bluuebunny/crossref_metadata_2025 huggingface dataset:
B-vitamins and prevention of dementia
Authors: Clarke Robert
Published: January 2008

Elevated plasma homocysteine (Hcy) concentrations have been implicated with risk of cognitive impairment and dementia, but it is unclear whether low vitamin B12 or folate status is responsible for cognitive decline. Most studies reporting associations between cognitive function and Hcy or B-vitamins have used a cross-sectional or case–control design and have been unable to exclude the possibility that such associations are a result of the disease rather than being causal. The Hcy hypothesis of dementia has attracted considerable interest, as Hcy can be easily lowered by folic acid and vitamin B12, raising the prospect that B-vitamin supplementation could lower the risk of dementia. While some trials assessing effects on cognitive function have used folic acid alone, vitamin B12 alone or a combination, few trials have included a sufficient number of participants to provide reliable evidence. An individual-patient-data meta-analysis of all randomised trials of the effects on cognitive function and vascular risk of lowering Hcy with B-vitamins will maximise the power to assess the epidemiologically-predicted differences in risk. Among the twelve large randomised Hcy-lowering trials for prevention of vascular disease, data should be available on about 30 000 participants with cognitive function. The principal investigators of such trials have agreed to combine individual-participant data from their trials after their separate publication.
Epidemiological and nutrition transition in developing countries: impact on human health and development
Authors: Amuna Paul , Zotor Francis B.
Published: January 2008

Whereas common infectious and parasitic diseases such as malaria and the HIV/AIDS pandemic remain major unresolved health problems in many developing countries, emerging non-communicable diseases relating to diet and lifestyle have been increasing over the last two decades, thus creating a double burden of disease and impacting negatively on already over-stretched health services in these countries. Prevalence rates for type 2 diabetes mellitus and CVD in sub-Saharan Africa have seen a 10-fold increase in the last 20 years. In the Arab Gulf current prevalence rates are between 25 and 35% for the adult population, whilst evidence of the metabolic syndrome is emerging in children and adolescents. The present review focuses on the concept of the epidemiological and nutritional transition. It looks at historical trends in socio-economic status and lifestyle and trends in nutrition-related non-communicable diseases over the last two decades, particularly in developing countries with rising income levels, as well as the other extreme of poverty, chronic hunger and coping strategies and metabolic adaptations in fetal life that predispose to non-communicable disease risk in later life. The role of preventable environmental risk factors for obesity and the metabolic syndrome in developing countries is emphasized and also these challenges are related to meeting the millennium development goals. The possible implications of these changing trends for human and economic development in poorly-resourced healthcare settings and the implications for nutrition training are also discussed.
The food multimix concept: new innovative approach to meeting nutritional challenges in Sub-Saharan Africa
Authors: Zotor F. B. , Amuna P.
Published: January 2008

Food insecurity, chronic hunger, starvation and malnutrition continue to affect millions of individuals throughout the developing world, especially Sub-Saharan Africa. Various initiatives by African governments and International Agencies such as the UN, the industrial nations, the International Monetary Fund, the World Bank and the World Trade Organisation to boost economic development, have failed to provide the much-needed solution to these challenges. The impact of these economic shifts and the failures of structural adjustment programmes on the nutritional well-being and health of the most vulnerable members of poor communities cannot be over-emphasised. The use of ad hoc measures as an adjunct to community-based rural integrated projects have provided little success and will be unsustainable unless they are linked to harnessing available local resources. The present paper therefore focuses on exploring alternative ways of harnessing the scant agricultural resources by employing a scientific approach to food-related problem-solving. The food multimix (FMM) concept offers a scientific contribution alongside other attempts currently in use by the World Food Programme, WHO and FAO to meet the food insecurity challenges that confront most of the developing world in the twenty-first century. It is an innovative approach that makes better use of traditional food sources as a tool for meeting community nutritional needs. The FMM concept employs a food-based approach using traditional methods of food preparation and locally-available, cheap and affordable staples (fruits, pulses, vegetables and legumes) in the formulation of nutrient-enriched multimixes. Developed recipes can provide ≥40% of the daily nutritional requirements of vulnerable groups, including patients with HIV/AIDS and children undergoing nutrition rehabilitation. The FMM approach can also be used as a medium- to long-term adjunct to community-based rural integration projects aimed at health improvement and economic empowerment in Sub-Saharan Africa.
Maternal and child nutrition in Sub-Saharan Africa: challenges and interventions
Authors: Lartey Anna
Published: January 2008

Women of child-bearing age (especially pregnant and lactating women), infants and young children are in the most nutritionally-vulnerable stages of the life cycle. Maternal malnutrition is a major predisposing factor for morbidity and mortality among African women. The causes include inadequate food intake, poor nutritional quality of diets, frequent infections and short inter-pregnancy intervals. Evidence for maternal malnutrition is provided by the fact that between 5 and 20% of African women have a low BMI as a result of chronic hunger. Across the continent the prevalence of anaemia ranges from 21 to 80%, with similarly high values for both vitamin A and Zn deficiency levels. Another challenge is the high rates of HIV infection, which compromise maternal nutritional status. The consequences of poor maternal nutritional status are reflected in low pregnancy weight gain and high infant and maternal morbidity and mortality. Suboptimal infant feeding practices, poor quality of complementary foods, frequent infections and micronutrient deficiencies have largely contributed to the high mortality among infants and young children in the region. Feeding children whose mothers are infected with HIV continues to remain an issue requiring urgent attention. There are successful interventions to improve the nutrition of mothers, infants and young children, which will be addressed. Interventions to improve the nutrition of infants and young children, particularly in relation to the improvement of micronutrient intakes of young children, will be discussed. The recent release by WHO of new international growth standards for assessing the growth and nutritional status of children provides the tool for early detection of growth faltering and for appropriate intervention.
Post-Political Theatre versus the Theatre of Political Struggle
Authors: Hamidi-Kim Bérénice
Published: January 2008

