bluuebunny/crossref_metadata_2025 huggingface dataset:
The cost of borderline personality disorder: societal cost of illness in BPD-patients
Authors: van Asselt A.D.I. , Dirksen C.D. , Arntz A. , Severens J.L.
Published: June 2007

Background

Borderline personality disorder (BPD) is a highly prevalent, chronic condition. Because of its very problematic nature BPD is expected to be associated with substantial societal costs, although this has never been comprehensively assessed.

Objective

Estimate the societal cost of BPD in the Netherlands.

Study Design

We used a prevalence-based bottom-up approach with a sample of 88 BPD patients who enrolled in a multicenter clinical trial comparing two kinds of outpatient psychotherapy. Costs were assessed by means of a structured interview, covering all healthcare costs, medication, informal care, productivity losses, and out-of-pocket expenses. Only BPD-related costs were included. All costs were expressed in Euros for the year 2000. A bootstrap procedure was performed to determine statistical uncertainty.

Patients

All patients had been diagnosed with BPD using DSM-IV criteria. Mean age was 30.5 years and 92% was female.

Results

Based on a prevalence of 1.1% and an adult population of 11,990,942, we derived that there were 131,900 BPD patients in the Netherlands. Total bootstrapped yearly cost of illness was €2,222,763,789 (€1,372,412,403–€3,260,248,300), only 22% was healthcare-related. Costs per patient were €16,852.

Conclusions

Although healthcare costs of non-institutionalized Borderline patients might not be disproportionate, total societal costs are substantial.
Effects of pH and salt concentration on the siRNA binding activity of the RNA silencing suppressor protein p19
Authors: Koukiekolo Roger , Sagan Selena M. , Pezacki John Paul
Published: June 2007

The RNA silencing pathway is an important component of the anti‐viral immune response in eukaryotes, particularly in plants. In turn, many viruses have evolved mechanisms to evade or suppress this pathway. Tombusviruses such as the Carnation Italian ringspot virus (CIRV) express a 19 kDa protein (p19) that is a suppressor of RNA silencing in infected plants. This protein acts as a dimer and binds specifically to short‐interfering RNA (siRNA) through electrostatic interactions between charged residues in the binding cleft. Since pH and salt concentrations can vary widely from host to host, we have investigated the influence of these parameters on the siRNA binding activity of CIRV p19. Previously, we established a convenient fluorescence‐based method for assaying CIRV p19:siRNA binding using Ni2+–NTA coated 96‐well plates. Using this method, we observe that the CIRV p19 protein binds to siRNA with nanomolar affinity and that this binding is sensitive to pH and salt concentration. The pH‐dissociation constant profile shows that CIRV p19:siRNA binding is dependent on three different apparent pK
a values. The values extrapolated from the curve are 7.1, 8.0 and 10.6 that we interpret as the ionization of one or more histidine, cysteine and lysine residues, respectively. We find that the optimal suppression of RNA silencing by CIRV p19 occurs in the pH range from 6.2 to 7.6.
Identification of the amino acids crucial for the activities of drought responsive element binding factors (DREBs) of Brassica napus
Authors: Zhao Tong-Jin , Liu Yang , Yan Yong-Bin , Feng Feng , Liu Wei-Qun , Zhou Hai-Meng
Published: June 2007

We have previously identified two homologous groups of BnDREBs in Brassica napus, the trans‐active BnDREBI and the trans‐inactive BnDREBII, which provided an ideal system to study the trans‐activation of DREB1/CBF. Deletion analysis indicated that the two additional regions in BnDREBI contributed little to the transcriptional activity. Domain swapping analysis indicated that all the domains contributed to the activity of BnDREBI, including the ERF/AP2 DNA binding domain. Through site‐directed mutagenesis, we identified nine residues that were involved in the activity of BnDREBI, among which six residues are specific to BnDREBI, and three are common to DREB1A.
The 5′ untranslated region of Perina nuda virus (PnV) possesses a strong internal translation activity in baculovirus‐infected insect cells
Authors: Wu Tzong-Yuan , Wu Chih-Yu , Chen Ying-Ju , Chen Chung-Yung , Wang Chung-Hsiung
Published: June 2007

A bicistronic baculovirus expression vector and fluorescent protein‐based assays were used to identify the sequences that possess internal translation activity in baculovirus‐infected insect cells. We demonstrated that the 5′ untranslated region (5′UTR; 473 nucleotides) of Perina nuda virus (PnV) and the 5′UTR (579 nucleotides) of Rhopalosiphum padi virus (RhPV), but not the IRES sequence of Cricket paralysis virus, have internal translation activity in baculovirus‐infected Sf21 cells. In addition, we found that including the first 22 codons of the predicted PnV open reading frame (ORF; a total of 539 nucleotides) enhanced internal translation activity by approximately 18 times. This is the first report of internal translation activity for a baculovirus expression system (BEVS) in the iflavirus 5′ sequence and may facilitate the development of polycistronic baculovirus transfer vectors that can be used in BEVS for the production of multiple protein complexes.
The Israeli Political Arena and Palestinian Contention: The Case of the ‘First’ Intifada
Authors: ALIMI EITAN Y.
Published: June 2007

