bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoluminescence Dating of the Middle Pleistocene Raised Beach of Sangatte (Northern France)
Authors: Balescu Sanda , Packman Susan C. , Wintle Ann G. , Grün Rainer
Published: July 2006

TL dating of both quartz and potassium feldspar grains from the Pleistocene beach of Sangatte, at the southern limit of the North Sea Basin, give self-consistent ages of 200,000 ± 45,000, 205,000 ± 14,000, and 229,000 ± 18,000 years, respectively. These results allow the beach deposits to be correlated with oxygen isotope stage 7 (244,000–190,000 yr) (Martinson et al., 1987). The existence of a fossil beach cliff line at 10 m above French O.D. demonstrates that the Strait of Dover was open during the penultimate interglaciation.
Genetic and ecological effects of salmon farming on wild salmon: modelling from experimental results
Authors: Hindar Kjetil , Fleming Ian A. , McGinnity Philip , Diserud Ola
Published: July 2006

Cultured salmonids are released or escape into the wild in large numbers and may make up significant proportions of wild salmonid populations in fresh- and saltwater, causing considerable concern for the fitness and productivity of these populations. This paper focuses on the effects of escaped farmed Atlantic salmon (Salmo salar) on wild salmon. Farmed salmon have been under artificial selection for growth and other economically important traits for 30 years and are genetically different in their origin at the molecular and quantitative genetic levels. Escaped farmed salmon spawn in the wild with limited success. Their offspring outgrow those of wild origin but suffer higher mortality. Whole-river experiments in Ireland and Norway have shown that the lifetime success of farmed salmon is reduced relative to wild salmon. Based on data from these experiments, we model the future of wild salmon populations experiencing invasions of escaped farmed salmon. Simulations with a fixed intrusion rate of 20% escaped farmed salmon at spawning suggest that substantial changes take place in wild salmon populations within ten salmon generations (∼40 years). Low-invasion scenarios suggest that farmed offspring are unlikely to become established in the population, whereas high-invasion scenarios suggest that populations are eventually mixtures of hybrid and farmed descendants. Recovery of the wild population is not likely under all circumstances, even after many decades without further intrusion. Managers of wild salmon will have difficulty in obtaining broodstock of the original wild population after a few generations of high intrusion. We conclude that further measures to reduce escapes of farmed salmon and their spawning in wild populations are urgently needed.
Sex trafficking in South Asia
Authors: Huda S.
Published: July 2006

Economic and social inequalities and political conflicts have led to the movement of persons within each country and across the borders in South Asia. Globalization has encouraged free mobility of capital, technology, experts and sex tourism. Illiteracy, dependency, violence, social stigma, cultural stereotypes, gender disparity and endemic poverty, among other factors, place women and children in powerless, non‐negotiable situations that have contributed to the emergence and breeding of the cavernous problem of sex trafficking in the entire region. This alarming spread of sex trafficking has fuelled the spread of HIV infection in South Asia, posing a unique and serious threat to community health, poverty alleviation and other crucial aspects of human development. Although the SAARC (South Asian Association for Regional Cooperation) Convention on Trafficking in Women and Children has been an important breakthrough, most of the countries in the region do not have anti‐trafficking legislation or means to protect the victims. Countries of the region should make a concerted effort to treat trafficking victims as “victims” of human rights violations in all anti‐trafficking strategies and actions.
The mid-Holocene sea-level highstand at Bogenfels Pan on the southwest coast of Namibia
Authors: Compton John S.
Published: July 2006

The radiocarbon ages of mollusc shells from the Bogenfels Pan on the hyper arid southern coast of Namibia provide constraints on the Holocene evolution of sea level and in particular, the mid-Holocene highstand. The Bogenfels Pan was flooded to depths of 3 m above mean sea level (amsl) to form a large subtidal lagoon from 7300 to 6500 calibrated radiocarbon years before present (cal yr BP). The mollusc assemblage of the wave sheltered lagoon includes Nassarius plicatellus, Lutraria lutraria, and the bivalves Solen capensis and Gastrana matadoa, both of which no longer live along the wave-dominated southern Namibian coast. The radiocarbon ages of mollusc shell from a gravely beach deposit exposed in a diamond exploration trench indicate that sea level fell to near or 1 m below its present-day position between 6500 and 4900 cal yr BP. The rapid emergence of the pan between 6500 and 4900 cal yr BP exceeds that predicted by glacio-isostatic models and may indicate a 3-m eustatic lowering of sea level. The beach deposits at Bogenfels indicate that sea level rose to 1 m amsl between 4800 and 4600 cal yr BP and then fell briefly between 4600 and 4200 cal yr BP before returning to 1 m amsl. Since 4200 cal yr BP sea level has remained within one meter of the present-day level and the beach at Bogenfels has prograded seaward from the delayed arrival of sand by longshore drift from the Orange River. A 6200 cal yr BP coastal midden and a 600 cal yr BP midden 1.7 km from the coast indicate sporadic human utilization of the area. The results of this study are consistent with previous studies and help to refine the Holocene sea-level record for southern Africa.
Stratigraphic evidence for multiple drainings of glacial Lake Missoula along the Clark Fork River, Montana, USA
Authors: Smith Larry N.
Published: July 2006

