bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of mechanical and biological prostheses when used to replace heart valves in children and adolescents with rheumatic fever
Authors: Travancas Paulo R. , Dorigo Ana H. , Simões Luiz C. , Fonseca Sandra C. , Bloch Kátia V. , Herdy Gesmar V.
Published: March 2009

Objective

To assess the outcomes in children and adolescents with rheumatic fever of the implantation of mechanical as opposed to biological heart valves.

Methods

We assessed 73 patients with rheumatic heart disease under the age of 18 years, who underwent replacement of heart valves between January, 1996, and December, 2005, at the National Institute of Cardiology in Rio de Janeiro, Brazil. Of the group, 71 patients survived, and were divided into a group of 52 receiving mechanical prostheses, and 19 with biological prostheses. We compared endpoints between the groups in terms of mortality, reoperation, haemorrhage, and stroke. Survival curves were estimated using the Kaplan-Meier method and were compared by the Mantel (log-rank) test.

Results

Overall mortality was 8.2%. In those receiving mechanical prostheses, 2 (3.8%) patients died, 5 (9.6%) underwent reoperation, 2 (3.8%) suffered severe haemorrhage, and 3 (5.8%) had strokes. In those receiving biological valves, 2 (10.5%) patients died, and 4 (21%) underwent reoperation. After 2, 4, and 8 years, overall survival was 96%, 93% and 86%, respectively, with a borderline difference between the groups (p = 0.06). The probabilities of remaining free from reoperation (p = 0.13), and from combined endpoints, showed no statistically significant difference between the groups (p = 0.28).

Conclusions

Patients with mechanical prostheses had lower mortality and required fewer reoperations, but when all combined endpoints were considered, the groups did not differ. The biological prosthesis proved to be a good option for cardiac surgery in children and adolescents with difficulties or risks of anticoagulation.
Assessment of the effects of physiological release of melatonin on arterial distensibility and blood pressure
Authors: Yildiz Mustafa , Akdemir Osman
Published: March 2009

Aim

The aim of our study was to investigate the effects of endogenous melatonin on arterial distensibility using measurements of the velocity of the aortic pulse wave between the carotid and femoral arteries in healthy young students assessed in the supine position.

Material and methods

We studied 29 healthy young students, aged between 18 and 27 years, with 19 being male. The measured the velocity of the aortic pulse wave between the carotid and femoral arteries, along the blood pressures and heart rate, while the subjects were in the supine position at two time points, namely from 01.30–02.30 and 13:30–14:30 hours, during a day, also taking plasma to measure the concentrations of melatonin. The velocity of the pulse waves was determined using an automatic device, the Complior Colson (France), which allowed on-line recording and automatic calculation of the velocity, the calculations being made by measuring the transit time of the pulse wave as it traversed the distance between two sites of recording according, the velocity of the pulse wave in meter per second being equal to the distance in meters divided by the time of transit in seconds.

Results

Although the velocity of the pulse wave, systolic, diastolic, and mean blood pressures, and heart rate were all increased in the morning relative to measurement made later in the day, levels of melatonin in the plasma were increased in the night. There was negative correlation between diurnal levels of melatonin and the velocity of the pulse wave.

Conclusion

Our findings indicate that increased levels of melatonin during the night may cause a decreased velocity of the aortic pulse wave, along with blood pressures and heart rate.
Commons as insurance: safety nets or poverty traps?
Authors: DELACOTE PHILIPPE
Published: March 2009

Common property resources are often used by households of developing countries as insurance in case of economic stress. The aim of this paper is to consider the potential poverty-trap implications of this use. If the capacity of the resource is low, or if the population in need of insurance is too large, the households are trapped in CPR extraction activity and cannot get more than their subsistence requirement. In this context, cooperation between households and the introduction of a cooperative insurance mechanism may sustain an equilibrium outside the poverty trap and relax pressure on the resource. Moreover, private insurance schemes could also be a potential solution to this poverty trap.
Measurement of environmental efficiency and productivity: a cross-country analysis
Authors: KUMAR SURENDER , KHANNA MADHU
Published: March 2009

This paper measures environmental efficiency (EE) and environmental productivity (EP) in 38 countries over the period 1971–92 and analyzes differences in these across countries. It explores several macro-economic factors that could explain these differences, such as income levels and the degree of openness in these countries. The average EE and EP indexes are found to be almost steady over the period 1971–92. In the annex-I countries, an increase in income levels initially leads to an increase in the average EE but subsequently to a decline in EE. In non-annex I countries, EE is increasing over the range of income in these countries. This study also finds an EKC type relationship between EP and per capita GDP in annex-I countries. The degree of openness has a significant positive impact on EE in annex-I countries.
Methodology for designing microwave acoustic filters with Butterworth/Chebyshev response
Authors: Menéndez Óscar , de Paco Pedro , Gemio Joan , Verdú Jordi , Corrales Edén
Published: March 2009

This work presents a methodology for designing microwave acoustic filters, based on two-port bulk acoustic wave resonators (also known as stacked crystal filters), with either Butterworth or Chebyshev response. The presented methodology makes it possible to design this type of filter without any optimization work, and, moreover, for its closed-form expressions design can be obtained. As a validation example, we address the design of a pair of filters for UMTS cellular phone handsets. The different simulations carried out show the good agreement between the transmission response of the designed filters and the theoretical response.
Lithographical bending control method for a piezoelectric actuator
Authors: Ikehashi Tamio , Ogawa Etsuji , Yamazaki Hiroaki , Ohguro Tatsuya
Published: March 2009

