bluuebunny/crossref_metadata_2025 huggingface dataset:
Defining and Measuring Investment Risk in Defined Benefit Pension Funds
Authors: Whelan S. F.
Published: May 2011

A formal definition of investment risk in actuarial investigations is given. Case studies estimating the investment risk associated with different investment strategies for defined benefit pension funds using historic market data are presented. It is shown that a few decades ago, when bond markets only extended in depth to 20-year maturities, the investment risk of investing in equities was of the same order of magnitude as the investment risk introduced by the duration mismatch from investing in bonds for immature schemes. It is shown that now, with the extension of the term of bond markets and introduction of strippable bonds, the least risk portfolio for the same pension liability is a bond portfolio of suitable duration. It is argued that investment risk voluntarily undertaken in defined benefit pension plans has grown markedly in recent decades, at a time when the ability to bear the investment risk has diminished. Investment risk in pension funds is quite different to investment risk for other investors, which leads to the possibility that current portfolios are not optimised — that is, there exist portfolios which increase the expected surplus without increasing risk. The formalising of our intuitive concept of investment risk in actuarial applications is a first step in the identification of more efficient portfolios.
The United Kingdom State Pension System: Analysis of Proposed Reforms and the Viability of Immigration-Based Policies in Response to Demographic Ageing
Authors: Kotecha K. N.
Published: May 2011

This paper briefly examines the options for reform proposed by the Pensions Commission in 2004 to sustain the United Kingdom state pension system in response to an ageing population. It further explores, under various scenarios, the long-term viability of immigration as an alternative policy response, by developing a population projection model to determine the replacement migration levels which would be required to maintain contributions (taxes) at current levels, using population data and assumptions in the public domain. The economic and social implications of immigration-based policies are also considered. This paper does not consider the specific policy recommendations in the Commission's Second Report published in autumn 2005, which at the time of writing was undergoing an internal consultation process.

The results indicate that not only does each policy option proposed by the Pensions Commission require changes which are too large for the policy to be implemented on its own, but that a combination of options is likely to require discomforting changes at the individual level when considered under plausible scenarios. Economic and social implications aside, the results also indicate that immigration is an inefficient and ineffective way of mitigating demographic ageing. The required replacement migration levels are abnormally high and too volatile for it to be considered as a viable policy alternative.
A Model for Ischaemic Heart Disease and Stroke III: Applications
Authors: Chatterjee T. , Macdonald A. S. , Waters H. R.
Published: May 2011

This is the third in a series of three papers. In the first paper we describe a comprehensive stochastic model of an individual's lifetime that includes diagnosis with ischaemic heart disease and stroke and also the development of the major risk factors for these conditions. The second paper discusses in some detail models for changes in body mass index (BMI) and also the effects of these changes, in particular the current trend towards increasing prevalence of obesity, on diabetes, cardiovascular diseases and expected future lifetime. This paper is devoted to the following applications of the model described in the first paper:

(a) quantifying the effects of smoking and of changes in smoking habits, and,

(b) quantifying the effects of treatment with statins (drugs designed to lower cholesterol).
Stochastic Actuarial Modelling of a Defined-Benefit Social Security Pension Scheme: An Analytical Approach
Authors: Iyer Subramaniam
Published: May 2011

Among the systems in place in different countries for the protection of the population against the long-term contingencies of old-age (or retirement), disability and death (or survivorship), defined-benefit social security pension schemes, i.e. social insurance pension schemes, by far predominate, despite the recent trend towards defined-contribution arrangements in social security reforms. Actuarial valuations of these schemes, unlike other branches of insurance, continue to be carried out almost exclusively on traditional, deterministic lines. Stochastic applications in this area, which have been restricted mainly to occasional special studies, have relied on the simulation technique. This paper develops an analytical model for the stochastic actuarial valuation of a social insurance pension scheme. Formulae are developed for the expected values, variances and covariances of and among the benefit expenditure and salary bill projections and their discounted values, allowing for stochastic variation in three key input factors, i.e., mortality, new entrant intake, and interest (net of salary escalation). Each deterministic output of the valuation is thus supplemented with a confidence interval, that is, a range with an attached probability. The treatment covers the premiums under the different possible financial systems for these schemes, which differ from the funding methods of private pensions, as well as the testing of the level of the Fund ratio when the future contributions schedule is pre-determined. Although it is based on a relatively simplified approach and refers only to retirement pensions, with full adjustment in line with salary escalation, the paper brings out the stochastic features of pension scheme projections and illustrates a comprehensive stochastic valuation. It is hoped that the paper will stimulate interest in further research, both of a theoretical and a practical nature, and lead to progressively increasing recourse to stochastic methods in social insurance pension scheme valuations.
Asset Allocation to Optimise Life Insurance Annuity Firm Economic Capital and Risk Adjusted Performance
Authors: Porteous Bruce T. , Tapadar Pradip
Published: May 2011

The impact that asset allocation has on the economic capital and the risk adjusted performance of financial services firms is considered in this article. A stochastic modelling approach is used in conjunction with a life insurance annuity firm illustrative example. It is shown that traditional solvency driven deterministic approaches to financial services firm asset allocation can yield sub optimal results in terms of minimising economic capital or maximising risk adjusted performance. Our results challenge the conventional wisdom that the assets backing life insurance annuities and financial services firm capital should be invested in low risk, bond type, assets. Implications for firms, customers, capital providers and regulators are discussed.
Individual Claim Loss Reserving Conditioned by Case Estimates
Authors: Taylor Greg , McGuire Gráinne , Sullivan James
Published: May 2011

This paper examines various forms of individual claim model for the purpose of loss reserving, with emphasis on the prediction error associated with the reserve. Each form of model is calibrated against a single extensive data set, and then used to generate a forecast of loss reserve and an estimate of its prediction error.