Are changes in political conditions objective features of the world or are they ultimately what social movement activists and adherents make of them? The position taken in this article argues that shifts in the Israeli structure of political opportunity, manifested in a series of transformative events, were framed by the Palestinians within the occupied territories as a political opportunity affecting their strategy of contention during the run up to the 1987 ‘first’ Intifada. Findings from content analysis data obtained from several Palestinian newspapers between 1974 and 1986 suggest that (a) the Palestinians collectively perceived Israeli domestic events as favourable political circumstances, and (b) their mutual interpretation of Israeli events as a reflection of divisions over the occupation was associated with rationalizing contention. Theoretical implications of bridging the culturally and structurally laden approaches to the study of collective action are offered.
European Opinion About Immigration: The Role of Identities, Interests and Information
Authors: SIDES JOHN , CITRIN JACK
Published: June 2007

This article assesses the influence of material interests and cultural identities on European opinion about immigration. Analysis of respondents in twenty countries sampled in the 2002–03 European Social Survey demonstrates that they are unenthusiastic about high levels of immigration and typically overestimate the actual number of immigrants living in their country. At the individual level, cultural and national identity, economic interests and the level of information about immigration are all important predictors of attitudes. ‘Symbolic’ predispositions, such as preferences for cultural unity, have a stronger statistical effect than economic dissatisfaction. Variation across countries in both the level and the predictors of opposition to immigration are mostly unrelated to contextual factors cited in previous research, notably the amount of immigration into a country and the overall state of its economy. The ramifications of these findings for policy makers are discussed in the context of current debates about immigration and European integration.
A Delayed Return to Historical Norms: Congressional Party Polarization after the Second World War
Authors: HAN HAHRIE , BRADY DAVID W.
Published: June 2007

Although a rich body of research has explored the sources of party polarization in the US House of Representatives, it has focused primarily on the House since the late 1970s. Drawing on a dataset of historical election outcomes, legislative voting and survey data, this article takes an alternative approach that examines both the US Senate and the House in their broader historical contexts. It is argued that the unusually bipartisan era of the 1950s created a set of circumstances that enabled congressional parties to remain relatively unpolarized throughout the 1960s and early 1970s. Although the national parties became more ideologically distinct in the mid-1960s, congressional parties lagged behind. As a result, a group of moderate legislators emerged who were cross-pressured between their national parties and their constituencies. Only when natural patterns of electoral loss and retirement replaced these legislators did congressional party polarization re-emerge.
Liberalism and the Politics of Compulsion
Authors: STEARS MARC
Published: June 2007

This review presents a critical account of the most powerful critique of liberal political thought to have emerged in recent years: a critique it calls the ‘politics of compulsion’. Drawing on the work of a wide range of critics of contemporary liberalism, this article contends that although those who advance this critique are divided in many ways they are nonetheless held together by a series of powerful descriptive and normative challenges to liberal political philosophy as it has developed since the publication of John Rawls's Political Liberalism. The article further demonstrates that most of these challenges centre on the place of coercive power in modern political life and suggests that, although these challenges should not undermine liberals' commitment to their central normative claims, they do nonetheless provide an essential rejoinder to some of liberalism's more complacent assumptions.
Beyond Durkheim: A Comment on Steven Lukes's ‘Liberal Democratic Torture’
Authors: LEVEY GEOFFREY BRAHM
Published: June 2007

In a recent article, Steven Lukes offers a thought-provoking reflection on the apparently growing resort to torture by liberal democracies today. Professor Lukes aptly asks whether ‘torture is just another case of dirty hands in politics?’ – that is, the idea that in order to do the right thing or achieve the best public outcome in the circumstances one cannot avoid committing a wrong, such as deceit or cruelty. His answer is that torture differs from other cases of dirty hands in that it cannot be made ‘liberal-democratically accountable’, thus raising the question of ‘how should it be addressed in liberal democracies?’ Here he suggests we can learn from the sociologist Emile Durkheim and, especially, his conception of modern societies as being held together by a ‘religion of individualism’. Allowing state officials to violate basic rights of the individual thus profanes against the religion and threatens the ‘moral disintegration’ of society itself. Lukes argues that Durkheim's account helps us see both the folly in ‘certain ways of thinking and talking about torture’, such as construing it as a ‘lesser evil’ given the competing claims of risk and security, and the damage that liberal democracies inflict on themselves, in responding to the threat of terrorism, by so readily compromising their own principles.

There is much that is appealing in Professor Lukes's remarks. I also share his concern about the current erosion of civil liberties in liberal democracies. I wish, however, to raise some doubts about three key aspects of his argument: that torture is not susceptible to liberal-democratic accountability; that the ‘Durkheimian argument’ effectively precludes the practice of torture; and that we cannot rightly speak of torture as a ‘lesser evil’.
A near‐global, 2‐hourly data set of atmospheric precipitable water from ground‐based GPS measurements
Authors: Wang Junhong , Zhang Liangying , Dai Aiguo , Van Hove Teresa , Van Baelen Joël
Published: June 2007