This paper presents the theoretical formulation of a lithographical bending control (LBC) method that uses lithographical degrees of freedom to control the bending of a multilayered beam. LBC is applied to a piezoelectric actuator that uses PZT as the piezoelectric material. The theoretical model is compared with measurements using a weakly fixed bridge structure suited for curvature measurement.
Schicht für Schicht - Die maβgeschneiderte Keratoplastik
Authors: Kaufmann Claude
Published: March 2009

Die perforierende Keratoplastik war für über ein Jahrhundert der Goldstandard der Hornhauttransplantation. In jüngster Zeit haben hingegen lamellierende Techniken stark an Bedeutung gewonnen, bei welchen anstelle der kompletten Hornhaut gezielt einzelne Hornhautschichten transplantiert werden. Die Hauptvorteile gegenüber der perforierenden Keratoplastik umfassen je nach Art der verwendeten Technik entweder eine reduzierte Rate endothelialer Abstoβungsreaktionen oder eine beschleunigte visuelle Rehabilitation. Die Indikationen sowie die Vor- und Nachteile der einzelnen Therapiemodalitäten werden in Form einer kurzen Übersichtsarbeit dargestellt.
Glaukom – Grüner Star
Authors: Funk Jens
Published: March 2009

Glaukom (im Volksmund «Grüner Star») ist ein Sammelbegriff für unterschiedliche Erkrankungen des Auges. Allen Unterformen gemeinsam ist, dass das Glaukom eine irreversible Schädigung des Sehnerven verursacht, die ihrerseits unbehandelt zur vollständigen Erblindung führt. In vielen Fällen bleibt es lange unentdeckt, wodurch das Glaukom auch heute noch zu den häufigsten Erblindungsursachen zählt. Nur intensive Aufklärung der Bevölkerung und die Mithilfe der nicht-ophthalmologischen Ärztekollegen und –kolleginnen können helfen, diese unnötig groβe Zahl von Erblindungen zu verringern.
Altersbezogene Makuladegeneration (AMD)
Authors: Michels Stephan , Kurz-Levin Malaika
Published: March 2009

Die altersbezogene Makuladegeneration (AMD) ist heute die wichtigste Ursache für eine Erblindung im gesetzlichen Sinn in der westlichen Welt. Das Risiko einer Erkrankung nimmt mit steigendem Alter zu. Die Pathogenese ist multifaktoriell, wobei genetische Prädisposition und Umweltfaktoren eine Rolle spielen. Zusätzlich sind modifizierbare Risikofaktoren, wie z.B. das Rauchen bekannt. Man unterscheidet auf Grund der klinischen Manifestation zwei Formen der AMD. Als prophylaktische Maβnahmen sind einerseits eine «gesunde» Ernährung und andererseits die Einnahme von Antioxidantien je nach klinischem Befund zu empfehlen. Eine Therapie ist derzeit nur bei der feuchten Form der AMD möglich.
Krankheitsbilder in der Kinderophthalmologie
Authors: Michels Rike
Published: March 2009

Eine häufige Erkrankung im Neugeborenenalter ist die angeborene Tränenwegsstenose. Diese hat einen sehr guten Spontanverlauf und bedarf nur selten einer Therapie. Hingegen gibt es deutlich seltenere Krankheitsbilder, wie z.B. das Glaukom im Kindesalter oder die angeborene Katarakt, die einer sofortigen Therapie bedürfen, da sonst eine starke Beeinträchtigung der Sehschärfe droht. Eine groβe Rolle bei der Früherkennung solch bedrohlicher Krankheitsbilder kommt den Kinderärzten und den Eltern selbst zu, da sie in der Regel die Symptome erfassen und den Augenarzt aufsuchen.
Refraktive Chirurgie
Authors: Epstein Daniel
Published: March 2009

Die refraktive Chirurgie zur Behandlung von Fehlsichtigkeiten hat sich in den letzten 20 Jahren zu einer anerkannten Subspezialität der Augenheilkunde etabliert. Verschiedenste operative Verfahren stehen zur Verfügung. So kann die Brechkraft des Auges durch Eingriffe auf der Hornhaut oder durch die Implantation einer Kunstlinse verändert werden. Dadurch können Kurzsichtigkeit und Weitsichtigkeit (mit oder ohne Stabsichtigkeit) reduziert oder eliminiert werden, so dass der Behandelte im besten Fall im groβen und ganzen ohne Brille oder Kontaktlinsen im täglichen Leben funktioneren kann.
Die Behandlung des komplexen regionalen Schmerzsyndroms der oberen Extremität mit wiederholter Lokalanästhesie des Ganglion stellatum
Authors: Pfister  , Fischer
Published: March 2009

Zwei Patientinnen wurden uns mit einem komplexen regionalen Schmerzsyndrom (CRPS) an der oberen Extremität zugewiesen. Bei der ersten Patientin trat das CRPS Typ 1 nach einer unkomplizierten Radiusfraktur auf, während die zweite Patientin nach einer Verletzung des Handgelenks und des N. ulnaris ein CRPS Typ 2 entwickelte. Beide Patientinnen zeigten trotz medikamentöser Behandlung (NSAR, Gabapentin, Calcitonin) und weiteren therapeutischen Massnahmen (Physiotherapie, Ergotherapie, Osteopathie) progrediente Schmerzen. Neben den Schmerzen traten autonome Symptome wie Ödeme, Hyperhidrosis, Störungen der Hautfarbe und -temperatur sowie eine starke Einschränkung der Handgelenks- und Fingerbeweglichkeit auf. Die Symptome von CRPS 1 und 2 sind identisch und nicht auf das Ausbreitungsgebiet eines bestimmten peripheren Nervs beschränkt. Der Sympathikus ist nicht nur der Hauptvermittler des Schmerzgeschehens über reflektorische Vorgänge im Segment und über die sympathisch-afferente Kopplung, er ist auch bei der Ausbildung von neuroplastischen Veränderungen im Zentralnervensystem und bei der neurogenen Entzündung beteiligt. Deshalb besteht die logische Therapie darin, die sympathische Dysregulation mittels Lokalanästhetika zu korrigieren. Dies geschieht bei Befall der oberen Extremität durch Injektionen an das Ganglion stellatum (und an den lumbalen Grenzstrang bei Befall der unteren Extremität). Bei beiden Patientinnen bewirkten die wiederholten Injektionen ans Ganglion stellatum schlagartige Verbesserungen der Schmerzen und der übrigen Symptome.
Therapie zentralisierter Schmerzstörungen
Authors: Egloff  , Egle  , Känel von
Published: March 2009

