bluuebunny/crossref_metadata_2025 huggingface dataset:
Disguise as an evasive stratagem of parasitic organisms
Authors: McLaren Diane J.
Published: August 2011

It is now well established that animal parasites elicit vigorous immune responses in their hosts and that the resistance to reinfection thus acquired is mediated through conventional humoral and/or cellular effector mechanisms. It is also recognized, however, that some parasites exhibit extreme longevity in the face of a potentially hostile or lethal environment, and it may be assumed therefore that such organisms possess a repertoire of highly sophisticated and successful evasive strategies. Of all the survival mechanisms thus far proposed, the concept of antigen sharing, or disguise, is probably the most contentious. Arguments have arisen over the nature and origin of the shared determinants and over the validity of their role in ensuring parasite survival within the fully immunocompetent host. This presentation reviews published data concerning the existence of a disguise stratagem amongst medically important parasites and evaluates experiments designed to investigate the functional importance of disguise in immune evasion.
Antigenic variation in parasites
Authors: Turner M.J.
Published: August 2011

Antigenic variation is a powerful survival strategy adapted by certain species of parasitic protozoa to allow them to survive in the immunized host. It is exemplified by the African trypanosomes, which provide far and away the best characterized and most studied system of this kind. Why have the trypanosomes developed antigenic variation to such a sophisticated level? Because the trypanosome lives its life in the bloodstream of its mammalian host and is therefore in continuous conflict with the host's immune system. Antigenic variation represents its whole survival strategy, with some help provided by its ability to immunosuppress the host. The importance of antigenic variation to the trypanosome is underscored by the estimate that up to 10% of the trypanosome genome may be devoted to variant antigen genes (Van der Ploeget al.1982). Most other parasitic protozoa prefer a less confrontational existence and usually adopt an intracellular home for at least a part of their life-cycle within the mammalian host. That being the case, do other parasitic protozoa need antigenic variation within their armorarium ? The answer seems to be yes, although the reasons why are by no means clear. For example, the stages in the life-cycle which exhibit antigenic variation might be expected to be those which are released free into the bloodstream – in malaria, sporozoites and merozoites, for example. Yet there seems to be no evidence for phenotypic variation at all in these stages. Rather, it is the intracellular stages which, in bothPlasmodiumandBabesia, seem to elaborate molecules which are expressed at the surface of the parasitized cell, and which are capable of both eliciting an immune response and of avoiding the con- sequences of such a response by phenotypic antigenic variation. Why are such antigens expressed, and what is their functional significance?
Do the variable surface glycoproteins of parasites have a function?
Authors: Skehel J. J.
Published: August 2011

In common with a number of parasite surface antigens about which we have heard, the influenza haemagglutinin is a membrane glycoprotein which varies in antigenicity.

A question which often arises concerns the contribution of the carbohydrate side-chains to antigenicity, and we have recently observed that a number of monoclonal antibodies are able to discriminate between glycosylated and nonglycosylated haemagglutinin molecules. Specifically these antibodies select antigenic variants with haemagglutinins which contain asparagine substitutions in the sequence asparagine–cysteine–threonine and the asparagine is glycosylated. By infecting cells incubated in medium containing tunicamycin non-glycosylated variant haemagglutinin can be obtained, and it is possible to show that such molecules are precipitated by the antibodies used to select the variant. These results directly indicate that carbohydrate side-chains can modulate the antigenic properties of glycoproteins and may be involved in antigenic variation.
The application of recombinant DNA technology to problems of helminth identification
Authors: Rollinson D. , Walker T. K. , Simpson A. J. G.
Published: August 2011

During the past decade, enormous technological developments have occurred in biology that have led to significant and revolutionary advances. New techniques of DNA cloning, restriction-enzyme analyses and nucleotide sequencing are providing a mass of data concerning the genomes of a wide variety of organisms. Such insights are having a great impact upon many areas of biological investigation, and would seem to be of considerable potential value for studies of taxonomy and population biology. The application of these new approaches to the characterization and identification of parasitic helminths has only recently begun, but they promise to become powerful additional tools for this purpose. Better methods of characterization are required for more precise definition of the parasites of man and domestic animals and for determining vectors and intermediate hosts as well as possible animal reservoir hosts. Moreover, a greater understanding of the genetic diversity of parasitic organisms is required since many helminths, which are morphologically similar, show marked differences in epidemiologically significant factors such as infectivity, pathogenicity, immunogenicity and drug sensitivity.
Molecular cloning of schistosome genes
Authors: Taylor D. W. , Cordingley J. S. , Dunne D. W. , Johnson K. S. , Haddow W. J. , Hormaeche C. E. , Nene V. , Butterworth A. E.
Published: August 2011