A 2‐hourly data set of atmospheric precipitable water (PW) has been produced from the zenith path delay (ZPD) derived from ground‐based Global Positioning System (GPS) measurements. The PW data are available every 2 hours from 80 to 268 International GNSS Service (IGS, formally International GPS Service) ground stations from 1997 to 2004. The accuracy of the IGS ZPD product is roughly 4 mm. An analysis technique is developed to convert ZPD to PW on a global scale. Special efforts are made on deriving surface pressure (Ps) and water‐vapor‐weighted atmospheric mean temperature (Tm), which are two key parameters for converting ZPD to PW. Ps is derived from global, 3‐hourly surface synoptic observations with temporal, vertical and horizontal adjustments. Tm is calculated from NCEP/NCAR reanalysis with temporal, vertical and horizontal interpolations. The derived Ps and Tm at the GPS location and height have root‐mean‐square (rms) errors of 1.65 hPa and 1.3 K, respectively. A theoretical error analysis concludes that typical PW error associated with the errors in ZPD, Tm and Ps is on the order of 1.5 mm. The PW data set is compared with radiosonde, microwave radiometer (MWR) and satellite data. The GPS and radiosonde PW comparisons at 98 stations around the globe show a mean difference of 1.08 mm (drier for radiosonde data) with a standard deviation of differences of 2.68 mm, which corresponds to mean percentage difference and standard deviation of 5.5% and 10.6%, respectively. The bias is primarily due to known dry biases in the Vaisala radiosonde data. The RMS difference between GPS and radiosonde/MWR data ranges from 1.2 mm to 2.83 mm. The latitudinal and seasonal variations of PW derived from the GPS data agree well with that from International Satellite Cloud Climatology Project (ISCCP) data if the ISCCP data are sampled only at grid boxes containing GPS stations. The large difference between GPS and ISCCP data in the subtropics is interesting, but is not easily explained. The comparisons did not reveal any systematic bias in GPS PW data and show that a RMS difference of less than 3 mm between GPS‐derived PW and other data sets is achieved. The comparison study also illustrates the value of GPS‐estimated PW for examining the quality of other data sets, such as those from radiosondes and MWR. Preliminary analysis of this data set shows interesting and significant diurnal variations in PW in four different regions.
Fitting model fields to observations by using singular value decomposition: An ensemble‐based 4DVar approach
Authors: Qiu Chongjian , Shao Aimei , Xu Qin , Wei Li
Published: June 2007

An ensemble‐based four‐dimensional variational data assimilation (4DVar) method is proposed to fit the model field to 4‐D observations in an increment form in the analysis step of data assimilation. The fitting is similar to that in the 4DVar but the analysis increment is expressed by a linear combination of the leading singular vectors extracted from an ensemble of 4‐D perturbation solutions, so the fitting is computationally very efficient and does not require any adjoint integration. In the cost function used for the fitting, the background error covariance matrix is constructed implicitly by the perturbation solutions (through their representative singular vectors) similarly to that in the ensemble Kalman filter, but the perturbation solutions are not updated by the analysis into the next assimilation cycle, so the analysis is simpler and more efficient than that in the ensemble Kalman filter. The potential merits of the method are demonstrated by three sets of observing system simulation experiments performed with a shallow‐water equation model. The method is shown to be robust even when the model is imperfect and the observations are incomplete.
Production of space charge at the boundaries of layer clouds
Authors: Zhou Limin , Tinsley Brian A.
Published: June 2007

The ionosphere‐Earth current density Jz creates space charge at the upper and lower boundaries of layer clouds. This occurs because clouds have an order of magnitude lower conductivity than the clear air at the same altitude, and as the current density flows through the boundaries, it creates a gradient of electric field that must be satisfied by the accumulation of space charge, according to Gauss's law. We have modeled the production of space charge and its partition between charges on droplets, aerosol particles, and ions and performed sensitivity tests for the variation of a number of relevant atmospheric parameters. We find typical droplet charges of 50–100 elementary charges, positive at cloud top and negative at cloud base, consistent with recent observations. The charges are of sufficient magnitude to suggest measurable electrical effects on scavenging of ice‐forming nuclei and cloud condensation nuclei. The results are relevant to the modeling of solar or internally forced changes of Jz and space charge on cloud microphysics as a possible cause of small effects on weather and climate.
Widespread acceleration of tidewater glaciers on the Antarctic Peninsula
Authors: Pritchard H. D. , Vaughan D. G.
Published: June 2007

Over the last half century, the Antarctic Peninsula (AP) has been among the most rapidly warming regions on Earth. This has led to increased summer snowmelt, loss of ice shelves, and retreat of 87% of marine and tidewater glacier fronts. Tidewater‐glacier flow is sensitive to changes in basal water supply and to thinning of the terminus, and faster flow leads directly to sea level rise. The flow rates of most AP tidewater glaciers have never been measured, however, and hence their dynamic response to the recent changes is unknown. We present repeated flow rate measurements from over 300 glaciers on the AP west coast through nine summers from 1992 to 2005. We show that the flow rate increased by ∼12% on average and that this trend is greater than the seasonal variability in flow rate. We attribute this widespread acceleration trend not to meltwater‐enhanced lubrication or increased snowfall but to a dynamic response to frontal thinning. We estimate that as a result, the annual sea level contribution from this region has increased by 0.047 ± 0.011 mm between 1993 and 2003. This contribution, together with previous studies that assessed increased runoff from the area and acceleration of glaciers resulting from the removal of ice shelves, implies a combined AP contribution of 0.16 ± 0.06 mm yr−1. This is comparable to the contribution from Alaskan glaciers, and combined with estimated mass loss from West Antarctica, is probably large enough to outweigh mass gains in East Antarctica and to make the total Antarctic sea level contribution positive.
Flare imaging with multibeam systems: Data processing for bubble detection at seeps
Authors: Schneider von Deimling J. , Brockhoff J. , Greinert J.
Published: June 2007