Schmerz ist ein Signal, das in der Regel durch eine periphere, körperliche Schädigung ausgelöst wird. Die schmerzperzeptierenden Strukturen des Nervensystems sind aber ihrerseits nicht inert sondern unterliegen – v.a. bei chronischer Einwirkung – einer Modulierbarkeit, welche ein eigenes Krankheitspotenzial in sich birgt und zu Schmerzkrankheiten beiträgt. Somatische Schmerzvorerfahrung (Priming, Wind-up), psychobiographische Prägung (Pain proneness) und Stressbelastung (Action proneness) sind die Hauptfaktoren, welche zu einer veränderten Schmerzverarbeitung des ZNS führen. Klinisch zeigt sich diese Entwicklung durch Schmerzsensibilisierung und Schmerzkonservierung. Bei vielen chronischen Schmerzpatienten liegt eine Mischung dieser sensibilisierenden Einflüsse vor. Im Gegensatz zur Therapie des akuten, peripher begründeten Schmerzes ist die Therapie chronisch-zentralisierter Schmerzstörungen stets nur in einem multimodalen Vorgehen realisierbar. Letztlich zielen alle Therapiemassnahmen darauf ab, die «anti-nozizeptiven» Anteile der zerebralen Schmerzmatrix zu stärken. Die Medikamentenlisten für neuropathische Schmerzen und somatoforme Schmerzen weisen verständlicherweise grosse Überlappungen auf. Psychotherapeutische Massnahmen dienen der verbesserten Schmerzkontrolle, emotionalen Entlastung und Verhaltensoptimierung. Dieser Artikel gilt als Fortsetzung und Vertiefung unseres Aufsatzes «Weder Descartes noch Freud», in dem wir uns bereits von einem allzu dichotomen Schmerzverständnis (organisch versus psychogen) verabschiedet haben [1].
Strontium distribution in the shell of the aragonite bivalve Arctica islandica
Authors: Foster Laura C. , Allison Nicola , Finch Adrian A. , Andersson Carin
Published: March 2009

The behavior of Sr in the aragonite shells of the bivalve Arctica islandica has been explored to determine its potential for high‐resolution environmental reconstruction. The structural state of Sr in the shell was investigated using X ray absorption fine structure (XAFS) and Sr/Ca variations across the prismatic layer in the umbo and outer shell were determined by secondary ionization mass spectrometry (SIMS) and laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) respectively. XAFS data suggest that Sr randomly substitutes for Ca within the shell aragonite. Sr/Ca in both the umbo and the outer shell exhibits significant seasonal variation but does not correlate with seawater temperature. Sr/Ca varies significantly between parallel transects across the same annual bands. Sr concentrations are highest in transects along the maximum growth axis of the outer shell but lowest in these transects in the umbo. Scanning electron microscopy indicates changes in crystal morphology both within and between transects. We do not, however, observe a clear relationship between shell growth rate and Sr/Ca. Fluctuations in Sr/Ca are most likely to be controlled by a complex interaction of biological and kinetic processes.
Radiolaria: Major exporters of organic carbon to the deep ocean
Authors: Lampitt R. S. , Salter I. , Johns D.
Published: March 2009

Very large pulses of particulate organic matter intermittently sink to the deep waters of the open ocean in the Northeast Atlantic. These pulses, measured by moored sediment traps since 1989, can contribute up to 60% of the organic flux to 3000 m in a particular year and are thus a major cause of the variability in carbon sequestration from the atmosphere in the region. Pulses occur in the late summer and are characterized by material that is very rich in organic carbon but with low concentrations of the biominerals opal and calcite. A number of independent lines of evidence have been examined to determine the causes of these pulses: (1) Data from the Continuous Plankton Recorder (CPR) survey show that in this region, radiolarian protozoans intermittently reach high abundances in the late summer just preceding organic pulses to depth. (2) CPR data also show that the interannual variability in radiolarian abundance since 1997 mirrors very closely the variability of deep ocean organic deposition. (3) The settling material collected in the traps displays a strong correlation between fecal pellets produced by radiolaria and the measured organic carbon flux. These all suggest that the pulses are mediated by radiolarians, a group of protozoans found throughout the world's oceans and which are widely used by paleontologists to determine past climate conditions. Changes in the upper ocean community structure (between years and on longer timescales) may have profound effects on the ability of the oceans to sequester carbon dioxide from the atmosphere.
Effects of freezing, growth, and ice cover on gas transport processes in laboratory seawater experiments
Authors: Loose B. , McGillis W. R. , Schlosser P. , Perovich D. , Takahashi T.
Published: March 2009

