bluuebunny/crossref_metadata_2025 huggingface dataset:
LINEAR WEINGARTEN HYPERSURFACES IN A REAL SPACE FORM
Authors: SHU SHICHANG
Published: August 2010

In this paper, we investigate linear Weingarten hypersurfaces with two distinct principal curvatures in a real space form Mn+1(c), we obtain two rigidity results and give some characterization of the Riemannian product Sk(a) × Sn−k($\sqrt{1-a^2})\$), 1 ≤ k ≤ n − 1 in Mn+1(c)(c = 1), the Riemannian product Rk × Sn−k(a), 1 ≤ k ≤ n −1 in Mn+1(c)(c = 0) and the Riemannian product Hk(tanh2 ρ−1) × Sn−k(coth2 ρ−1), 1 ≤ k ≤ n −1 in Mn+1(c)(c = −1).
QUASI-DETERMINANTS AND q-COMMUTING MINORS
Authors: LAUVE AARON
Published: August 2010

We present two new proofs of the q-commuting property holding among certain pairs of quantum minors of a q-generic matrix. The first uses elementary quasi-determinantal arithmetic; the second involves paths in a directed graph. Together, they indicate a means to build the multi-homogeneous coordinate rings of flag varieties in other non-commutative settings.
AN INVERSE THEOREM FOR THE GOWERSU4-NORM
Authors: GREEN BEN , TAO TERENCE , ZIEGLER TAMAR
Published: August 2010

We prove the so-calledinverse conjecture for the Gowers Us+1-normin the cases= 3 (the casess< 3 being established in previous literature). That is, we show that iff: [N] → ℂ is a function with |f(n)| ≤ 1 for allnand ‖f‖U4≥ δ then there is a bounded complexity 3-step nilsequenceF(g(n)Γ) which correlates withf. The approach seems to generalise so as to prove the inverse conjecture fors≥ 4 as well, and a longer paper will follow concerning this.

By combining the main result of the present paper with several previous results of the first two authors one obtains the generalised Hardy–Littlewood prime-tuples conjecture for any linear system of complexity at most 3. In particular, we have an asymptotic for the number of 5-term arithmetic progressionsp1<p2<p3<p4<p5≤Nof primes.
ON SINGULARITIES OF QUIVER MODULI
Authors: DOMOKOS MÁTYÁS
Published: August 2010

Any moduli space of representations of a quiver (possibly with oriented cycles) has an embedding as a dense open subvariety into a moduli space of representations of a bipartite quiver having the same type of singularities. A connected quiver is Dynkin or extended Dynkin if and only if all moduli spaces of its representations are smooth.
ON MAZUR'S CONJECTURE FOR TWISTED L-FUNCTIONS OF ELLIPTIC CURVES OVER TOTALLY REAL OR CM FIELDS
Authors: VIRDOL CRISTIAN
Published: August 2010

Let E be an elliptic curve defined over a number field F, and let Σ be a finite set of finite places of F. Let L(s, E, ψ) be the L-function of E twisted by a finite-order Hecke character ψ of F. It is conjectured that L(s, E, ψ) has a meromorphic continuation to the entire complex plane and satisfies a functional equation s ↔ 2 − s. Then one can define the so called minimal order of vanishing ats = 1 of L(s, E, ψ), denoted by m(E, ψ) (see Section 2 for the definition).
ON WITTEN MULTIPLE ZETA-FUNCTIONS ASSOCIATED WITH SEMI-SIMPLE LIE ALGEBRAS IV
Authors: KOMORI YASUSHI , MATSUMOTO KOHJI , TSUMURA HIROFUMI
Published: August 2010

In our previous work, we established the theory of multi-variable Witten zeta-functions, which are called the zeta-functions of root systems. We have already considered the cases of types A2, A3, B2, B3 and C3. In this paper, we consider the case of G2-type. We define certain analogues of Bernoulli polynomials of G2-type and study the generating functions of them to determine the coefficients of Witten's volume formulas of G2-type. Next, we consider the meromorphic continuation of the zeta-function of G2-type and determine its possible singularities. Finally, by using our previous method, we give explicit functional relations for them which include Witten's volume formulas.
Sloshing and slamming oscillations in a collapsible channel flow
Authors: STEWART PETER S. , HEIL MATTHIAS , WATERS SARAH L. , JENSEN OLIVER E.
Published: August 2010

We consider laminar high-Reynolds-number flow through a finite-length planar channel, where a portion of one wall is replaced by a thin massless elastic membrane that is held under longitudinal tension T and subject to a linear external pressure distribution. The flow is driven by a fixed pressure drop along the full length of the channel. We investigate the global stability of two-dimensional Poiseuille flow using a method of matched local eigenfunction expansions, which is compared to direct numerical simulations. We trace the neutral stability curve of the primary oscillatory instability of the system, illustrating a transition from high-frequency ‘sloshing’ oscillations at high T to vigorous ‘slamming’ motion at low T. Small-amplitude sloshing at high T can be captured using a low-order eigenmode truncation involving four surface-based modes in the compliant segment of the channel coupled to Womersley flow in the rigid segments. At lower tensions, we show that hydrodynamic modes increasingly contribute to the global instability, and we demonstrate a change in the mechanism of energy transfer from the mean flow, with viscous effects being destabilizing. Simulations of finite-amplitude oscillations at low T reveal a generic slamming motion, in which the flexible membrane is drawn close to the opposite rigid wall before recovering rapidly. A simple model is used to demonstrate how fluid inertia in the downstream rigid channel segment, coupled to membrane curvature downstream of the moving constriction, together control slamming dynamics.
Molecular and biochemical mining of heat-shock and 14-3-3 proteins in drug-induced protoscolices ofEchinococcus granulosusand the detection of a candidate gene for anthelmintic resistance
Authors: Pan D. , Das S. , Bera A.K. , Bandyopadhyay S. , Bandyopadhyay S. , De S. , Rana T. , Das S.K. , Suryanaryana V.V. , Deb J. , Bhattacharya D.
Published: August 2010