Glacial Lake Missoula, a source of Channeled Scabland flood waters, inundated valleys of northwest Montana to altitudes of ∼ 1265 m and to depths of >600 m, as evidenced by shorelines and silty lacustrine deposits. This study describes previously unrecognized catastrophic lake-drainage deposits that lie stratigraphically beneath the glacial-lake silts. The unconsolidated gravelly flood alluvium contains imbricated boulder-sized clasts, cross-stratified gravel with slip-face heights of 2–> 35 m, and 70- to 100-m-high gravel bars which all indicate a high-energy, high-volume alluvial environment. Gravel bars and high scablands were formed by catastrophic draining of one or possibly more early, high lake stands (1200–1265 m). Most glacial-lake silt, such as the Ninemile section, was deposited stratigraphically above the earlier deposits, represents a lower lake stand(s) (1050–1150 m), and was not deposited in lake(s) responsible for the highest discharge events. The glaciolacustrine silt-covered benches are incised by relict networks of valleys formed during the drainage of the last glacial lake. Significant erosion associated with the last lake draining was confined to the inner Clark Fork River canyon.
Defining and classifying occupational rhinitis
Authors: Castano R , Thériault G
Published: July 2006

Three categories of rhinitis may occur in the workplace: occupational rhinitis, work-aggravated rhinitis and rhinitis-like conditions. In the present paper, we propose a new definition and a new classification of occupational rhinitis that takes into account mechanisms of induction as well as clinical presentation. In parallel with occupational asthma, occupational rhinitis is defined as a type of rhinitis characterized by intermittent or sometimes permanent nasal airflow limitation due to causes and conditions attributable to the work environment. Occupational rhinitis is classified according to its mechanism of induction as immunological or irritant-induced (non-immunological) rhinitis. Occupational rhinitis of the immunological type can itself be episodic or persistent, whereas the non-immunological type is subdivided into acute, chronic and corrosive.
Intratympanic gentamicin treatment in Meniere's disease: Patients' experiences and outcomes
Authors: Smith W K , Sandooram D , Prinsley P R
Published: July 2006

Objective: The aim of this study was to assess the experiences and outcomes of patients receiving intratympanic gentamicin treatment for Ménière's disease in Norfolk, UK.

Design: This study was based on a retrospective questionnaire survey and a review of patients' medical records.

Setting: Two district hospitals.

Participants: All 29 patients treated between 1999 and 2001, with a minimum follow up of two years post-treatment, were included in the study. Twenty-three patients completed the questionnaires (79 per cent response rate).

Main outcome measures: Glasgow benefit inventory (GBI) and vertigo symptom scale (VSS) scores, plus change in hearing thresholds.

Results: The mean GBI total score was +36, indicating substantial improvement in patients' overall quality of life following gentamicin treatment. The VSS scores demonstrated low levels of vertigo or unsteadiness in treated patients. Three patients suffered deterioration in their hearing thresholds following a single injection of gentamicin. However, 96 per cent of responders stated that they would be willing to have such treatment again, if necessary.

Conclusion: Intratympanic gentamicin treatment ought to be offered to Ménière's patients suffering from disabling vertigo, with the proviso that they be made aware of the possibility of hearing deterioration.
Revolution and the Ritual Year: Religious Conflict and Innovation in Cristero Mexico
Authors: BUTLER MATTHEW
Published: July 2006

This article analyses Catholic responses to persecution of the Church by the Mexican state during Mexico's cristero rebellion (1926–9) and seeks to make a new contribution to the revolt's religious history. Faced with the Calles regime's anticlericalism, the article argues, Mexico's episcopate developed an alternative cultic model premised on a revitalised lay religion. The article then focuses on changes and continuities in lay – clerical relations, and on the new religious powers of the faithful, now empowered to celebrate ‘white’ masses and certain sacraments by themselves. The article concludes that persecution created new spaces for lay religious participation, showing the 1910–40 Revolution to be a period of religious, as well as social, upheaval.
Environmental Governance in Mexico: Two Case Studies of Oaxaca's Community Forest Sector
Authors: MITCHELL ROSS E.
Published: July 2006

This article recognises the paucity of scholarly work on environmental governance in Latin America. More specifically, it is hypothesised that community-based forest management in Mexico serves as an ideal case of ecologically beneficial and democratic decision-making, or ecological democracy. After introducing some of the relevant literature, this hypothesis is tested through a comparison of two indigenous forest-based communities in Oaxaca's Sierra Norte. Four key themes primarily emerged from semi-structured interviews, participant observation and other data collection techniques: local governance, equitable decision-making, forest management and environmental awareness. In comparing these two Mexican communities, this article aims to extend ideas of ecological democracy by linking empirical findings to political ecology theory and community forestry literature. While it is true that ecological democracy in Mexico has been facilitated under certain socio-cultural conditions, it is concluded that it can be simultaneously hindered. The empirical findings provide an analytical framework for subsequent research on ecological democracy in Latin America.
Interactions between land use/land cover change, forest fires and landscape structure in Sierra de Gredos (Central Spain)
Authors: VIEDMA OLGA , MORENO JOSÉ M. , RIEIRO IGNACIO
Published: July 2006