As part of an integrated programme investigating human schistosomiasis, work which involves epidemiological surveys and detailed immunological studies as well as biochemical investigations, we have, over the last three years, been cloning schistosome genes in a variety of plasmid and lambda vector systems. In this lecture we present a review of some selected aspects of work primarily aimed at production of experimental vaccines against the disease but which, on a broader front, is also concerned with developmental regulation of gene expression around the parasite's life-cycle. Specifically, we are interested in cloning three groups of genes. First, those encoding surface antigens; second, those associated with sexual maturity and egg production; and third, antigens which may provide a basis for a specific immunodiagnostic test.
The Wellcome Trust Lecture: Genes for antigens ofPlasmodium falciparum
Authors: Kemp D. J. , Coppel R. L. , Stahl H. D. , Bianco A. E. , Corcoran L. M. , McIntyre P. , Langford C. J. , Favaloro J. M. , Crewther P. E. , Brown G. V. , Mitchell G. F. , Culvenor J. G. , Anders R. F.
Published: August 2011

Sporozoites ofP. falciparumand other Plasmodia appear to be fairly simple antigenically, in that there is a dominant antigen, the circumsporozoite (CS) protein that forms the sporozoite surface coat (Potocnjak, Yoshida, Nussenzweig & Nussensweig, 1980; Santoroet al.1983). Consequently, the CS protein and the gene encoding it have now been studied in considerable detail (Elliset al.1983; Godsonet al.1983; Ozakiet al.1983; Dameet al.1984; Eneaet al.1984). In contrast to sporozoites, the asexual blood stagesof P. falciparumare antigenically complex. Two-dimensional gel analyses of immunoprecipitated, biosynthetically labelled antigens indicate that repeated infection withP. falciparumresults in the synthesis of antibodies against a large number of distinct antigens (Perrin & Dayal, 1982; Brownet al.1981, 1983). In further contrast to the sporozoite, the asexual blood stages of differentP. falciparumisolates exhibit a high degree of antigenic heterogeneity (Brownet al.1983; Hallet al.1983; McBride, Walliker & Morgan, 1982). Much of this antigenic diversity is no doubt due to allelic differences but clonal populations of parasites may also have the capacity to undergo antigenic variation (Hommel, David & Oligino, 1983).
Host immune response and pathological expression in malaria: possible implications for malaria vaccines
Authors: Grau G. E. , Giudice G. Del , Lambert P.-H.
Published: August 2011

Recent progress in parasite immunobiology has led to the identification of several plasmodial antigens representing the target of the protective antibody response of the infected host. As a consequence, some of these antigens have been envisaged as potential malaria vaccines in man. However, in spite of these achievements, the fine mechanisms which lead to the development of a state of partial protective immunity or to the triggering of immunopathology during malaria infection are not yet fully understood. Thus, it may be appropriate to evaluate the relative importance of individual host immune responsiveness to parasite epitopes involved in the induction of immunity, or of some immunologically mediated adverse reactions such as glomerulonephritis, anaemia, thrombocytopenia, and cerebral syndrome.
Immunopathological mechanisms in the induction of parasitic diseases with particular reference to type III hypersensitivity reactions
Authors: Steward M. W.
Published: August 2011

During the primary immune response to an infectious agent, specific memory cells are generated which enable the immune system to respond more rapidly and efficiently to re-exposure to the same agent. Under normal circumstances, this acquired resistance leads to the effective elimination of the agent, and recovery. However, under certain circumstances these secondary infections, rather than aiding recovery, actually produce tissue damage and often contribute to the disease process. This stage has been termed hypersensitivity and such hypersensitivity reactions play an important role in the immunopathology of several diseases. Coombs & Gell (1963) have classified hypersensitivity into four types of reaction. Types I, II and III involve antibody-mediated processes whereas type IV is mediated solely by lymphocytes. Many parasitic infections have characteristics which would appear to predispose the host to the development of hypersensitivity states and consequent immunopathology. These include (1) the chronicity of the infections, (2) the release of parasite antigens in large amounts and their persistence in the circulation and host tissues, (3) the sharing of antigens between parasite and host and (4) the ability of the parasite to damage host tissues and alter their antigenicity. However, direct evidence that these mechanisms lead to the development of immunopathology in parasitic infections is limited. In this article, these four types of hypersensitivity will be briefly discussed in the context of the immunopathology following parasite infection. There then follows a more extensive consideration of type III hypersensitivity with particular emphasis on the mechanisms underlying the development of immune-complex mediated disease.
Concluding remarks
Authors: Bradley D.J.
Published: August 2011

Good wine needs no bush, and good papers need no third-party summary. The papers presented today at this symposium on the pathophysiology of parasitic disease have been splendid, and I shall not be so foolish as to attempt the impossible task of summarizing them. This stage in the meeting does, however, provide an opportunity to look forward in the light of what has been presented today, and there are some points that are of particular interest and which will bear repetition or comment in the closing minutes of this symposium.
Ontogenetic changes in helminth membrane function
Authors: Arme C.
Published: August 2011

