
The goalposts of transition: football as a metaphor for Serbia's long journey to the rule of law
Authors: Nielsen Christian Axboe
Published: December 2009

Football (soccer) provides a useful prism for analysis of the long transition of the Serbian state and society since 1991. To a striking extent, the world of professional football and the attendant phenomena of financial corruption and football hooliganism have informed both the dissolution of the former Yugoslavia and the current concerted attempt to create a “European Serbia.” During the 1990s, football in Serbia to a significant extent became synonymous with organized crime and the criminalization of the Serbian state. Since 2000, the persistent phenomena of crime, violent hooliganism and lethargic reforms have mirrored the difficult and halting transition of the post-Milošević state. Although recent events highlight the reluctance of the Serbian authorities to confront these problems, both government and sports officials are coming to see reform of Serbian football as a key element of the establishment of the rule of law.
Russian military patriotic education: a control tool against the arbitrariness of veterans
Authors: Sieca-Kozlowski Elisabeth
Published: December 2009

The military had been concerned about military patriotic education for a long time when Putin's Patriotic Education Programme was published. As soon as the collapse of the Soviet Union occurred, followed a few years later by the creation of the Russian armed forces, they had already been developing patriotic education programmes aimed primarily at youth, aided by veterans of local wars, both volunteers and recruits. The aim of this article is to show that the military version of patriotic education aims openly to encourage military service, and that the Russian state will try to enlist veterans of the Afghanistan and Chechen wars in activities linked to military patriotic education and its spread in military and civilian spheres. Our hypothesis is that the determination to bring veterans together around a common project has two aims: (1) to federate veterans around the authorities and (2) to channel a population that escapes government control and some of whose excesses on their return to civilian life (violence towards the population in the context of their function, for veterans of the Interior Ministry in particular) have darkened the image of the ministries known as the “power” ministries.
Communist regimes, legitimacy and the transition to democracy in Eastern Europe
Authors: Ciobanu Monica
Published: December 2009

The purpose of this article is to clarify the relationship between forms of political legitimacy employed by communist regimes in East and Central Europe and subsequent models of revolutionary change in 1989. The conceptual basis of the analysis lies in Max Weber's theoretical framework of legitimacy. The four cases selected for comparison are Bulgaria, Hungary, Poland and Romania. The attempts of de-Stalinization and reformation of these party-state regimes through the introduction of paternalistic and also more goal-oriented measures could not prevent their disintegration in the 1980s and their subsequent collapse in 1989. But, I argue, it was the withdrawal of ideological support by elites that ultimately brought communism to an end. The differences in revolutionary scenarios and transitions to democracy in the four cases indicate the importance of a shift in both rulers and masses towards interest in dialogue and compromise. Hungary and Poland represent the clearest scenarios in which communist parties acted as agents of regime change in a rational-legal direction. The Bulgarian case stands as an intermediary case between these two and Romania. Finally, Romania represents an extreme case of violent revolution and the overthrow of a traditionalist and sultanistic regime and illustrates the difficulties following a complete collapse of political authority.
The social construction of social construction: implications for theories of nationalism and identity formation
Authors: Motyl Alexander J.
Published: December 2009

Although most contemporary theories of nationalism and identity formation rest on some form of social constructivism, few theorists of nationalism and identity formation interrogate social constructivism as a social construction – a social science concept “imposed” on the non-self-consciously constructivist behaviors of people, who generally do not believe they are engaging in construction. Since social constructivism – unless it is a metaphysics about what is real – is really about theconceptof social construction, the first task of constructivists is to ask not how various populations have engaged in social construction but how social construction should be defined. As this article shows, constructivism is at best a run-of-the-mill theoretical approach – perfectly respectable, but no different from any other theoretical approach in the social sciences. It is only when social constructivism makes outlandishly radical claims – that all of reality or all of social reality is constructed – that it is unusual, exciting, and wrong.
Peer mediation services for conflict resolution in schools: What transformations in activity characterise successful implementation?
Authors: Sellman Edward
Published: December 2009