In fire-prone areas, like the Mediterranean, land abandonment and forestation may interact with fire to alter landscape properties and eventually fire hazard and occurrence. However, the spatial interactions among the two processes (land-use/land cover change [LULC] and fire) are poorly known. Here, we analysed the relative effect of LULC change and fire on the landscape structure of an area of Central Spain frequently affected by fire. A series of Landsat MSS images from 1975 to 1990 was analysed to quantify annual changes in LULC, map fire perimeters and evaluate the changes in landscape properties. The temporal dynamics were analysed by annually computing the fraction occupied by each LULC type and landscape structural properties (number, size, shape and arrangement of patches) that might play a role in fire propagation. All of these were calculated separately for the unburned or the burned areas during the study period, as well as for the entire area. At the whole landscape level, or in the unburned area, LULC changes were small, yet the two more flammable LULC types tended to increase, and the landscape tended to become more homogeneous. In the burned area, the area covered by pine woodlands tended to decrease, and that covered by shrublands to increase. Burned areas turned into shrublands only five years after fire. Landscape indices indicative of reduced fragmentation were also found. Both LULC change and fire altered landscape patterns in the whole area to create a less fragmented and more contiguous landscape than in 1975. The changes induced in the whole landscape by fire, in spite of the overall low disturbance rate, were sufficient to closely determine the changes in landscape composition (LULC types) and patterns.
Langfristige Förderung von Fähigkeitsselbstkonzept und impliziter Fähigkeitstheorie durch computerbasiertes attributionales Feedback
Authors: Dresel Markus , Ziegler Albert
Published: July 2006

Zusammenfassung. Es wird ein computerbasierter Interventionsansatz zur Förderung von Fähigkeitsselbstkonzept und impliziter Fähigkeitstheorie vorgestellt, der auf der Darbietung von attributionalem Feedback basiert. Untersucht wurden N = 140 Schüler der 7. Jahrgangsstufe, die mit einer Mathematiklernsoftware arbeiteten, die attributionales Feedback generiert und nach der Bearbeitung von Aufgaben präsentiert. Neben einer Placebogruppe wurden drei Bedingungen realisiert, in denen nach Erfolgen Fähigkeits- und Anstrengungsattributionen in verschiedener Kombination dargeboten wurden. Als geeignet zur nachhaltigen Förderung von Fähigkeitsselbstkonzept und impliziter Fähigkeitstheorie erwies sich vor allem die Sequenz, bei der Erfolge erst auf hohe Anstrengungen und später auf hohe Fähigkeiten attribuiert wurden. Mediiert über diese Fördereffekte wurden positive Veränderungen bei Kontrollüberzeugungen und Hilflosigkeit erzielt. Eine verzögerte Trainingswirkung konnte bei der Schulleistung beobachtet werden.
Fähigkeitsselbstkonzepte
Authors: Dickhäuser Oliver
Published: July 2006

Zusammenfassung. Fähigkeitsselbstkonzepte sind ein bedeutender Untersuchungsgegenstand der Pädagogischen Psychologie. In diesem Artikel werden relevante Strukturmodelle des Selbstkonzepts sowie Modelle der Selbstkonzeptgenese beschrieben und Lücken der bisherigen Selbstkonzeptforschung dargestellt. Der Artikel zeigt, wie die Beiträge in diesem Themenschwerpunktheft diese Forschungslücken zu schließen versuchen.
Der “Saisonarbeiter” - genauer betrachtet
Authors: Mischo Christoph
Published: July 2006

Zusammenfassung. Diese Studie knüpft an eine frühere Untersuchung an, in der das häusliche Arbeitsverhalten im Fach Latein untersucht wurde und in der das diskontinuierliche Arbeitsverhalten der schlechten Schüler (“Saisonarbeiter”) auf motivationale Defizite zurückgeführt worden war. In der nun vorliegenden Studie wurden die Motivation und das häusliche Arbeitsverhalten (Hausaufgabenzeit vs. zusätzliche Lernzeit) im Fach Englisch differenzierter und über einen Zeitraum von drei Wochen vor einer Klassenarbeit mit einem Tagebuch erfasst. An der Studie nahmen 103 Schülerinnen und Schüler der Klassen sieben bis neun teil. Eine Clusteranalyse führte sowohl für die Hausaufgabenzeit als auch für die zusätzliche Lernzeit zu je zwei Verlaufstypen (Saisonarbeiter vs. kontinuierliche Arbeiter), wobei sich nur die Verlaufstypen der zusätzlichen Lernzeit in den Schulleistungen und in motivationalen Variablen unterschieden. Diese Unterschiede zeigten auffallende Ähnlichkeiten mit dem Konstrukt der motivationalen Orientierungen/Zielorientierungen. Zusätzlich durchgeführte individuelle Wachstumsanalysen ergaben einen Effekt der Handlungsorientierung und der persönlichen Wichtigkeit der Klassenarbeit auf die tägliche Lernzeit, wobei der Einfluss der persönlichen Wichtigkeit mit dem Herannahen der Klassenarbeit zunahm.
P and S velocity structure of the upper mantle beneath the Transantarctic Mountains, East Antarctic craton, and Ross Sea from travel time tomography
Authors: Watson Timothy , Nyblade Andrew , Wiens Douglas A. , Anandakrishnan Sridhar , Benoit Margaret , Shore Patrick J. , Voigt Donald , VanDecar John
Published: July 2006