During their life-cycle many parasites experience a wide range of environments including free living and those provided by a variety of intermediate and final hosts. The nutritional requirements of parasites are met by physiological processes adapted to exploit the physico-chemical characteristics provided by different hosts. In helminth parasites these adaptations are frequently expressed on the tegumentary surface. As an example of adaptations within the Trematoda, the control of monosaccharide transport inProterometrasp. is described. Environmental sodium, although not directly involved in the uptake process, nevertheless regulates the expression of transport capabilities. In the Cestoda, the uptake of monosaccharides and amino acids is described forHymenolepis diminuta. The metacestode of this tapeworm inhabits the blood system of an arthropod, and the adult the gut of a mammal. There are quantitative and qualitative differences in the amino acids and monosaccharides in these two environments and these are reflected in the transport mechanisms exhibited by the two forms of the life-cycle. InEchinococcus granulosusthe transfer of amino acids, sugars and macromolecules across the membranes of hydatid cysts and protoscoleces is described. The major difference between these two stages in the life-cycle relates to the ability of hydatid cysts to absorb macromolecules, whereas protoscoleces are impermeable to these compounds. The potential for future work is emphasized.
The relative roles of the intestines and external surfaces in the nutrition of monogeneans, digeneans and nematodes
Authors: Pappas P. W.
Published: August 2011

Several major groups of parasitic helminths (Monogenea, Digenea and Nematoda) possess two surfaces that are potentially absorptive in nature. These are an external surface, a tegument in the platyhelminths and cuticle in the nematodes, and the intestine. This paper discusses the relative contributions of these absorptive surfaces in the nutrition of these parasitic helminths. There are many factors that determine the availability of, and a parasite's ability to absorb nutrients via either of these surfaces, and this review discusses individually some of the more important morphological, physiological and environmental factors affecting the potential nutritional roles of these surfaces. It is clear from such a summary of previous studies that the intestines and teguments (cuticles) of helminth parasites can each serve an important nutritional role. However, insufficient data make it impossible at this time to determine the relative nutritional roles of these surfaces in any single parasitic helminth.
Urbanization and human health
Authors: Phillips D.R.
Published: August 2011

Urbanization involves a physical change in which increasing proportions of populations live in urban settings, however defined. It also implies considerable changes in the ways in which these people live, how they earn their livelihoods, the food which they eat, and the wide range of environmental factors to which they are exposed. There is another underlying assumption that, increasingly, urban populations will be more healthy than their rural counterparts and that higher levels of urbanization will equate with better health status. This paper discusses some of the assumptions underlying this contention. It takes issue with certain of them, particularly the assumption that urbanization affects the health of all residents equally. It is manifestly evident that in many cities, particularly in the developing world, the poor are exposed to greater risks and have much lower health status than their richer neighbours. In addition, whilst urban residents may theoretically have a better access to health care and services than do residents in many rural areas, and whilst many indicators of health do appear better in more highly urbanized societies than ones less so, there are caveats. The paper introduces the concept of epidemiological transition, which suggests that, whilst life expectancy might be higher in many urbanized countries and in certain cities, the inhabitants are often merely suffering from different forms of ill-health, often chronic or degenerative, rather than infective. In certain cities in middle-income countries, residents, particularly the poor, are exposed to a double risk of both infection and chronic degenerative ailments. The paper concludes with a consideration of more general recent statements from the World Health Organization among others, on the impact of urbanization on health. The ‘Healthy Cities’ project is also discussed. WHO identifies a range of general determinants of urban health: physical, social, cultural and environmental. Many represent the by-products of modernization and especially industrialization. It is emphasized that urbanization, and the concentration of human beings into new areas in particular, can bring exposure to new risk factors for large numbers of people. The growth of infectious and parasitic disease in some urban settings must therefore be recognized, as must the emergence of chronic diseases, with the concomitant need for investment in new types of health and social care. However, a number of constraints militate against the achievement of improved urban health, especially in developing countries. The paper concludes by considering some important constraints: the very scale of urban health problems; the impacts of structural adjustment programmes which cut public expenditure on environmental health, health services and nutrition, thereby increasing the vulnerability of the poor; urban management problems; lack of political will; and the difficulties of measuring change in health and effects of policies.
Intestinal parasitic infections in an industrialized country; a new focus on children with better DNA-based diagnostics
Authors: VERWEIJ JACO J. , VAN LIESHOUT LISETTE
Published: August 2011