The basis of this is a model of the “paids” type, in which the sizes of strictly positive individual finalised claims are expressed in terms of a small number of covariates, most of which are in some way functions of time. Such models can be found in the literature.

The purpose of the current paper is to extend these to individual claim “incurreds” models. These are constructed by the inclusion of case estimates in the model's conditioning information. This form of model is found to involve rather more complexity in its structure.

For the particular data set considered here, this did not yield any direct improvement in prediction error. However, a blending of the paids and incurreds models did so.
Tax-Efficient Pension Choices in the UK
Authors: Sweeting Paul
Published: May 2011

The special tax treatment of United Kingdom pensions means that the decision on how to use pension assets is particularly involved. In particular, the ability to take up to 25% of pension assets as a tax-free cash lump sum at retirement, offers retirees opportunities to enhance their pension above that possible through the purchase of a compulsory purchase annuity (“CPA”). The tax-free cash lump sum can be used to buy a tax-efficient purchased life annuity (“PLA”), or in a phased retirement strategy. Income withdrawal can also be used to defer the purchase of an annuity until age 75 and, potentially, to generate a higher income. In this paper I compare the options available to retirees using stochastic modelling. I compare the expected excess pension and expected shortfall, both relative to the alternative risk-free pension available, to assess the various options. I find that if the maximum amount of tax-free cash is available to be used to enhance retirement income, then phased retirement offers the best risk/reward trade off. The advantage is greatest for higher-rate tax payers. As the level of tax-free cash falls, income withdrawal becomes more attractive to those wishing to take greater risks.
Modelling Income Protection Claim Termination Rates by Cause of Sickness III: Mortality
Authors: Ling S. Y. , Waters H. R. , Wilkie A. D.
Published: May 2011

This is the third of three papers in which we present methods and results for the estimation and modelling of claim termination rates for Income Protection (IP) insurance, allowing for different causes of claim. In the first paper we discussed recoveries. We model the mortality of IP claimants as the sum of two components: a base mortality, which is a function of age and calendar year, but not of the specific cause of sickness or its current duration, and a cause-specific component which does depend on the current duration of the sickness. The modelling of the base mortality, using data for UK assured lives, was discussed in the second paper. In this paper we discuss the modelling of the cause-specific component of the mortality of IP claimants. We use data supplied by the Continuous Mortality Investigation relating to IP claims paid in the years 1975 to 2002.

In the final section of this paper we present some numerical results for cause-specific claim annuity rates for current claims and aggregate claim termination rates based on the models developed in all three papers.
Das Arbeitsverhalten in homogenen Begabtenklassen
Authors: Pröscholdt Marie V. , Stumpf Eva , Schneider Wolfgang
Published: May 2011

Zusammenfassung. In einer systematischen Beobachtung im Klassenzimmer wurde untersucht, ob sich das Arbeitsverhalten von Schülerinnen und Schülern in gymnasialen Begabtenklassen im Unterricht vom Arbeitsverhalten von Schülerinnen und Schülern in regulären Gymnasialklassen unterscheidet. Als im Unterricht beobachtbare Komponenten des Arbeitsverhaltens wurden die Variablen Aufmerksamkeit, Unaufmerksamkeit, Störverhalten und Aktive Beteiligung gewählt, die mithilfe des Münchener Aufmerksamkeitsinventars von Helmke (1988) erfasst wurden. Über jeweils 12 Schulstunden wurden zwei 7. und zwei 6. Gymnasialklassen mit jeweils einer Begabten- und einer regulären Gymnasialklasse (Kontrollklassen) beobachtet. Wie die Ergebnisse zeigten, ergaben sich hinsichtlich Aufmerksamkeit, Unaufmerksamkeit und Aktiver Mitarbeit keine systematischen, bedeutsamen Unterschiede zwischen den Schülerinnen und Schülern der Begabten- vs. Kontrollklassen. Die Schülerinnen und Schüler der Begabtenklassen störten allerdings den Unterricht deutlich seltener als die Schülerinnen und Schüler der regulären Gymnasialklassen.
Insights into mantle composition and mantle melting beneath mid‐ocean ridges from postspreading volcanism on the fossil Galapagos Rise
Authors: Haase Karsten M. , Regelous Marcel , Duncan Robert A. , Brandl Philipp A. , Stroncik Nicole , Grevemeyer Ingo
Published: May 2011