Cystic echinococcosis (CE) caused by the larval stage ofEchinococcus granulosusis a disease that affects both humans and animals. In humans the disease is treated by surgery with a supplementary option of chemotherapy with a benzimidazole compound. During the present study heat-shock protein 60 (HSP 60) was identified as one of the most frequently expressed biomolecules byE. granulosusafter albendazole treatment. Data were correlated with 14-3-3 protein signature, and overexpression of this molecule after albendazole induction was an indicator of cell survival and signal transduction duringin vitromaintenance ofE. granulosusfor up to 72 h. This observation was further correlated with a uniform expression pattern of a housekeeping gene (actin II). Out of three β-tubulin gene isoforms ofE. granulosus, β-tubulin gene isoform 2 showed a conserved point mutation indicative of benzimidazole resistance.
Homelessness and the Mobile Shelter System: Public Transportation as Shelter
Authors: NICHOLS LAURA , CÁZARES FERNANDO
Published: August 2010

Those without housing often use public space differently than those who are housed. This can cause dilemmas for and conflicts among public officials as guardians of public space and goods. In this paper, we look at one such utilisation of space from the perspective of those who board 24-hour public transportation routes and ride the bus all night for shelter. We describe the results of a preliminary survey, observations and informal conversations with unhoused riders on the bus over three nights in one county in the United States. We found that a substantial number of the unhoused riders we surveyed used the bus as their main form of night-time shelter throughout the year, and that some have ridden the bus for shelter for many years. Men were more likely to say that they used the bus to sleep, while women rode the bus for safety. While some unhoused riders also utilised shelters or did not know about other shelter options, many actively choose the bus over emergency shelters. The potential implications of the study for service providers, researchers and policy-makers are addressed.
Early Occupational Aspirations and Fractured Transitions: A Study of Entry into ‘NEET’ Status in the UK
Authors: YATES SCOTT , HARRIS ANGEL , SABATES RICARDO , STAFF JEREMY
Published: August 2010

There has been significant recent research and policy interest in issues of young people's occupational aspirations, transitions to employment and the antecedents of NEET (not in employment, education or training) status. Many have argued that changes to the youth labour market over the past 30 years have led to transitions to work becoming more individualised, complex and troublesome for many, particularly those from poorer backgrounds. However, little research has examined the connection between early uncertainty or misalignment in occupational aspirations and entry into NEET status. This paper draws on the British Cohort Study to investigate these issues, and finds that young people with uncertain occupational aspirations or ones misaligned with their educational expectations are considerably more likely to become NEET by age 18. Uncertainty and misalignment are both more widespread and more detrimental for those from poorer backgrounds. These findings are discussed in the context of recent research and debates on emerging adulthood and the youth labour market.
The ‘Deserving’ Rich? Inequality, Morality and Social Policy
Authors: ROWLINGSON KAREN , CONNOR STUART
Published: August 2010

There is a long tradition in social policy of discussing and critiquing the notion of ‘deservingness’ in relation to ‘the poor’. This paper will apply such debates to ‘the rich’ to consider the grounds on which this group might be considered ‘deserving’. The paper identifies three sets of arguments. The first set of arguments concerns the appropriateness ofrewardingmerit/hard work/effort/risk-taking etc. The second concerns more consequentialist/economic arguments about providingincentivesfor wealth creation. And the third considers thecharacterand behaviour of the rich. As well as discussing the potential criteria for deservingness, the paper will also debate whether thedegreeof income and wealth gained by the rich is deserved. Finally, the paper will discuss the social policy implications, including taxation policies, which emerge from this debate.
Making the Transition from Sure Start Local Programmes to Children's Centres, 2003–2008
Authors: LEWIS JANE , ROBERTS JONATHAN , FINNEGAN CATHY
Published: August 2010

Sure Start local programmes (SSLPs), an area-based early intervention programme for under fives in England set up in 1998, was replaced by children's centres (CCs), a universal, mainstream service, under the control of local authorities in 2003. This paper uses qualitative data from three urban authorities in an exploratory study that investigates how far CCs differ from SSLPs, and how far they are more recognisably similar to one another than were SSLPs. We explore interviewees’ understandings of the idea of an SSLP and of a CC; differences between the core offers of the two programmes in terms of funding, consistency, local responsiveness and the balance of services; issues arising from making CCs a mainstream service; and changes in governance in terms of information flows, lines of accountability and parent participation. We find that while CCs differ from SSLPs in significant respects, they also differ one from the other, and we offer some reflections on the possible causes of this.
Gilbert Murray and International Relations: Hellenism, liberalism, and international intellectual cooperation as a path to peace
Authors: WILSON PETER
Published: August 2010