This article presents the findings from research conducted at nine schools (seven primary, two secondary) in England, which had previously implemented a peer mediation service for students experiencing interpersonal conflict. This analysis was informed by themes from a previous stage of research conducted at one additional primary school, where the process from pre‐ to post‐intervention had been observed in greater detail. The article utilises activity theory as a conceptual framework for understanding and describing these processes for a number of reasons that will be briefly explained. The findings of this research highlight the need for realistic anticipation of the degree of cultural transformation required to fully support such pupil empowerment initiatives in schools. Peer mediation was most successful in schools where there was a considerable shift in the division of labour, accompanied by the production of new cultural tools that promoted new ways of thinking, speaking and acting with regard to conflict.
Sculpting the dynein regulatory complex
Authors: deCathelineau Aimee
Published: December 2009

Cryoelectron tomography materializes the (missing) nexin link.
Tarun Kapoor: In the right position to study chromosomes
Authors: Sedwick Caitlin
Published: December 2009

Kapoor uses small molecule inhibitors and high-resolution microscopy to explore metaphase chromosome alignment.
The dynein regulatory complex is the nexin link and a major regulatory node in cilia and flagella
Authors: Heuser Thomas , Raytchev Milen , Krell Jeremy , Porter Mary E. , Nicastro Daniela
Published: December 2009

Cilia and flagella are highly conserved microtubule (MT)-based organelles with motile and sensory functions, and ciliary defects have been linked to several human diseases. The 9 + 2 structure of motile axonemes contains nine MT doublets interconnected by nexin links, which surround a central pair of singlet MTs. Motility is generated by the orchestrated activity of thousands of dynein motors, which drive interdoublet sliding. A key regulator of motor activity is the dynein regulatory complex (DRC), but detailed structural information is lacking. Using cryoelectron tomography of wild-type and mutant axonemes from Chlamydomonas reinhardtii, we visualized the DRC in situ at molecular resolution. We present the three-dimensional structure of the DRC, including a model for its subunit organization and intermolecular connections that establish the DRC as a major regulatory node. We further demonstrate that the DRC is the nexin link, which is thought to be critical for the generation of axonemal bending.
Valosin-containing protein (VCP) is required for autophagy and is disrupted in VCP disease
Authors: Ju Jeong-Sun , Fuentealba Rodrigo A. , Miller Sara E. , Jackson Erin , Piwnica-Worms David , Baloh Robert H. , Weihl Conrad C.
Published: December 2009

Mutations in valosin-containing protein (VCP) cause inclusion body myopathy (IBM), Paget's disease of the bone, and frontotemporal dementia (IBMPFD). Patient muscle has degenerating fibers, rimmed vacuoles (RVs), and sarcoplasmic inclusions containing ubiquitin and TDP-43 (TARDNA-binding protein 43). In this study, we find that IBMPFD muscle also accumulates autophagosome-associated proteins, Map1-LC3 (LC3), and p62/sequestosome, which localize to RVs. To test whether VCP participates in autophagy, we silenced VCP or expressed adenosine triphosphatase–inactive VCP. Under basal conditions, loss of VCP activity results in autophagosome accumulation. After autophagic induction, these autophagosomes fail to mature into autolysosomes and degrade LC3. Similarly, IBMPFD mutant VCP expression in cells and animals leads to the accumulation of nondegradative autophagosomes that coalesce at RVs and fail to degrade aggregated proteins. Interestingly, TDP-43 accumulates in the cytosol upon autophagic inhibition, similar to that seen after IBMPFD mutant expression. These data implicate VCP in autophagy and suggest that impaired autophagy explains the pathology seen in IBMPFD muscle, including TDP-43 accumulation.
Clinical and Economic Impact of Methicillin-Resistant Staphylococcus aureus Colonization or Infection on Neonates in Intensive Care Units
Authors: Song Xiaoyan , Perencevich Eli , Campos Joseph , Short Billie L. , Singh Nalini
Published: December 2009

Objective.