New major and trace element and Sr, Nd, and Pb isotope data, together with 39Ar‐40Ar ages for lavas from the extinct Galapagos Rise spreading center in the eastern Pacific reveal the evolution in magma compositions erupted during slowdown and after the end of active spreading at a mid‐ocean ridge. Lavas erupted at 9.2 Ma, immediately prior to the end of spreading are incompatible element depleted mid‐ocean ridge tholeiitic basalts, whereas progressively younger (7.5 to 5.7 Ma) postspreading lavas are increasingly alkalic, have higher concentrations of incompatible elements, higher La/Yb, K/Ti, 87Sr/86Sr, and lower 143Nd/144Nd ratios and were produced by smaller degrees of mantle melting. The large, correlated variations in trace element and isotope compositions can only be explained by melting of heterogenous mantle, in which incompatible trace element enriched lithologies preferentially contribute to smaller degree mantle melts. The effects of variable degrees of melting of heterogeneous mantle on lava compositions must be taken into account when using mid‐ocean ridge basalt (MORB) to infer the conditions of melting beneath active spreading ridges. For example, the stronger “garnet signature” inferred from Sm/Nd and 143Nd/144Nd ratios for postspreading lavas from the Galapagos Rise results from a larger contribution from enriched lithologies with high La/Yb and Sm/Yb, rather than from a greater proportion of melting in the stability field of garnet peridotite. Correlations between ridge depth and Sm/Yb and fractionation‐corrected Na concentrations in MORB worldwide could result from variations in mantle fertility and/or variations in the average degree of melting, rather than from large variations in mantle temperature. If more fertile mantle lithologies are preferentially melted beneath active spreading ridges, then the upper mantle may be significantly more “depleted” than is generally inferred from the compositions of MORB.
Seasonal variability of black carbon mass in the tropical tropopause layer
Authors: Spackman J. R. , Gao R. S. , Schwarz J. P. , Watts L. A. , Fahey D. W. , Pfister L. , Bui T. P.
Published: May 2011

While most black carbon (BC)‐containing particles are removed in the lower troposphere in the tropics, some are lofted to higher altitudes via convection where they may be distributed globally throughout the tropical tropopause layer (TTL). Single‐particle measurements of BC aerosol were made from the NASA WB‐57F aircraft during both the dry (February 2006) and wet (August 2007) seasons in Central America. BC mass loadings declined sharply with increasing altitude from the ground to 5 km. In the TTL, they were up to six times higher in the wet relative to the dry season. The variability in BC mass was examined using convective‐influence back trajectories to determine the source regions. The seasonal differences in the vertical profiles are explained by long‐range transport of (1) low‐BC air from the southern hemisphere in the dry season and (2) high‐BC air from biomass‐burning or pollution sources in Africa and Asia advected by the Asian monsoon circulation in the wet season.
Spatial scale dependence of ecohydrologically mediated water balance partitioning: A synthesis framework for catchment ecohydrology
Authors: Thompson Sally E. , Harman Ciaran J. , Troch Peter A. , Brooks Paul D. , Sivapalan Murugesu
Published: May 2011

The difficulties in predicting whole catchment water balance from observations at patch scales motivate a search for theories that can account for the complexity of interactions in catchments. In this paper we suggest that the spatial patterns of vegetation may offer a lens through which to investigate scale dependence of hydrology within catchments. Vegetation patterns are attractive because they are observable drivers of evapotranspiration, often a dominant component in catchment water balance, and because the spatial distribution of vegetation is often driven by patterns of water availability. We propose that nontrivial, scale‐dependent spatial patterns in both vegetation distribution and catchment water balance are generated by the presence of a convergent network of flow paths and a two‐way feedback between vegetation as a driver of evapotranspiration and vegetation distribution as a signature of water availability. Implementing this hypothesis via a simple network model demonstrated that such organization was controlled by catchment properties related to aridity, the network topology, the sensitivity of the vegetation response to water availability, and the point‐scale controls on partitioning between evapotranspiration and lateral drainage. The resulting self‐organization generated spatial dependence in areally averaged hydrologic variables, water balance, and parameters describing hydrological partitioning. This spatial scale dependence provides a theoretical approach to connect water balance at patch and catchment scales. Theoretical and empirical studies for understanding the controls of vegetation spatial distribution, point‐scale hydrological partitioning, and the implications of complex flow network topologies on the spatial scale dependence of catchment water balance are proposed as a research agenda for catchment ecohydrology.
Most B cells in non‐lymphoid tissues are naïve
Authors: Inman Charlotte F , Murray Tamsin Zangerle , Bailey Mick , Cose Stephen
Published: May 2011

The current view of lymphocyte migration states that naïve lymphocytes re‐circulate between the blood and the lymph via the lymph nodes, but are not able to access non‐lymphoid tissues. We examined B lymphocytes in peripheral tissues and found that the majority were phenotypically similar to naïve B cells in lymphoid tissues and were located within the parenchyma, not associated with blood vessels. The mutation rate within the Vh region of these cells was substantially less than the rate attributed to somatic hypermutation and was identical to that observed in naïve B cells isolated from the lymph nodes, showing the presence of naïve B cells in the non‐lymphoid organs. Further, using FTY720‐treated mice, we showed that naïve B cells migrate through the peripheral tissues and, using pertussis toxin, that the entry of B cells was not controlled by chemokine‐mediated signalling events. Overall, these results show that naïve B lymphocytes constitute the majority of the total B‐cell population in non‐lymphoid tissues and suggest that these cells may re‐circulate through the periphery as part of their normal migration pathway. This has implications for the current view of the role of naïve B cells in priming and tolerance.
A Mindful Approach to Stuttering Intervention
Authors: Plexico Laura W. , Sandage Mary J.
Published: May 2011