In recent years, the isolation of parasitic DNA from faecal samples and PCR techniques, have been improved and simplified. Moreover, the introduction of real-time PCR has made it possible to multiplex different targets into one reaction. These new technical possibilities make it feasible to introduce PCR with its unsurpassed sensitivity and specificity in a routine laboratory setting for the diagnosis of intestinal parasites. Detection rates of the parasitic infections included in the PCR are increased significantly compared with microscopy. Molecular diagnostics, especially in children, reveal a possible cause of the gastrointestinal complaints in many more cases compared with conventional methods. Usually in GP patients no other pathogenic parasites are detected using microscopy and in the returning travellers additional parasites are found with microscopy in a minority of cases only. Multiplex real-time PCR offers a highly sensitive and specific diagnostic alternative for labour intensive microscopy in clinical laboratory practice. Additional diagnostic methods for the detection of parasitic infections that are not included as PCR target can be limited to a selected group of patients.
The public health nutrition intervention management bi-cycle: a model for training and practice improvement
Authors: Hughes Roger , Margetts Barrie
Published: August 2011

Objective

The present paper describes a model for public health nutrition practice designed to facilitate practice improvement and provide a step-wise approach to assist with workforce development.

Design

The bi-cycle model for public health nutrition practice has been developed based on existing cyclical models for intervention management but modified to integrate discrete capacity-building practices.

Setting

Education and practice settings.

Subjects

This model will have applications for educators and practitioners.

Results

Modifications to existing models have been informed by the authors’ observations and experiences as practitioners and educators, and reflect a conceptual framework with applications in workforce development and practice improvement. From a workforce development and educational perspective, the model is designed to reflect adult learning principles, exposing students to experiential, problem-solving and practical learning experiences that reflect the realities of work as a public health nutritionist. In doing so, it assists the development of competency beyond knowing to knowing how, showing how and doing. This progression of learning from knowledge to performance is critical to effective competency development for effective practice.

Conclusions

Public health nutrition practice is dynamic and varied, and models need to be adaptable and applicable to practice context to have utility. The paper serves to stimulate debate in the public health nutrition community, to encourage critical feedback about the validity, applicability and utility of this model in different practice contexts.
Effekte kompetenzieller Rückmeldung beim wissenschaftlichen Denken
Authors: Wollenschläger Mareike , Möller Jens , Harms Ute
Published: August 2011

Zusammenfassung. Kompetenzielle Rückmeldung wurde in dieser Studie als Leistungsbewertung in Relation zu definierten Kompetenzstufen eines domänenspezifischen Kompetenzmodells verstanden. In einem Pre-Posttest-Design (N = 38) wurde eine Experimentalbedingung mit kompetenzieller Rückmeldung mit einer Kontrollgruppe ohne Rückmeldung verglichen. Die Ergebnisse zeigen, dass Lernende, die während der Bearbeitung von Aufgaben zum wissenschaftlichen Denken eine kompetenzielle Rückmeldung erhielten, besser abschnitten als Lernende, die keine Rückmeldung erhielten. Zudem zeigten sich tendenziell positive Effekte der kompetenziellen Rückmeldung auf motivationale Variablen, wie beispielsweise Interesse und Kompetenzerleben der Lernenden.
A high temperature high pressure cell for quasielastic neutron scattering
Authors: Yang F. , Kaplonski J. , Unruh T. , Mamontov E. , Meyer A.
Published: August 2011

We present our recent development of a high temperature high pressure cell for neutron scattering. Combining a water cooled Nb1Zr pressure cell body with an internal heating furnace, the sample environment can reach temperatures of up to 1500 K at a pressure of up to 200 MPa at the sample position, with an available sample volume of about 700 mm3. The cell material Nb1Zr is specifically chosen due to its reasonable mechanical strength at elevated temperatures and fairly small neutron absorption and incoherent scattering cross sections. With this design, an acceptable signal-to-noise ratio of about 10:1 can be achieved. This opens new possibilities for quasielastic neutron scattering studies on different types of neutron spectrometers under high temperature high pressure conditions, which is particularly interesting for geological research on, e.g., water dynamics in silicate melts.
Relativistic solitary waves with phase modulation embedded in long laser pulses in plasmas
Authors: Sanchez-Arriaga G. , Siminos E. , Lefebvre E.
Published: August 2011

We investigate the existence of nonlinear phase-modulated relativistic solitary waves embedded in an infinitely long circularly polarized electromagnetic wave propagating through a plasma. These states are exact nonlinear solutions of the 1-dimensional Maxwell-fluid model for a cold plasma composed of electrons and ions. The solitary wave, which consists of an electromagnetic wave trapped in a self-generated Langmuir wave, presents a phase modulation when the group velocity V and the phase velocity Vph of the long circularly polarized electromagnetic wave do not match the condition VVph = c2. The main properties of the waves as a function of their group velocities, wavevectors, and frequencies are studied, as well as bifurcations of the dynamical system that describes the waves when the parameter controlling the phase modulation changes from zero to a finite value. Such a transition is illustrated in the limit of small amplitude waves where an analytical solution for a grey solitary wave exists. The solutions are interpreted as the stationary state after the collision of a long laser pulse with an isolated solitary wave.
On the accuracy of the state space restriction approximation for spin dynamics simulations
Authors: Karabanov Alexander , Kuprov Ilya , Charnock G. T. P. , van der Drift Anniek , Edwards Luke J. , Köckenberger Walter
Published: August 2011