Gas exchange through sea ice is a determining factor in the polar ocean budget of climatically‐active gases. We use SF6 and O2 as conservative gas tracers to observe transport between the water, ice and air during conditions of freezing and partial ice cover in artificial seawater. During ice growth, O2 and SF6, as non‐polar solutes, were rejected from the ice into the underlying water at a faster rate than that observed for salt. Measurements of the gas exchange rate, k, through partial ice cover exceeded that expected from linear scaling between 100% open water (k100%) and complete ice cover: at 15% open water, k was 25% of k100%. These results indicate that the net flux of gas through the ice pack may not scale linearly with open water area, as circulation processes under the ice affect the gas exchange rate.
Frictional behavior of materials in the 3D SAFOD volume
Authors: Carpenter B. M. , Marone C. , Saffer D. M.
Published: March 2009

We report on frictional properties of rocks within the 3‐D crustal volume surrounding the San Andreas Fault Observatory at Depth (SAFOD). Samples include lithologies adjacent to the San Andreas Fault (SAF) in the subsurface, SAFOD borehole rocks, and synthetic fault gouge composed of talc, serpentinite, and quartz. Granodiorite, arkosic sandstone, and siltstone samples from the SAFOD borehole are frictionally strong (μ = 0.56 − 0.66). Sand and clay‐rich lithologies from outcrop exhibit friction in the range μ = 0.56 − 0.68. Natural serpentinite thought to abut the SAF at depth exhibits low friction (μ = 0.18 − 0.26). Our results indicate that 1) serpentinite exhibits low strength, but is not weak enough to completely satisfy weak fault models, 2) all other samples are consistent with a strong fault and crust and, 3) if the SAF is weak (μ ≤ 0.2) due to the presence of serpentinite or talc, these minerals would likely need to constitute over 50% by weight of the shear zone.
Two‐spacecraft observations of an interplanetary slow shock
Authors: Lin C. C. , Feng H. Q. , Wu D. J. , Chao J. K. , Lee L. C. , Lyu L. H.
Published: March 2009

Slow‐mode shocks in space have been identified via one spacecraft observation by many authors since 1970. However, Feng et al. suggested that the analysis using single‐spacecraft observation based only on the Rankine‐Hugoniot relations could misinterpret a tangential discontinuity as a slow shock. In this paper, we identify a slow‐mode shock using a model fitting based on both the Rankine‐Hugoniot relations and intraspacecraft timing. As a result, we found a slow‐shock solution that, including the local parameters and propagation time, agrees well with the observations. The slow shock may be associated with an asymmetric reconnection exhaust at a heliospheric current sheet.
“Geography” of ion acceleration in the magnetotail: X‐line versus current sheet effects
Authors: Grigorenko E. E. , Hoshino M. , Hirai M. , Mukai T. , Zelenyi L. M.
Published: March 2009

Field‐aligned ion beams are often observed in the Plasma Sheet Boundary Layer (PSBL) of Earth's magnetotail. We studied two types of ion beams observed in the magnetotail at different times. Both types of ion beams are pitch angle‐collimated along the magnetic field direction but they differ significantly with the width of ion velocity distribution functions in parallel energies. The first type represents energy‐collimated ion beams with observed durations of 3–23 min. The majority of such beams have energies ≤20 keV. Together with such ion beams, isotropic electron distributions are observed. We suggest that such ion beams are accelerated at spatially localized regions located rather far from the distant X‐line where magnetic field lines are already closed. Another type of PSBL ion distributions represents wide in parallel energy ion beams with typical energies ≥ tens of keV. The registered durations of such beams are 1–6 min. They are observed together with anisotropic electron velocity distributions formed by the cold and hot counter‐streaming components. This feature is peculiar for the magnetic separatrix and indicates that the spacecraft crosses still open or very recently closed magnetic field lines. We have analyzed 987 crossings of the high‐latitude edge of the PSBL by Geotail at −220 RE < X < −20 RE. The majority of Type‐I ion beams are moving earthward at X ≥ −110 RE and so have their sources located earthward from the distant X‐line (at X < −110 RE). These ion beams were observed during quiet geomagnetic periods. More than 50% of Type‐II ion beams move tailward at X ≤ −50 RE. Thus their acceleration sources are located closer to Earth. Type‐II ion beams were observed during both quiet and disturbed periods. The energy distribution of the first type of ion beams along the dawn‐dusk direction approximately conforms to the assumption about their non‐adiabatic acceleration by the quasi‐steady dawn‐dusk electric field. On the other hand, we suggest that ion beams of the second type are generated in close proximity to the X‐line. The energy distribution of such ion beams along the Y direction indicates ion energization by a strong (presumably inductive) electric field, especially in cases of ion acceleration tailward from the X‐line.
Scaling relationship for Vulcanian explosions derived from broadband seismic signals
Authors: Zobin Vyacheslav M. , Reyes Gabriel A. , Guevara Enrique , Bretón Mauricio
Published: March 2009