In this article Bérénice Hamidi-Kim tests the hypothesis that two conflicting interpretations of the notion of ‘political theatre’ exist on the French stage today. She suggests that each is based on a specific ideology stemming from a specific conception of history and policy, which results in a legitimation of the theatre and of artists both in the theatrical field and in society at large. One, which she calls ‘post-political theatre’, seems to proceed from a radical anthropological and political pessimism, and has deliberately severed all links with all previous forms of political theatre and given up any revolutionary ambitions. The other, which she calls ‘political-struggle theatre’, proudly embraces the legacy of the earlier forms of revolutionary political theatre – the epic form of documentary theatre in particular – and is attempting to revive the political ambition of contributing to a comprehensive, coherent critical project, based on the assumption that theatre is a preparatory school for reality and for political action. Bérénice Hamidi-Kim's doctoral thesis was entitled ‘The Cities of Political Theatre in France from 1989 to 2007’. She is also author of ‘Quelle place politique et culturelle pour le cadre de l'Etat-Nation dans le théâtre de gauche français?’ in the e-review Sens Public (2006), and of ‘Théâtre populaire, immigration, intégration, et identité nationale’, forthcoming in the February 2008 issue of Etudes Théâtrales.
Bosnia v. Serbia: Lessons from the Encounter of the International Court of Justice with the International Criminal Tribunal for the Former Yugoslavia
Authors: GOLDSTONE RICHARD J. , HAMILTON REBECCA J.
Published: January 2008

This article uses the recent judgment of the ICJ in Bosnia v. Serbia to highlight the potential problems that arise when international courts have to adjudicate on overlapping situations. It describes the dispute between the ICJ and the ICTY on the appropriate legal standard for the attribution of state responsibility, and finds that the ICJ's approach in this case suggests that those keen to minimize the fragmentation of international law between adjudicative bodies should not overlook the need for consistency within those bodies. With regard to fact finding, this article raises serious concerns about the manner in which the ICJ relied on the ICTY's work. The decision of the ICJ not to demand crucial documents from Serbia is discussed and criticized. Based on its approach to fact finding in this case, doubts are raised as to whether the ICJ will ever hold a state responsible for genocide outside the parameters of the prior criminal convictions of individual perpetrators.
Does the United States Really Prosecute Its Service Members for War Crimes? Implications for Complementarity before the International Criminal Court
Authors: PITTMAN THOMAS WAYDE , HEAPHY MATTHEW
Published: January 2008

This article addresses the prosecution of service members by the United States for the commission of war crimes, specifically whether or not the offences charged in such cases can truly be considered ‘war crimes’. The answer has implications in terms of application of the complementarity provision of the Rome Statute, as well as the stigmatic effect that is avoided when the United States prosecutes ordinary criminal offences rather than war crimes.
A Tightrope Walk between Legality and Legitimacy: An Analysis of the Israeli Supreme Court's Judgment on Targeted Killing
Authors: KELLER HELEN , FOROWICZ MAGDALENA
Published: January 2008

The Israeli official policy of targeted killing has often been a subject of controversy and criticism. Although still applied by the state of Israel, this cruel practice was recently limited in a courageous decision handed down by the Israeli Supreme Court. The new restrictions on targeted killing represent an important step towards its criminalization. Despite this, the Court's interpretation of the international humanitarian law requirements is still too broad and there is a need for more restrictive safeguards. In addition, the current uncertainties of this field of law, replicated in the decision, exacerbate the problem further. The main difficulty, however, lies in the theoretical assumption that targeted killing is legal. This article proposes instead to view targeted killing as an exception to the presumption of protection of the civilian population. The authors review the recent trends in international humanitarian law in order to assess the impact of the Court's reasoning. Although this landmark case represents an important breakthrough, it will certainly not be the last word on targeted killing.
Parliament and Good Governance: A Bangladeshi Perspective
Authors: RAHAMAN MUHAMMAD MUSTAFIZUR
Published: January 2008

The attainment of good governance is the question of the day in Bangladesh. This paper discusses the ‘bedrock of good governance’, parliamentary accountability, and assesses the effectiveness of the Bangladesh Parliament in ensuring governmental accountability and promoting good governance since 1991 when the country re-entered into parliamentary democracy. Considerable discrepancies between the expected role and practical performances are identified and the study further identified a number of problems that severely hinder parliament's accountability function. This paper primarily argues that Bangladesh vested excessive powers in the hands of the executive branch; it, therefore, lacks the proper checks and balances a strong parliament could provide.
Defining hospital markets for antitrust enforcement: new approaches and their applicability to The Netherlands
Authors: VARKEVISSER MARCO , CAPPS CORY S. , SCHUT FREDERIK T.
Published: January 2008

