bluuebunny/crossref_metadata_2025 huggingface dataset:
Timelines, borderlines and conflicts
Authors: Bartels Rogier
Published: September 2009

Calls have been made in recent years for the legal distinction between international and non-international armed conflicts to be removed. Also as of late, confusion regarding the applicable legal regime has been created by so-called transnational conflicts involving non-state entities. These situations do not fit naturally into the two traditional types of armed conflict recognized by IHL from 1949 onwards. The present article centres on how the legal divide that still exists between international and non-international armed conflict can be explained historically. It aims to further the discussion on whether such a distinction is still relevant, as well as on how certain situations could be classified in the existing typology of IHL.
Armed violence in fragile states:
Authors: Geiβ Robin
Published: September 2009

The gradual process of state failure is commonly accompanied by armed violence. Apart from occasional outbreaks, armed violence in fragile states tends to smoulder with relatively low intensity, often over an extended period of time. The actual level of violence may oscillate around the level of violence that is commonly accepted as triggering the application of international humanitarian law (IHL). In addition, because of the specific objectives typically – though not necessarily always – pursued by armed groups in failed state conflict scenarios, cross-border spillover effects are fairly frequent. The qualification of armed violence in such scenarios according to the conflict categories laid down in IHL thus raises some rather specific issues. Moreover, weak states, failing states, and ultimately failed states are increasingly perceived as a key threat to international security. States seem increasingly inclined to assume sporadic order maintenance functions in the place of disabled governments so as to maintain the perceived security threat at a tolerable level. Current efforts to repress acts of piracy off the coast of Somalia are an evident case in point. Since the Security Council, in Resolution 1851, at least implied the possibility of applying IHL in that specific context, the application of this legal regime to sporadic law enforcement operations by third parties also demands further scrutiny.
Typology of armed conflicts in international humanitarian law: legal concepts and actual situations
Authors: Vité Sylvain
Published: September 2009

Although international humanitarian law has as its aim the limitation of the effects of armed conflict, it does not include a full definition of those situations which fall within its material field of application. While it is true that the relevant conventions refer to various types of armed conflict and therefore afford a glimpse of the legal outlines of this multifaceted concept, these instruments do not propose criteria that are precise enough to determine the content of those categories unequivocally. A certain amount of clarity is nonetheless needed. In fact, depending on how the situations are legally defined, the rules that apply vary from one case to the next. By proposing a typology of armed conflicts from the perspective of international humanitarian law, this article seeks to show how the different categories of armed conflict anticipated by that legal regime can be interpreted in the light of recent developments in international legal practice. It also reviews some actual situations whose categorization under existing legal concepts has been debated.
Experimental tests of the generation mechanism of auroral medium frequency burst radio emissions
Authors: Bunch N. L. , LaBelle J. , Weatherwax A. T. , Hughes J. M. , Lummerzheim D.
Published: September 2009

Medium frequency (MF) burst is an impulsive auroral radio emission at 1.3–4.5 MHz commonly detected by ground‐based instruments for a few minutes at substorm onsets. It is thought to arise from mode conversion radiation. The Dartmouth College MF radio interferometer at Toolik Field Station, Alaska (68.51° invariant latitude), measured spectra, amplitudes, and directions of arrival (DOA) of 47 MF burst events during 2006–2007 and 49 events during 2007–2008. Statistical analysis of these events shows that they come predominantly from the south and east of Toolik, as expected because propagation conditions are more favorable poleward and westward of the active auroral arcs than equatorward or eastward during premidnight (westward moving) substorm onset activity. Case studies of a selected MF burst event on 20 November 2007 show that motions of the radio emissions qualitatively track the motions of auroral arcs simultaneously observed with all‐sky camera. Case studies of DOA data of selected MF burst events on 31 January and 20 November 2007 show that higher‐frequency components of MF burst arrive at higher elevation angles than lower‐frequency components. Statistical studies confirm this trend. Ray‐tracing analysis shows that this trend implies that sources of the higher‐frequency components of the MF burst are at higher altitudes than those of the lower‐frequency components. The analysis also shows that the MF burst comes from the bottomside F region ionosphere. These observations are consistent with a mechanism of MF burst emission whereby the emissions originate from mode conversion of Langmuir or upper hybrid waves excited over a range of altitudes in the bottomside F region.
The kinetics of microstructural evolution during deformation of calcite
Authors: Austin Nicholas , Evans Brian
Published: September 2009

There is a strong coupling between the microstructure and the strength of rocks that is thought to play a key role in the evolution of shear zones and in our ability to interpret the mechanics of natural deformation processes. To investigate the microstructural evolution of calcite‐rich rocks, we have performed a series of hydrostatic and deformation experiments on synthetic calcite aggregates at 1023 K and 300 MPa. The mechanical data from our experiments were broadly consistent with a composite flow law for concurrent dislocation and diffusion creep. Recrystallization rates responded to the deformation conditions. When the bulk strain rate was dominated by diffusion creep, calcite grains grew at the same rate as occurs by normal grain growth under isostatic conditions. When the dominant deformation mechanism was dislocation creep, the matrix grain size was reduced at a rate that varied directly with product of stress, strain rate, and the square of grain size. Thus, reduction rate was proportional to mechanical work rate. If the stable grain size achieved during deformation depends on the product of stress and strain rate, rather than stress alone, then that grain size is an indication of the work rate and can be used as a paleowattmeter. Following this line of thought suggests that the gradient of recrystallized grain sizes that is often observed in the highly deformed portions of shear zones would not require a gradient in stress but could also be explained by material softening, resulting in locally elevated strain rates under constant stresses.
Impact of changes in atmospheric conditions in modulating summer dust concentration at Barbados: A back‐trajectory analysis
Authors: Engelstaedter S. , Washington R. , Mahowald N.
Published: September 2009