Multibeam sonar surveys have been conducted since their invention in the 1970s; however, mainly reflections from the seafloor were considered so far. More recently, water column imaging with multibeam is becoming of increasing interest for fisheries, buoy, mooring, or gas detection in the water column. Using ELAC SEABEAM 1000 data, we propose a technique to detect gas bubbles (flares) although this system is originally not designed to record water column data. The described data processing represents a case study and can be easily adapted to other multibeam systems. Multibeam data sets from the Black Sea and the North Sea show reflections of gas bubbles that form flares in the water column. At least for reasonably intense gas escape the detection of bubbles is feasible. The multibeam technique yields exact determination of the source position and information about the dimension of the gas cloud in the water. Compared to conventional flare imaging by single‐beam echo sounders, the wide swath angle of multibeam systems allows the mapping of large areas in much shorter time.
Bid activation during induction of extrinsic and intrinsic apoptosis in eosinophils
Authors: Segal Manav , Niazi Sultan , Simons Michael P , Galati Steven A , Zangrilli James G
Published: June 2007

Eosinophils readily undergo apoptosis when removed from a physiological environment via activation of the intrinsic cell death pathway. This can be further enhanced by certain chemicals (for example, glucocorticoid), or by extrinsic means (that is, Fas receptor engagement). In this investigation, we examined the relative importance of these pathways in cultured human peripheral blood eosinophils in the context of expression and activation of the BH3‐only Bcl2 homologue Bid. Bid activation was examined under conditions where programmed cell death was either stimulated (via Fas engagement or glucocorticoid treatment) or inhibited (interleukin‐5 (IL‐5)) relative to control. Full‐length Bid was found to be highly expressed in eosinophils, and processed to a similar extent during either agonist anti‐Fas or glucocorticoid treatment. IL‐5 blocked intrinsic Bid activation during factor withdrawal or glucocorticoid treatment, and partially attenuated that caused by Fas activation. Caspase 8 (but not caspase 9) antagonism partly but significantly affected receptor‐mediated Bid activation and cell death; these processes were not altered by either caspase inhibitor during simple factor withdrawal or glucocorticoid treatment. Bid processing appears to be central to both intrinsic and extrinsic pathways of cell death in eosinophils. The role of IL‐5 in blocking the intrinsic pathway of eosinophil apoptosis is underscored. Results of specific inhibition support the existence of Bid activation pathways in eosinophils other than those mediated by the classic initiator caspases.
Determination of the phosphorus content in diamond using cathodoluminescence spectroscopy
Authors: Barjon J. , Desfonds P. , Pinault M.-A. , Kociniewski T. , Jomard F. , Chevallier J.
Published: June 2007

In n-type diamond doped with phosphorus, exciton properties have been investigated by cathodoluminescence as a function of the phosphorus concentration and the temperature. The homoepitaxial diamond layers were grown by microwave plasma-assisted chemical vapor deposition and doped using a liquid organic precursor of phosphorus (tertiarybutylphosphine). The phosphorus concentration ranges from 5.2×1016 to 3.3×1018 cm−3 as measured by secondary ion mass spectrometry. It is shown that the ratio between the luminescence intensities of the neutral phosphorus-bound exciton and the free exciton follows the dopant concentration. Calibration graphs are presented to determine the phosphorus contents in diamond using cathodoluminescence spectroscopy.
Cathodoluminescence study of single zinc oxide nanopillars with high spatial and spectral resolution
Authors: Schirra M. , Reiser A. , Prinz G. M. , Ladenburger A. , Thonke K. , Sauer R.
Published: June 2007

Single zinc oxide (ZnO) nanopillars grown by the vapor-liquid-solid process on a-plane sapphire are investigated by spatially resolved cathodoluminescence on the nanometer scale in a scanning electron microscope. Spectra were recorded by exciting luminescence along single pillars and across the underlying wetting layer. Luminescence from the excited pillar spots exhibited sharp bound exciton lines and intrinsic free-exciton recombination, whereas the wetting layer showed only very weak luminescence. Along the pillars, virtually no shift of the lines was observed. This is interpreted as evidence for strain-free growth of the pillars. In the bottom region of the pillars aluminum incorporation from the substrate material was found. There are indications for an incorporation of gallium along the pillars due to unintentional doping introduced by the source material. The spot-resolved results are compared to integral photoluminescence measurements with large-area excitation carried out on the same sample region.
Modeling of multiphase smart hydrogels responding to pH and electric voltage coupled stimuli
Authors: Li Hua , Luo Rongmo , Birgersson Erik , Lam K. Y.
Published: June 2007