Effective antitrust enforcement is of crucial importance for countries with a market-based health care system in which hospitals are expected to compete. Assessing hospital market power – a central issue to competition policy – is, however, complicated because the presence of third party payers and the general unobservability of prices make it difficult to apply the standard methods of market definition. Alternative, less formal methods historically employed in the hospital industry have proven inaccurate; these methods were even called inapplicable in a recent US court decision. In this paper, we discuss the strengths and weaknesses of several new approaches to defining hospital markets that are suggested in the recent economic literature. In particular, we discuss the applicability of the time-elasticity approach, competitor-share approach, and option-demand approach to the recently partly deregulated Dutch hospital market. We conclude that the appropriate approach depends crucially on how health insurers contract with hospitals and how patients select their hospital.
Ist Amalgam eine Gefahr für die Gesundheit?
Authors: Göhring Till N. , Schicht Olivier O. , Imfeld Thomas
Published: January 2008

Amalgam wird seit über 100 Jahren erfolgreich als Füllungsmaterial in kariesbedingten Zahnhartsubstanzdefekten verwendet. Eine nicht sehr sachlich geführte Diskussion hat den Werkstoff Anfang der 1990er-Jahre in Misskredit gebracht, da geringe Mengen Quecksilberdampf aus Amalgamfüllungen freigesetzt werden können. Neuere Studien und Übersichtsarbeitenenen zeigen wenig bis keine Zusammenhänge zwischen systemischen oder lokalen Erkrankungen und dem Vorhandensein von Amalgamfüllungen am Menschen. Allergien auf Bestandteile des Amalgams sind selten. Da die größte Quecksilberdampfbelastung beim Anfertigen und Entfernen von Amalgamfüllungen auftritt, wird empfohlen, bei schwangeren und stillenden Frauen auf umfangreiche Sanierungen mit Amalgam zu verzichten. Bis heute gibt es kein Material, das Amalgam als Füllungsmaterial vollumfänglich ersetzen kann. Nach heutigem Wissensstand besteht durch Amalgam keine Gefahr für die Gesundheit.
Zahnärztliche Eingriffe bei antikoagulierten Patienten
Authors: Mutzbauer Till S. , Imfeld Thomas
Published: January 2008

Früher galt es als Standard, eine Antikoagulation mit Cumarin durch ein Heparin-Präparat zu ersetzen und zahnärztlich-chirurgische Eingriffe erst durchzuführen, wenn der Quick-Wert eine bestimmte Schwelle überschritten hatte. Heute hat sich diese Einstellung dahingehend gewandelt, nur bei invasiven großflächigen chirurgischen Maßnahmen in dieser Weise zu verfahren. Die Extraktion einzelner Zähne, die Entnahme einer Biopsie oder einfache parodontalchirurgische Eingriffe können bei Einsatz hämostyptischer Maßnahmen unter vollständiger Belassung der antikoagulatorischen Medikation durchgeführt werden. Es hat sich nämlich gezeigt, dass Blutungskomplikationen bei Anwendung einer adäquaten blutstillenden Maßnahme in der Zahnmedizin deutlich weniger wahrscheinlich sind als dies für Thrombose- oder Embolie-bedingte Komplikationen beim Absetzen der antikoagulatorischen Medikation der Fall ist.
Parodontitis und Herz-Kreislaufkrankheiten
Authors: Persson G. Rutger , Imfeld Thomas
Published: January 2008

Die Prävalenz von Parodontitis und Herzkreislaufkrankheiten ist hoch. Die Ätiologie, ein Biofilm-Infekt, ist für Parodontitis bekannt, für Herzkreislaufkrankheiten noch nicht völlig etabliert. Kofaktoren wie Rauchgewohnheiten, Stress, Rasse, Genetik, sozio-ökonomische Faktoren und Alter beeinflussen beide Erkrankungen. Ziel dieser Arbeit ist es, klinisch relevante Gemeinsamkeiten von Parodontitis und Herzkreislauferkrankungen aufzuzeigen. Die Hypothese eines Zusammenhanges zwischen den beiden Erkrankungen basiert auf Studien über eine gemeinsame Infektionsquelle, Studien über eine gemeinsame hyperinflammatorische Immunantwort, epidemiologische Case-control Studien sowie klinische Untersuchungen über positive kardiologische Effekte der Parodontitisbehandlung. Streptokokken der Gruppe S.mitis und S.anginosus wurden in parodontalen Läsionen gefunden. Sie sind auch als Pathogene der Endokarditis bekannt und könnten über Bakteriämie aus der Mundhöhle verbreitet werden. Andere parodontale Bakterien wie Porphyromonas gingivalis, Fusobacterium nucleatum und Peptostreptococcus micros sind β-lactamase produzierende Bakterien, welche die Antibiotikaresistenz fördern können. Chlamydia pneumoniae- und P. gingivalis-Lipopolysaccharide führen zu Hitzeschockproteinen und erzeugen eine Kaskade proinflammatorischer Zytokine. Ein Zusammenhang zwischen Parododontis und Herzkreislaufkrankheiten konnte in vielen gut kontrollierten Studien gezeigt werden. Auch ein positiver Einfluss der Behandlung der Parodontitis auf kardiovaskuläre Werte konnte gezeigt werden. Ärzte, die kardiovaskuläre Risikopatienten behandeln, sollten den parodontalen Zustand ihrer Patienten kennen und mit den zahnärztlichen Kollegen zusammen arbeiten. Zahnärzte sollten ihr medizinisches Wissen verbessern und bei Patienten mit Parodontitis, insbesondere bei solchen mit zusätzlichen Risikofaktoren (z.B. Übergewicht, Rauchen, Stress) eine medizinische Beurteilung des kardiovaskulären Zustandes durch den Arzt veranlassen.
Bad breath — aetiology, differential diagnosis and therapy
Authors: Imfeld Thomas
Published: January 2008