Atmospheric dust concentrations have been measured continuously since 1965 at Barbados providing one of the longest records of modern atmospheric dust downwind the dust transport route from North Africa toward the Caribbean. The Barbados dust concentration (BDC) record shows a high variability on daily to decadal timescales. This study aims to assess the importance of four processes that have the potential to contribute to the observed day‐to‐day variability: (1) changes in the transport pathways, (2) changes in atmospheric transport time, (3) changes in the atmospheric dust loadings in the source regions in North Africa, and (4) changes in rainfall. Back‐trajectories are calculated for low and high dust days in June (peak month in annual cycle) and analyzed with respect to these four processes. The results show that statistically significant differences exist between low and high BDC days for all four processes. For high BDC days we observe (1) an increase in the number of trajectories (especially at 100 and 150 hPa above the surface) which originated over the North African continent due to differences in the transport pathways, (2) a faster trans‐Atlantic transport at the height of the SAL by up to 0.87 days which would mean less dust being removed as a result of dry deposition and less diffusion, (3) increased dust loadings over West Africa and the tropical North Atlantic, and (4) less rainfall in ITCZ region which may have a minor impact of dust loadings due to wet deposition. Our results support the findings of previous studies that changes in dust emission and rainfall impact dust variability over the Atlantic Ocean and the Caribbean. In addition to these two processes, our findings suggest that also changes in the synoptic meteorology over the North Atlantic and varying transport speed can affect BDC variability by modulating dust transport pattern.
Evolution of first‐year and second‐year snow properties on sea ice in the Weddell Sea during spring‐summer transition
Authors: Nicolaus Marcel , Haas Christian , Willmes Sascha
Published: September 2009

Observations of snow properties, superimposed ice, and atmospheric heat fluxes have been performed on first‐year and second‐year sea ice in the western Weddell Sea, Antarctica. Snow in this region is particular as it does usually survive summer ablation. Measurements were performed during Ice Station Polarstern (ISPOL), a 5‐week drift station of the German icebreaker RV Polarstern. Net heat flux to the snowpack was 8 W m−2, causing only 0.1 to 0.2 m of thinning of both snow cover types, thinner first‐year and thicker second‐year snow. Snow thinning was dominated by compaction and evaporation, whereas melt was of minor importance and occurred only internally at or close to the surface. Characteristic differences between snow on first‐year and second‐year ice were found in snow thickness, temperature, and stratigraphy. Snow on second‐year ice was thicker, colder, denser, and more layered than on first‐year ice. Metamorphism and ablation, and thus mass balance, were similar between both regimes, because they depend more on surface heat fluxes and less on underground properties. Ice freeboard was mostly negative, but flooding occurred mainly on first‐year ice. Snow and ice interface temperature did not reach the melting point during the observation period. Nevertheless, formation of discontinuous superimposed ice was observed. Color tracer experiments suggest considerable meltwater percolation within the snow, despite below‐melting temperatures of lower layers. Strong meridional gradients of snow and sea‐ice properties were found in this region. They suggest similar gradients in atmospheric and oceanographic conditions and implicate their importance for melt processes and the location of the summer ice edge.
Evolution of the ice phase in tropical altocumulus: SAMUM lidar observations over Cape Verde
Authors: Ansmann A. , Tesche M. , Seifert P. , Althausen D. , Engelmann R. , Fruntke J. , Wandinger U. , Mattis I. , Müller D.
Published: September 2009

The formation of the ice phase in tropical altocumulus has been studied with multiwavelength aerosol‐cloud Raman lidar, wind Doppler lidar, and radiosonde, providing information on geometrical and optical properties, cloud phase, cloud top temperature, updraft and downdraft velocity, and fall speed of ice crystals. The observations were conducted at Praia (15°N, 23.5°W), Cape Verde, in the tropical North Atlantic in the framework of the Saharan Mineral Dust Experiment (SAMUM) project in January and February 2008. More than 200 different altocumulus layers were analyzed. The coldest liquid cloud had a temperature of −36°C and appeared at a height of 9800 m. Tropical altocumulus is found to be geometrically (262 ± 137 m) and optically thin (0.69 ± 0.61), mostly short‐lived, and horizontally small with extents of less than 50 km in 80% of the cases. A clear relationship between the occurrence of the ice phase in altocumulus and cloud top temperature is observed, even more clear after the removal of effects of cloud seeding, which is found to be an important process of ice production in lower layers of multilayer altocumulus systems. Because almost all altocumulus layers (99%) showed a liquid cloud top (region in which ice nucleation begins), we conclude that deposition and condensation ice nucleation are unimportant processes during the initial phase of altocumulus glaciation. A pronounced impact of aerosols such as mineral particles known to be favorable ice nuclei is not found in this region with strong dust‐smoke outbreaks from Africa. The different phases of an almost complete life cycle of an altocumulus were monitored over 5 hours. The observed processes of droplet and ice formation are discussed based on height‐resolved depolarization‐ratio (cloud phase) and vertical‐velocity time series.
Use of high‐resolution geophysical data to characterize heterogeneous aquifers: Influence of data integration method on hydrological predictions
Authors: Dafflon B. , Irving J. , Holliger K.
Published: September 2009