The rising incidence and mortality of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection in children has become a great concern. This study aimed to determine the clinical and economic impact of MRSA colonization or infection on infants and to measure excess mortality, length of stay, and hospital charges attributable to MRSA.

Design.

This is a retrospective cohort study.

Setting and Patients.

The study included infants admitted to a level III-IV neonatal intensive care unit from September 1, 2004, through March 31, 2008.

Methods.

A time-dependent proportional hazard model was used to analyze the association between MRSA colonization or infection and mortality. The relationships between MRSA colonization or infection and length of stay and between MRSA colonization or infection and hospital charges were assessed using a matched cohort study design.

Results.

Of 2,280 infants, 191 (8.4%) had MRSA colonization or infection. Of 132 MRSA isolates with antibiotic susceptibility results, 106 were resistant to clindamycin and/or trimethoprim-sulfamethoxazole, thus representing a noncommunity phenotype. The mortality rate was 17.8% for patients with MRSA colonization or infection and 11.5% for control subjects. Neither MRSA colonization (hazard ratio [HR], 0.9 [95% confidence interval {CI}, 0.5-1.5]; P > .05) nor infection (HR, 1.2 [95% CI, 0.7-1.9]; P > .05) was associated with increased mortality risk. Infection caused by MRSA strains that were resistant to clindamycin and/or trimethoprim-sulfamethoxazole increased the mortality risk by 40% (HR, 1.4 [95% CI, 0.9-2.2]; P > .05), compared with the mortality risk of control subjects, but the increase was not statistically significant. MRSA infection independently increased length of stay by 40 days (95% CI, 34.2—45.6; P < .001) and was associated with an extra charge of $164,301 (95% CI, $158,712-$169,889; P < .001).

Conclusions.

MRSA colonization or infection in infants is associated with significant morbidity and financial burden but is not independently associated with increased mortality.
Individual growth pattern and variability in Serranus scriba: a Bayesian analysis
Authors: Alós Josep , Palmer Miquel , Balle Salvador , Grau Antoni Maria , Morales-Nin Beatriz
Published: December 2009

Alós, J., Palmer, M., Balle, S., Grau, A. M., and Morales-Nin, B. 2010. Individual growth pattern and variability in Serranus scriba: a Bayesian analysis. – ICES Journal of Marine Science, 67: 502–512. Variability in growth patterns at an individual level in Serranus scriba is described using a Bayesian approach for a generalized von Bertalanffy growth model that accommodates one change in growth rate at a specific point during the lifespan. The approach enables individual growth curves to be inferred, even in a species with a relatively short lifespan and no commercial value, i.e. limited sample sizes available, but potentially endangered by recreational fishing. The change in growth rate may be the result of differing allocation of energy between reproductive and somatic activities at different ages. Overall, the approach presented provides adequate input for future implementation of population dynamics models that take into account individual variability, e.g. individual-based models, even for species for which limited data are available.
Stochastic two-delay differential model of delayed visual feedback effects on postural dynamics
Authors: Boulet Jason , Balasubramaniam Ramesh , Daffertshofer Andreas , Longtin André
Published: December 2009

We report on experiments and modelling involving the ‘visuo-postural control loop’ in the upright stance. We experimentally manipulated an artificial delay to the visual feedback during standing, presented at delays ranging from 0 to 1 s in increments of 250 ms. Using stochastic delay differential equations, we explicitly modelled the centre-of-pressure (COP) and centre-of-mass (COM) dynamics with two independent delay terms for vision and proprioception. A novel ‘drifting fixed point’ hypothesis was used to describe the fluctuations of the COM with the COP being modelled as a faster, corrective process of the COM. The model was in good agreement with the data in terms of probability density functions, power spectral densities, short- and long-term correlations (Hurst exponents) as well the critical time between the two ranges.
Bifurcation to fronts due to delay
Authors: Erneux T. , Kozyreff G. , Tlidi M.
Published: December 2009