P and S wave travel times from teleseismic earthquakes recorded by the Transantarctic Mountains Seismic Experiment (TAMSEIS) have been used to tomographically image upper mantle structure beneath portions of the Transantarctic Mountains (TAM), the East Antarctic (EA) craton, and the West Antarctic rift system (WARS) in the vicinity of Ross Island, Antarctica. The TAM form a major tectonic boundary that divides the stable EA craton and the tectonically active WARS. Relative arrival times were determined using a multichannel cross‐correlation technique on teleseismic P and S phases from earthquakes with mb ≥ 5.5. 3934 P waves were used from 322 events, and 2244 S waves were used from 168 events. Relative travel time residuals were inverted for upper mantle structure using VanDecar's method. The P wave tomography model reveals a low‐velocity anomaly in the upper mantle of approximately δVp = −1 to −1.5% in the vicinity of Ross Island extending laterally 50 to 100 km beneath the TAM from the coast, placing the contact between regions of fast and slow velocities well inland from the coast beneath the TAM. The magnitude of the low‐velocity anomaly in the P wave model appears to diminish beneath the TAM to the north and south of Ross Island. The depth extent of the low‐velocity anomaly is not well constrained, but it probably is confined to depths above ∼200 km. The S wave model, within resolution limits, is consistent with the P wave model. The low‐velocity anomaly within the upper mantle can be attributed to a 200–300 K thermal anomaly, consistent with estimates obtained from seismic attenuation measurements. The presence of a thermal anomaly of this magnitude supports models invoking a thermal buoyancy contribution to flexurally driven TAM uplift, at least in the Ross Island region of the TAM. Because the magnitude of the anomaly to the north and south of Ross Island may diminish, the thermal contribution to the uplift of the TAM could be variable along strike, with the largest contribution in the Ross Island region. The tomography results reveal faster than average velocities beneath East Antarctica, as expected for cratonic upper mantle.
Shortwave radiative closure studies for clear skies during the Atmospheric Radiation Measurement 2003 Aerosol Intensive Observation Period
Authors: Michalsky J. J. , Anderson G. P. , Barnard J. , Delamere J. , Gueymard C. , Kato S. , Kiedron P. , McComiskey A. , Ricchiazzi P.
Published: July 2006

The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large aerosol intensive observation period (AIOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this AIOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear‐sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar‐zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are in the worst case 1%, and biases between modeled and measured diffuse irradiances are less than 1.9%.
Geochemistry of rainfall at Stromboli volcano (Aeolian Islands): Isotopic composition and plume‐rain interaction
Authors: Liotta M. , Brusca L. , Grassa F. , Inguaggiato S. , Longo M. , Madonia P.
Published: July 2006

The chemical and isotopic compositions of the precipitation at Stromboli Island, Italy, were investigated between October 2003 and October 2005. We employed a rain gauge network designed to cover the range in exposures and elevations of the volcanic edifice. The hydrogen and oxygen isotopic ratios vary greatly on a seasonal basis and correlate with air temperature. Deuterium excess values show a positive correlation with altitude. No direct contribution of volcanogenic H or O is evident in the isotopic composition of the rainwater. The chemical composition of the rainwater is principally controlled by the sea aerosol contribution at the coastal sites, whereas it is significantly influenced by volcanic activity near the summit vents. Interaction with volcanic acid gases is indicated by the pH, which is usually 1–2 units lower near the craters than at the coastal sites. The S/Cl, Cl/F, and S/F molar ratios in rainwater 1.5 km from the craters are consistent with those measured in the volcanic plume using other methods (diffusive tubes and Fourier transform infrared spectroscopy). Rising of undegassed magmas changes these molar ratios because of the differential degassing of sulphur, chlorine, and fluorine from the magma. We therefore propose that the chemical composition of precipitation, within 1.5 km of the craters, provides additional information that is useful for monitoring volcanic activity at Stromboli Island. Moreover, this paper presents estimates of the fluxes of F, Cl, S, Na, K, Ca, and Mg to the soil that could be useful for geochemical studies on groundwater.
Role of plasma waves in Mars' atmospheric loss
Authors: Ergun R. E. , Andersson L. , Peterson W. K. , Brain D. , Delory G. T. , Mitchell D. L. , Lin R. P. , Yau A. W.
Published: July 2006

Recent observations of plasma waves, electron fluxes, and ion fluxes in Mars' ionosphere indicate that ion heating may have had a significant impact on Mars' atmospheric loss. We discuss two energy sources of plasma waves: the solar wind interaction with Mars and field‐aligned currents in regions of crustal magnetic fields. These plasma waves can damp through cyclotron resonance with the O+ population in the ionosphere leading to heating and subsequent O+ escape supporting the ∼1025 atoms s−1 (∼0.4 kg/s) O+ outflow indicated by present‐day observations. A stronger solar wind and O+ source of ∼4 Gyr ago could support losses of ∼100 kg/s, enough to strip Mars' atmosphere or 10 m of water in a ∼0.3 Gyr period. The observational evidence for ion heating is, with current data sets, largely circumstantial so we suggest needed observations.
Interannual variability of the South China Sea throughflow inferred from wind data and an ocean data assimilation product
Authors: Wang Dongxiao , Liu Qinyan , Huang Rui Xin , Du Yan , Qu Tangdong
Published: July 2006

The Luzon Strait transport, as an index for the South China Sea throughflow, has attracted much attention recently. In this study the interannual variability of Luzon Strait transport is examined, using the Island Rule and results from ocean data assimilation. Transport variability obtained from these two approaches is consistent with each other. Assessment of contribution from each integral segment involved in the Island Rule indicates that wind stress in the western and central equatorial Pacific is the key factor regulating the interannual variability of the Luzon Strait transport, whereas the effect of local wind stress in the vicinity of the Luzon Strait is secondary. Analysis also shows that when the westerly (easterly) wind anomalies in the tropical Pacific break out, the Luzon Strait transport increases (decreases), associated with the variations in the North Equatorial Current during El Niño (La Niña) events.
Low frequency variation of sea surface salinity in the tropical Atlantic
Authors: Grodsky Semyon A. , Carton James A. , Bingham Frederick M.
Published: July 2006