The integration of geophysical data into the subsurface characterization problem has been shown in many cases to significantly improve hydrological knowledge by providing information at spatial scales and locations that is unattainable using conventional hydrological measurement techniques. The investigation of exactly how much benefit can be brought by geophysical data in terms of its effect on hydrological predictions, however, has received considerably less attention in the literature. Here, we examine the potential hydrological benefits brought by a recently introduced simulated annealing (SA) conditional stochastic simulation method designed for the assimilation of diverse hydrogeophysical data sets. We consider the specific case of integrating crosshole ground‐penetrating radar (GPR) and borehole porosity log data to characterize the porosity distribution in saturated heterogeneous aquifers. In many cases, porosity is linked to hydraulic conductivity and thus to flow and transport behavior. To perform our evaluation, we first generate a number of synthetic porosity fields exhibiting varying degrees of spatial continuity and structural complexity. Next, we simulate the collection of crosshole GPR data between several boreholes in these fields, and the collection of porosity log data at the borehole locations. The inverted GPR data, together with the porosity logs, are then used to reconstruct the porosity field using the SA‐based method, along with a number of other more elementary approaches. Assuming that the grid‐cell‐scale relationship between porosity and hydraulic conductivity is unique and known, the porosity realizations are then used in groundwater flow and contaminant transport simulations to assess the benefits and limitations of the different approaches.
Role of rivers in the seasonal variations of terrestrial water storage over global basins
Authors: Kim Hyungjun , Yeh Pat J.‐F. , Oki Taikan , Kanae Shinjiro
Published: September 2009

The role of rivers in total terrestrial water storage (TWS) variations is evaluated in 29 basins. The contribution of individual storage components to total TWS is investigated by using ensemble hydrological simulations with river routing. The observed Gravity Recovery And Climate Experiment (GRACE) TWS data are used to validate model simulations. It is found TWS simulations are more accurate when river storage is taken into account except for dry basins. Rivers play different roles in various climatic regions as indicated by two new indices quantifying the significance of each TWS component and their interactions. River storage, which effectively includes downslope movement of shallow groundwater, explains up to 73% of TWS variations in Amazon. It also acts as “buffer” which smoothes TWS seasonal variations particularly in snow‐dominated basins. Neglecting river storage may lead to mismatch in the amplitude and phase of TWS seasonal variations compared to the GRACE observations.
Atmospheric origin of cold ion escape from Mars
Authors: Lundin R. , Barabash S. , Holmström M. , Nilsson H. , Yamauchi M. , Dubinin E. M. , Fraenz M.
Published: September 2009

Cold ionospheric ions dominate the plasma escape from Mars. The flow pattern versus altitude, latitude and local time suggests a fairly symmetric transport of ionospheric plasma from the dayside into the nightside/tail region of Mars. An interesting aspect of the plasma escape from Mars is the large abundance of molecular ions, implying that the outflow source region extends down to the lower ionosphere where molecular ions dominate. We also find a fair amount of ionized molecular hydrogen, H2+, in the ion outflow, the H2+ outflow corresponding to some 1/10 of the H+ outflow. Because the cold ionospheric ion outflow is dominated by H+, H2+, O+ and O2+, the average CO2+ outflow corresponding to about 10% of the heavy ion outflow, we have made a stoichiometric analysis of the ion escape. Adding the total outflow of hydrogen and oxygen respectively, we get H/O = 0.6–1.3. Altogether this suggests that the ultimate origin of the bulk ion escape from Mars is a minor constituent in the Martian atmosphere ‐ water.
On the relationship between ocean DMS and solar radiation
Authors: Derevianko Gregory J. , Deutsch Curtis , Hall Alex
Published: September 2009

Biologically produced dimethylsulfide (DMS) is an important source of sulfur to the marine atmosphere that may affect cloud formation and properties. DMS is involved in a complex set of biochemical transformations and ecological exchanges so its global distribution is influenced by numerous factors, including oxidative stress from UV radiation. We re‐examine correlations between global surface DMS concentrations and mixed layer solar radiation dose (SRD), and find that SRD accounts for only a very small fraction (14%) of total variance in DMS measurements when using minimal aggregation methods. Moreover this relationship arises in part from the fact that when mixed layers deepen, both SRD and DMS decrease. When we control for this confounding effect, the correlation between DMS and SRD is reduced even further. These results indicate that factors other than solar irradiance play a leading role in determining global DMS emissions.
Deriving daily snapshots of the Earth's gravity field from GRACE L1B data using Kalman filtering
Authors: Kurtenbach Enrico , Mayer‐Gürr Torsten , Eicker Annette
Published: September 2009