A proposed conceptual model of Vulcanian explosions describes the volcanic explosion process as consisting of two stages (the movement of the fragmented magma to the surface and a subsequent explosion) and is constrained by four source parameters inferred from broadband seismic records (the counter force of the eruption F acting in the conduit before an explosion and governing the fragmented magma movement to the surface, the time D1 of the movement of fragmented magma in the conduit before an explosion, the duration of the explosion in the conduit D2, and the energy E of the explosion). Our paper discusses, within the framework of the proposed conceptual model, the source scaling relationship inferred from the parameters of 135 Vulcanian explosions occurring at two Mexican andesitic volcanoes: Volcán de Colima and Popocatépetl during 1996–2006. Two groups of explosions are discriminated, small (E < 1011 J) and large (E ≥ 1011 J), characterized by a different type of scaling and origin. The scaling of the counter force F on the source duration τ of the single force is different for large and small explosions but is characterized by the same tendency of F ∼ τ2. According to the dependence E versus D1, large explosions are generated within the narrow depth zone in the conduit corresponding to D1 from 3.5 to 7.5 s while small explosions are generated within a wide depth zone corresponding to D1 from 0 to 13 s. The counter force of the eruption strongly governs the energy of explosions. The duration of the explosion at the explosion surface within the conduit, D2, has a tendency to negatively correlate with the energy of the explosion.
Formation of highly hygroscopic soot aerosols upon internal mixing with sulfuric acid vapor
Authors: Khalizov Alexei F. , Zhang Renyi , Zhang Dan , Xue Huaxin , Pagels Joakim , McMurry Peter H.
Published: March 2009

The hygroscopic properties of submicron soot particles during internal mixing with gaseous sulfuric acid have been investigated using a combined tandem differential mobility analyzer (TDMA) and differential mobility analyzer–aerosol particle mass analyzer (DMA‐APM) technique. Fresh particles exhibit no change in mobility size and mass at subsaturated conditions, whereas particles exposed to gaseous sulfuric acid (109–1010 molecule cm−3, 12 s contact time) experience significant mobility size and mass changes with increasing relative humidity (RH). The DMA‐APM measurements reveal that particles of all sizes exposed to H2SO4 vapor gain mass with increasing RH because of absorption of water by sulfuric acid coating. However, on the basis of mobility size measurements using TDMA, upon humidification H2SO4‐coated soot agglomerates display distinct hygroscopic growth patterns depending on their initial size and the mass fraction of condensed sulfuric acid. While small particles experience an increase in their mobility sizes, larger particles exhibit a marked shrinkage due to compaction. We suggest that determination of the hygroscopic properties of soot particles using a TDMA alone can be inconclusive. Restructuring of the soot agglomerates and filling of the voids that accompany the condensation of water‐soluble materials and subsequent water absorption lead to little or no observable changes in particle mobility size at subsaturated RH even for particles that contain aqueous coatings. Extrapolation of our experimental results to the urban atmosphere indicates that initially hydrophobic soot particles acquire sufficient sulfate coating to become efficient CCN (cloud condensation nuclei) within a time period ranging from a few hours to a few days, dependent on the ambient H2SO4 level. The results imply that internal mixing with sulfuric acid through H2SO4 vapor condensation likely represents a common aging process for a variety of atmospheric aerosols. The variations in the size and hygroscopicity of soot particles during atmospheric processing influence their optical properties, cloud‐forming potential, and human health effects.
Limb observations of CO2 and CO non‐LTE emissions in the Venus atmosphere by VIRTIS/Venus Express
Authors: Gilli G. , López‐Valverde M. A. , Drossart P. , Piccioni G. , Erard S. , Cardesín Moinelo A.
Published: March 2009

We report and analyze here observations of strong infrared emissions from the limb of the Venus upper atmosphere during daytime, taken by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard Venus Express. We focus on the measurements taken during the first 4 months of nominal operations. The emissions observed at 4.3 μm and at 2.7 μm are attributed to CO2 fluorescence of solar radiation and are detected up to about 160 km and 130 km, respectively, while the CO fluorescence at 4.7 μm is observed up to about 120 km. The emissions are detected in both the channels of VIRTIS, at different spatial and spectral resolutions (resolving powers about 1800 and 400), for the periapsis and the apoapsis of the Venus Express orbit. From these data sets we built up 2‐D maps of the emissions as well as vertical profiles, which are then studied in order to characterize their variations with geophysical parameters, like solar illumination and emission altitude. Several analyses are performed in order to understand the VIRTIS behavior, to determine systematic effects in the data, and to propose appropriate corrections. We also present comparisons with a theoretical nonlocal thermodynamic equilibrium (non‐LTE) model of the Venus upper atmosphere. The agreement is very encouraging, in general, and the main variability observed in the data, with solar zenith angle and altitude, can be understood with the model. We conclude that the present data set opens brilliant perspectives for deriving densities and rotational temperatures in the upper mesosphere and lower thermosphere of Venus.
Reflectance spectroscopy of organic compounds: 1. Alkanes
Authors: Clark Roger N. , Curchin John M. , Hoefen Todd M. , Swayze Gregg A.
Published: March 2009

Reflectance spectra of the organic compounds comprising the alkane series are presented from the ultraviolet to midinfrared, 0.35 to 15.5 μm. Alkanes are hydrocarbon molecules containing only single carbon‐carbon bonds, and are found naturally on the Earth and in the atmospheres of the giant planets and Saturn's moon, Titan. This paper presents the spectral properties of the alkanes as the first in a series of papers to build a spectral database of organic compounds for use in remote sensing studies. Applications range from mapping the environment on the Earth, to the search for organic molecules and life in the solar system and throughout the universe. We show that the spectral reflectance properties of organic compounds are rich, with major diagnostic spectral features throughout the spectral range studied. Little to no spectral change was observed as a function of temperature and only small shifts and changes in the width of absorption bands were observed between liquids and solids, making remote detection of spectral properties throughout the solar system simpler. Some high molecular weight organic compounds contain single‐bonded carbon chains and have spectra similar to alkanes even when they fall into other families. Small spectral differences are often present allowing discrimination among some compounds, further illustrating the need to catalog spectral properties for accurate remote sensing identification with spectroscopy.
Multiple stable states in hydrological models: An ecohydrological investigation
Authors: Peterson T. J. , Argent R. M. , Western A. W. , Chiew F. H. S.
Published: March 2009