The stability of a steady-state front (kink) subject to a time-delayed feedback control (TDFC) is examined in detail. TDFC is based on the use of the difference between system variables at the current moment of time and their values at some time in the past. We first show that there exists a bifurcation to a moving front. We then investigate the limit of large delays but weak feedback and obtain a global bifurcation diagram for the propagation speed. Finally, we examine the case of a two-dimensional front with radial symmetry and determine the critical radius above which propagation is possible.
Oscillatory response in a sensory network of ON and OFF cells with instantaneous and delayed recurrent connections
Authors: Lefebvre J. , Longtin A. , Leblanc V. G.
Published: December 2009

A neural field model with multiple cell-to-cell feedback connections is investigated. Our model incorporates populations of ON and OFF cells, receiving sensory inputs with direct and inverted polarity, respectively. Oscillatory responses to spatially localized stimuli are found to occur via Andronov–Hopf bifurcations of stationary activity. We explore the impact of multiple delayed feedback components as well as additional excitatory and/or inhibitory non-delayed recurrent signals on the instability threshold. Paradoxically, instantaneous excitatory recurrent terms are found to enhance network responsiveness by reducing the oscillatory response threshold, allowing smaller inputs to trigger oscillatory activity. Instantaneous inhibitory components do the opposite. The frequency of these response oscillations is further shaped by the polarity of the non-delayed terms.
Interplay of time-delayed feedback control and temporally correlated noise in excitable systems
Authors: Brandstetter S. , Dahlem M. A. , Schöll E.
Published: December 2009

The interplay of time-delayed feedback and temporally correlated coloured noise in a single and two coupled excitable systems is studied in the framework of the FitzHugh–Nagumo (FHN) model. By using coloured noise instead of white noise, the noise correlation time is introduced as an additional time scale. We show that in a single FHN system the major time scale of oscillations is strongly influenced by the noise correlation time, which in turn affects the maxima of coherence with respect to the delay time. In two coupled FHN systems, coloured noise input to one subsystem influences coherence resonance and stochastic synchronization of both subsystems. Application of delayed feedback control to the coloured noise-driven subsystem is shown to change coherence and time scales of noise-induced oscillations in both systems, and to enhance or suppress stochastic synchronization under certain conditions.
Quantifying stochasticity in the dynamics of delay-coupled semiconductor lasers via forbidden patterns
Authors: Tiana-Alsina Jordi , Buldú Javier M. , Torrent M. C. , García-Ojalvo Jordi
Published: December 2009

We quantify the level of stochasticity in the dynamics of two mutually coupled semiconductor lasers. Specifically, we concentrate on a regime in which the lasers synchronize their dynamics with a non-zero lag time, and the leader and laggard roles alternate irregularly between the lasers. We analyse this switching dynamics in terms of the number of forbidden patterns of the alternate time series. The results reveal that the system operates in a stochastic regime, with the level of stochasticity decreasing as the lasers are pumped further away from their lasing threshold. This behaviour is similar to that exhibited by a single semiconductor laser subject to external optical feedback, as its dynamics shifts from the regime of low-frequency fluctuations to coherence collapse.
Controlling biological networks by time-delayed signals
Authors: Orosz Gábor , Moehlis Jeff , Murray Richard M.
Published: December 2009

This paper describes the use of time-delayed feedback to regulate the behaviour of biological networks. The general ideas on specific transcriptional regulatory and neural networks are demonstrated. It is shown that robust yet tunable controllers can be constructed that provide the biological systems with model-engineered inputs. The results indicate that time delay modulation may serve as an efficient biocompatible control tool.
Delayed feedback of sampled higher derivatives
Authors: Insperger Tamas , Stepan Gabor , Turi Janos
Published: December 2009