A model, entitled the multi-effect-coupling pH-electric-stimuli (MECpHe) model, is presented and analyzed for the response of smart hydrogels to changes in the coupled stimuli of an external electric field and the solution pH. It considers finite deformations, the electric potential and distribution of fixed charge density in the hydrogel and surrounding solvent. The MECpHe model is validated with previously published experimental measurements and good agreement is shown. A steady-state study is carried out for various pH values and applied electric voltages to ascertain the impact of these on the deformation of the hydrogel and distribution of ionic species, electric potential, and fixed charge density, both inside the hydrogel as well as in the surrounding solvent.
Origin of the in-plane alignment transformation on YBa2Cu3Ox liquid-phase epitaxial films affected by the atmosphere environment
Authors: Cai Y. Q. , Tang C. Y. , Sun L. J. , Yao X. , Rao Q. L. , Lai Y. J.
Published: June 2007

The preferential growth phenomenon of the polycrystalline YBa2Cu3Ox seed film deposited on (100) MgO substrate was investigated using liquid phase epitaxy (LPE). The x-ray diffraction and the polarized Raman spectroscope were used to evaluate the in-plane and out-of-plane orientation of as-grown films. It is found that a so-called 45° oriented in-plane alignment preferentially formed under the pure oxygen atmosphere, which is dissimilar to the 0°-oriented grains presenting under the air environment. The mechanism study on the initial stage of REBa2Cu3Ox (REBCO, RE=Y, Nd) LPE growth was performed, in which the morphology evolution shows a breaking coalescence of 45° islands by entrapped fluxes in an intensive manner in the 45° LPE film. The peak around 230 cm−1 in Raman spectrums was detected only in the 45° LPE film, indicating relatively weak grain connectivity, which agrees well with broken coalescence structure. Moreover, a general comparison comprising interfacial terminal layer, oxygen content, geometrical coherence, the minimum energy cut, and experimental results from different REBCO systems was made for comprehensive understanding. It highlights the significance of oxygen content status in choosing the most stable interfacial layer and elucidates the origin of the preferential 45°-oriented growth under pure oxygen condition.
Reactions between CO and small molybdenum suboxide cluster anions
Authors: Wyrwas Richard B. , Robertson Erika M. , Jarrold Caroline Chick
Published: June 2007

Reaction products resulting from small molybdenum suboxide cluster anions and carbon monoxide were studied with both mass spectrometry and anion photoelectron (PE) spectroscopy. In addition to the C6O6− product proposed previously, a number of unsaturated carbonyls were identified as terminal products in these reactions. A new PE spectrum of what may be C6O6−, in which the contribution from the Fe(CO)4− contaminant is subtracted, is reported. Additionally, the PE spectra of Mo(CO)5−, MoO(CO)3−, and MoO2(CO)n− (n=1 and 2) are presented, along with a new PE spectrum of an additional contaminant, Ni(CO)3−. Evidence of photodissociation of MoO(CO)3− to MoO−+3CO is observed in the PE spectrum of MoO(CO)3−.
Synthesis and spectroscopic properties of neodymium doped lead chloride
Authors: Brown E. , Hömmerich U. , Bluiett A. G. , Trivedi S. B. , Zavada J. M.
Published: June 2007

The crystal growth and infrared spectroscopic properties of Nd doped lead chloride (Nd:PbCl2) are reported. Lead halide based materials have recently emerged as laser hosts with low maximum phonon energies. In this work, Nd:PbCl2 crystals were grown by a self-seeded Bridgman technique. Following optical pumping at 750 and 808nm, Nd:PbCl2 exhibited several infrared (IR) emission lines between 800 and 1600nm as well as a broad mid-IR band centered at ∼5.19μm. It was found that for Nd3+ concentrations larger than ∼1×1019cm−3, the mid-IR emission is predominantly due to the transition I11∕24→I9∕24. From a Judd-Ofelt analysis, the radiative quantum efficiency of the 5.19μm emission was determined to be ∼27%. The multiphonon decay rates of several closely spaced Nd3+ transitions were modeled using the well known energy-gap law and the host dependent parameters B and β were determined to be 9.5×109s−1 and 1.26×10−2cm, respectively. The obtained energy-gap law parameters were subsequently used to describe the temperature dependence of the 5.19μm mid-IR emission lifetime for a range from 77to450K.
Exchange bias in Co-Cr2O3 nanocomposites
Authors: Kumar P. Anil , Mandal K.
Published: June 2007

The possibility of using exchange bias in a ferromagnetic-antiferromagnetic system to overcome the effect of superparamagnetism in small ferromagnetic nanoparticles is explored. We have prepared Co-Cr2O3 nanocomposite powders using a chemical method and shown that the effect of superparamagnetism in cobalt nanoparticles could be overcome using exchange bias between Co and Cr2O3. The superparamagnetic blocking temperature of 3 nm cobalt particles has been increased to above room temperature. The choice of Cr2O3 is vital as its TN is higher compared to other antiferromagnetic materials used for this purpose such as CoO. The field cooled and zero field cooled hysteresis measurements of the samples confirm the existence of exchange bias interaction in this system.
Experimental and theoretical investigation of the effects of sample size on copper plasma immersion ion implantation into polyethylene
Authors: Zhang Wei , Wu Zhengwei , Liu Chenglong , Pu Shihao , Zhang Wenjun , Chu Paul K.
Published: June 2007