Examination of the observational record suggests that the near‐surface waters in the tropical Atlantic underwent a major salinification during the twenty‐five year period 1960–1985 at a rate of 0.1 psu/decade. A reversal of this trend has occurred during the most recent decade. While year‐to‐year changes in salinity are related to precipitation, we attribute decadal changes in salinity at least in part to low frequency changes of winds in the deep tropics and their role in altering both upwelling and possibly, evaporation rates.
An Independent Component Analysis Approach for Minimizing Effects of Recirculation in Dynamic Susceptibility Contrast Magnetic Resonance Imaging
Authors: Wu Yang , An Hongyu , Krim Hamid , Lin Weili
Published: July 2006

In dynamic susceptibility contrast (DSC) perfusion-weighted imaging, effects of recirculation are normally minimized by a gamma-variate fitting procedure of the concentration curves before estimating hemodynamic parameters. The success of this method, however, hinges largely on the extent to which magnetic resonance signal is altered in the presence of a contrast agent and a temporal separation between the first and subsequent passages of the contrast agent. Moreover, important physiologic information might be compromised by imposing an analytic equation to all measured concentration curves. This investigation proposes to exploit independent component analysis to minimize effects of recirculation in DSC. Results obtained from simulation, normal healthy volunteers, and acute stroke patients show that such a technique can greatly minimize the effects of recirculation despite a substantial overlap between the first passage and recirculation. This in turn should improve estimation of cerebral hemodynamics particularly when an overlap between the first passage and recirculation is suspected as in an ischemic lesion.
Matrix Metalloproteinase-Mediated Disruption of Tight Junction Proteins in Cerebral Vessels is Reversed by Synthetic Matrix Metalloproteinase Inhibitor in Focal Ischemia in Rat
Authors: Yang Yi , Estrada Eduardo Y , Thompson Jeffrey F , Liu Wenlan , Rosenberg Gary A
Published: July 2006

Matrix metalloproteinases (MMPs) disrupt the blood—brain barrier (BBB) during reperfusion. Occludin and claudins are recently described tight junction proteins (TJPs) that form the BBB. We hypothesized that the opening of the BBB was because of the degradation of TJPs by the MMPs. Spontaneously hypertensive rats had a 90 mins middle cerebral artery occlusion with reperfusion for 2, 3, or 24 h. Matrix metalloproteinases were measured by immunohistochemistry and in situ and gel zymography. Real-time polymerase chain reaction (PCR) measured mRNAs of MMP-2 and −9, furin, membrane-type MMP (MT1-MMP), occludin, and claudin-5. There was opening of the BBB in the piriform cortex after 3 h of reperfusion, and an MMP inhibitor, BB-1101 (30 mg/kg), prevented the opening. At 3 h, in situ zymograms showed gelatinase activity. Zymography and PCR showed greater increases in MMP-2 than in MMP-9. There were increased mRNA and immunohistochemistry for MT1-MMP and furin, which activate MMP-2. Claudin-5 and occludin mRNA expression decreased at 2 h in both hemispheres with fragments of both proteins seen on Western blot by 3 h on the ischemic side; treatment with BB-1101 reversed the degradation of the TJPs. Immunohistochemistry at 3 h showed fragmented TJPs within the endothelial cell clefts. By 24 h, in situ zymography showed gelatinase activity and gel zymography showed elevated levels of MMP-9. Disrupted TJPs previously seen in endothelial cells appeared in the surrounding astrocytes. Our results provide direct evidence that MMPs open the BBB by degrading TJPs and that an MMP inhibitor prevents degradation of the TJPs by MMPs.
Pure germanium nitride formation by atomic nitrogen radicals for application to Ge metal-insulator-semiconductor structures
Authors: Maeda Tatsuro , Yasuda Tetsuji , Nishizawa Masayasu , Miyata Noriyuki , Morita Yukinori , Takagi Shinichi
Published: July 2006

We have investigated the nitridation of germanium using atomic nitrogen radicals generated by a remote rf plasma source. Pure amorphous Ge3N4 films without oxygen are obtained by the direct nitridation of clean Ge substrates. The conformal growth with smooth surface and sharp interface can be achieved in the Ge3N4 films grown at 100°C, where the maximum thickness of the Ge3N4 films is approximately 3nm. While the surfaces of the Ge3N4 films are partially oxidized by the exposure to air, the Ge3N4 films exhibit the high resistance against oxygen diffusion. The Ge3N4 films are water insoluble and soluble in HF. These results demonstrate that pure direct nitridation of Ge substrates has a possibility to be used not only as a passivation layer but also as a diffusion barrier layer against oxygen for Ge metal-insulator-semiconductor field effect transistor applications.
Dielectric constant of particles determined by impedance spectroscopy
Authors: Petrovsky Vladimir , Manohar Abhishek , Dogan Fatih
Published: July 2006