Rund jede vierte Person hat Mundgeruch. Dabei muss zwischen Foetor ex ore (90%) und Halitosis (10%) unterschieden werden. Ersterer ist nur im Mundatem perzeptierbar und hat seine Ursache in der Mundhöhle. Halitosis ist im Mund- und/oder Nasenatem feststellbar und die Ursache liegt entweder nasal/pharyngeal (lokale Halitosis nur im Nasenatem), pulmonal oder selten gastrointestinal (systemische Halitosis im Mund- und Nasenatem). Eine entsprechende Differenzialdiagnose ist Voraussetzung für die Kausaltherapie. Verantwortlich für den Foetor ex ore sind flüchtige Schwefelverbindungen, welche durch proteolytische Mikroorganismen in der Mundhöhle produziert werden. Prophylaxe und Therapie basieren auf der mechanischen und chemischen Reduktion dieser Erreger. Mundgeruch kann ein nachhaltiges soziales Handikap sein, weshalb das Thema nicht tabuisiert werden darf.
High‐latitude Earth's magnetopause outside the cusp: Cluster observations
Authors: Panov E. V. , Büchner J. , Fränz M. , Korth A. , Savin S. P. , Rème H. , Fornaçon K.‐H.
Published: January 2008

We investigated the ambient plasma and magnetic field conditions at high latitudes, as well as the macroparameters of the magnetopause. For this purpose we used Cluster spacecraft plasma and magnetic field data when all the interspacecraft distances were less than 300 km. We analyzed 154 magnetosheath‐magnetosphere transitions which allow to distinguish different boundaries between the magnetosphere and the magnetosheath. First, we found transitions similar to the low‐latitude boundary layer, the plasma mantle, and cusp‐associated transitions. Second, we estimated the length of these transitions. Third, we found with high statistical evidence sub‐Alfvénic magnetosheath plasma flows just above the plasma mantle. These flows are supposed to stabilize magnetopause reconnection. Fourth, we carried out an analysis of the magnetopause pressure balance. We found a group of 24 transitions during which both the thermal and the magnetic magnetosheath pressure exceeded the magnetospheric pressure, providing conditions for unusual magnetopause formation. Fifth, for 52 magnetopause crossings we obtained the orientation as well as distributions of velocity, thickness, and current density of the magnetopause. It was found that the magnetopause with an attached plasma mantle moves slower, is thinner, and reaches higher current densities than the one with an adjacent low‐latitude‐like boundary layer. A comparison with the magnetopause at low latitudes revealed that the high‐latitude magnetopause is about two times thicker.
South Asian dust episode in June 2006: Aerosol observations in the central Himalayas
Authors: Hegde P. , Pant P. , Naja M. , Dumka U. C. , Sagar R.
Published: January 2008

A dust storm blew through the Thar Desert on 12 June 2006, which has significantly influenced aerosol physical and optical properties over the central Himalayas (Nainital, 29.4°N; 79.5°E, 1958 m amsl) on 13 June 2006. Aerosol number concentrations in the coarse and giant modes on 13 June 2006 are found to be five (26 × 106 m−3) and ten (17.2 × 103 m−3) times higher compared to their respective monthly mean values. Aerosol optical depth values also showed two to four times increase, particularly at longer wavelengths suggesting increase in the concentrations of coarse and giant particles. This is supported by three to five times increase in Ångström turbidity coefficient (β) and significant reduction in Ångström wavelength exponent (α). Absence of enhancements in black carbon and accumulation mode particles suggests negligible changes in the influences of anthropogenic activities at the site during the study period.
Millennial‐scale precipitation changes in southern Brazil over the past 90,000 years
Authors: Wang Xianfeng , Auler Augusto S. , Edwards R. L. , Cheng Hai , Ito Emi , Wang Yongjin , Kong Xinggong , Solheid Maniko
Published: January 2008

A U‐Th dated 90,000 year‐long speleothem oxygen isotope record from southern Brazil anti‐correlates remarkably with the cave calcite records from eastern China, but positively correlates with the speleothem record from northeastern Brazil, suggesting an interhemispheric anti‐phasing of rainfall on both millennial and orbital timescales, likely related to displacement in the mean position of the intertropical convergence zone and associated asymmetry in Hadley circulation. The phase relationships among these records are consistent with the hypothesis that abrupt climate events during the last glacial period are triggered by oceanic circulation changes in the high latitudes and enhanced by tropical feedbacks.
Self‐consistent wave‐particle interactions in dispersive scale long‐period field‐line‐resonances
Authors: Rankin R. , Watt C. E. J. , Samson J. C.
Published: January 2008