Polymers are frequently surface modified to achieve special surface characteristics such as antibacterial properties, wear resistance, antioxidation, and good appearance. The application of metal plasma immersion ion implantation (PIII) to polymers is of practical interest as PIII offers advantages such as low costs, small instrument footprint, large area, and conformal processing capability. However, the insulating nature of most polymers usually leads to nonuniform plasma implantation and the surface properties can be adversely impacted. Copper is an antibacterial element and our previous experiments have shown that proper introduction of Cu by plasma implantation can significantly enhance the long-term antibacterial properties of polymers. However, lateral variations in the implant fluence and implantation depth across the insulating substrate can lead to inconsistent and irreproducible antibacterial effects. In this work, the influence of the sample size on the chemical and physical properties of copper plasma-implanted polyethylene is studied experimentally and theoretically using Poisson’s equation and plasma sheath theory. Our results indicate that the sample size affects the implant depth profiles. For a large sample, more deposition occurs in the center region, whereas the implantation to deposition ratio shows less variation across the smaller sample. However, the Cu elemental chemical state is not affected by this variation. Our theoretical study discloses that nonuniform metal implantation mainly results from the laterally different surface potential on the insulating materials due to surface charge buildup and more effective charge transfer near the edge of the sample.
Electrical transport in the copper germanide-n-GaN system: Experiment and numerical model
Authors: Schuette Michael L. , Lu Wu
Published: June 2007

Ultraviolet photoemission measurements of the copper germanide work function and numerical modeling of measured current-voltage data show that the Fermi level at the interface of Cu–Ge films on non-plasma-treated n-GaN cleaned by wet chemicals is pinned near 0.5eV below the conduction band edge, and that 300°C annealing lessens this pinning. Annealing Schottky diode structures at 400–600°C decreases the Cu–Ge∕n-GaN Schottky barrier height and increases electron tunneling through the barrier. Leakage currents are not dominated by edge effects, and are independent of measurement temperature, collectively indicating a tunneling transport mechanism for non-plasma-treated Schottky diodes. A plasma treatment of the GaN surface induces ∼0.5eV of downward near-surface band bending and increases surface oxidation, and these effects are responsible for low-resistance Ohmic behavior. Increased surface doping associated with plasma-treated material, when compared with non-plasma-treated n-GaN, causes greater tunneling due to a thinned depletion layer and reduces the Schottky barrier height through image-force barrier lowering and band gap narrowing. The combination of these two effects causes the I-V behavior of these Cu–Ge contacts to shift from rectifying to Ohmic.
Waveguiding in two-dimensional piezoelectric phononic crystal plates
Authors: Vasseur J. O. , Hladky-Hennion A.-C. , Djafari-Rouhani B. , Duval F. , Dubus B. , Pennec Y. , Deymier P. A.
Published: June 2007

We investigate the possibility of designing phononic crystal-based devices for telecommunication applications using materials commonly employed in microfabrication. We focus our attention on a phononic crystal made of a square array of cylindrical holes drilled in an active piezoelectric PZT5A matrix. Two different structures are considered, namely, a freestanding phononic crystal plate and a plate deposited on a silicon substrate. The geometrical characteristics of the phononic crystal plates (lattice parameter and thickness) were chosen to ensure the existence of an absolute band gap around 1.5GHz; a common frequency in radio frequency telecommunications. Computations of the dispersion curves of these active structures were conducted with the help of the finite element method. We demonstrate the existence of absolute band gaps in the band structure of the phononic crystal plates and, then, the possibility of guided modes inside a linear defect created by removing one row of air holes in the phononic crystal. In the case of the supported phononic crystal plates, we show the existence of an absolute forbidden band in the plate modes when the thickness of the substrate significantly exceeds the plate thickness. We discuss the conditions to realize waveguiding through a linear defect inside the supported plate. The present work provides evidences that phononic crystal properties can be integrated with existing silicon based microdevice technology.
Observation of vibronic emission spectrum of jet-cooled duryl radical in corona excitation
Authors: Lee Gi Woo , Lee Sang Kuk
Published: June 2007

The vibronically excited but jet-cooled 2,4,5-trimethylbenzyl (duryl) radical was formed in a corona excitation from precursor 1,2,4,5-tetramethylbenzene (durene) seeded in a large amount of inert carrier gas helium using a pinhole-type glass nozzle. The vibronically resolved emission spectrum of the jet-cooled duryl radical was recorded, for the first time, with a long path monochromator in the visible region. The spectrum was analyzed to obtain an accurate electronic energy of the D1→D0 transition and vibrational mode frequencies in the ground electronic state by comparing with those of the precursor and those from an ab initio calculation.
Chemical hardness and the discontinuity of the Kohn-Sham exchange-correlation potential
Authors: Gázquez José L. , Garza Jorge , Hinojosa Fernando D. , Vela Alberto
Published: June 2007