Electrical characterization of slurries prepared by mixing dielectric powders with solvents can be used to estimate dielectric properties of the particles. In particular, dielectric constant of the particles can be calculated from effective dielectric constant of the slurry measured at high frequency by using the Lorentz-Lorenz or similar equations based on mixing rules. Unfortunately, this approach leads to high margin of errors in dielectric constant estimation and is very sensitive to any slurry nonidealities such as sedimentation or agglomeration of particles. Impedance spectroscopy techniques are introduced to measure dielectric properties of particles at different frequency ranges. Dielectric constant of strontium titanate particles, suspended in butoxyethanol, was determined reproducibly by impedance spectroscopy using an appropriate equivalent circuit model.
Interface structure and thermal stability of epitaxial SrTiO3 thin films on Si (001)
Authors: Goncharova L. V. , Starodub D. G. , Garfunkel E. , Gustafsson T. , Vaithyanathan V. , Lettieri J. , Schlom D. G.
Published: July 2006

We have used medium energy ion scattering, temperature programmed desorption, and atomic force microscopy to study the interface composition and thermal stability of epitaxial strontium titanate thin films grown by molecular-beam epitaxy on Si (001). The composition of the interface between the film and the substrate was found to be very sensitive to the recrystallization temperature used during growth, varying from a strontium silicate phase when the recrystallization temperature is low to a Ti-rich phase for a higher recrystallization temperature. The films are stable towards annealing in vacuum up to ∼550°C, where SrO desorption begins and the initially flat film starts to roughen. Significant film disintegration occurs at 850°C, and is accompanied by SiO and SrO desorption, pinhole formation, and finally titanium diffusion into the silicon bulk.
Mechanically induced crystallization of an amorphous CoFeZrB alloy
Authors: Bednarčík J. , Burkel E. , Saksl K. , Kollár P. , Roth S.
Published: July 2006

The short-time (12h) ball milling of the amorphous Co56Fe16Zr8B20 (at. %) alloy resulted in the formation of bcc-Fe nanocrystals embedded in an amorphous matrix. X-ray diffraction (XRD) using synchrotron radiation, differential scanning calorimetry (DSC), vibrating sample magnetometery (VSM), and the Faraday magnetic balance experiments were used to characterize the materials. XRD and DSC show that the fraction of crystallized bcc-Fe gradually increases with the milling time. The VSM measurements confirm the structure observations showing that the saturation magnetization increases with the milling time as the fraction of crystallized bcc-Fe increases. After 12h of milling, the powder sample exhibited a Curie temperature of the amorphous phase TCam, which is approximately 55K higher compared to the as-quenched ribbon (TCam=601K). Thermomagnetic measurements of heat-treated ribbons suggest that such an increase in TCam is not only due to temperature rises during the milling but may also be attributed to the combination of mechanical and thermal effects connected with the nature of milling.
Low-field electrical and thermal transport in lattice-mismatched n-GaN grown on sapphire: Two-layer model calculations
Authors: Shrestha S. , Sarkar C. K. , Chakraborty A.
Published: July 2006

Gallium nitride (GaN) is an important material but it is not found in bulk crystalline form. Therefore it is grown on different substrates. Due to the lattice mismatch between GaN and the substrate, a highly conducting and dislocated interfacial layer is formed near the interface. Assuming that the lattice-mismatched GaN is made of two layers, the layer close to the interface, having a large number of dislocations, is called interfacial layer and the layer far from the interface, having very few dislocations, is known as bulk layer. Considering a two-layer model for GaN grown on sapphire, temperature-dependent various low-field electrical and thermal transport parameters such as mobility, Seebeck coefficient, thermal conductivity due to electron, and the thermoelectric figure of merit of n-GaN are calculated. In our model, various low- and high-temperature scattering mechanisms in the bulk layer and only the dislocation scattering mechanism in the interfacial layer is considered to calculate the above transport parameters. Our results of conductivity and Seebeck coefficient are also found to agree reasonably well with the experimental data when we consider the interfacial layer having the thickness as equal as that of the bulk layer, i.e., the thickness ratio is equal to 1:1. Hence, it is concluded that in order to calculate low field transport parameters of lattice-mismatched GaN the two-layer model is quite suitable. Furthermore, the inclusion of the interfacial layer is very important for the evaluation of electrical and thermal transport parameters. The thermoelectric figure of merit for GaN has been studied to assess its capability as thermoelectric devices. The figure of merit is found to increase with temperature and is also found to have higher value for thickness ratio 1:1 as compared to that of 24:1.
Influence of lattice volume on magnetic states of Ce2Fe16MnDy compounds (y=,1,2.3)
Authors: Prokhnenko O. , Arnold Z. , Kuchin A. , Ritter C. , Isnard O. , Kamarád J. , Iwasieczko W. , Drulis H.
Published: July 2006