Gilbert Murray was one of the towering figures of 20th century cultural and intellectual life, and the foremost Hellenist of his generation. He was also a tireless campaigner for peace and international reconciliation, and a pioneer in the development of international intellectual cooperation, not least in the field of International Relations (IR). Yet in IR today he is largely forgotten. This article seeks to put Murray back on the historiographical map. It argues that while in many ways consistent with the image of the inter-war ‘utopian’, Murray's thinking in certain significant ways defies this image. It examines the twin foundations of his international thought – liberalism and Hellenism – and their manifestation in a version of international intellectual cooperation that while aristocratic and outmoded in some respects, nonetheless contains certain enduring insights.
Structure, norms and normative theory in a re-defined English School: accepting Buzan's challenge
Authors: WILLIAMS JOHN
Published: August 2010

This article looks at the significance of Barry Buzan's 2004 reformulation of the English School from the perspective of the normative dimension of English School theory. Picking up a challenge that Buzan set, but which has largely gone unanswered, for those who see normative theory as a key aspect of the English School's contribution, the article assesses three possible responses. It rejects a stance denying the relevance of Buzan's approach to normative theory and is dissatisfied with a second line that distinguishes methodologically between Buzan's social structural theorising and an approach to normative theory that draws principally on political theory. Instead, it argues for the inherent normativity of Buzan's position because of its reliance on values, arguing that many of the analytical benefits of Buzan's approach can also be deployed normatively because of the way he highlights contested and competing dynamics in play at different times and at different levels. The article suggests that this has the potential to revive pluralism as a normative position in the English School in a way that retains and extends the enhanced analytical power that Buzan's reformulation offers.
The meaning of materiality: reconsidering the materialism of Gramscian IR
Authors: MCCARTHY DANIEL R.
Published: August 2010

Gramsican approaches in International Relations (IR) have sought to outline the relationship between ideas and material forces in the construction of world order. Scholars working within this broad school have sought to emphasise that ideasarematerial forces, and must be considered as concrete historical structures (Cox, 1987) central to the establishment of particular historical and hegemonic blocs. This literature has primarily focused on the discursive construction of hegemony by international elites and the impact this has on political practices. While these insights are important in understanding the construction of world order, it is necessary to extend them to include the creation of actual physical structures – that is, it is vital to link the ideational aspects of hegemony with actual material processes. I will argue that a consideration of the role of technology provides an ideal vehicle for this process, building on the preliminary work of Bieler and Morton in this regard (2008). Technological structures are the product of particular cultural values and embed these cultural values within their very structure. Physical material factors thereby express ideational values constructed by specific social forces. Social practices are thus not only a function of the dominance of certain ideological formations, but also the product of the material environment itself and the manner in which the human metabolism with nature must function through these physical constructions.
Hearth and Soul: Economics and Culture in Partisan Conceptions of the Family in the Progressive Era, 1900–1920
Authors: Alphonso Gwendoline
Published: August 2010

Both political scientists and popular commentators have reacted to the culture wars of the 1990s as something new in American politics, a deviation from the durable grounding of politics in economic interests. However, as recent work, along with many of the classic treatments of the Populist and Progressive eras demonstrate, American politics has long been infused with both culture and economics. The interesting question is thus not “which one” but rather “how” these two dimensions of political value have intersected through time and what the dynamics of those intersections reveal. The paper uses congressional family policy debates to demonstrate two alternative policy frameworks during the Progressive Era, each with its own alignment of the two dimensions and one emerging as a harbinger to the New Deal welfare state. Through systematic discursive analysis of committee hearings transcripts of the Fifty-sixth to Sixty-sixth Congresses, it assembles two dominant conceptual frameworks of family as illustrative of the two approaches. The progressive understanding viewed family economics as foundational, circumscribing its cultural qualities and legitimating state intervention. In contrast, the traditionalist conception privileged self-regulating families' cultural qualities as more fundamental, only loosely related to economic condition, such that active state intervention into family economics was seen as inappropriate and ineffective. These alternative approaches to state and family relations viewed culture or economics alternatively as foundational or epiphenomenal, if related at all. As history unfolded, the progressive conception ultimately prevailed in New Deal and postwar social policies, which continued to emphasize the economic dimension as subsuming the cultural one. Investigating the dynamics of intersectionality between economics and culture is suggested as a potential pathway to bridge work emphasizing durable economic interests in politics with other work focused instead on the endurance of moral conflicts in political deliberations, implying that in the Progressive Era the parties were not only divided in terms of which set of issues were more important but also over how the two dimensions of political value related to each other, if at all.
The contribution of injury severity, executive and implicit functions to awareness of deficits after traumatic brain injury (TBI)
Authors: MORTON NICHOLAS , BARKER LYNNE
Published: August 2010