The purpose of this paper is to describe the construct of mindfulness and how this can be applied to stuttering intervention. To increase understanding of the construct, mindfulness is defined, its origin is discussed, and the ways it is traditionally taught and assessed are reviewed. The use of mindfulness in stuttering intervention to facilitate improved well-being, desensitization, increased self-acceptance, reduction of stress and anxiety, and increased internal locus of control also is discussed.
Co2MnGe-based current-perpendicular-to-the-plane giant-magnetoresistance spin-valve sensors for recording head applications
Authors: Carey M. J. , Maat S. , Chandrashekariaih S. , Katine J. A. , Chen W. , York B. , Childress J. R.
Published: May 2011

Magnetic and magnetotransport properties of current-perpendicular-to-the-plane (CPP) giant-magnetoresistance (GMR) spin-valve sensors containing the Heusler alloy Co2MnGe are presented. The geometrical and head integration constraints which exist for recording head applications are discussed and dictate various design compromises which determine the final device properties. Here we show that even for small total sensor thicknesses 400 Å and anneal temperatures < 250 °C we can obtain CPP-GMR signal levels up to ΔRA = 4 mΩ-μm2 at room temperature when inserting Co2MnGe in both the free layer and reference layers of the spin valve. Output levels increase to 10 mΩ-μm2 when reducing the temperature below 100 K, demonstrating the strong temperature dependence of the spin-dependent scattering in the Co2MnGe-based magnetic layers.
Schottky contact on ZnO nano-columnar film with H2O2 treatment
Authors: Nakamura A. , Temmyo J.
Published: May 2011

The surface treatment with boiling hydrogen peroxide (H2O2) solution on the surface of ZnO nano-columnar film was investigated. Field emission-SEM and TEM analysis revealed that amorphous ZnO2 layer covers the ZnO nano-column surface through the H2O2 treatment at 100°C for 1 min. X-ray photoemission spectroscopy (XPS) has been conducted on the H2O2 treated ZnO surface. The surface exhibits high resistive conductivity after the H2O2 treatment, suggesting that the treatment promotes a compensation effect. We demonstrate that dramatic improvement in the rectifying behavior on the Schottky diodes can be achieved by inserting a ZnO2 interface layer between the Pt Schottky electrode and the ZnO nano-column film. The ZnO2 interface layer promotes surface passivation and suppresses the surface leakage current. This is expected to increase the Schottky barrier height to 0.78 eV. The H2O2 treated Schottky diode showed five orders of magnitude in current rectification between forward and reverse bias at 3 V.
Synthesis and pore filling mechanism in anatase TiO2 nanostructured network mediated by PbS molecular adsorption
Authors: Dutta N. , Mohanta D. , Choudhury A.
Published: May 2011

In this work, we show that anatase nanoporous titanium dioxide (TiO2) structures can be sensitized by adequate PbS molecular adsorption. This was substantiated through x-ray diffraction, electron microscopy, atomic force microscopy, and nitrogen adsorption/desorption studies. The atomic force micrograph of the PbS/TiO2 system is characterized by a smooth surface topography as compared to the untreated TiO2 network. Further, N2 adsorption/desorption studies have revealed that the pores having a size greater than the Bohr exciton size (∼3.1 nm) of TiO2 can be efficiently filled by PbS molecules, whereas the smaller pores remain unfilled. The pore filling aspects, along with the kinetics of molecular adsorption in the coupled heterogeneous nanostructured system, would help to reveal the underlying mechanism of interfacial charge leakage phenomena in miniaturized nanoelectronic and nanophotonic junctions/components.
Study of surface magnetism, exchange bias effect, and enhanced ferromagnetism in α-Fe1.4Ti0.6O3 alloy
Authors: Naresh N. , Bhowmik R. N. , Ghosh B. , Banerjee S.
Published: May 2011

Magnetic properties of mechanical alloyed α-Fe1.4Ti0.6O3 were studied at broad scale of temperatures, starting from room temperature down to 5 K. Morin transition of the base compound α-Fe2O3 was not observed after Ti doping. Enhanced ferromagnetism and exchange bias effect were exhibited in the alloyed compound α-Fe1.4Ti0.6O3. The observations were examined from different aspects of the alloying process, e.g., magnetic solution (spin ordering) at the interfaces of rhombohedral planes and core-shell structure of the nano-grains. Interfacial magnetic modifications were seen to be affected by the factors associated with grain size variation during alloy formation and thermal annealing of the alloy. Detailed analyses were made to understand the surface magnetism and exchange bias effect in the samples. Magnetic features of the present samples in many cases were found to be unconventional in comparison with the simple grain size effect of magnetic particles.
Magnetoelectric coupling study in multiferroic Pb(Fe0.5Nb0.5)O3 ceramics through small and large electric signal standard measurements
Authors: Raymond Oscar , Font Reynaldo , Portelles Jorge , Siqueiros Jesús M.
Published: May 2011