The substitution of Mn for Fe in Ce2Fe17 suppresses its ferromagnetic ground state completely for Mn contents x⩾0.5Mn∕f.u. Ce2Fe16Mn has only an antiferromagnetic phase (incommensurate helix along c axis) below TN=198K. In this paper, we present and discuss the effects of deuterium insertion (that can be considered as an application of negative chemical pressure) on the magnetostructural properties of Ce2Fe16Mn. Application of (positive) high pressures up to 10kbar on Ce2Fe16MnDy deuterides (y=1,2.3) allowed us to estimate the role of lattice volume and to divide it from the role of modified electronic band structure that both determines the magnetic states of the deuterated compounds. The results show that a ferromagnetic phase is stabilized by the insertion of D into the antiferromagnetic Ce2Fe16Mn. The Curie temperature TC of Ce2Fe16MnDy deuterides increases with increasing D content reaching TC=258K for y=2.3 and remarkably decreases with pressure dTC∕dP=−5.4K∕kbar and dTC∕dP=−3.6K∕kbar for Ce2Fe16MnD1 and Ce2Fe16MnD2.3, respectively. Significant difference between the magnetization of Ce2Fe16MnD1 under pressure and the one of the parent compound at ambient pressure indicates that changes of the volume alone cannot determine the magnetic states upon the initial deuteration. However, the volume expansion becomes dominant when increasing the deuterium content up to 2.3D∕f.u.
Vertically integrated optics for ballistic electron emission luminescence: Device and microscopy characterizations
Authors: Yi Wei , Appelbaum Ian , Russell Kasey J. , Narayanamurti Venkatesh , Schalek Richard , Hanson Micah P. , Gossard Arthur C.
Published: July 2006

By integrating a p-i-n photodiode photodetector directly into a ballistic electron emission luminescence (BEEL) heterostructure with GaAs quantum-well active region, we have obtained a photon detection efficiency of more than 10%. This is many orders of magnitude higher than conventional far-field detection scheme with the most sensitive single-photon counters, enabling BEEL microscopy in systems with no optical components. Detailed analysis shows found a parasitic bipolar injection in parallel with the desired optical coupling between the BEEL heterostructure and the integrated photodiode beyond a characteristic collector bias, which may be solved by improved device design or limiting the operating window of the collector bias. Preliminary BEEL microscopy images of a homogeneous GaAs quantum-well luminescent layer show lateral variations of photon emission correlated with the collector current injection level modulated by surface features or interface defects.
Kinetic roughening during vapor deposition of polymer films: A Monte Carlo study
Authors: Vree C. , Mayr S. G.
Published: July 2006

Surface evolution during the vapor deposition of chainlike model polymers onto a substrate is investigated with the help of Monte Carlo simulations. Polymer chains are deposited as linear chains of inseparably bonded particles and subsequently relax via a reptation type of dynamics. We investigate the impact of processing parameters on kinetic roughening and find a crossover from single particle behavior to continuous growth behavior in early growth stages. The continuous growth behavior is characterized by a growth exponent β=0.20±0.02 and a roughness exponent α=0.38±0.02 for most preparation conditions. In the high thickness regime a strong roughening and concurrent structural change of morphologies is observed.
Microwave dielectric relaxation in cubic bismuth based pyrochlores containing titanium
Authors: Wang Hong , Kamba Stanislav , Du Huiling , Zhang Meiling , Chia Chih-Ta , Veljko S. , Denisov S. , Kadlec F. , Petzelt Jan , Yao Xi
Published: July 2006

Cubic pyrochlore (Bi1.5Zn0.5)(Zn0.5−x∕3TixNb1.5−2x∕3)O7 ceramics with 0⩽x⩽1.5 were synthesized and investigated between 100Hz and 100THz by means of broadband dielectric spectroscopy, time-domain terahertz transmission spectroscopy, Fourier transform infrared reflectivity spectroscopy and Raman scattering. Bi1.5ZnNb1.5O7 exhibits a microwave dielectric relaxation which slows down and broadens remarkably on cooling. Careful structural investigations confirmed that the relaxation originates in hopping of disordered Bi and part of Zn atoms in the A sites of the pyrochlore structure. Substitution of Ti atoms to the B sites, i.e., increasing x, results in an increase of the microwave permittivity from 150 to 200 of the relaxation frequency and also of the microwave quality Q. Low temperature Raman scattering experiments did not reveal any phase transition in the samples under study.
Pressure- and temperature-induced phase transition in the B–C system
Authors: Zinin P. V. , Ming L. C. , Kudryashov I. , Konishi N. , Manghnani M. H. , Sharma S. K.
Published: July 2006

A direct transformation from the g-BC1.6 phase to a diamondlike BC1.6 phase was obtained in a diamond-anvil cell at high temperature, 2230±140K, and high pressure, 45GPa. Such a transition has not been observed in the B–C system before. The recovered samples were examined using both synchrotron-based x-ray diffraction and confocal micro-Raman spectroscopy at ambient conditions. The lattice parameter of the diamondlike phase (3.5745Å) is close to that of diamond. The measured visible laser-excited Raman spectra of a diamondlike BC1.6 phase reveal a peak at 1315cm−1 which is attributed to the LO mode. It is also found that the orthorhombic/hexagonal phase was formed under high pressure in the areas where heating was not enough to make transformation in the cubic phase.
The Stark effect on excitons in a bilayer system
Authors: Wang Li , Li Shu-Shen
Published: July 2006

The Stark effect on excitons in a bilayer system is investigated theoretically within the framework of the effective-mass approximation. The calculations indicate that the energy of the excitons decreases as the value of the in-plane electric field F increases at a fixed value of the distance d between the layers. However, the energy of the excitons increases with d at a fixed value of F. In particular, it increases linearly at small values of d but increases as 1∕d at large values. Therefore, it can be concluded that excitons in a bilayer system have a small binding energy equal to the absolute value of the excitonic energy at large d or small F. In addition, the radiative lifetime of heavy-hole excitons in this system is calculated and is found to be short at small values of both F and d. The radiative lifetime of heavy-hole excitons in a bilayer system can be increased by two orders by an in-plane electric field of 2kV∕cm when d is twice the excitonic Rydberg.
Influence of buffer layer texture on magnetic and electrical properties of IrMn spin valve magnetic tunnel junctions
Authors: Wiśniowski P. , Stobiecki T. , Kanak J. , Reiss G. , Brückl H.
Published: July 2006