Deficits in self-awareness are commonly seen after Traumatic Brain Injury (TBI) and adversely affect rehabilitative efforts, independence and quality of life (Ponsford, 2004). Awareness models predict that executive and implicit functions are important cognitive components of awareness though the putative relationship between implicit and awareness processes has not been subject to empirical investigation (Crosson et al., 1989; Ownsworth, Clare, & Morris, 2006; Toglia & Kirk, 2000). Severity of injury, also thought to be a crucial determinant of awareness outcome post-insult, is under-explored in awareness studies (Sherer, Boake, Levin, Silver, Ringholz, & Walter, 1998). The present study measured the contribution of injury severity, IQ, mood state, executive and implicit functions to awareness in head-injured patients assigned to moderate/severe head-injured groups using several awareness, executive, and implicit measures. Severe injuries resulted in greater impairments across most awareness, executive and implicit measures compared with moderate injuries, although deficits were still seen in the moderate group. Hierarchical regression results showed that severity of injury, IQ, mood state, executive and implicit functions made significant unique contributions to selective aspects of awareness. Future models of awareness should account for both implicit and executive contributions to awareness and the possibility that both are vulnerable to disruption after neuropathology. (JINS, 2010,16, 1089–1098.)
Estimating the cost of smoking to the NHS in England and the impact of declining prevalence
Authors: Callum Christine , Boyle Seán , Sandford Amanda
Published: August 2010

Smoking cost the National Health Service (NHS) in England in 1996 an estimated £1.4–£1.7 billion. In 1998, in Smoking Kills, the Government outlined an action plan for reducing smoking prevalence. This paper estimates 2006 costs and the impact of declining prevalence. Estimates are derived from costs, service use, and attributable proportions based on current and ex-smokers’ prevalence and relative risk compared with never-smokers. Comparable 1996 costs were estimated by substituting 1996 prevalence. Smoking-attributable hospital admissions cost the NHS an estimated £1 billion in 2006, outpatient attendances cost £190 million, general practitioner (GP) consultations £530 million, practice nurse consultations £50 million and GP prescriptions £900 million; £2.7 billion in total. This represents 5% of adult hospital admission costs, 4% outpatients, 11% GP and 8% practice nurse consultations and 12% of prescription costs. Smoking accounted for 24% of respiratory disease hospital admission costs and 16% of cancer and cardiovascular disease costs (people aged ⩾35 years). The 2006 cost is estimated to be 13% lower than if smoking had remained at 1996 levels. Smoking represents a substantial cost throughout the NHS. Significant savings are associated with a reduction in prevalence, but much of this stems from an earlier phase of the smoking epidemic. Securing future such savings requires further policies to reduce smoking prevalence.
Spatial justice: law and the geography of withdrawal
Authors: Philippopoulos-Mihalopoulos Andreas
Published: August 2010

While spatial justice could be the most radical offspring of law’s recent spatial turn, it remains instead a geographically informed version of social justice. The majority of the existing literature on the subject has made some politically facile assumptions about space, justice and law, thereby subsuming the potentially radical into the banal. In this article, I suggest that the concept of spatial justice is the most promising platform on which to redefine, not only the connection between law and geography, but more importantly, the conceptual foundations of both law and space. More concretely, the article attempts two things: first, a radical understanding of legal spatiality. Space is not just another parameter for law, a background against which law takes place, or a process that the law needs to take into consideration. Space is intertwined with normative production in ways that law often fails to acknowledge, and part of this article is a re-articulation of the connection. Second, to suggest a conception of spatial justice that derives from a spatial law. Such a conception cannot rely on given concepts of distributive or social justice. Instead, the concept of spatial justice put forth here is informed by post-structural, feminist, post-ecological and other radical understandings of emplacement and justice, as well as arguably the most spatial of philosophical discourses, that of Deleuze–Guattari and the prescribed possibilities of space as manifold.
Lines, barred lines. Movement, territory and the law
Authors: Brighenti Andrea Mubi
Published: August 2010

In this paper an attempt is made to analyse the complex relationship between law, territory and movement. Beginning with a quick overview of the notion of property, the paper suggests that this legal notion represents a way of imagining the practice of inhabiting the planet. Dwelling and travelling are explored as two alternative and complementary ways of inhabiting, and a closer inspection is paid to the moments when they confront each other both ideologically and practically. A territorial question is identified at the core of law, namely the issue of the movement of bodies in space (or motility), together with the control of such movements. From this perspective, movement is not simply one among the many objects over which law exerts control, rather law itself is a territorial endeavour, a movement that acts upon other movements.
The space of the city in reconstruction: the lawscapes of Barcelona and Berlin
Authors: Mazzoleni Chiara
Published: August 2010

The momentous changes that have affected European cities over the last two centuries have had profound consequences for the configuration of urban space. Urban planning and architecture, torn between the dialectically opposed forces of permanence and change, particularly in building practices and the use of urban space, have had an important influence on the material construction of cities. The outcome was a strong focus on the individual architectural artefact and, at the same time, the spread of a process of atopical fragmentation of urban space and the gradual loss of status of contact space. The latter suffered a process of deterioration due to disaffection and abandonment of the practice and a rapid shift of interest towards space decontextualised and standardised by the networks. The recent experiences of Barcelona and Berlin have been a reaction to this impoverishment of the meaning of the city, drawing on the heuristic contribution of the Italian school of urban analysis to recover the constituent elements of urban space and the conventions that have determined the appearance of European cities and are part of the tacit understanding of their inhabitants.
Biopolitics and the regulation of vulnerability: the case of the female trafficked migrant
Authors: FitzGerald Sharron A.
Published: August 2010