Multifunctional multiferroic materials such as the single phase compound Pb(Fe0.5Nb0.5)O3 (PFN), where ferroelectric and antiferromagnetic order coexist, are very promising and have great interest from the academic and technological points of view. In this work, coupling of the ferroelectric and magnetic moments is reported. For this study, a combination of the small signal response using the impedance spectroscopy technique and the electromechanical resonance method with the large signal response through standard ferroelectric hysteresis measurement, has been used with and without an applied magnetic field. The measurements to determine the electrical properties of the ceramic were performed as functions of the bias and poling electric fields. A simultaneous analysis of the complex dielectric constant ɛ̃, impedance Z̃, electric modulus M̃, admittance Ỹ, and the electromechanical parameters and coupling factors is presented. The results are correlated with a previous study of structural, morphological, small signal dielectric frequency-temperature response, and the ferroelectric hysteretic, magnetic and magnetodielectric behaviors. The observed shifts of the resonance and antiresonance frequency values can be associated with change of the ferroelectric domain size favored by the readjustment of the oxygen octahedron when the magnetic field is applied. From P-E hysteresis loops obtained without and with an external applied magnetic field, a dc magnetoelectric coupling effect with maximum value of 4 kV/cm T (400 mV/cm Oe) was obtained.
Influence of the 1,2,4-linking hyperbranched poly(arylenevinylene) structure on organic light emitting diode performance as compared to conventional 1,3,5-linking one
Authors: Coya C. , Álvarez A. L. , Yoon W. S. , Park S. Y.
Published: May 2011

The influence of a novel 1,2,4-linking hyperbranched poly(arylenevinylene) (1,2,4-hb-PAV) material, designed to feature intramolecular energy-funneling, on the transport and emission properties of organic light emitting diodes (OLEDs) has been studied. A comparison to conventional hyperbranched 1,3,5-linking polymers (1,3,5-hb-PAV), which do not exhibit this effect, has been made. For this purpose, single-layer organic light emitting diodes with a glass/indium–tin oxide/poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate)/active layer/Ca/Al structure and different active layer thicknesses have been fabricated and characterized, using either 1,2,4-hb-PAV or 1,3,5-hb-PAV as active layers. The current–voltage response has been interpreted in terms of a numerical model that includes a field-dependent carrier mobility, which allows us to estimate carrier mobility in the diodes. Stable green emission with Commission Internationale de L’Eclairage coordinates at (0.41,0.56) and a high luminous efficiency of 28 Cd/A has been obtained at very low driving currents (10 μA) for 1,2,4-hb-PAV material, versus 2.1 Cd/A for the conventional 1,3,5-linking material, in spite of the high photoluminescence quantum yield in thin film exhibited by both materials. The significant improvements in the performance of OLEDs based on 1,2,4-hb-PAV with respect to other conventional hyperbranched polymers are attributed to the inherent energy gradient from the shorter branches to the longer conjugated stem in this structure, which enables the characteristic funneling effect.
Magnetic field induced martensitic transformation linked to the arrested austenite in a Ni-Mn-In-Co shape memory alloy
Authors: Pérez-Landazábal J. I. , Recarte V. , Sánchez-Alarcos V. , Gómez-Polo C. , Kustov S. , Cesari E.
Published: May 2011

The so-called metamagnetic shape memory alloys transform from a ferromagnetic austenite into a weak magnetic martensitic phase, thus the application of a magnetic field, stabilizing the high magnetization phase, can induce the reverse martensitic transformation. Moreover, the martensitic transformation itself becomes arrested as its temperature range is lowered by the application of high enough magnetic fields. In this work the effect of the magnetic field on a Ni-Mn-In-Co metamagnetic shape memory has been studied by SQUID magnetometry. The arrest of the transformation produced by the field results in metastable states, whose evolution when the field is removed or reduced, follows logarithmic time dependence. The observed behavior is interpreted in terms of the magnetic contribution to the total entropy change associated with the magnetostructural transformation.
Integrated electronic transport and thermometry at milliKelvin temperatures and in strong magnetic fields
Authors: Samkharadze N. , Kumar A. , Manfra M. J. , Pfeiffer L. N. , West K. W. , Csáthy G. A.
Published: May 2011

We fabricated a He-3 immersion cell for transport measurements of semiconductor nanostructures at ultra low temperatures and in strong magnetic fields. We have a new scheme of field-independent thermometry based on quartz tuning fork Helium-3 viscometry which monitors the local temperature of the sample's environment in real time. The operation and measurement circuitry of the quartz viscometer is described in detail. We provide evidence that the temperature of two-dimensional electron gas confined to a GaAs quantum well follows the temperature of the quartz viscometer down to 4 mK.
Characteristics of an actuator-driven pulsed water jet generator to dissecting soft tissue
Authors: Seto Takeshi , Yamamoto Hiroaki , Takayama Kazuyoshi , Nakagawa Atsuhiro , Tominaga Teiji
Published: May 2011

This paper reports characteristics of an actuator-driven pulsed water jet generator applied, in particular, to dissect soft tissues. Results of experiments, by making use of high speed recording of optical visualization and varying nozzle diameter, actuator time interval, and their effects on dissection performance are presented. Jet penetration characteristics are compared with continuous water jet and hence potential assessment of pulsed water jets to clinical applications is performed.
Realization of spectrally engineered semiconductor Fabry-Perot lasers with narrow geometrical tolerances
Authors: Adolfsson Göran , Bengtsson Jörgen , Haglund Åsa , Nilsson Bengt , Larsson Anders
Published: May 2011