Different GRACE data analysis centers provide temporal variations of the Earth's gravity field as monthly, 10‐daily or weekly mean fields. These solutions are derived independently for each time span, i.e., no correlation between the analyzed batches is considered. Following this procedure, an increase in temporal resolution is accompanied by a loss in accuracy. To avoid this problem, a new approach is followed, which takes into account the temporal correlations of the gravity field variations thus enabling the enhancement of the temporal resolution up to daily snapshots. The GRACE Level‐1B (L1B) instrument data processing is performed within the framework of a Kalman filter estimation procedure, where the information about the temporal correlation patterns can be derived from geophysical models. The WaterGAP hydrological model was analyzed to derive the required information in terms of an empirical auto‐covariance function. First results are presented and compared to GFZ‐RL04 monthly and weekly gravity field solutions.
On remote sensing of transient luminous events' parent lightning discharges by ELF/VLF wave measurements on board a satellite
Authors: Lefeuvre F. , Marshall R. , Pinçon J. L. , Inan U. S. , Lagoutte D. , Parrot M. , Berthelier J. J.
Published: September 2009

First recordings of satellite ELF/VLF waveform data associated with transient luminous event (TLE) observations are reported from the summer 2005 campaign coordinated by Stanford University and Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPCE). TLEs are optically observed from the U.S. Langmuir Laboratory, while ELF/VLF waveform data are simultaneously recorded on board the Centre National d'Etudes Spatiales microsatellite DEMETER and on the ground at Langmuir. Analyses of ELF/VLF measurements associated with sprite events observed on 28 July 2005 and 3 August 2005 are presented. Conditions to trace back the wave emissions from the satellite to the source region of the parent lightning discharge are discussed. The main results concern: (1) the identification from a low Earth orbit satellite of the 0+ whistler signatures of the TLE causative lightning; (2) the identification of the propagation characteristics of proton whistlers triggered by the 0+ whistlers of the causative lightning, and the potential use of those characteristics; (3) recognition of the difficulty to observe sprite‐produced ELF bursts in the presence of proton‐whistlers; (4) the use of geographical displays of the average power received by the DEMETER electric field antennas over the U.S. Navy transmitter North West Cape (NWC) located in Western Australia to evaluate VLF transmission cones which explain the presence (28 July events) or the absence (3 August events) of propagation links between sferics observed at ground and 0+ whistlers observed on DEMETER; and (5) owing to electron‐collisions, an optimum transfer of energy from the atmosphere to the ionosphere for waves with k vectors antiparallel, or quasi‐antiparallel, to Earth's magnetic field direction.
Derivation of fluid conservation relations to infer near‐Sun properties of coronal mass ejections from in situ measurements
Authors: Riley Pete , McComas D. J.
Published: September 2009

Coronal mass ejections (CMEs) are observed both near the Sun using remote solar measurements, as well as in the solar wind using in situ measurements. While many relationships have been made between these relatively disparate data sets, a number of connections remain poorly known. In this study, we use mass, momentum, and energy conservation to derive a set of conservation relations based on the observed in situ properties of CMEs and the ambient environment into which they propagate. We focus on fast CMEs that drive shocks and produce sheath regions. These relations allow us to infer the plasma and magnetic field properties of the ejecta close to the Sun based primarily on in situ observations. In this first paper, we consider the limit where both magnetic and thermal plasma pressure can be neglected and derive an equation for the initial speed of the ejecta. We apply this result to (1) a simulated fast CMEs (for which the true initial speed is known) to verify that the approach produces reasonable results and (2) an observed CME for which several other empirical techniques for inferring initial speed have been applied. Finally, using these results, we derive an estimate for the transit time of a CME from the Sun to 1 AU. Our results are promising, yet tentative. More extensive studies will be necessary to either support or refute this technique.
The complete genome sequence of the algal symbiont Dinoroseobacter shibae: a hitchhiker's guide to life in the sea
Authors: Wagner-Döbler Irene , Ballhausen Britta , Berger Martine , Brinkhoff Thorsten , Buchholz Ina , Bunk Boyke , Cypionka Heribert , Daniel Rolf , Drepper Thomas , Gerdts Gunnar , Hahnke Sarah , Han Cliff , Jahn Dieter , Kalhoefer Daniela , Kiss Hajnalka , Klenk Hans-Peter , Kyrpides Nikos , Liebl Wolfgang , Liesegang Heiko , Meincke Linda , Pati Amrita , Petersen Jörn , Piekarski Tanja , Pommerenke Claudia , Pradella Silke , Pukall Rüdiger , Rabus Ralf , Stackebrandt Erko , Thole Sebastian , Thompson Linda , Tielen Petra , Tomasch Jürgen , von Jan Mathias , Wanphrut Nittaya , Wichels Antje , Zech Hajo , Simon Meinhard
Published: September 2009