Using 1D Vlasov drift‐kinetic computer simulations, it is shown that electron trapping in long period standing shear Alfvén waves (SAWs) provides an efficient energy sink for wave energy that is much more effective than Landau damping. It is also suggested that the plasma environment of low altitude auroral‐zone geomagnetic field lines is more suited to electron acceleration by inertial or kinetic scale Alfvén waves. This is due to the self‐consistent response of the electron distribution function to SAWs, which must accommodate the low altitude large‐scale current system in standing waves. We characterize these effects in terms of the relative magnitude of the wave phase and electron thermal velocities. While particle trapping is shown to be significant across a wide range of plasma temperatures and wave frequencies, we find that electron beam formation in long period waves is more effective in relatively cold plasma.
Mid‐depth freshening in the North Pacific subtropical gyre observed along the JMA repeat and WOCE hydrographic sections
Authors: Nakano Toshiya , Kaneko Ikuo , Soga Taizou , Tsujino Hiroyuki , Yasuda Tamaki , Ishizaki Hiroshi , Kamachi Masafumi
Published: January 2008

We report a freshening at mid‐depth in the North Pacific subtropical gyre by using long‐term repeat hydrographic data along the 137°E section and one‐time hydrographic data along the World Ocean Circulation Experiment Hydrographic Program (WHP) P2 and P3 sections. North of 15°N along the 137°E section, we estimated a linear freshening trend of 0.0015/yr between the main thermocline and the salinity minimum layer of the North Pacific Intermediate Water, mainly caused by isopycnal surface deepening due to warming, and by westward shifts of the salinity‐minimum tongue due to strengthening of the subtropical gyre. Furthermore, along the WHP‐P2 section, the linear freshening trend could be classified into several groups according to longitude. Such spatial differences in the freshening trend seem to reflect differences in the formation processes and mid‐depth pathways of the salinity minimum waters.
A large abrupt change in the abyssal water masses of the eastern Mediterranean
Authors: Rubino Angelo , Hainbucher Dagmar
Published: January 2008

In this letter we report observations showing, for the first time, the occurrence of a new, major transformation in the thermohaline cell of the eastern Mediterranean Sea. After 2 decades, during which waters of Aegean origin dominated the abyssal layers of that basin, the Adriatic Sea has returned to represent a major source of Eastern Mediterranean Deep Water (EMDW). The observed characteristics of such water, however, profoundly differ from those observed previously in the abyssal layers of the Ionian basin. In fact, the newly formed EMDW we observed there is saltier, warmer, and denser than EMDW observed before and during the Eastern Mediterranean Transient (EMT). Thus, during the past 2 decades, the thermohaline cell of the eastern Mediterranean, once considered steady, showed two large, abrupt, somehow opposite fluctuations. As in the case of the first one, origins, climatic implications, and fate of this second fluctuation have to be clarified.
Injection of a bubble into the inner magnetosphere
Authors: Zhang J.‐C. , Wolf R. A. , Sazykin S. , Toffoletto F. R.
Published: January 2008

Magnetic reconnection in the magnetotail or other forms of current sheet disruption are believed to produce plasma bubbles, which consist of flux tubes that have lower entropy content PV5/3 than their surroundings. We present an initial Rice‐Convection‐Model‐based simulation of the injection of a bubble into the inner magnetosphere and explore the consequences on ring current formation. As the bubble moves into the inner magnetosphere, region‐1‐sense Birkeland currents form along its eastward and westward edges while strong westward electric field and earthward flow form inside it; gradient/curvature drift causes it to drift westward. The simulations indicate that the presence of a bubble results in an increase in the peak particle pressure in the ring current region. Results are presented from several computer experiments to determine sensitivities to assumptions.
Magnetic double gradient mechanism for flapping oscillations of a current sheet
Authors: Erkaev N. V. , Semenov V. S. , Biernat H. K.
Published: January 2008

A new kind of magnetohydrodynamic waves are analyzed for a current sheet in a presence of a small normal magnetic field component varying along the sheet. As a background, two simplified models of a current sheet are considered with a uniform and nonuniform current distributions in the current sheet. On a basis of these two models, the flapping‐type waves are obtained which are related to a coexistence of two gradients of the tangential and normal magnetic field components along the normal and tangential directions with respect to the current sheet. A stable situation for the current sheet is associated with a positive result of the multiplication of the two magnetic gradients, and unstable (wave growth) condition corresponds to a negative result of the product. In the stable region, the “kink”‐like wave mode is interpreted as so called flapping waves observed in the Earth's magnetotail current sheet.
Comparison of kilometric continuum latitudinal radiation patterns with linear mode conversion theory
Authors: Boardsen Scott A. , Green James L. , Reinisch Bodo W.
Published: January 2008

Using 80 observations of kilometric continuum (KC) radiation patterns detected by the Radio Plasma Imager on the IMAGE spacecraft, the latitudinal variation of these radiation patterns is compared with the predictions of linear mode conversion theory (LMCT). Six of these comparisons are presented in this paper. Because the location and shape of the plasmapause at the source cannot be simultaneously determined with all of the KC observations, we estimated the minimum frequency‐dependent beaming angle possible based on a statistical upper limit plasma density versus L‐shell profile. This density versus L‐shell profile is equated to the 90th percentile plasma density versus L‐shell curve derived from over 40,000 in situ measurements of the upper hybrid resonance frequency made over the first 3 years of the IMAGE mission. For all cases, starting at frequencies approximately >150 kHz, the model beam center was found to lie just within or outside the radiation pattern. Unrealistic peak densities are required at the equatorial source L‐shell locations which are necessary to force the beam centers to lie deep within the observed radiation patterns. We present this as strong evidence that LMCT cannot be used to explain KC. In order to explain the latitudinal location of the high‐frequency end of these KC radiation patterns a theory is required in which these frequencies are beamed at equatorial angles that are much smaller than the predictions of LMCT. Hashimoto et al. (2005), analyzing one KC radiation pattern detected by CRRES, reached the same conclusion. We present one case in which the source location was inferred by equating the harmonic spacing in the KC radiation pattern with the model electron cyclotron frequency at the source. The LMCT model beams, for this source location, were found to lie outside of the radiation pattern at all frequencies, again consistent with Hashimoto et al. (2005). In addition a survey of KC observations by IMAGE in MLT is presented in which the probability of occurrence peaks in both the dawn and evening sectors.
A global hybrid model for Titan's interaction with the Kronian plasma: Application to the Cassini Ta flyby
Authors: Modolo R. , Chanteur G. M.
Published: January 2008