Chemical hardness, identified as the difference between the vertical first ionization potential I and the vertical electron affinity A, is analyzed in the context of the ionization theorems to derive expressions for its evaluation at different levels of approximation that arise as a direct consequence of the derivative discontinuity of the exchange-correlation potential. The quantities involved in these expressions incorporate indirectly the effects of the discontinuity, but their values may be calculated with any functional of the local density approximation, generalized gradient approximation, or optimized effective potential type, with or without derivative discontinuity, and with or without the correct asymptotic behavior. By comparison with the vertical energy difference values of I and A, which requires the calculation of the N-, (N−1)-, and (N+1)-electron systems, it is found, for a set of 14 closed shell molecules, that the difference between the eigenvalues of the highest occupied molecular orbitals of the N- and (N+1)-electron systems leads to rather accurate values, when the correct asymptotic behavior is incorporated, and that a second-order one-body perturbation approach that only requires information from the N-electron system leads to reasonable values.
Intrinsic current gain cutoff frequency of 30GHz with carbon nanotube transistors
Authors: Le Louarn A. , Kapche F. , Bethoux J.-M. , Happy H. , Dambrine G. , Derycke V. , Chenevier P. , Izard N. , Goffman M. F. , Bourgoin J.-P.
Published: June 2007

High frequency capabilities of carbon nanotube field-effect transistors (CNTFETs) are investigated. Structures with a large number of single-walled carbon nanotubes were fabricated using dielecrophoresis to increase the density of nanotubes in the device channel. The authors obtained an intrinsic current gain cutoff frequency of 30GHz establishing state-of-the-art high frequency (hf) potentialities of CNTFETs. The device also showed a maximum stable gain above 10dB at 20GHz. Finally, the parameters of an equivalent circuit model of multitube CNTFET at 20GHz are determined, which open the route to the modeling of nanotubes-based hf electronics.
Interface effect on dielectric constant of HfO2∕Al2O3 nanolaminate films deposited by plasma-enhanced atomic layer deposition
Authors: Park Pan Kwi , Cha Eun-Soo , Kang Sang-Won
Published: June 2007

The effect of the interface between Al2O3 and HfO2 sublayers on the dielectric constant was investigated in HfO2∕Al2O3 nanolaminate films deposited using plasma-enhanced atomic layer deposition. After annealing at 700°C, the dielectric constants of the nanolaminate films with a sublayer thickness of 40Å or greater were the same as the calculated values for a series of capacitors consisting of amorphous Al2O3 and monoclinic or tetragonal HfO2. As the sublayer thickness was reduced to 10Å, the dielectric constant increased up to 17.7 because a thin Hf–O–Al mixture layer, of which the number increases drastically in the nanolaminate films with thin sublayers, is formed at the interface.
Separation of coherent and incoherent contributions to reflectance difference spectra
Authors: Schmidegg K. , Zeppenfeld P.
Published: June 2007

The authors present a method for the analysis of azimuthal dependent reflectance difference spectroscopy data that enables a separation of coherent and incoherent contributions to reflectance difference spectra. The latter can originate from back side reflections of transparent films if their thickness is larger than the coherence length of the light. Furthermore, instrument artifacts can be suppressed and additional contributions with different optical eigenaxes can be identified.
Intrinsic dephasing in one-dimensional ultracold atom interferometers
Authors: Bistritzer R. , Altman E.
Published: June 2007

Quantum-phase fluctuations prevent true long-range phase order from forming in interacting 1D condensates, even at zero temperature. Nevertheless, by dynamically splitting the condensate into two parallel decoupled tubes the system can be prepared with a macroscopic relative phase, facilitating interferometric measurement. Here, we describe a dephasing mechanism whereby the quantum-phase fluctuations, which are so effective in equilibrium, act to destroy the macroscopic relative phase that was imposed as a nonequilibrium initial condition. We show that the phase coherence between the condensates decays exponentially with a dephasing time that depends on intrinsic parameters: the interaction strength, sound velocity, and density. Interestingly, significant temperature dependence appears only above a cross-over scale
T
∗. In contrast to the usual phase diffusion, which is essentially an effect of confinement and leads to Gaussian decay, the exponential dephasing caused by fluctuations is a bulk effect that survives the thermodynamic limit.
Major Caribbean and Central American frog faunas originated by ancient oceanic dispersal
Authors: Heinicke Matthew P. , Duellman William E. , Hedges S. Blair
Published: June 2007

Approximately one-half of all species of amphibians occur in the New World tropics, which includes South America, Middle America, and the West Indies. Of those, 27% (801 species) belong to a large assemblage, the eleutherodactyline frogs, which breed out of water and lay eggs that undergo direct development on land. Their wide distribution and mode of reproduction offer potential for resolving questions in evolution, ecology, and conservation. However, progress in all of these fields has been hindered by a poor understanding of their evolutionary relationships. As a result, most of the species have been placed in a single genus,Eleutherodactylus, which is the largest among vertebrates. Our DNA sequence analysis of a major fraction of eleutherodactyline diversity revealed three large radiations of species with unexpected geographic isolation: a South American Clade (393 sp.), a Caribbean Clade (171 sp.), and a Middle American Clade (111 sp.). Molecular clock analyses reject the prevailing hypothesis that these frogs arose from land connections with North and South America and their subsequent fragmentation in the Late Cretaceous (80–70 Mya). Origin by dispersal, probably over water from South America in the early Cenozoic (47–29 million years ago, Mya), is more likely.
Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants
Authors: Fox Jennifer E. , Gulledge Jay , Engelhaupt Erika , Burow Matthew E. , McLachlan John A.
Published: June 2007