Many physical‐based models of surface and groundwater hydrology are constructed without the possibility of multiple stable states for the same parameter set. For such a conceptualization, at the cessation of a transient hydrological disturbance of any magnitude the model will return to the same stable state and thus show an infinite resilience. To highlight and falsify this assumption, a numerical distributed ecohydrological model (coupled hillslope Boussinesq‐vertically lumped vadose zone) is presented, in which qualitatively different steady state water table elevations exist for the same parameter set. The multiple steady states are shown to emerge from a positive feedback arising from a reduction in leaf area index (LAI) and thus transpiration, as a saline water table approaches the surface. Limit cycle continuation is also undertaken to quantify the state‐space location of the threshold (repellor) between the steady states (attractors) and quantify the resilience. While the model is biophysically simple, it is sufficiently complex to challenge this potentially significant assumption within water resource planning.
Multiattribute optimization of restoration options: Designing incentives for watershed management
Authors: Randhir Timothy O. , Shriver Deborah M.
Published: March 2009

Watershed restoration requires careful assessment of impairment in ecosystem attributes to design appropriate conservation policies. This study applies a multiattribute optimization framework for evaluating relative gains in restoration based on potential improvements in economic and environmental attributes related to water quality, habitat, and urbanization. Policy mechanisms through direct compensation of restoration activities are evaluated based on single‐attribute and multiattribute optimization and watershed response to varying levels of restoration incentives. Results indicate that tradeoffs in economic and environmental objectives are critical to identifying optimal restoration strategies at a watershed scale. The multiattribute optimization method developed in this study balances levels of multiple attributes and reflects tradeoffs in preferences for each attribute. Through an evaluation of a variety of attributes for relative gains and costs, opportunities exist for strategic selection of restoration activities in subwatersheds. The multiattribute method is found to be superior to the single‐objective method in incorporation of tradeoffs, balancing economic and environmental impacts, and development of participatory solutions. Multiattribute assessment and policies are important for cost‐effective and consensus‐based watershed restoration practices.
Applications of Reference Materials in Analytical Chemistry
Authors: Walker Ron , Bedson Peter , Lawn Richard , Barwick Vicki J , Burke Shaun , Roper Peter
Published: March 2009

Reference materials play an important role in analytical chemistry, where they are used by analysts for a variety of purposes, including: checking and calibrating instruments; validating methods and estimating the uncertainty of analytical measurements; checking laboratory and analyst performance; and internal quality control. This book provides guidance and information for the users of certified reference materials (CRMs), explaining how they can best be used to achieve valid analytical measurements and improve quality in the analytical laboratory. General information on CRMs and how they are produced sets the scene for readers. The statistics relating to CRM use are then explained in an easy-to-understand manner, and this is followed by sections covering the main uses of CRMs. Detailed worked examples are used throughout. Structured and comprehensive in coverage, this book will be welcomed by all users of certified reference materials.
Ferromagnetic microdisks as carriers for biomedical applications
Authors: Rozhkova E. A. , Novosad V. , Kim D.-H. , Pearson J. , Divan R. , Rajh T. , Bader S. D.
Published: March 2009

We report the fabrication process, magnetic behavior, as well as the surface modification of ferromagnetic microdisks suspended in aqueous solution. They posses unique properties such as high magnetization of saturation, zero remanence due to spin vortex formation, intrinsic spin resonance at low frequencies, and the capability of delivering various biomolecules at once. Furthermore, because of their anisotropic shape, our magnetic particles rotate under alternating magnetic fields of small amplitude. This can be used to promote the idea of advanced therapies, which include combined drug delivery and magnetomechanical cell destruction when targeting tumor cells. The approach enables us to fabricate suitable magnetic carriers with excellent size tolerances, and then release them from the wafer into solution, ready for surface modification and therapeutic use. The particles have a magnetic core and are covered with few nanometers of gold on each side to provide stability at ambient conditions as well as biocompatibility and selective adhesion functions. A successful attempt to bind thiolates, including SH-modified antibody, to the disk’s surface was demonstrated.
Fabrication and morphologies of large directly ordered L1 FePt nanoparticles in gas phase
Authors: Liu Xiaoqi , Wang Jian-Ping
Published: March 2009

Gas phase synthesis of large directly ordered L10 FePt nanoparticles was studied. Simultaneous control of the chemical ordering and the size of the FePt nanoparticle was successfully achieved. It was found that the chemical ordering of the FePt nanoparticles was mainly influenced by the energy conditions (thermal environments at nucleation and growth regions), which could be adjusted by varying the process parameters including the sputtering current density, the Ar gas pressure, etc. The sizes of ordered FePt nanoparticles were more related to the Fe and Pt atoms’ density at the initial stage (close to target surface). Multiply twinned structures were observed in L10 FePt nanoparticles with 12 and 17 nm mean sizes, but were absent in L10 FePt nanoparticles with 6 nm mean size, which caused the relatively low coercivity of large L10 FePt nanoparticles.
Excitation and dephasing of circularly polarized plasmon modes in spherical nanoshells for application in all-optical magnetic recording
Authors: Mayergoyz Isaak , McAvoy Patrick , Lang Garrett , Bowen David , Krafft Charles
Published: March 2009