We present an algebraic foundation for the state space restriction approximation in spin dynamics simulations and derive applicability criteria as well as minimal basis set requirements for practically encountered simulation tasks. The results are illustrated with nuclear magnetic resonance (NMR), electron spin resonance (ESR), dynamic nuclear polarization (DNP), and spin chemistry simulations. It is demonstrated that state space restriction yields accurate results in systems where the time scale of spin relaxation processes approximately matches the time scale of the experiment. Rigorous error bounds and basis set requirements are derived.
Invited Article: The coherent optical laser beam recombination technique (COLBERT) spectrometer: Coherent multidimensional spectroscopy made easier
Authors: Turner Daniel B. , Stone Katherine W. , Gundogdu Kenan , Nelson Keith A.
Published: August 2011

We have developed an efficient spectrometer capable of performing a wide variety of coherent multidimensional measurements at optical wavelengths. The two major components of the largely automated device are a spatial beam shaper which controls the beam geometry and a spatiotemporal pulse shaper which controls the temporal waveform of the femtosecond pulse in each beam. We describe how to construct, calibrate, and operate the device, and we discuss its limitations. We use the exciton states of a semiconductor nanostructure as a working example. A series of complex multidimensional spectra—displayed in amplitude and real parts—reveals increasingly intricate correlations among the excitons.
Methanol nucleation in a supersonic nozzle
Authors: Laksmono Hartawan , Tanimura Shinobu , Wyslouzil Barbara E.
Published: August 2011

We determined the partial pressures pJmax, temperatures TJmax, monomer supersaturations SJmax, and characteristic times ΔtJmax  corresponding to the maximum nucleation rates of methanol in a supersonic nozzle. We found that TJmax increased from 202.2 K to 223.7 K as pJmax increased from 67.1 to 413.2 Pa, while the maximum nucleation rate Jmax changed by less than a factor of 4 over the measurement range. Our nucleation rates appear reasonably consistent with measurements in other devices and are within one order of magnitude of the nucleation rates predicted by classical nucleation theory.
Asymmetric single-particle triple-resonant metamaterial in terahertz band
Authors: Zhang Ya-Xin , Qiao Shen , Huang Wanxia , Ling Wei , Li Liang , Liu Sheng-gang
Published: August 2011

This paper presents the design, simulation, and measurement of an asymmetric triple-band metamaterial composed of single geometry electric field coupled resonators in the terahertz region. Theoretical and experimental results show that the structure has three distinct and strong absorption frequency peaks near 0.38, 0.58, and 0.74 THz, all of which are related to the inductance-capacitance resonance of the metamaterial. Due to the well-separating of different resonances in the particle, this metamaterial shows potentially application promises in the design of multiband terahertz devices.
Incorporation of charge transfer into the explicit polarization fragment method by grand canonical density functional theory
Authors: Isegawa Miho , Gao Jiali , Truhlar Donald G.
Published: August 2011

Molecular fragmentation algorithms provide a powerful approach to extending electronic structure methods to very large systems. Here we present a method for including charge transfer between molecular fragments in the explicit polarization (X-Pol) fragment method for calculating potential energy surfaces. In the conventional X-Pol method, the total charge of each fragment is preserved, and charge transfer between fragments is not allowed. The description of charge transfer is made possible by treating each fragment as an open system with respect to the number of electrons. To achieve this, we applied Mermin's finite temperature method to the X-Pol wave function. In the application of this method to X-Pol, the fragments are open systems that partially equilibrate their number of electrons through a quasithermodynamics electron reservoir. The number of electrons in a given fragment can take a fractional value, and the electrons of each fragment obey the Fermi–Dirac distribution. The equilibrium state for the electrons is determined by electronegativity equalization with conservation of the total number of electrons. The amount of charge transfer is controlled by re-interpreting the temperature parameter in the Fermi–Dirac distribution function as a coupling strength parameter. We determined this coupling parameter so as to reproduce the charge transfer energy obtained by block localized energy decomposition analysis. We apply the new method to ten systems, and we show that it can yield reasonable approximations to potential energy profiles, to charge transfer stabilization energies, and to the direction and amount of charge transferred.
Optimization of energy resources for cooking and heating—A fuzzy goal programming approach
Authors: Jinturkar A. M. , Deshmukh S. S.
Published: August 2011