The interaction between the corotating magnetospheric plasma of Saturn and the exosphere of Titan is investigated by means of a three‐dimensional and multispecies hybrid simulation model coupling charged and neutral species via three ionizing mechanisms: the absorption of extreme ultraviolet solar photons, the impacts of magnetospheric electrons, and the charge exchange reactions between ions and neutral atoms or molecules. The simulation model includes the low and energetic components of the magnetospheric plasma, the main exospheric neutral species (molecular hydrogen and nitrogen and methane), and the atmospheric slowing down of charged particles penetrating below the exobase. Ionization rates of the exospheric species are computed as consistently as possible for each of the three ionizing mechanisms by making use of the relevant local number densities and cross sections or ionization frequencies. This model is thus able to provide a priori estimates of the escaping fluxes of exospheric ionic species and to separate for the contributions of the different ionization sources. A simulation run has been made for the conditions encountered by spacecraft Cassini during flyby Ta of Titan on 26 October 2004. Results are presented to characterize the main features of the simulated plasma environment of Titan: the induced magnetic tail and the flow of magnetospheric plasma around Titan, as well as the wake and the acceleration of the planetary plasma. Considering the coarse spatial resolution of the present simulation, these features are in reasonable agreement with in situ plasma measurements made by spacecraft Cassini.
Observations of the development of electron temperature anisotropies in Earth's magnetosheath
Authors: Masood W. , Schwartz S. J.
Published: January 2008

Electron velocity distributions in Earth's magnetosheath exhibit a number of nonequilibrium characteristics, including a flat‐topped shape at thermal energies and anisotropies relative to the magnetic field, with T⊥e > T∥e. These features are related to processes at the bow shock and within the magnetosheath. In the present investigation we focus our attention on the development of the electron temperature anisotropy in the magnetosheath, employing the simultaneous multispacecraft data obtained by the Plasma Electron and Current Experiment (PEACE) on board Cluster. Such studies remove the temporal ambiguities introduced by single‐spacecraft analyses. We find that the electron velocity space distributions just behind the bow shock are nearly isotropic with a slight T∥e > T⊥e anisotropy, whereas deeper into the magnetosheath the electrons exhibit a significant T⊥e > T∥e anisotropy. We find observational evidence for two processes that contribute to the sheath anisotropy. There is a clear decrease of suprathermal electrons at 0° and 180° pitch angles, suggesting that this population suffers losses (e.g., into the upstream region) related to the global configuration. Additionally, an ongoing local mechanism inflates the 90° pitch angle suprathermal electron population.
Modeling short‐term variability of α‐hexachlorocyclohexane in Northern Hemispheric air
Authors: Hansen Kaj M. , Christensen Jesper H. , Brandt Jørgen , Frohn Lise M. , Geels Camilla , Skjøth Carsten Ambelas , Li Yi‐Fan
Published: January 2008

The POP version of the Danish Eulerian Hemispheric Model (DEHM‐POP) is a further development of a 3‐D dynamic atmospheric chemistry transport model covering the Northern Hemisphere, which was originally developed to study atmospheric transport of conventional air pollutants and other atmospheric constituents (e.g., SOX, heavy metals, and CO2). Four different surface compartments (soil, ocean water, vegetation, and snow) are introduced in DEHM‐POP with each compartment including the most dominant dynamic processes determining the exchange between air and the surface type to account for the consecutive cycles of deposition and reemission of persistent organic pollutants (POPs). This model setup makes it possible to study short‐term atmospheric variability of POPs, which is exemplified in this paper by a study of the atmospheric variability of α‐hexachlorocyclohexane (α‐HCH), the major component of the worldwide most used insecticide: technical HCH. Simulated α‐HCH air concentrations are evaluated against measurements from 21 monitoring stations within the model domain, and the model is able to predict the annual average concentration as well as the long‐term trend for the 1990s. Significant correlations between simulated and measured short‐term atmospheric concentrations of α‐HCH are also found at the majority of the investigated monitoring stations, which shows that it is possible to resolve the atmospheric variability of POPs using an atmospheric chemistry transport model. Differences between simulated and measured atmospheric α‐HCH variability can arise because the measurements may be influenced by local features that are not accounted for in the model with the relatively coarse horizontal resolution and surface description.
Did North Atlantic overturning halt 17,000 years ago?
Authors: Keigwin Lloyd D. , Boyle Edward A.
Published: January 2008