The analysis of the time dynamics of excitation and dephasing of circularly polarized plasmon modes in spherical nanoshells is presented. The analytical formulas for steady-state amplitudes of these modes for resonance and off-resonance excitations are also given.
Role of dopant, defect, and host oxide in the observed room temperature ferromagnetism: Co–ZnO versus Co–CeO2
Authors: Shah Lubna R. , Wang Weigang , Zhu Hao , Ali Bakhtyar , Song Y. Q. , Zhang H. W. , Shah S. I. , Xiao J. Q.
Published: March 2009

A comparative study on the room temperature ferromagnetism of Co doped ZnO and CeO2 bulk samples is presented. Co–ZnO system has been observed to switch between ferromagnetic and paramagnetic by controlling the donor defects, interstitial zinc: Zni. On the other hand, Co–CeO2 is always ferromagnetic. However, ferromagnetism increases/decreases with increase/decrease in donor defects, oxygen vacancies: VO. Systemic structural, magnetic, and transport analyses reveal that the nature of donor defects and host oxide plays a vital role in establishing ferromagnetism. This study provides an insight into the underlying mechanisms that are responsible for the ferromagnetism in Co–ZnO and Co–CeO2. Moreover, the proposed mechanisms are supported by the electronic structure of magnetic impurity ions and defects.
A compressible wall-adapting similarity mixed model for large-eddy simulation of the impinging round jet
Authors: Lodato Guido , Vervisch Luc , Domingo Pascale
Published: March 2009

Wall-jet interaction is studied with large-eddy simulation (LES) in which a mixed-similarity subgrid scale (SGS) closure is combined with the wall-adapting local eddy-viscosity (WALE) model for the eddy-viscosity term. The macrotemperature and macropressure are introduced to deduce a weakly compressible form of the mixed-similarity model, and the relevant formulation for the energy equation is deduced accordingly. LES prediction capabilities are assessed by comparing flow statistical properties against experiment of an unconfined impinging round jet at Reynolds numbers of 23 000 and 70 000. To quantify the benefit of the proposed WALE-similarity mixed model, the lower Reynolds number simulations are also performed using the standard WALE and Lagrangian dynamic Smagorinsky approaches. The unsteady compressible Navier–Stokes equations are integrated over 2.9 M, 3.5 M, and 5.5 M node Cartesian grids with an explicit fourth-order finite volume solver. Nonreflecting boundary conditions are enforced using a methodology accounting for the three-dimensional character of the turbulent flow at boundaries. A correct wall scaling is achieved from the combination of similarity and WALE approaches; for this wall-jet interaction, the SGS closure terms can be computed in the near-wall region without the necessity of resorting to additional specific treatments. The possible impact of turbulent energy backscatter in such flow configurations is also addressed. It is found that, for the present configuration, the correct reproduction of reverse energy transfer plays a key role in the estimation of near-wall statistics, especially when the viscous sublayer is not properly resolved.
Magnetic disorder in Ti doped ErCo2: High-magnetic-field study
Authors: Öner Yildirhan , Guillot M.
Published: March 2009

Magnetization measurements have been carried out on ErCo(2−x)Tix (x=0, 0.01, 0.02, 0.03, 0.04, and 0.05) alloys in the temperature range of 4–300 K under high dc magnetic fields of up to 23 T. The substitution of Ti for Co causes no change in the crystal structure of ErCo2 (cubic Laves phase C15 with space group Fd3¯m). The lattice parameter a decreases almost linearly with increasing x up to x=0.04 and then increases slightly for the largest Ti concentration. The Curie temperature TC shows a similar change with Ti concentration. Above TC all the studied samples show a small but unambiguous hysteresis associated with a metamagnetic transition. The observed hysteresis is attributed to the coexistence of the paramagnetic and the field-induced ferrimagnetic states. Linear temperature extrapolations of the critical fields Hc1 (where the hysteresis sets in) and Hc2 (the highest field where the hysteresis is observed) were done for each sample. Two different critical temperatures were found suggesting the existence of Co clusters. Indeed, weak negative magnetization values in low fields at low temperatures were observed for zero-field-cooling magnetic measurements. The negative magnetization is also attributed to the existence of Co clusters above TC. The spontaneous magnetization values Ms of the samples were deduced as a function of Ti concentration from the high-field data. Ms passes through a maximum for the x=0.03 sample with a maximum value of 7.15μB (6.30μB in pure ErCo2). We show how a decrease in the Er–Co antiferromagnetic exchange coupling with Ti doping may lead to such an observed maximum.
Fatigue damage assessment by the continuous examination of the magnetomechanical and mechanical behavior
Authors: Vandenbossche Lode , Dupré Luc
Published: March 2009

To evaluate the material degradation of ferritic steels caused by low cycle stress-induced fatigue, the continuous examination of changes in the magnetomechanical behavior during the cyclic mechanical loading is proposed, and this is validated by comparing with the continuous examination of changes in the mechanical stress-strain behavior. In this context two magnetomechanical examination methods are investigated, differing only in the magnetic field that is continuously applied to the sample during the stress-controlled cyclic mechanical loading, i.e., a constant magnetic field (method Hstat) or a time-varying magnetic field (method Hdyn), with the magnetic frequency significantly larger than the mechanical frequency. In both methods the magnetization variation M(σ,H) during each stress cycle due to the magnetomechanical effect and the strain ε(σ) are continuously measured throughout the complete cyclic mechanical loading test. When analyzing the fatigue-induced changes in the magnetization trajectory M(σ,H) determined by both methods (Hstat and Hdyn), several stages in the fatigue lifetime can be distinguished (i.e., a steady state and a final stage for as-received samples and an initial stage, a steady state and a final stage for annealed samples), which fully mimic the corresponding stages in the inelastic strain-stress behavior. All investigated magnetomechanical and mechanical parameters change significantly during the final fatigue stage (i.e., the last 2%–5% of the fatigue lifetime). This information can be used to estimate the remaining life of steel components.
Tuning interlayer coupling and domain structure in [Co/Pd]nCo/Ru[Co/Pd(x)]m multilayer by controlling the thickness x of the weak-ferromagnetic Pd layers in the lower Co/Pd multilayer
Authors: Fu Y. , Ishio S. , Wang T. , Pei W. , Hasegawa T. , Yamane H. , Saito H.
Published: March 2009