This article interrogates the connections between normativity and geographical space. Specifically it focuses on the biopolitical discourses that operate around the idiom of the vulnerable female trafficked migrant in the United Kingdom. The article’s structure and argument question how state parties frame the notion of female vulnerability as a distinct biopolitical category. I argue that this process produces and sustains the perceived need for biopolitical regulation of the national community. I question how the state’s regulation of the bodies and behaviours of female trafficked migrants is entangled with anti-immigration agendas that aim to extend the power of the state extra-territorially.
Unreal City, Unreal Law
Authors: Wolcher Louis E.
Published: August 2010

The law of the city degrades time to the dimension of space. The cityscape replaces a horizon made by woods, fields and streams with a jagged silhouette of rectilinear buildings, lots and thoroughfares. Geometrically speaking, a city street is a line that has been transected into segments called blocks. Blocks, in turn, are further segmented by the placement of individual buildings, which are enumerated as ‘addresses’ in the manner of sequenced moments on the universal timeline. The city, like the law, is produced by human hands according to the logic of the conceptual pairs which the idea of linear time makes possible: ‘cause and caused’, ‘ground and grounded’ and ‘means and end’. But there is something profoundly unreal about both of these institutional spaces: at the end of the day, the Unreal City mentioned in T. S. Eliot’s The Waste Land corresponds to a sort of Unreal Law. Both the city and the law manifest freedom’s impossible attempt to realise its own antithesis by substituting space for time, being for becoming, reason for chance, justification for responsibility and redemption for tragedy.
Therapie der chronischen Hepatitis B und C – Update 2010
Authors: Mertens  , Geier  , Müllhaupt
Published: August 2010

Die Therapie der chronischen Virushepatitiden ist in den letzten Jahren aufgrund neuer Pharmaka und Therapieregime komplexer geworden. Bei der chronischen Hepatitis B ebenso wie bei der chronischen Hepatitis C gehen in die Therapieentscheidungen zunehmend individuelle Patientencharakteristika des Therapieansprechens und Infektionsverlaufs ein. Zudem befinden sich neue Substanzen in klinischen Studien vor der Zulassung. Das nachfolgende Update soll einen Überblick über die aktuellen individualisierten Therapiekonzepte der chronischen Virushepatitiden geben.
A Synthesis of Recent Research on Obesity with the Rorschach and Suggestions for the Future
Authors: Elfhag Kristina
Published: August 2010

This article reviews recent research made on obesity using the Rorschach (Comprehensive System: CS) as the main assessment procedure. It focuses on the main results of a research program performed by the author within the Karolinska Institutet in Stockholm, Sweden. When we studied Rorschach characteristics related to obesity, patients demonstrated difficulties with emotions and coping with everyday demands. We found that severe obesity was associated with lower mental distress and bodily concern. In experimentations, Rorschach predicted outcomes such as eating behaviors and weight. Larger weight loss in obesity treatments was explained by physical or dependency needs for food. These aspects could be specifically altered by treatment interventions targeting hunger or eating habits. Ego dysfunctions such as distortions in perception of reality predicted smaller weight loss and indicated more profound difficulties in obesity.
Ocean loading effects on stress at near shore plate boundary fault systems
Authors: Luttrell Karen , Sandwell David
Published: August 2010

Changes in eustatic sea level since the Last Glacial Maximum create a differential load across coastlines globally. The resulting plate bending in response to this load alters the state of stress within the lithosphere within a half flexural wavelength of the coast. We calculate the perturbation to the total stress tensor due to ocean loading in coastal regions. Our stress calculation is fully 3‐D and makes use of a semianalytic model to efficiently calculate stresses within a thick elastic plate overlying a viscoelastic or fluid half‐space. The 3‐D stress perturbation is resolved into normal and shear stresses on plate boundary fault planes of known orientation so that Coulomb stress perturbations can be calculated. In the absence of complete paleoseismic indicators that span the time since the Last Glacial Maximum, we investigate the possibility that the seismic cycle of coastal plate boundary faults was affected by stress perturbations due to the change in sea level. Coulomb stress on onshore transform faults, such as the San Andreas and Alpine faults, is increased by up to 1–1.5 MPa, respectively, promoting failure primarily through a reduction in normal stress. These stress perturbations may perceptibly alter the seismic cycle of major plate boundary faults, but such effects are more likely to be observed on nearby secondary faults with a lower tectonic stress accumulation rate. In the specific instance of rapid sea level rise at the Black Sea, the seismic cycle of the nearby North Anatolian fault was likely significantly advanced.
Observation analysis of land‐atmosphere interactions over the Loess Plateau of northwest China
Authors: Wang Guoyin , Huang Jianping , Guo Weidong , Zuo Jinqing , Wang Jiemin , Bi Jianrong , Huang Zhongwei , Shi Jinsen
Published: August 2010