Spectrally engineered semiconductor Fabry-Perot laser resonators are designed to enhance the optical feedback for selected longitudinal modes, which thereby require less gain for lasing. This is achieved by introducing refractive index perturbations along the length of the resonator. However, the physical realization of these resonators is a challenge because of very narrow tolerances; in particular the need for precise positioning of the end facets of the resonator in relation to the perturbations, and the excess propagation loss associated with the perturbations, has been a major concern. We report on a method to achieve high-quality end facet mirrors enabling precise positioning relative to the perturbations, the latter which are realized as lateral corrugations of the waveguide. Measurements show that the mirror quality is comparable to that of cleaved mirrors and that the additional loss introduced by the perturbations adds.10 cm−1 to the overall propagation loss, provided that the perturbations are densely enough spaced along the resonator. This implies that the number of perturbations should be large, which is beneficial for the realization of strongly perturbed resonators enabling the most flexible engineering of the spectral properties of the laser.
Room-temperature ferromagnetism in CrSi2(core)/SiO2(shell) semiconducting nanocables
Authors: Hou Te-Chien , Han You-Hong , Lo Shen-Chuan , Lee Cheng-Tse , Ouyang Hao , Chen Lih-Juann
Published: May 2011

Room-temperature ferromagnetism has been observed in high density free-standing CrSi2(core)/SiO2(shell) semiconducting nanocables, which is contrast to diamagnetic properties of both CrSi2 and SiO2 in bulk. The hexagonal CrSi2 C40-type nanowires, sheathed with a thin amorphous SiO2 layer, grow along [0001] direction. The results of first-principles simulations indicate that Cr atoms around the interface are with anomalously high magnetization (about 2 μB/atom), due to distorted/dangling bonds and surrounded oxygen atoms. Evaluations can be very consistent with measurements by further considering the effects of interfacial roughness and more distribution of oxygen around the interface. These results point toward a different way to tune nanomagnetism in core/shell nanowires.
Influence of La and Ce additions on the magnetocaloric effect of Fe–B–Cr-based amorphous alloys
Authors: Law J. Y. , Franco V. , Ramanujan R. V.
Published: May 2011

The magnetic entropy change (ΔSM), temperature of peak ΔSM (Tpk) and refrigerant capacity (RC) in Fe(RE)80B12Cr8 (RE=La, Ce, or Gd) alloys were studied. Increasing La, Ce, and Gd content led to relatively constant, decrease, and increase in Tpk, respectively. Both the phenomenologically constructed universal curve for ΔSM and field dependence power laws demonstrated that these alloys exhibited similar critical exponents at Curie temperature. With 5% Ce added to Fe80B12Cr8, Tpk could be tuned near room temperature with relatively constant peak ΔSM. Fe79B12Cr8La1 exhibited enhanced RC compared to Gd5Si2Ge1.9Fe0.1. The tunable Tpk and enhanced RC are needed in active magnetic regenerators.
Electric field penetration in Au/Nb:SrTiO3 Schottky junctions probed by bias-dependent internal photoemission
Authors: Hikita Y. , Kawamura M. , Bell C. , Hwang H. Y.
Published: May 2011

Electric field penetration into the metallic side of a Schottky junction is in principle a universal phenomenon, the magnitude of which increases with the semiconductor permittivity. Here, we quantitatively probe this effect using bias-dependent internal photoemission spectroscopy at the Schottky junction between a large dielectric permittivity semiconductor SrTiO3 and gold. A clear linear reduction in the barrier height with increasing interface electric field was observed, highlighting the importance of field penetration into the gold. The interfacial permittivity of SrTiO3 at the interface is reduced from the bulk value, reflecting intrinsic suppression at the interface.
Switchable diode effect and ferroelectric resistive switching in epitaxial BiFeO3 thin films
Authors: Wang Can , Jin Kui-juan , Xu Zhong-tang , Wang Le , Ge Chen , Lu Hui-bin , Guo Hai-zhong , He Meng , Yang Guo-zhen
Published: May 2011

Current-voltage hysteresis and switchable rectifying characteristics have been observed in epitaxial multiferroic BiFeO3 (BFO) thin films. The forward direction of the rectifying current can be reversed repeatedly with polarization switching, indicating a switchable diode effect and large ferroelectric resistive switching. With analyzing the potential barriers and their variation with ferroelectric switching at the interfaces between the metallic electrodes and the semiconducting BFO, the switchable diode effect can be explained qualitatively by the polarization-modulated Schottky-like barriers.
Resistive switching behaviors of NiO films with controlled number of conducting filaments
Authors: Kim Y. S. , Kim J.-S. , Choi J. S. , Hwang I. R. , Hong S. H. , Kang S.-O. , Park B. H.
Published: May 2011

We deposited NiO films by using reactive dc sputtering on Pt/Ti/SiO2/Si substrates. Before depositing top Pt electrodes, conducting filaments are preformed using conductive atomic force microscope. Pt/NiO/Pt capacitor structures with controlled number of conducting filaments show unipolar resistive switching behaviors strongly dependent on the number of conducting filaments. Especially, set switching voltage distribution increases with the number of conducting filament.
Enhanced relative biological effectiveness of proton radiotherapy in tumor cells with internalized gold nanoparticles
Authors: Polf Jerimy C. , Bronk Lawrence F. , Driessen Wouter H. P. , Arap Wadih , Pasqualini Renata , Gillin Michael
Published: May 2011