Spin valve magnetic tunnel junctions (SV-MTJs) with the structure Si(100)∕SiOx∕buffer(A,B)∕IrMn∕CoFe∕AlOx∕NiFe∕Ta have been deposited on two buffers: Cu (group A) and Ta∕Cu (group B). The A junctions were characterized by a low degree of texture and a small amplitude of roughness, and B junctions by a high degree of texture and a high amplitude of roughness. The strongly textured buffer Ta∕Cu (group B) grew in a columnarlike fashion and induced interfacial roughness. The texture and the roughness modified strongly the interlayer and the exchange bias coupling fields in the SV-MTJs. A substantial influence of the roughness, due to barrier thickness fluctuation, on the resistance area product (R×A) of junctions was also observed. The influence on the temperature dependence of conductance and tunnel magnetoresistance (TMR) was, however, small and only observable at low temperature for the two groups of junctions. A significantly larger increase of the conductance and decrease of the TMR with increasing bias voltage was found for the A junctions. The obtained results imply that composition of buffer layers and their sequence can be used as one of the ways to improve the magnetic and tunneling properties of SV-MTJs.
Transmission electron microscopy study on FeSi2 nanoparticles synthesized by electron-beam evaporation
Authors: Won Jong Han , Sato Kazuhisa , Ishimaru Manabu , Hirotsu Yoshihiko
Published: July 2006

We have synthesized epitaxially grown iron disilicide (FeSi2) nanoparticles using an electron-beam evaporation technique and characterized them by transmission electron microscopy (TEM). An Fe film was deposited on a Si(100) substrate, followed by thermal annealing at 1073K for 2h. It was found that epitaxially grown nanoparticles with an average size of ∼10nm were formed just beneath the Si surface, suggesting that the deposited Fe atoms diffuse into the substrate. Every single phase of nanoparticles was examined in detail by TEM observation, nanobeam electron diffraction, and energy-dispersive x-ray spectroscopy. Plan-view and cross-sectional TEM observations revealed that these nanoparticles consist of α-, β-, and γ-FeSi2. It was found that the morphology of nanoparticles is closely related to the phases. The α and β phases consist of angled hemisphere and asymmetric triangle-shaped nanoparticles, respectively, while the γ phase consists of hemispherical or columnar-shaped nanoparticles. These particle morphologies are discussed with respect to the lattice mismatches between the particles and the matrix.
In situ oxygen incorporation and related issues in CdTe∕CdS photovoltaic devices
Authors: Emziane M. , Durose K. , Halliday D. P. , Bosio A. , Romeo N.
Published: July 2006

Cd Te ∕ Cd S ∕ Sn O 2 ∕ ITO : F solar cell devices were investigated using quantitative secondary ion mass spectrometry (SIMS) depth profiling. They were grown on sapphire substrates and potentially active impurity species were analyzed. The SIMS data were calibrated for both CdS window layer (grown by sputtering) and CdTe absorber layer (deposited by close-space sublimation). For comparison, some of the samples were grown with and without oxygen incorporation into the CdTe layer during its deposition, and with and without postgrowth cadmium chloride (CdCl2) annealing in air and chemical etching. These devices were back contacted using Mo∕Sb2Te3 sputtered layers. It was shown that for CdTe and CdS layers there was a correlation between the concentrations of oxygen and chlorine. In situ oxygen incorporation in the CdTe layer yielded a substantial improvement in the device parameters and achieved an efficiency of 14% compared to 11.5% for devices fabricated in the same conditions without oxygen incorporation in CdTe. In light of our previous reports, this study also led to a clear determination of the origin of Na and Si traces found in these devices.
Hopping conduction in size-controlled Si nanocrystals
Authors: Rafiq M. A. , Tsuchiya Y. , Mizuta H. , Oda S. , Uno Shigeyasu , Durrani Z. A. K. , Milne W. I.
Published: July 2006

We investigate the temperature dependence of conduction in size-controlled silicon nanocrystals. The nanocrystals are ∼8nm in diameter, covered by ∼1.5nm thick SiO2 shells. In 300nm thick films for temperatures T from 30to200K, the conductivity σ follows a ln(σ) vs 1∕T1∕2 dependence. This may be associated with either percolation-hopping conductance or Efros-Shklovskii variable range hopping. Assuming hopping sites only on the nanocrystals, the data agree well with the percolation model.
Peak polarity overturn for charged particles in laser ablation process
Authors: Zhang P. , Ji Y. J. , Lai X. M. , Bian B. M. , Li Z. H.
Published: July 2006

The charged particles emitted during laser ablation off a brass target are detected using a metal probe in air. A special phenomenon is found in the recorded signals: following a giant electromagnetic peak observed immediately after the emission of the pulsed laser, a minor peak occurs whose polarity merely depends on the distance between the probe and the laser focal spot on the target. Under the condition of our experiment, the overturn point is 1.47mm, i.e., the minor peak remains negative when the probe distance is less than 1.47mm; it becomes positive while the probe is set at a distance beyond 1.47mm. A hypothesis is proposed to explain the overturn that takes the flight behavior of the charged particles both in plasma and propagating shock wave into consideration.