Arid and semi‐arid areas of the Loess Plateau over northwestern China are one of the dust aerosol source regions featured by its unique underlying surface. These areas, suffering the severe aridity trend in past decades, are also known as the transitional zone of climate and ecosystem change. To better understand the basic characteristics of the land surface energy budget, seasonal and diurnal variations of moisture and heat flux over this region, field observations collected at the Semi‐Arid Climate and Environment Observatory of Lanzhou University (SACOL, 35°57′N, 104°08′E, Elev. 1965.8 m) from January 2007 to December 2008 were analyzed systematically, especially focusing on land surface energy partitioning and energy balance. The results indicate that all four radiative components had distinct seasonal and diurnal cycles, except for the diurnal variation of downward longwave radiation. They maintained high values during the growing season and low values during the non‐growing season. The highest daily mean value of DSR (downward shortwave radiation, 369.2 Wm−2), DLR (downward longwave radiation, 386.8 Wm−2) and ULR (upward longwave radiation, 484.2 Wm−2) measured in summer while the highest daily mean value of USR (upward shortwave radiation, 150.1 Wm−2) occurred in winter as the snow cover. The highest surface albedo was also found in winter as a result of the snow cover. Surface albedo was lower in the growing season (wet season) due to the larger vegetation fraction and wetter soil. The components of the land surface energy budget varied seasonally except for the surface soil heat flux, and all showed strong diurnal cycles. Net radiation increased from winter to summer and decreased from summer to winter associated with the variation of DSR. Sensible (latent) heat flux was the main consumer of the available energy in winter and spring (summer and autumn). The energy imbalance problem was also identified. When the soil heat storage in the surface soil and vegetation canopy was neglected, the energy imbalance ratio was about 22%. While given the surface heat storage calculated by the thermal diffusion equation and correction method (TDEC), the imbalance ratio was only 14%. Furthermore, taking the soil heat storage into account, this ratio was only 8% in spring, and 15% in summer and autumn. Compared with the bare surface layer in spring, it is likely that a part of energy was stored in the vegetation canopy in summer and autumn. In addition, the sensible and latent heat fluxes over different land surface types of the Loess Plateau are analyzed. Sensible and latent heat fluxes are utterly different substantially over those different underlying surfaces due to the factors such as vegetation, precipitation, and soil moisture.
Controls on authigenic carbonate precipitation at cold seeps along the convergent margin off Costa Rica
Authors: Karaca Deniz , Hensen Christian , Wallmann Klaus
Published: August 2010

Five sediment cores from cold seeps at the forearc off Costa Rica were used to explore the relationship between fluid advection, dissolved Ca concentrations in upward migrating fluids, and authigenic CaCO3 precipitation. A numerical transport‐reaction model was used to determine rates of anaerobic oxidation of methane (AOM), CaCO3 precipitation, and benthic fluxes of solutes. Production of carbonate alkalinity and formation of authigenic carbonates is most intense at intermediate flow rates (3–40 cm a−1) and reduced under low and high flux conditions (0.1 and 200 cm a−1). Dissolved Ca concentrations observed in the vent fluids off Costa Rica cover a wide range between 4 and 31 mM, clearly exceeding seawater concentrations at two locations. Systematic model runs showed that high Ca concentrations in ascending fluids enhance the rate of authigenic carbonate production at moderate flow rates leading to an almost quantitative fixation of deeply derived Ca in authigenic carbonates. Hence, CaCO3 precipitation is not only controlled by Ca diffusing into the sediment from bottom water, but also by the Ca concentration in ascending fluids. Thus, Ca enriched fluids offer a reason for enhanced subsurface CaCO3 precipitation and the occurrence of carbonate caps on dewatering structures in the Central American fore‐arc. Based on average precipitation rates deduced from the systematic model runs it is possible to give a rough estimate of the global Ca‐fixation at cold seeps (∼2·1010 mol Ca a−1), which suggests that cold seeps are most likely not of key importance with respect to Ca cycling in the ocean.
Simulations of the photoelectron sheath and dust levitation on the lunar surface
Authors: Poppe Andrew , Horányi Mihály
Published: August 2010

The lunar surface represents a complex plasma environment due to the presence of solar ultraviolet (UV) radiation, the incoming solar wind flux and charged, levitated micron‐ and sub‐micron sized dust particles. Photoemission due to solar UV radiation dominates the charging environment, creating a photoelectron sheath above the lunar surface. To further investigate the dusty plasma environment on the surface of the Moon, a one‐dimensional particle‐in‐cell (PIC) code has been designed specifically for the lunar surface. The code has been validated against analytic solutions for photoelectron sheaths with basic photoelectron energy distributions. Simulations have focused on the role of the emitted photoelectron energy distribution and solar UV variability in determining the sheath profile. Additionally, the charging and levitation of test dust particles in the photoelectron sheath are studied. Limits on the maximum size and height of levitated dust grains are also presented.
Surface charging of Saturn's plasma‐absorbing moons
Authors: Roussos E. , Krupp N. , Krüger H. , Jones G. H.
Published: August 2010

Recent results from the study of the interaction of Earth's moon with the solar wind have highlighted lunar surface charging as an important physical process not only for the local interaction of the surface and the impinging plasma but also for charged dust ejection and transport. Excluding Earth's moon, however, such studies have been limited to very few solar system bodies. Here we assess the importance of surface charging for the Saturnian plasma‐absorbing moons. In this initial study, we focus on the various moons' trailing hemispheres and their variable charging patterns as a function of their magnetospheric local time. With only a few exceptions, our results indicate negative potentials for all moons, with the most extreme values predicted for Rhea. When the leading hemisphere is partially sunlit, the surface potential profile can be quite complex with many different transition regions. We also find that electrostatic acceleration of dust is at least equally as (if not more) important as it is for Earth's moon for the submicron grains, but it is probably not sufficient to explain the detection of the larger micron‐sized grains in the vicinity of the large moons of the outer planets. Regarding Saturn's asteroid‐sized moons, we predict that electrostatic forces can accelerate grains above the escape velocity and populate the Saturnian system and/or contribute to dust transport across those moons' surfaces. On the basis of these results, we also propose several methods by which Cassini's instruments could be used to directly observe the effects of surface charging.
Basal Cerebral Blood Volume during the Poststimulation Undershoot in BOLD MRI of the Human Brain
Authors: Dechent Peter , Schütze Gunther , Helms Gunther , Merboldt Klaus Dietmar , Frahm Jens
Published: August 2010