A fuzzy goal programming (FGP) approach is used for rural energy resource allocation for heating and cooking. The detail survey has been conducted to determine the potential of biogas and biomass and to find energy consumption pattern in four villages of Buldhana district, Maharashtra, India. Four fuzzy objective functions and six constrains based on the local availability are considered in this model. Four scenarios have been developed such as equal priority, cost priority, emission priority, and local resources priority. Due to vast uncertainty in energy data at micro level, fuzzy goal approach has been found suitable to take into consideration the variation in energy consumption rate. The proposed model can provide the best possible options for micro-level energy planning to the decision maker.
Cosmic ray diffusion: Detailed investigation of a recent model
Authors: Lerche Ian , Tautz R. C.
Published: August 2011

A recently proposed model [A. Shalchi, Astrophys. J. 720, L127 (2010)] of perpendicular cosmic ray scattering is investigated in detail, with special emphasis to the relevant diffusion coefficients. Solution of a pair of critical equations, as well as a fundamental integral needed to describe the particle transport, are represented via a mathematically correct expansion procedure, thus modifying the previously available approximations. It is hoped that these significant improvements will aid in allowing a clearer understanding of precisely what the model is capable of evaluating.
Accurate non-Born-Oppenheimer calculations of the complete pure vibrational spectrum of D2 with including relativistic corrections
Authors: Bubin Sergiy , Stanke Monika , Adamowicz Ludwik
Published: August 2011

In this work we report very accurate variational calculations of the complete pure vibrational spectrum of the D2 molecule performed within the framework where the Born-Oppenheimer (BO) approximation is not assumed. After the elimination of the center-of-mass motion, D2 becomes a three-particle problem in this framework. As the considered states correspond to the zero total angular momentum, their wave functions are expanded in terms of all-particle, one-center, spherically symmetric explicitly correlated Gaussian functions multiplied by even non-negative powers of the internuclear distance. The nonrelativistic energies of the states obtained in the non-BO calculations are corrected for the relativistic effects of the order of α2 (where α = 1/c is the fine structure constant) calculated as expectation values of the operators representing these effects.
Note: Detection of a single cobalt microparticle with a microfabricated atomic magnetometer
Authors: Maser D. , Pandey S. , Ring H. , Ledbetter M. P. , Knappe S. , Kitching J. , Budker D.
Published: August 2011

We present magnetic detection of a single, \documentclass[12pt]{minimal}\begin{document}$\rm 2\, \mu m$\end{document}2μm diameter cobalt microparticle using an atomic magnetometer based on a microfabricated vapor cell. These results represent an improvement by a factor of 105 in terms of the detected magnetic moment over previous work using atomic magnetometers to detect magnetic microparticles. The improved sensitivity is due largely to the use of small vapor cells. In an optimized setup, we predict detection limits of \documentclass[12pt]{minimal}\begin{document}$\rm 0.17\, \mu m^3$\end{document}0.17μm3.
The new cold neutron chopper spectrometer at the Spallation Neutron Source: Design and performance
Authors: Ehlers G. , Podlesnyak A. A. , Niedziela J. L. , Iverson E. B. , Sokol P. E.
Published: August 2011

The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.
Magnetoconductance responses in organic charge-transfer-complex molecules
Authors: Lee Tsung-Hsun , Li Jhen-Hao , Huang Wei-Shun , Hu Bin , Huang J. C. A. , Guo Tzung-Fang , Wen Ten-Chin
Published: August 2011

Blending 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), a high electron affinity organic molecule, with N,N′-bis-(1-naphyl)-N,N′-diphenyl-1,1′-biphenyl′-4,4′-diamine (NPB) creates the charge-transfer-complex molecules and modulates the magnetoconductance (MC) responses of devices by an applied electrical bias. A negative MC response (−0.60%) is observed for the device made of NPB:F4-TCNQ(30%) film as the active layer, which has a distinct characteristic to negligible MC responses in pristine NPB- and F4-TCNQ-based devices. We attribute the MC responses to the magnetic-field-dependent transport of injected charge carriers through charge-transfer-complex molecules in the NPB:F4-TCNQ system, which are varied with the F4-TCNQ blending concentrations and the injection of minority charge carriers. Results of this study demonstrate a turning point of MC responses at the bias voltage near the threshold of the bipolar injection.
Backward elastic light scattering of malaria infected red blood cells
Authors: Lee Seungjun , Lu Wei
Published: August 2011