Dinoroseobacter shibae DFL12T, a member of the globally important marine Roseobacter clade, comprises symbionts of cosmopolitan marine microalgae, including toxic dinoflagellates. Its annotated 4 417 868 bp genome sequence revealed a possible advantage of this symbiosis for the algal host. D. shibae DFL12T is able to synthesize the vitamins B1 and B12 for which its host is auxotrophic. Two pathways for the de novo synthesis of vitamin B12 are present, one requiring oxygen and the other an oxygen-independent pathway. The de novo synthesis of vitamin B12 was confirmed to be functional, and D. shibae DFL12T was shown to provide the growth-limiting vitamins B1 and B12 to its dinoflagellate host. The Roseobacter clade has been considered to comprise obligate aerobic bacteria. However, D. shibae DFL12T is able to grow anaerobically using the alternative electron acceptors nitrate and dimethylsulfoxide; it has the arginine deiminase survival fermentation pathway and a complex oxygen-dependent Fnr (fumarate and nitrate reduction) regulon. Many of these traits are shared with other members of the Roseobacter clade. D. shibae DFL12T has five plasmids, showing examples for vertical recruitment of chromosomal genes (thiC) and horizontal gene transfer (cox genes, gene cluster of 47 kb) possibly by conjugation (vir gene cluster). The long-range (80%) synteny between two sister plasmids provides insights into the emergence of novel plasmids. D. shibae DFL12T shows the most complex viral defense system of all Rhodobacterales sequenced to date.
Horizontal transfer of the nitrogen fixation gene cluster in the cyanobacterium Microcoleus chthonoplastes
Authors: Bolhuis Henk , Severin Ina , Confurius-Guns Veronique , Wollenzien Ute I A , Stal Lucas J
Published: September 2009

The filamentous, non-heterocystous cyanobacterium Microcoleus chthonoplastes is a cosmopolitan organism, known to build microbial mats in a variety of different environments. Although most of these cyanobacterial mats are known for their capacity to fix dinitrogen, M. chthonoplastes has not been assigned as a diazotrophic organism. None of the strains that were correctly identified as M. chthonoplastes has been shown to fix dinitrogen and it has repeatedly been reported that these organisms lacked the cyanobacterial nifH, the structural gene for dinitrogenase reductase. In this study, we show that a complete nif-gene cluster is present in the genome of M. chthonoplastes PCC 7420 and that the three structural nitrogenase genes, nifHDK, are present in a collection of axenic strains of M. chthonoplastes from distant locations. Phylogenetic analysis of nifHDK revealed that they cluster with the Deltaproteobacteria and that they are closely related to Desulfovibrio. The nif operon is flanked by typical cyanobacterial genes, suggesting that it is an integral part of the M. chthonoplastes genome. In this study, we provide evidence that the nif operon of M. chthonoplastes is acquired through horizontal gene transfer. Moreover, the presence of the same nif-cluster in M. chthonoplastes isolates derived from various sites around the world suggests that this horizontal gene transfer event must have occurred early in the evolution of M. chthonoplastes. We have been unable to express nitrogenase in cultures of M. chthonoplastes, but we show that these genes were expressed under natural conditions in the field.
Importance of the bioenergetic reserve capacity in response to cardiomyocyte stress induced by 4-hydroxynonenal
Authors: Hill Bradford G. , Dranka Brian P. , Zou Luyun , Chatham John C. , Darley-Usmar Victor M.
Published: September 2009

Mitochondria play a critical role in mediating the cellular response to oxidants formed during acute and chronic cardiac dysfunction. It is widely assumed that, as cells are subjected to stress, mitochondria are capable of drawing upon a ‘reserve capacity’ which is available to serve the increased energy demands for maintenance of organ function, cellular repair or detoxification of reactive species. This hypothesis further implies that impairment or depletion of this putative reserve capacity ultimately leads to excessive protein damage and cell death. However, it has been difficult to fully evaluate this hypothesis since much of our information about the response of the mitochondrion to oxidative stress derives from studies on mitochondria isolated from their cellular context. Therefore the goal of the present study was to determine whether ‘bioenergetic reserve capacity’ does indeed exist in the intact myocyte and whether it is utilized in response to stress induced by the pathologically relevant reactive lipid species HNE (4-hydroxynonenal). We found that intact rat neonatal ventricular myocytes exhibit a substantial bioenergetic reserve capacity under basal conditions; however, on exposure to pathologically relevant concentrations of HNE, oxygen consumption was increased until this reserve capacity was depleted. Exhaustion of the reserve capacity by HNE treatment resulted in inhibition of respiration concomitant with protein modification and cell death. These data suggest that oxidized lipids could contribute to myocyte injury by decreasing the bioenergetic reserve capacity. Furthermore, these studies demonstrate the utility of measuring the bioenergetic reserve capacity for assessing or predicting the response of cells to stress.
A large-conductance calcium-activated potassium channel in potato (Solanum tuberosum) tuber mitochondria
Authors: Koszela-Piotrowska Izabela , Matkovic Karolina , Szewczyk Adam , Jarmuszkiewicz Wieslawa
Published: September 2009