One of the characteristics of the blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) response to functional challenges of the brain is the poststimulation undershoot, which has been suggested to originate from a delayed recovery of either cerebral blood volume (CBV) or cerebral metabolic rate of oxygen to baseline. Using bolus-tracking MRI in humans, we recently showed that relative CBV rapidly normalizes after the end of stimulation. As this observation contradicts at least part of the blood-pool contrast agent studies performed in animals, we reinvestigated the CBV contribution by dynamic T1-weighted three-dimensional MRI (8 seconds temporal resolution) and Vasovist at 3 T (12 subjects). Initially, we determined the time constants of individual BOLD responses. After injection of Vasovist, CBV-related T1-weighted signal changes revealed a signal increase during visual stimulation (1.7%±0.4%), but no change relative to baseline in the poststimulation phase (0.2%±0.3%). This finding renders the specific nature of the contrast agent unlikely to be responsible for the discrepancy between human and animal studies. With the assumption of normalized cerebral blood flow after stimulus cessation, a normalized CBV lends support to the idea that the BOLD MRI undershoot reflects a prolonged elevation of oxidative metabolism.
Autoregulation of Cerebral Blood Flow to Changes in Arterial Pressure in Mild Alzheimer's Disease
Authors: Zazulia Allyson R , Videen Tom O , Morris John C , Powers William J
Published: August 2010

Studies in transgenic mice overexpressing amyloid precursor protein (APP) demonstrate impaired autoregulation of cerebral blood flow (CBF) to changes in arterial pressure and suggest that cerebrovascular dysfunction may be critically important in the development of pathological Alzheimer's disease (AD). Given the relevance of such a finding for guiding hypertension treatment in the elderly, we assessed autoregulation in individuals with AD. Twenty persons aged 75±6 years with very mild or mild symptomatic AD (Clinical Dementia Rating 0.5 or 1.0) underwent 15O-positron emission tomography (PET) CBF measurements before and after mean arterial pressure (MAP) was lowered from 107±13 to 92±9 mm Hg with intravenous nicardipine; 11C-PIB-PET imaging and magnetic resonance imaging (MRI) were also obtained. There were no significant differences in mean CBF before and after MAP reduction in the bilateral hemispheres (−0.9±5.2 mL per 100 g per minute, P=0.4, 95% confidence interval (CI)=−3.4 to 1.5), cortical borderzones (−1.9±5.0 mL per 100 g per minute, P=0.10, 95% CI=−4.3 to 0.4), regions of T2W-MRI-defined leukoaraiosis (−0.3±4.4 mL per 100 g per minute, P=0.85, 95% CI=−3.3 to 3.9), or regions of peak 11C-PIB uptake (−2.5±7.7 mL per 100 g per minute, P=0.30, 95% CI=−7.7 to 2.7). The absence of significant change in CBF with a 10 to 15 mm Hg reduction in MAP within the normal autoregulatory range demonstrates that there is neither a generalized nor local defect of autoregulation in AD.
Simultaneous Monitoring of Tissue Po2 and NADH Fluorescence During Synaptic Stimulation and Spreading Depression Reveals a Transient Dissociation between Oxygen Utilization and Mitochondrial Redox State in Rat Hippocampal Slices
Authors: Galeffi Francesca , Somjen George G , Foster Kelley A , Turner Dennis A
Published: August 2010

Nicotinamide adenine dinucleotide (NADH) imaging can be used to monitor neuronal activation and ascertain mitochondrial dysfunction, for example during hypoxia. During neuronal stimulation in vitro, NADH normally becomes more oxidized, indicating enhanced oxygen utilization. A subsequent NADH overshoot during activation or on recovery remains controversial and reflects either increased metabolic activity or limited oxygen availability. Tissue Po2 measurements, obtained simultaneously with NADH imaging in area CA1 in hippocampal slices, reveal that during prolonged train stimulation (ST) in 95% O2, a persistent NADH oxidation is coupled with increased metabolic demand and oxygen utilization, for the duration of the stimulation. However, under conditions of either decreased oxygen supply (ST-50% O2) or enhanced metabolic demand (K+-induced spreading depression (K+-SD) 95% O2) the NADH oxidation is brief and the redox balance shifts early toward reduction, leading to a prolonged NADH overshoot. Yet, oxygen utilization remains elevated and is correlated with metabolic demand. Under these conditions, it appears that the rate of NAD+ reduction may transiently exceed oxidation, to maintain an adequate oxygen flux and ATP production. In contrast, during SD in 50% O2, the oxygen levels dropped to a point at which oxidative metabolism in the electron transport chain is limited and the rate of utilization declined.
Hemoglobin and Iron Handling in Brain after Subarachnoid Hemorrhage and the Effect of Deferoxamine on Early Brain Injury
Authors: Lee Jin-Yul , Keep Richard F , He Yangdong , Sagher Oren , Hua Ya , Xi Guohua
Published: August 2010