We investigated the backward light scattering pattern of healthy and malaria (Plasmodium falciparum) parasitized red blood cells. The spectrum could clearly distinguish between predominant ring stage infected blood cells and healthy blood cells. Further, we found that infected samples mixed with different stages of P. falciparum showed different signals, suggesting that even variance in parasite stages could also be detected by the spectrum. These results together with the backward scattering technique suggest the potential of non-invasive diagnosis of malaria through light scattering of blood cells near the surface of human body, such as using eyes or skin surface.
Opto-electronic characterization of electron traps upon forming polymer oxide memory diodes
Authors: Chen Qian , Bory Benjamin F. , Kiazadeh Asal , Rocha Paulo R. F. , Gomes Henrique L. , Verbakel Frank , De Leeuw Dago M. , Meskers Stefan C. J.
Published: August 2011

Metal-insulator-polymer diodes where the insulator is a thin oxide (Al2O3) layer are electroformed by applying a high bias. The initial stage is reversible and involves trapping of electrons near the oxide/polymer interface. The rate of charge trapping is limited by electron transport through the polymer. Detrapping of charge stored can be accomplished by illuminating with light under short-circuit conditions. The amount of stored charge is determined from the optically induced discharging current transient as a function of applied voltage and oxide thickness. When the charge density exceeds 8 × 1017/m2, an irreversible soft breakdown transition occurs to a non-volatile memory diode.
Disambiguation of Mental Rotation by Spatial Frames of Reference
Authors: Asakura Nobuhiko , Inui Toshio
Published: August 2011

Previous research has shown that our ability to imagine object rotations is limited and associated with spatial reference frames; performance is poor unless the axis of rotation is aligned with the object-intrinsic frame or with the environmental frame. Here, we report an active effect of these reference frames on the process of mental rotation: they can disambiguate object rotations when the axis of rotation is ambiguous. Using novel mental rotation stimuli, in which the rotational axes between pairs of objects can be defined with respect to multiple frames of reference, we demonstrate that the vertical axis is preferentially used for imagined object rotations over the object-intrinsic axis for an efficient minimum rotation. In contrast, the object-intrinsic axis can play a decisive role when the vertical axis is absent as a way of resolving the ambiguity of rotational motion. When interpreted in conjunction with recent advances in the Bayesian framework for motion perception, our results suggest that these spatial frames of reference are incorporated into an internal model of object rotations, thereby shaping our ability to imagine the transformation of an object's spatial structure.
Economic and geographic drivers of wildlife consumption in rural Africa
Authors: Brashares Justin S. , Golden Christopher D. , Weinbaum Karen Z. , Barrett Christopher B. , Okello Grace V.
Published: August 2011

The harvest of wildlife for human consumption is valued at several billion dollars annually and provides an essential source of meat for hundreds of millions of rural people living in poverty. This harvest is also considered among the greatest threats to biodiversity throughout Africa, Asia, and Latin America. Economic development is often proposed as an essential first step to win–win solutions for poverty alleviation and biodiversity conservation by breaking rural reliance on wildlife. However, increases in wealth may accelerate consumption and extend the scale and efficiency of wildlife harvest. Our ability to assess the likelihood of these two contrasting outcomes and to design approaches that simultaneously consider poverty and biodiversity loss is impeded by a weak understanding of the direction and shape of their interaction. Here, we present results of economic and wildlife use surveys conducted in 2,000 households from 96 settlements in Ghana, Cameroon, Tanzania, and Madagascar. We examine the individual and interactive roles of wealth, relative food prices, market access, and opportunity costs of time spent hunting on household rates of wildlife consumption. Despite great differences in biogeographic, social, and economic aspects of our study sites, we found a consistent relationship between wealth and wildlife consumption. Wealthier households consume more bushmeat in settlements nearer urban areas, but the opposite pattern is observed in more isolated settlements. Wildlife hunting and consumption increase when alternative livelihoods collapse, but this safety net is an option only for those people living near harvestable wildlife.
Conditions associated with protected area success in conservation and poverty reduction
Authors: Ferraro Paul J. , Hanauer Merlin M. , Sims Katharine R. E.
Published: August 2011

Protected areas are the dominant approach to protecting biodiversity and the supply of ecosystem services. Because these protected areas are often placed in regions with widespread poverty and because they can limit agricultural development and exploitation of natural resources, concerns have been raised about their potential to create or reinforce poverty traps. Previous studies suggest that the protected area systems in Costa Rica and Thailand, on average, reduced deforestation and alleviated poverty. We examine these results in more detail by characterizing the heterogeneity of responses to protection conditional on observable characteristics. We find no evidence that protected areas trap historically poorer areas in poverty. In fact, we find that poorer areas at baseline seem to have the greatest levels of poverty reduction as a result of protection. However, we do find that the spatial characteristics associated with the most poverty alleviation are not necessarily the characteristics associated with the most avoided deforestation. We show how an understanding of these spatially heterogeneous responses to protection can be used to generate suitability maps that identify locations in which both environmental and poverty alleviation goals are most likely to be achieved.
Land-use poverty traps identified in shifting cultivation systems shape long-term tropical forest cover
Authors: Coomes Oliver T. , Takasaki Yoshito , Rhemtulla Jeanine M.
Published: August 2011