The development and use of sensitizing agents to improve the effectiveness of radiotherapy have long been sought to improve our ability to treat cancer. In this letter, we have studied the relative biological effectiveness of proton beam radiotherapy on prostate tumor cells with and without internalized gold nanoparticles. The effectiveness of proton radiotherapy for the killing of prostate tumor cells was increased by approximately 15%–20% for those cells containing internalized gold nanoparticles.
The positive-column plasma in low-pressure noble gas d.c. discharge as an integral plasma-field system
Authors: Kurbatov P. F.
Published: May 2011

A one-dimension model for positive-column plasma is analyzed. In the framework of this model, a complete, self-consistent set of equations for the plasma column is proposed and justified. Basic prerequisites for the model and the equations used in it are discussed at length to clarify the mathematics and physics that underlie the proposed generalized description of plasma states. A study of the equations has unveiled the existence of two structurally stable types of steady states and three integrals of motion in the plasma system. The first type of states corresponds to spatially homogeneous plasma, and the second type, to the self-forming plasma structure with striations. Analysis of spatio-temporal plasma structures (spatially homogeneous and stratified stationary plasma states) and their attendant phenomena is given in detail. It is shown that the equations offer a more penetrating insight into the physical states and properties of positive-column plasma in dc-driven gas discharges, and into the various phenomena proceeding in the discharge system. Such a behavior is intimately related to the influence which the electric field has on the rate of ionization reactions. The theoretical results are compared to experimental data and can be used for to place the great body of experimental data in their proper framework. The modern fluid bifurcation model proposed to describe the properties of non-isothermic positive-column plasma in dc-driven low-pressure noble-gas discharges proved to be rather realistic, capable of adequately reproducing the basic properties of real field-plasma systems.
Cone opsin determines the time course of cone photoreceptor degeneration in Leber congenital amaurosis
Authors: Zhang Tao , Zhang Ning , Baehr Wolfgang , Fu Yingbin
Published: May 2011

Mutations in RPE65 or lecithin-retinol acyltransferase (LRAT) disrupt 11-
cis
-retinal recycling and cause Leber congenital amaurosis (LCA), the most severe retinal dystrophy in early childhood. We used

Lrat
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, a murine model for LCA, to investigate the mechanism of rapid cone degeneration. Although both M and S cone opsins mistrafficked as reported previously, mislocalized M-opsin was degraded whereas mislocalized S-opsin accumulated in

Lrat
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cones before the onset of massive ventral/central cone degeneration. As the ventral and central retina express higher levels of S-opsin than the dorsal retina in mice, our results may explain why ventral and central cones degenerate more rapidly than dorsal cones in

Rpe65
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and

Lrat
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LCA models. In addition, human blue opsin and mouse S-opsin, but not mouse M-opsin or human red/green opsins, aggregated to form cytoplasmic inclusions in transfected cells, which may explain why blue cone function is lost earlier than red/green-cone function in patients with LCA. The aggregation of short-wavelength opsins likely caused rapid cone degenerations through an endoplasmic reticulum stress pathway, as demonstrated in both the

Lrat
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retina and transfected cells. Replacing rhodopsin with S-opsin in

Lrat
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rods resulted in mislocalization and aggregation of S-opsin in the inner segment and the synaptic region of rods, ER stress, and dramatically accelerated rod degeneration. Our results demonstrate that cone opsins play a major role in determining the degeneration rate of photoreceptors in LCA.
Crossmodal reorganization in the early deaf switches sensory, but not behavioral roles of auditory cortex
Authors: Meredith M. Alex , Kryklywy James , McMillan Amee J. , Malhotra Shveta , Lum-Tai Ryan , Lomber Stephen G.
Published: May 2011

It is well known that early disruption of sensory input from one modality can induce crossmodal reorganization of a deprived cortical area, resulting in compensatory abilities in the remaining senses. Compensatory effects, however, occur in selected cortical regions and it is not known whether such compensatory phenomena have any relation to the original function of the reorganized area. In the cortex of hearing cats, the auditory field of the anterior ectosylvian sulcus (FAES) is largely responsive to acoustic stimulation and its unilateral deactivation results in profound contralateral acoustic orienting deficits. Given these functional and behavioral roles, the FAES was studied in early-deafened cats to examine its crossmodal sensory properties as well as to assess the behavioral role of that reorganization. Recordings in the FAES of early-deafened adults revealed robust responses to visual stimulation as well as receptive fields that collectively represented the contralateral visual field. A second group of early-deafened cats was trained to localize visual targets in a perimetry array. In these animals, cooling loops were surgically placed on the FAES to reversibly deactivate the region, which resulted in substantial contralateral visual orienting deficits. These results demonstrate that crossmodal plasticity can substitute one sensory modality for another while maintaining the functional repertoire of the reorganized region.
Revised age of late Neanderthal occupation and the end of the Middle Paleolithic in the northern Caucasus
Authors: Pinhasi Ron , Higham Thomas F. G. , Golovanova Liubov V. , Doronichev Vladimir B.
Published: May 2011