In the present study, we describe the existence of a novel potassium channel in the plant [potato (Solanum tuberosum) tuber] mitochondrial inner membrane. We found that substances known to modulate large-conductance calcium-activated potassium channel activity influenced the bioenergetics of potato tuber mitochondria. In isolated mitochondria, Ca2+ and NS1619 {1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-ben-zimidazole-2-one; a potassium channel opener} were found to depolarize the mitochondrial membrane potential and to stimulate resting respiration. These effects were blocked by iberiotoxin (a potassium channel inhibitor) in a potassium-dependent manner. Additionally, the electrophysiological properties of the large-conductance potassium channel present in the potato tuber inner mitochondrial membrane are described in a reconstituted system, using planar lipid bilayers. After incorporation in 50/450 mM KCl gradient solutions, we recorded large-conductance potassium channel activity with conductance from 502±15 to 615±12 pS. The probability of channel opening was increased by Ca2+ and reduced by iberiotoxin. Immunological analysis with antibodies raised against the mammalian plasma-membrane large-conductance Ca2+-dependent K+ channel identified a pore-forming α subunit and an auxiliary β2 subunit of the channel in potato tuber mitochondrial inner membrane. These results suggest that a large-conductance calcium-activated potassium channel similar to that of mammalian mitochondria is present in potato tuber mitochondria.
Statins have beneficial effects on platelet free radical activity and intracellular distribution of GTPases in hyperlipidaemia
Authors: Hamilton Paul K. , Hughes Sinead M.T. , Plumb Richard D. , Devine Adrian , Leahey William , Lyons Kristopher S. , Johnston Dennis , McVeigh Gary E.
Published: September 2009

In addition to lowering cholesterol, statins may alter endothelial release of the vasodilator NO and harmful superoxide free radicals. Statins also reduce cholesterol intermediates including isoprenoids. These are important for post-translational modification of substances including the GTPases Rho and Rac. By altering the membrane association of these molecules, statins affect intracellular positioning and hence activity of a multitude of substances. These include eNOS (endothelial NO synthase), which produces NO (inhibited by Rho), and NADPH oxidase, which produces superoxide (dependent on Rac). Statins may improve endothelial function by enhancing production of NO while decreasing superoxide production. A total of 40 hypercholesterolaemic patients were randomized to treatment with either atorvastatin or placebo; 20 normolipidaemic patients were also studied. Platelet nitrite, NO and superoxide were examined as was the cellular distribution of the GTPases Rho and Rac at baseline and after 8 weeks of treatment. Following atorvastatin therapy, platelet NO was increased (3.2 pmol/108 platelets) and superoxide output was attenuated [−3.4 pmol·min−1·(108 platelets)−1] when compared with placebo. The detection of both Rho and Rac was significantly reduced in the membranes of platelets, implying reduced activity. In conclusion, the results of the present study show altered NO/superoxide production following statin therapy. A potential mechanism for this is the change in the distribution of intracellular GTPases, which was considered to be secondary to decreases in isoprenoid intermediates, suggesting that the activity of the former had been affected by atorvastatin.
The effect of surface bond reconstruction of thermal contact surfaces on phonon transport in atomic wire
Authors: Li Jing , Au Yeung T. C. , Kam C. H. , Zhao Xuean , Chen Qing-Hu , Peng Yue , Sun Chang Q.
Published: September 2009

The effect of surface bond reconstruction (SBR) of Si contact surfaces on phonon transport in Si atomic wire is investigated. Green’s function method is applied to calculate the thermal conductance and local heat currents. Results show that the phonon transport in atomic wires is enhanced significantly by SBR at the thermal contact surface. A blue shift for phonon transmission function is induced by the SBR.
Above-bandgap ordinary optical properties of GaSe single crystal
Authors: Choi S. G. , Levi D. H. , Martinez-Tomas C. , Muñoz Sanjosé V.
Published: September 2009

We report above-bandgap ordinary optical properties of ε-phase GaSe single crystal. Reference-quality pseudodielectric function ⟨ε(E)⟩=⟨ε1(E)⟩+i⟨ε2(E)⟩ and pseudorefractive index ⟨N(E)⟩=⟨n(E)⟩+i⟨k(E)⟩ spectra were measured by spectroscopic ellipsometry from 0.73to6.45eV at room temperature for the light polarization perpendicular to the optic axis (E⃑⊥ĉ). The ⟨ε⟩ spectrum exhibited several interband-transition critical-point structures. Analysis of second-energy derivatives calculated numerically from the measured data yielded the critical-point energy values.
X-ray ablation of hyaluronan hydrogels: Fabrication of three-dimensional microchannel networks
Authors: Weon B. M. , Chang S. , Yeom J. , Hahn S. K. , Je J. H. , Hwu Y. , Margaritondo G.
Published: September 2009

We present a simple and highly versatile protocol for polymer ablation: hard x-ray irradiation makes it possible to rapidly depolymerize hyaluronan hydrogels and fabricate three-dimensional network of microchannels. Photodynamic and photochemical analyses show that x-ray irradiation directly cleaves the polymer backbone and the total dose controls the degradation kinetics. This nonthermal ablation protocol may offer opportunities for processing organic polymers and biological materials.
Polymer adsorption in finite range surface potentials: Planar and spherical adsorbing surfaces
Authors: Chervanyov A. I. , Heinrich G.
Published: September 2009