Interlayer coupling has been studied in a series of perpendicular antiferromagnetically coupled multilayers with asymmetric structures Pd(20 Å)/[Pd(15.7 Å)/Co(3.6 Å)]5/Ru(4.1 Å)/Co(3.6 Å)/[Pd(x Å)/Co(3.6 Å)]3/Pd(50 Å)/Si substrate. The coupling oscillates between antiferromagnetic and ferromagnetic as a function of x in the bottom sublayers. The strong antiferromagnetic coupling with a maximum value of 2430 Oe, which was determined by the minor-loop shift, was obtained. The pinning direction of the antiferromagnetic coupling also changes with the variation in x. The oscillatory behavior can be attributed to multiple reflections of electron waves at the Co/Pd interfaces and their interference. Micromagnetic structure evolves with a variety of interlayer couplings are observed by magnetic force microscopy. An antiferrostripe domain without a ferromagnetic shift is observed at the as-deposited state. Stray-field induced ferromagnetic domains appear in multilayers with weak antiferromagnetic coupling.
Superconductivity of various borides: The role of stretched c-parameter
Authors: Mudgel Monika , Awana V. P. S. , Kishan H. , Felner I. , Alvarez Dr. G. A. , Bhalla G. L.
Published: March 2009

The superconductivity of MgB2, AlB2, NbB2+x, and TaB2+x is intercompared. The stretched c-lattice parameter (c=3.52 Å) of MgB2 in comparison to NbB2.4 (c=3.32 Å) and AlB2 (c=3.25 Å) decides empirically the population of their π and σ bands and as a result their transition temperature Tc values, respectively, at 39 and 9.5 K for the first two and no superconductivity for the later. The nonstoichiometry induces an increase in c parameter with Boron excess both in NbB2+x and TaB2+x. Magnetization (M-T) and resistivity measurements (ρ-T) in case of niobium boride samples show the absence of superconductivity in stoichiometric NbB2 sample (c=3.26 Å) while a clear diamagnetic signal and a ρ=0 transition for boron excess NbB2+x samples. On the other hand, superconductivity is not achieved in TaB2+x case. The probable reason behind is the comparatively lesser or insufficient stretching of c parameter.
Competing magnetic interactions in the intermetallic compound Ho2Mn3Si5
Authors: Nirmala R. , Morozkin A. V. , Lamsal Jagat , Chu Z. , Sankaranarayanan V. , Sethupathi K. , Yamamoto Y. , Hori H. , Yelon W. B. , Malik S. K.
Published: March 2009

The compound Ho2Mn3Si5 exhibits multiple magnetic transitions: (i) an ordering at ∼78 K, (ii) a second magnetic transition at ∼16 K, and (iii) an anomaly at ∼4 K. Its paramagnetic Curie temperature is found to be small but positive. Assuming a free ion effective paramagnetic moment of 10.6μB for Ho3+ ion, the effective paramagnetic moment per Mn in this compound is calculated to be 1.73μB, which indicates the itinerant nature of Mn d electrons. The various transitions in magnetization data are perhaps due to the ordering of rare earth and Mn moments. The magnetization at 2 K in applied fields of up to 7 T has linear field dependence, indicating dominant antiferromagnetic interactions in the system. Neutron diffraction studies point to a complex amplitude modulated incommensurate magnetic structure at 9 K.
Composition dependent properties of Fe3Si films grown on GaAs(113)A substrates
Authors: Muduli P. K. , Friedland K.-J. , Herfort J. , Schönherr H.-P. , Ploog K. H.
Published: March 2009

Structural, electrical, and magnetic properties of Fe3Si/GaAs(113)A hybrid structures are studied, dependent on the layer composition varying from 15 to 26 at. % Si. The presence of superlattice reflections in x-ray diffraction and lower resistivity confirms the long-range atomic ordering in the stoichiometric Fe3Si films, reflecting the D03 crystal structure. The observed atomic ordering is also found to influence the sign and magnitude of the antisymmetric component of the planar Hall effect observed in this orientation. However a finite disorder is observed even in nearly stoichiometric samples.
Non-skew-symmetric classical r-matrices, algebraic Bethe ansatz, and Bardeen–Cooper–Schrieffer–type integrable systems
Authors: Skrypnyk T.
Published: March 2009

We construct quantum integrable systems associated with non-skew-symmetric gl(2)-valued classical r-matrices. We find a new explicit multiparametric family of such the non-skew-symmetric classical r-matrices. We consider two classes of examples of the corresponding integrable systems, namely generalized Gaudin systems with and without an external magnetic field. In the case of arbitrary r-matrices diagonal in a standard gl(2)-basis, we calculate the spectrum of the corresponding quantum integrable systems using the algebraic Bethe ansatz. We apply these results to a construction of integrable fermionic models and obtain a wide class of integrable Bardeen–Cooper–Schrieffer (BCS)-type fermionic Hamiltonians containing the pairing and electrostatic interaction terms. We also consider special cases when the corresponding integrable Hamiltonians contain only pairing interaction term and are exact analogs of the “reduced BCS Hamiltonian” of Richardson.