Advances in direct radiocarbon dating of Neanderthal and anatomically modern human (AMH) fossils and the development of archaeostratigraphic chronologies now allow refined regional models for Neanderthal–AMH coexistence. In addition, they allow us to explore the issue of late Neanderthal survival in regions of Western Eurasia located within early routes of AMH expansion such as the Caucasus. Here we report the direct radiocarbon (
14
C) dating of a late Neanderthal specimen from a Late Middle Paleolithic (LMP) layer in Mezmaiskaya Cave, northern Caucasus. Additionally, we provide a more accurate chronology for the timing of Neanderthal extinction in the region through a robust series of 16 ultrafiltered bone collagen radiocarbon dates from LMP layers and using Bayesian modeling to produce a boundary probability distribution function corresponding to the end of the LMP at Mezmaiskaya. The direct date of the fossil (39,700 ± 1,100
14
C BP) is in good agreement with the probability distribution function, indicating at a high level of probability that Neanderthals did not survive at Mezmaiskaya Cave after 39 ka cal BP ("calendrical" age in kiloannum before present, based on IntCal09 calibration curve). This challenges previous claims for late Neanderthal survival in the northern Caucasus. We see striking and largely synchronous chronometric similarities between the Bayesian age modeling for the end of the LMP at Mezmaiskaya and chronometric data from Ortvale Klde for the end of the LMP in the southern Caucasus. Our results confirm the lack of reliably dated Neanderthal fossils younger than ∼40 ka cal BP in any other region of Western Eurasia, including the Caucasus.
Common polymorphisms in C3, factor B, and factor H collaborate to determine systemic complement activity and disease risk
Authors: Heurich Meike , Martínez-Barricarte Ruben , Francis Nigel J. , Roberts Dawn L. , Rodríguez de Córdoba Santiago , Morgan B. Paul , Harris Claire L.
Published: May 2011

Common polymorphisms in complement alternative pathway (AP) proteins C3 (C3R102G), factor B (fBR32Q), and factor H (fHV62I) are associated with age-related macular degeneration (AMD) and other pathologies. Our published work showed that fBR32Qinfluences C3 convertase formation, whereas fHV62Iaffects factor I cofactor activity. Here we show how C3R102G(C3S/F) influences AP activity. In hemolysis assays, C3102Gactivated AP more efficiently (EC50C3102G: 157 nM; C3102R: 191 nM;P< 0.0001). fB binding kinetics and convertase stability were identical, but native and recombinant fH bound more strongly to C3b102R(KDC3b102R: 1.0 μM; C3b102G: 1.4 μM;P< 0.0001). Accelerated decay was unaltered, but fH cofactor activity was reduced for C3b102G, favoring AP amplification. Combining disease “risk” variants (C3102G, fB32R, and fH62V) in add-back assays yielded sixfold higher hemolytic activity compared with “protective” variants (C3102R, fB32Q, and fH62I;P< 0.0001). These data introduce the concept of a functional complotype (combination of polymorphisms) defining complement activity in an individual, thereby influencing susceptibility to AP-driven disease.
γδ intraepithelial lymphocytes are essential mediators of host–microbial homeostasis at the intestinal mucosal surface
Authors: Ismail Anisa S. , Severson Kari M. , Vaishnava Shipra , Behrendt Cassie L. , Yu Xiaofei , Benjamin Jamaal L. , Ruhn Kelly A. , Hou Baidong , DeFranco Anthony L. , Yarovinsky Felix , Hooper Lora V.
Published: May 2011

The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. Here we show that γδ intraepithelial lymphocytes (γδ IEL) of the small intestine produce innate antimicrobial factors in response to resident bacterial “pathobionts” that penetrate the intestinal epithelium. γδ IEL activation was dependent on epithelial cell-intrinsic MyD88, suggesting that epithelial cells supply microbe-dependent cues to γδ IEL. Finally, γδ T cells protect against invasion of intestinal tissues by resident bacteria specifically during the first few hours after bacterial encounter, indicating that γδ IEL occupy a unique temporal niche among intestinal immune defenses. Thus, γδ IEL detect the presence of invading bacteria through cross-talk with neighboring epithelial cells and are an essential component of the hierarchy of immune defenses that maintain homeostasis with the intestinal microbiota.
CD4
+
T cells support cytotoxic T lymphocyte priming by controlling lymph node input
Authors: Kumamoto Yosuke , Mattei Lisa M. , Sellers Stephanie , Payne Geoffrey W. , Iwasaki Akiko
Published: May 2011

Rapid induction of CD8
+
cytotoxic T lymphocyte (CTL) responses is critical to combat acute infection with intracellular pathogens. CD4
+
T cells help prime antigen-specific CTLs in secondary lymphoid organs after infection in the periphery. Although the frequency of naïve precursors is very low, the immune system is able to efficiently screen for cognate CTLs through mechanisms that are not well understood. Here we examine the role of CD4
+
T cells in early phases of the immune response. We show that CD4
+
T cells help optimal CTL expansion by facilitating entry of naïve polyclonal CD8
+
T cells into the draining lymph node (dLN) early after infection or immunization. CD4
+
T cells also facilitate input of naïve B cells into reactive LNs. Such “help” involves expansion of the arteriole feeding the dLN and enlargement of the dLN through activation of dendritic cells. In an antigen- and CD40-dependent manner, CD4
+
T cells activate dendritic cells to support naïve lymphocyte recruitment to the dLN. Our results reveal a previously unappreciated mode of CD4
+
T-cell help, whereby they increase the input of naïve lymphocytes to the relevant LN for efficient screening of cognate CD8
+
T cells.