Models indicate that a complete shutdown of deep and intermediate water production is a possible consequence of extreme climate conditions in the northern North Atlantic, and the high ratio of 231Pa to 230Th on Bermuda Rise is evidence that this might have happened ∼17 ka during Heinrich event 1 (H1). However, new radiocarbon data from bivalves that lived at ∼4.6 km on the Bermuda Rise during H1 lead to a different conclusion. The bivalve data do indeed indicate ventilation of the deep western North Atlantic was suppressed during H1 but not as much as it was during the last glacial maximum. We propose that high diatom flux to the Bermuda Rise during H1 is at least in part responsible for increased 231Pa/230Th at that time. Although we cannot say for sure why opal production was so high in a gyre center location at that time, increased leakage of silica rich waters from the Southern Ocean to the North Atlantic is one possibility.
Potential energy surface of HDO up to 25000cm−1
Authors: Yurchenko S. N. , Voronin B. A. , Tolchenov R. N. , Doss N. , Naumenko O. V. , Thiel W. , Tennyson Jonathan
Published: January 2008

A new spectroscopically determined potential energy surface (PES) for HDO16 is presented. This surface is constructed by adjusting the high accuracy ab initio PES of Polyansky et al. [Science 299, 539 (2003)] by fitting to both published experimental data and our still unpublished data. This refinement used experimentally derived term values up to 25000cm−1 and with J⩽8: a data set of 3478 energy levels once some levels with ambiguous assignment is excluded. To improve the extrapolation properties of the empirical PES, the restraint that the resulting PESs remain close to the ab initio surface was imposed. The new HDO̱07 PES reproduces the experimental data, including high J levels not included in the fit, with a root mean square error of 0.035cm−1. Predictions for rotation-vibration term values up to J=12 are made.
Topological analysis of electron densities from Kohn-Sham and subsystem density functional theory
Authors: Kiewisch Karin , Eickerling Georg , Reiher Markus , Neugebauer Johannes
Published: January 2008

In this study, we compare the electron densities for a set of hydrogen-bonded complexes obtained with either conventional Kohn-Sham density functional theory (DFT) calculations or with the frozen-density embedding (FDE) method, which is a subsystem approach to DFT. For a detailed analysis of the differences between these two methods, we compare the topology of the electron densities obtained from Kohn-Sham DFT and FDE in terms of deformation densities, bond critical points, and the negative Laplacian of the electron density. Different kinetic-energy functionals as needed for the frozen-density embedding method are tested and compared to a purely electrostatic embedding. It is shown that FDE is able to reproduce the characteristics of the density in the bonding region even in systems such as the F–H–F− molecule, which contains one of the strongest hydrogen bonds. Basis functions on the frozen system are usually required to accurately reproduce the electron densities of supermolecular calculations. However, it is shown here that it is in general sufficient to provide just a few basis functions in the boundary region between the two subsystems so that the use of the full supermolecular basis set can be avoided. It also turns out that electron-density deformations upon bonding predicted by FDE lack directionality with currently available functionals for the nonadditive kinetic-energy contribution.
New concept of solute distribution around a diffusive crystal-solution interface of a binary Lennard-Jones mixture from the viewpoint of molecular dynamics
Authors: Maeda Kouji , Asakuma Yusuke , Fukui Keisuke
Published: January 2008

Directional crystallization from a binary mixture was performed by pseudo-NpT ensemble molecular dynamics. The initial crystal phase having a face-centered-cubic (fcc) structure grew toward the whole cell according to the temperature gradient in the universal cell. The growing crystal phase was not planar even though the solute molecules grew in two-dimensional coordinates because the solvent molecules disturbed the crystallization of the solute molecules at the diffusive crystal-solution interface. This represented the essential phenomenon of solute distribution during crystallization. Consequently, the growing crystal phase still contained solvent molecules having a liquid structure. The time change of the solute composition in the early phase of crystal growth showed an increase in solute composition as the time step proceeded. The resulting solute composition in this early phase was considered at different temperature gradients in the universal cell and it increased as the temperature of the initial crystal-solution interface increased. A new distribution coefficient model was proposed as a function of the difference between the local solute composition and bulk solute composition in the solution around the crystal-solution interface. The impurity-solvent distribution coefficient could be represented by the new model for faster growth of the lower temperature’s initial interface. As regards a better distribution coefficient, there was found to be a very dilute solution phase over the crystal phase. The new variable “distribution rate” instead of the ambiguous variable “growth rate” was considered as a function of temperature gradient in the universal cell.
Study of thermal stability and luminescence quenching properties of bismuth-doped silicate glasses for fiber laser applications
Authors: Truong V. G. , Bigot L. , Lerouge A. , Douay M. , Razdobreev I.
Published: January 2008

In the present work, we report on the luminescence properties of bismuth-doped silicate preforms and fibers under the influence of high temperature annealing and hydrogen-loading then annealing processes. Bismuth-related luminescence is found to be very sensitive to thermal annealing processes and can even totally disappear for specific annealing processes. The observed quenching of the luminescence was attributed to the reduction of part of bismuth ions responsible for the infrared luminescence into a lower valence state of bismuth.
Structure, phase transformation, and magnetic properties of R16Fe76−xCoxC8 (R≡Nd, Dy; 0⩽x⩽76) alloys prepared by a remilling process
Authors: Lv X. K. , Liu W. , Cui W. B. , Zhao X. G. , Ren W. J. , Zhang Z. D.
Published: January 2008