Unprecedented agricultural intensification and increased crop yield will be necessary to feed the burgeoning world population, whose global food demand is projected to double in the next 50 years. Although grain production has doubled in the past four decades, largely because of the widespread use of synthetic nitrogenous fertilizers, pesticides, and irrigation promoted by the “Green Revolution,” this rate of increased agricultural output is unsustainable because of declining crop yields and environmental impacts of modern agricultural practices. The last 20 years have seen diminishing returns in crop yield in response to increased application of fertilizers, which cannot be completely explained by current ecological models. A common strategy to reduce dependence on nitrogenous fertilizers is the production of leguminous crops, which fix atmospheric nitrogen via symbiosis with nitrogen-fixing rhizobia bacteria, in rotation with nonleguminous crops. Here we show previously undescribed
in vivo
evidence that a subset of organochlorine pesticides, agrichemicals, and environmental contaminants induces a symbiotic phenotype of inhibited or delayed recruitment of rhizobia bacteria to host plant roots, fewer root nodules produced, lower rates of nitrogenase activity, and a reduction in overall plant yield at time of harvest. The environmental consequences of synthetic chemicals compromising symbiotic nitrogen fixation are increased dependence on synthetic nitrogenous fertilizer, reduced soil fertility, and unsustainable long-term crop yields.
Fragile X mental retardation protein FMRP and the RNA export factor NXF2 associate with and destabilize Nxf1 mRNA in neuronal cells
Authors: Zhang Meiqin , Wang Qiaoqiao , Huang Yingqun
Published: June 2007

Fragile X syndrome is caused by the inactivation of the X-linked
FMR1
gene, leading to the loss of its encoded protein FMRP. Although macroorchidism and defects in neuronal architecture and function have been associated with lack of FMRP, the exact molecular mechanism underlying this disease remains unclear. We have reported previously that in the brain and testis of mice, FMRP specifically interacts with a distinct mRNA nuclear export factor NXF2 but not with its close relative NXF1, a ubiquitously expressed essential mRNA nuclear export factor. This interaction marked NXF2 as a putative functional partner of FMRP. Here, we demonstrate by immunoprecipitation and quantitative real-time RT-PCR that, in cultured mouse neuronal cells, both FMRP and NXF2 are present in Nxf1 mRNA-containing ribonucleoprotein particles. Further, we show that expression of NXF2 leads to the destabilization of Nxf1 mRNA and that this effect is abolished when Fmr1 expression is reduced by siRNA, arguing that both proteins collaborate to exert this effect. Importantly, these findings correlate well with our observations that in both mouse hippocampal neurons and male germ cells where the expression of FMRP and NXF2 is most prominent, the expression of NXF1 is relatively poorly expressed. Our studies thus identify Nxf1 mRNA as a likely biologically relevant
in vivo
target of both FMRP and NXF2 and implicate FMRP, in conjunction with NXF2, as a posttranscriptional regulator of a major mRNA export factor. Such regulation may prove important in the normal development and function of neurons as well as of male germ cells.
Transient climate–carbon simulations of planetary geoengineering
Authors: Matthews H. Damon , Caldeira Ken
Published: June 2007

Geoengineering (the intentional modification of Earth's climate) has been proposed as a means of reducing CO
2
-induced climate warming while greenhouse gas emissions continue. Most proposals involve managing incoming solar radiation such that future greenhouse gas forcing is counteracted by reduced solar forcing. In this study, we assess the transient climate response to geoengineering under a business-as-usual CO
2
emissions scenario by using an intermediate-complexity global climate model that includes an interactive carbon cycle. We find that the climate system responds quickly to artificially reduced insolation; hence, there may be little cost to delaying the deployment of geoengineering strategies until such a time as “dangerous” climate change is imminent. Spatial temperature patterns in the geoengineered simulation are comparable with preindustrial temperatures, although this is not true for precipitation. Carbon sinks in the model increase in response to geoengineering. Because geoengineering acts to mask climate warming, there is a direct CO
2
-driven increase in carbon uptake without an offsetting temperature-driven suppression of carbon sinks. However, this strengthening of carbon sinks, combined with the potential for rapid climate adjustment to changes in solar forcing, leads to serious consequences should geoengineering fail or be stopped abruptly. Such a scenario could lead to very rapid climate change, with warming rates up to 20 times greater than present-day rates. This warming rebound would be larger and more sustained should climate sensitivity prove to be higher than expected. Thus, employing geoengineering schemes with continued carbon emissions could lead to severe risks for the global climate system.
Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts
Authors: Daskalov Georgi M. , Grishin Alexander N. , Rodionov Sergei , Mihneva Vesselina
Published: June 2007

Large-scale transitions between alternative states in ecosystems are known as regime shifts. Once described as healthy and dominated by various marine predators, the Black Sea ecosystem by the late 20th century had experienced anthropogenic impacts such as heavy fishing, cultural eutrophication, and invasions by alien species. We studied changes related to these “natural experiments” to reveal the mechanisms of regime shifts. Two major shifts were detected, the first related to a depletion of marine predators and the second to an outburst of the alien comb jelly
Mnemiopsis leidyi
; both shifts were triggered by intense fishing resulting in system-wide trophic cascades. The complex nature of ecosystem responses to human activities calls for more elaborate approaches than currently provided by traditional environmental and fisheries management. This implies challenging existing practices and implementing explanatory models of ecosystem interactions that can better reconcile conservation and ecosystem management ideals.