We analytically solve the problem of the reversible adsorption of Gaussian polymers onto the planar and spherical surfaces in the presence of the square well attractive potential. By making use of the obtained exact solution of the Edwards equation, we calculate the end density and surface excess of the polymers at the planar and spherical substrates. We derive the exact equation that determines the surface bound states that give rise to the dominant contributions to the polymer surface excess. In the case of the spherical substrate, the exact expression for the polymer surface excess is obtained in the remarkably simple form of a quadratic function of the radius of the substrate. Using the calculated polymer surface excesses, we obtain the adsorption-desorption diagrams of the polymers adsorbed onto the spherical and planar surface in terms of the introduced “effectiveness” of the adsorption potential. By performing the analogous calculation based of the standard boundary condition approach, we demonstrate that this method overlooks the effect of the spatial interplay between the depletion and adsorption forces acting on the adsorbed polymers. Based on the comparison with the obtained exact solutions, we propose a modification of the boundary condition for the spherical substrate that preserves, in particular, the correct “protein” limit.
Pseudospin filter for graphene via laser irradiation
Authors: Martinez J. C. , Jalil M. B. A. , Tan S. G.
Published: September 2009

We study graphene monolayer charge carriers irradiated by an electromagnetic vortex. From this, two scenarios are envisaged: canonical oscillator coherent states, which form for large particle numbers and from which a sublattice filter can be constructed, and pair-coherent states, which emerge when the carrier velocity is much less than the Fermi velocity and which can exhibit nonclassical properties. The first should be useful in the control (e.g., confinement and guided transport) of graphene electrons, while the second provides a physical system for examining nonclassical properties of wave packets.
Unstable state in epitaxial films of sodium niobate
Authors: Tyunina M. , Levoska J.
Published: September 2009

Epitaxial perovskite-type films of sodium niobate were grown by pulsed laser deposition, and their crystal structure and dielectric properties were experimentally studied. The dielectric permittivity, inverse permittivity and its derivative, and dielectric hysteresis were analyzed and compared with those of antiferroelectric lead zirconate films. At temperatures in the interval of 80–600 K, the state of the sodium niobate films with relaxed misfit strain is interpreted as an unstable coexistence of antiferroelectric and ferroelectric phases. The origin of the ferroelectric phase is discussed.
Antifreeze protein NMR sensor to detect water molecular reorientation in the surface of ice
Authors: Mao Yougang , Lin Wei , Ba Yong
Published: September 2009

The century-old puzzle of the existence of a quasiliquid layer in the surface of ice was revisited using ice-surface binding type I antifreeze proteins with specific side chain C13 labeled methyl groups. Variable temperature dependent C13 spin lattice relaxation NMR experiments were carried out below 0 °C to probe the water molecular reorientations surrounding the methyl groups. The result shows that water molecular reorientations in ice surface are much more dynamic than those in bulk ice. This study demonstrates that antifreeze proteins can be used as a sensor to detect the dynamics of water in the surface of ice.
Measurement of the temperature-dependent threshold shear-stress of red blood cell aggregation
Authors: Lim Hyun-Jung , Nam Jeong-Hun , Lee Yong-Jin , Shin Sehyun
Published: September 2009

Red blood cell (RBC) aggregation is becoming an important hemorheological parameter, which typically exhibits temperature dependence. Quite recently, a critical shear-stress was proposed as a new dimensional index to represent the aggregative and disaggregative behaviors of RBCs. The present study investigated the effect of the temperature on the critical shear-stress that is required to keep RBC aggregates dispersed. The critical shear-stress was measured at various temperatures (4, 10, 20, 30, and 37 °C) through the use of a transient microfluidic aggregometry. The critical shear-stress significantly increased as the blood temperature lowered, which accorded with the increase in the low-shear blood viscosity with the lowering of the temperature. Furthermore, the critical shear-stress also showed good agreement with the threshold shear-stress, as measured in a rotational Couette flow. These findings assist in rheologically validating the critical shear-stress, as defined in the microfluidic aggregometry.
An organic charge trapping memory transistor with bottom source and drain contacts
Authors: Debucquoy Maarten , Bode Dieter , Genoe Jan , Gelinck Gerwin H. , Heremans Paul
Published: September 2009

We present an organic charge trapping memory transistor with lithographically defined bottom source and drain contacts. This device can be written and erased at voltages as low as 15 V. More than 500 write and erase cycles and the retention of the trapped charge over more than three months are shown, demonstrating the possibilities of this device as a reprogramable nonvolatile organic memory element.
Photoelectric charging of dust particles: Effect of spontaneous and light induced field emission of electrons
Authors: Sodha M. S. , Dixit A.
Published: September 2009