The effect of Co substitution on structure, phase transformation, and magnetic properties of R16Fe76−xCoxC8 (R≡Nd, Dy; 0⩽x⩽76) alloys prepared by a remilling process has been studied systematically. The process of remilling and subsequent annealing is more beneficial for the formation of Nd2(Fe,Co)14C compound in Nd16Fe76−xCoxC8 alloys than in Dy16Fe76−xCoxC8 alloys. The R2(Fe,Co)14C phase is obtained for Nd16Fe76−xCoxC8 alloys with 0⩽x⩽20 and Dy16Fe76−xCoxC8 alloys with 0⩽x⩽25. Higher Co content results in the formation of Nd2(Fe,Co)17Cδ-type phase and Dy(Fe,Co)7 phase for Nd16Fe76−xCoxC8 and Dy16Fe76−xCoxC8 alloys, respectively. The high coercivity, Hci=48.5kOe, is achieved for Dy16Fe51Co25C8 alloy.
Improving upon CCSD(T): ΛCCSD(T). I. Potential energy surfaces
Authors: Taube Andrew G. , Bartlett Rodney J.
Published: January 2008

Despite the successes of spin-restricted coupled-cluster singles, doubles, and perturbative triples [CCSD(T)], it fails for systems away from equilibria, which might raise questions about transition states, e.g. In an attempt to remedy this failure, we implemented ΛCCSD(T) in a general purpose form for open and closed shells and with arbitrary single determinant reference functions, and applied it to a wide variety of bond-breaking examples. ΛCCSD(T) is shown to substantially improve the behavior of CCSD(T) at long bond lengths without significantly affecting the quality of the equilibrium results. Weighted average nonparallelity errors for HF, C2, N2, and H2O are reduced from 22mhartree for CCSD(T) to 10mhartree for ΛCCSD(T). Using ΛCCSD(T) with a Brueckner reference provides the best single reference coupled-cluster description of N2’s dissociation curve to date. Application of CCSD(T) and ΛCCSD(T) to the concerted transition state of 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX) indicates that this transition state is well described by either methods, and indicates that the activation barrier is too high for it to be a major pathway of decomposition.
Mapping the geometry of the E6 group
Authors: Bernardoni Fabio , Cacciatori Sergio L. , Cerchiai Bianca L. , Scotti Antonio
Published: January 2008

In this paper, we present a construction for the compact form of the exceptional Lie group E6 by exponentiating the corresponding Lie algebra e6, which we realize as the sum of f4, the derivations of the exceptional Jordan algebra J3 of dimension 3 with octonionic entries, and the right multiplication by the elements of J3 with vanishing trace. Our parametrization is a generalization of the Euler angles for SU(2) and it is based on the fibration of E6 via an F4 subgroup as the fiber. It makes use of a similar construction we have performed in a previous article for F4. An interesting first application of these results lies in the fact that we are able to determine an explicit expression for the Haar invariant measure on the E6 group manifold.
Magnetic domain structure of amorphous Fe73.5Si13.5B9Nb3Cu1 wires under torsional stress
Authors: Hernando B. , Sánchez M. L. , Prida V. M. , Santos J. D. , Olivera J. , Belzunce F. J. , Badini G. , Vázquez M.
Published: January 2008

The evolution of the magnetic domain structure with the applied torsion has been studied by means of the Bitter technique on high magnetostrictive Fe73.5Si13.5B9Nb3Cu1 amorphous wires. A drastic change in domain patterns is observed by applying a very low torsional strain value as small as 2.4 (2πrad∕m) in the wire. The domain structure on the wire surface changes from a maze configuration, with zigzag walls, to a helical one. When the magnitude of the applied torsion is increased, both in clockwise or counterclockwise senses, a change in the values for the domain width as well as the wall angle tilting with respect to the wire axis are clearly observed, showing a saturation value of 45° for an applied torsional strain equal or higher than 10 (2πrad∕m). Also, the coercive field variation with the applied torsion shows a minimum value of 26Am−1 just for a torsional strain of 2.4 (2πrad∕m), suggesting that the internal and the applied helical anisotropies are then balanced, at least partially, resulting in the softest magnetic state for the amorphous wire with respect to the coercive field of 40Am−1 for the untwisted wire.
Design and analysis of a transverse flux permanent-magnet machine using three-dimensional scalar magnetic potential finite element method
Authors: Wang Jiankuan , Chau K. T. , Jiang J. Z. , Yu Chuang
Published: January 2008

In this paper, a new transverse flux permanent-magnet machine is proposed and implemented. It features a unique configuration that it is composed of assembled stators and flux-concentrating rotor, hence offering low manufacturing cost while retaining high torque density and low cogging torque. Because of its unique configuration, the proposed machine is analyzed by a newly developed three-dimensional scalar magnetic potential finite element method. Both calculated and experimental results are given to support the validity of the proposed design and analysis.
Frequency dispersion of hysteresis in core/shell magnetic nanoparticle: Monte Carlo simulation
Authors: Wu M. H. , Dong S. , Liu J.-M.
Published: January 2008

Based on the uniaxially anisotropic Heisenberg model, we investigated the frequency dispersion of dynamic hysteresis for an exchange-biased ferromagnetic core/antiferromagnetic shell nanoparticle using Monte Carlo simulation. The frequency dispersion of the dynamic hysteresis shows both the spin-reversal resonance and spin-tilting resonance. The power-law scaling behaviors over both the low-frequency and high-frequency regimes are demonstrated, and it is shown that the exchange coupling on the core/shell interface has no effect on the power-law scaling of the hysteresis dispersion. The dynamic effect of the exchange bias is insignificant either.