The purpose of this study was to investigate hemoglobin and iron handling after subarachnoid hemorrhage (SAH), examine the relationship between iron and neuroglial cell changes, and determine whether deferoxamine (DFX) can reduce SAH-induced injury. The SAH was induced in Sprague-Dawley rats ( n=110) using an endovascular perforation technique. Animals were treated with DFX (100 mg/kg) or vehicle 2 and 6 hours after SAH induction followed by every 12 hours for 3 days. Rats were killed at 6 hours, Days 1 and 3 to determine nonheme iron and examine iron-handling proteins using Western blot and immunohistochemistry. 8-Hydroxyl-2′-deoxyguanosine and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining were performed to assess oxidative DNA damage and neuronal cell death. After SAH, marked heme-oxygenase-1 (HO-1) upregulation at Day 3 ( P<0.01) was accompanied by elevated nonheme iron ( P<0.01), transferrin (Tf) ( P<0.01), Tf receptor ( P<0.05), and ferritin levels ( P<0.01). Deferoxamine treatment reduced SAH-induced mortality (12% versus 29%, P<0.05), brain nonheme iron concentration, iron-handling protein expression, oxidative stress, and neuronal cell death at Day 3 ( P<0.01) after SAH. These results suggest that iron overload in the acute phase of SAH causes oxidative injury leading to neuronal cell death. Deferoxamine effectively reduced oxidative stress and neuronal cell death, and may be a potential therapeutic agent for SAH.
Reduced Ca2+ Spark Activity after Subarachnoid Hemorrhage Disables BK Channel Control of Cerebral Artery Tone
Authors: Koide Masayo , Nystoriak Matthew A , Krishnamoorthy Gayathri , O'Connor Kevin P , Bonev Adrian D , Nelson Mark T , Wellman George C
Published: August 2010

Intracellular Ca2+ release events (‘Ca2+ sparks’) and transient activation of large-conductance Ca2+-activated potassium (BK) channels represent an important vasodilator pathway in the cerebral vasculature. Considering the frequent occurrence of cerebral artery constriction after subarachnoid hemorrhage (SAH), our objective was to determine whether Ca2+ spark and BK channel activity were reduced in cerebral artery myocytes from SAH model rabbits. Using laser scanning confocal microscopy, we observed ∼50% reduction in Ca2+ spark activity, reflecting a decrease in the number of functional Ca2+ spark discharge sites. Patch-clamp electrophysiology showed a similar reduction in Ca2+ spark-induced transient BK currents, without change in BK channel density or single-channel properties. Consistent with a reduction in active Ca2+ spark sites, quantitative real-time PCR and western blotting revealed decreased expression of ryanodine receptor type 2 (RyR-2) and increased expression of the RyR-2-stabilizing protein, FKBP12.6, in the cerebral arteries from SAH animals. Furthermore, inhibitors of Ca2+ sparks (ryanodine) or BK channels (paxilline) constricted arteries from control, but not from SAH animals. This study shows that SAH-induced decreased subcellular Ca2+ signaling events disable BK channel activity, leading to cerebral artery constriction. This phenomenon may contribute to decreased cerebral blood flow and poor outcome after aneurysmal SAH.
Evidence that OGG1 Glycosylase Protects Neurons against Oxidative DNA Damage and Cell Death under Ischemic Conditions
Authors: Liu Dong , Croteau Deborah L , Souza-Pinto Nadja , Pitta Michael , Tian Jingyan , Wu Christopher , Jiang Haiyang , Mustafa Khadija , Keijzers Guido , Bohr Vilhelm A , Mattson Mark P
Published: August 2010

7,8-Dihydro-8-oxoguanine DNA glycosylase (OGG1) is a major DNA glycosylase involved in base-excision repair (BER) of oxidative DNA damage to nuclear and mitochondrial DNA (mtDNA). We used OGG1-deficient (OGG1−/–) mice to examine the possible roles of OGG1 in the vulnerability of neurons to ischemic and oxidative stress. After exposure of cultured neurons to oxidative and metabolic stress levels of OGG1 in the nucleus were elevated and mitochondria exhibited fragmentation and increased levels of the mitochondrial fission protein dynamin-related protein 1 (Drp1) and reduced membrane potential. Cortical neurons isolated from OGG1−/– mice were more vulnerable to oxidative insults than were OGG1+/+ neurons, and OGG1−/– mice developed larger cortical infarcts and behavioral deficits after permanent middle cerebral artery occlusion compared with OGG1+/+ mice. Accumulations of oxidative DNA base lesions (8-oxoG, FapyAde, and FapyGua) were elevated in response to ischemia in both the ipsilateral and contralateral hemispheres, and to a greater extent in the contralateral cortex of OGG1−/– mice compared with OGG1+/+ mice. Ischemia-induced elevation of 8-oxoG incision activity involved increased levels of a nuclear isoform OGG1, suggesting an adaptive response to oxidative nuclear DNA damage. Thus, OGG1 has a pivotal role in repairing oxidative damage to nuclear DNA under ischemic conditions, thereby reducing brain damage and improving functional outcome.