The authors have analyzed the charging of dust particles in a plasma, taking into account the electron/ion currents to the particles, electron/ion generation and recombination, electric field emission, photoelectric emission and photoelectric field emission of electrons under the influence of light irradiation; the irradiance has been assumed to be at a level, which lets the particles retain the negative sign of the charge. Numerical results and discussion conclude the papers.
Intrinsic and boron-enhanced hydrogen diffusion in amorphous silicon formed by ion implantation
Authors: Johnson B. C. , McCallum J. C. , Atanacio A. J. , Prince K. E.
Published: September 2009

The concentration dependence of H diffusion in amorphous Si (a-Si) formed by ion implantation is reported for implanted H profiles. An empirical relationship is proposed which relates the diffusion coefficient to the H concentration valid up to 0.3 at. %. B-enhanced H diffusion is observed and shows trends with temperature typically associated with a Fermi level shifting dependence. A modified form of the generalized Fermi level shifting model is applied to these data.
Defect-mediated room temperature ferromagnetism in vanadium dioxide thin films
Authors: Yang Tsung-Han , Nori Sudhakar , Zhou Honghui , Narayan Jagdish
Published: September 2009

High quality epitaxial undoped vanadium oxide (VO2) thin films on c-plane sapphire (0001) substrate have been grown using pulsed laser deposition technique. The as-grown films exhibited excellent structural and transport properties without requiring further annealing treatments for these oxygen-deficient oxide films. The epitaxial growth has been achieved via domain matching epitaxy, where matching of integral multiples of planes occurs across the film-substrate interface. The magnetic properties of vanadium oxide (VO2) films investigated at different temperatures in the range of 10–360 K showed significant magnetic hysteresis as well as saturation of the magnetic moment. The origin of ferromagnetic properties with an estimated Curie temperature above 500 K is discussed in the absence of magnetic impurities in VO2 thin films as determined by x-ray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy.
Microwave resonance in Fe/SiO2 nanocomposite
Authors: Ma Ji , Li Jiangong , Ni Xia , Zhang Xudong , Huang Juanjuan
Published: September 2009

A broad resonance band in the 1–16 GHz range observed in Fe/SiO2 nanocomposite results from the coexsistence of natural resonance and exchange resonance. The natural resonance appears at 5.91 GHz and can be related to the core spins in the Fe nanoparticles, whereas the exchange resonance appears at 11.01 GHz and can be associated with the surface spins of the Fe nanoparticles in the Fe/SiO2 nanocomposite. Both resonance frequencies depend on the surface anisotropy of the Fe nanoparticles, which can be affected by the Fe particle size, and can be tuned by adjusting the Fe particle size.
Effect of inserted ultrathin barrier layer on luminescence of GaN/Al0.5Ga0.5N multiple quantum wells
Authors: Park Young S. , Kang Tae W. , Kim Yongmin , Im Hyunsik
Published: September 2009

We report that luminescence properties in GaN/Al0.5Ga0.5N multiquantum wells (multi-QWs) are tailored by inserting an ultrathin Al0.5Ga0.5N layer (∼5 Å) in the middle of QWs. The inserted layer causes a dramatic redshift in photoluminescence and cathodeluminescence because of a huge piezoelectric polarization due to the additional strain along the growth direction. Quantitative analysis on the effects of the ultrathin inserted layer on the luminescence properties is performed using self-consistent Schrödinger–Poisson band profile calculations.
Performative Design: A Performance-Based Model of Digital Architectural Design
Authors: Oxman Rivka
Published: September 2009

Though design for building performance is traditionally considered an evaluative act, current developments in the theory and technology of digital design are promoting new directions for performance-based models of design. This paper presents a theoretical basis for understanding the current shift in performance-based design and proposes a model of performance-based design in architecture, termed performative design. Automated processes related to the impact of environmental forces on form generation in digital design are the content of experimental processes upon which the paper reports. In the theoretical introduction the terms performative design and performative architecture are defined and discussed. Topics related to the current movement towards performance-based design in architecture, such as the role of topology, parametric design, associative geometry, and generative processes, are presented, and their implications for, and influence upon, performative design are discussed. An experimental design example in architectural design is demonstrated to illustrate various methodological issues in performative design.
Listeners Discern Affective Variation in Computer-Generated Musical Sounds
Authors: Bailes Freya , Dean Roger T
Published: September 2009

We carried out two experiments to test the relationship between real-time perception of structural change in stylistically unusual musical sounds, and perception of its affect (arousal and valence). Computer music was used because of its unfamiliarity and our capacity to control it in ecologically appropriate ways. In experiment 1, thirteen participants unselected for musical training participated in tasks to detect segmentation and changes in affect. Changes in affect occurred upon detection of segmentation; but not all algorithmically distinct segments conveyed distinct affect. Short segments followed by long segments led to greater changes in arousal and valence at the point of segmentation than vice versa. In experiment 2, intra-segment sound transitions were introduced. Sixteen musicians performed the same affect task as in experiment 1, and a novel change in sound task. Participants were slow to respond to a continuous transition, but quick to respond to instantaneous transitions. Contrary to literature on the perception of affect in more familiar music, the musician participants in experiment 2 differed more in their ratings of arousal than of valence, in spite of a strong correlation of arousal with the composition of the stimuli. These findings are discussed in relation to the positive valence attributed to the more familiar sounds in both experiments.