Systems where the present rate of change of the state depends on the past values of the higher rates of change of the state are described by so-called advanced functional differential equations (AFDEs). In an AFDE, the highest derivative of the state-space coordinate appears with delayed argument only. The corresponding linearized equations are always unstable with infinitely many unstable poles, and are rarely related to practical applications due to their inherently implicit nature. In this paper, one of the simplest AFDEs, a linear scalar first-order system, is considered with the delayed feedback of the second derivative of the state in the presence of sampling in the feedback loop (i.e. in the case of digital control). It is shown that sampling of the feedback may stabilize the originally infinitely unstable system for certain parameter combinations. The result explains the stable behaviour of certain dynamical systems with feedback delay in the highest derivative.
Efficacy of repetitive transcranial magnetic stimulation in alcohol dependence: a sham‐controlled study
Authors: Mishra Biswa R. , Nizamie S. Haque , Das Basudeb , Praharaj Samir K.
Published: December 2009

Objective  To study the anticraving efficacy of high‐frequency repetitive transcranial magnetic stimulation (rTMS) of the right dorsolateral pre‐frontal cortex (DLPFC) in patients with alcohol dependence.

Methods  We performed a prospective, single‐blind, sham‐controlled study involving 45 patients with alcohol dependence syndrome (according to ICD‐10 DCR), with Clinical Institute of Withdrawal Assessment in Alcohol Withdrawal (CIWA‐Ar) scores ≤10. Patients were allocated to active and sham rTMS in a 2 : 1 ratio, such that 30 patients received active and 15 patients sham rTMS to the right DLPFC (10 Hz frequency, 4.9 seconds per train, inter‐train interval of 30 seconds, 20 trains per session, total 10 sessions). The Alcohol Craving Questionnaire (ACQ‐NOW) was administered to measure the severity of alcohol craving at baseline, after the last rTMS session and after 1 month of the last rTMS session.

Results  Two‐way repeated‐measures analysis of variance (ANOVA) showed significant reduction in the post‐rTMS ACQ‐NOW total score and factor scores in the group allocated active rTMS compared to the sham stimulation. The effect size for treatment with time interaction was moderate (η2 = 0.401).

Conclusions  Right dorsolateral pre‐frontal high‐frequency rTMS was found to have significant anticraving effects in alcohol dependence. The results highlight the potential of rTMS which, combined with other anticraving drugs, can act as an effective strategy in reducing craving and subsequent relapse in alcohol dependence.
Cognitive enhancement as a pharmacotherapy target for stimulant addiction
Authors: Sofuoglu Mehmet
Published: December 2009

Background No medications have been proven to be effective for cocaine and methamphetamine addiction. Attenuation of drug reward has been the main strategy for medications development, but this approach has not led to effective treatments. Thus, there is a need to identify novel treatment targets in addition to the brain reward system.

Aim To propose a novel treatment strategy for stimulant addiction that will focus on medications enhancing cognitive function and attenuating drug reward.

Methods Pre‐clinical and clinical literature on potential use of cognitive enhancers for stimulant addiction pharmacotherapy was reviewed.

Results and conclusions Cocaine and methamphetamine users show significant cognitive impairments, especially in attention, working memory and response inhibition functions. The cognitive impairments seem to be predictive of poor treatment retention and outcome. Medications targeting acetylcholine and norepinephrine are particularly well suited for enhancing cognitive function in stimulant users. Many cholinergic and noradrenergic medications are on the market and have a good safety profile and low abuse potential. These include galantamine, donepezil and rivastigmine (cholinesterase inhibitors), varenicline (partial nicotine agonist), guanfacine (alpha2‐adrenergic agonist) and atomoxetine (norepinephrine transporter inhibitor). Future clinical studies designed optimally to measure cognitive function as well as drug use behavior would be needed to test the efficacy of these cognitive enhancers for stimulant addiction.