In this article we illustrate how fine-grained longitudinal analyses of land holding and land use among forest peasant households in an Amazonian village can enrich our understanding of the poverty/land cover nexus. We examine the dynamic links in shifting cultivation systems among asset poverty, land use, and land cover in a community where poverty is persistent and primary forests have been replaced over time—with community enclosure—by secondary forests (i.e., fallows), orchards, and crop land. Land cover change is assessed using aerial photographs/satellite imagery from 1965 to 2007. Household and plot level data are used to track land holding, portfolios, and use as well as land cover over the past 30 y, with particular attention to forest status (type and age). Our analyses find evidence for two important types of “land-use” poverty traps—a “subsistence crop” trap and a “short fallow” trap—and indicate that the initial conditions of land holding by forest peasants have long-term effects on future forest cover and household welfare. These findings suggest a new mechanism driving poverty traps: insufficient initial land holdings induce land use patterns that trap households in low agricultural productivity. Path dependency in the evolution of household land portfolios and land use strategies strongly influences not only the wellbeing of forest people but also the dynamics of tropical deforestation and secondary forest regrowth.
Lessons about parks and poverty from a decade of forest loss and economic growth around Kibale National Park, Uganda
Authors: Naughton-Treves Lisa , Alix-Garcia Jennifer , Chapman Colin A.
Published: August 2011

We use field data linked to satellite image analysis to examine the relationship between biodiversity loss, deforestation, and poverty around Kibale National Park (KNP) in western Uganda, 1996–2006. Over this decade, KNP generally maintained forest cover, tree species, and primate populations, whereas neighboring communal forest patches were reduced by half and showed substantial declines in tree species and primate populations. However, a bad decade for forest outside the park proved a prosperous one for most local residents. Panel data for 252 households show substantial improvement in welfare indicators (e.g., safer water, more durable roof material), with the greatest increases found among those with highest initial assets. A combination of regression analysis and matching estimators shows that although the poor tend to be located on the park perimeter, proximity to the park has no measureable effect on growth of productive assets. The risk for land loss among the poor was inversely correlated with proximity to the park, initial farm size, and decline in adjacent communal forests. We conclude the current disproportionate presence of poor households at the edge of the park does not signal that the park is a poverty trap. Rather, Kibale appears to provide protection against desperation sales and farm loss among those most vulnerable.
Nucleotide oligomerization domain-containing proteins instruct T cell helper type 2 immunity through stromal activation
Authors: Magalhaes Joao G. , Rubino Stephen J. , Travassos Leonardo H. , Le Bourhis Lionel , Duan Wei , Sellge Gernot , Geddes Kaoru , Reardon Colin , Lechmann Matthias , Carneiro Leticia A. , Selvanantham Thirumahal , Fritz Jorg H. , Taylor Betsy C. , Artis David , Mak Tak Wah , Comeau Michael R. , Croft Michael , Girardin Stephen E. , Philpott Dana J.
Published: August 2011

Although a number of studies have examined the development of T-helper cell type 2 (Th2) immunity in different settings, the mechanisms underlying the initiation of this arm of adaptive immunity are not well understood. We exploited the fact that immunization with antigen plus either nucleotide-binding oligomerization domain-containing proteins 1 (Nod1) or 2 (Nod2) agonists drives Th2 induction to understand how these pattern-recognition receptors mediate the development of systemic Th2 immune responses. Here, we show in bone-marrow chimeric mice that Nod1 and Nod2 expression within the stromal compartment is necessary for priming of effector CD4+Th2 responses and specific IgG1 antibodies. In contrast, sensing of these ligands by dendritic cells was not sufficient to induce Th2 immunity, although these cells contribute to the response. Moreover, we determined that CD11c+cells were the critical antigen-presenting cells, whereas basophils and B cells did not affect the capacity of Nod ligands to induce CD4+Th2 effector function. Finally, we found that full Th2 induction upon Nod1 and Nod2 activation was dependent on both thymic stromal lymphopoietin production by the stromal cells and the up-regulation of the costimulatory molecule, OX40 ligand, on dendritic cells. This study provides in vivo evidence of how systemic Th2 immunity is induced in the context of Nod stimulation. Such understanding will influence the rational design of therapeutics that could reprogram the immune system during an active Th1–mediated disease, such as Crohn's disease.
Three-dimensional structure of a sheet crumpled into a ball
Authors: Cambou Anne Dominique , Menon Narayanan
Published: August 2011

When a thin sheet is crushed into a small three-dimensional volume, it invariably forms a structure with a low volume fraction but high resistance to further compression. Being a far-from-equilibrium process, forced crumpling is not necessarily amenable to a statistical description in which the parameters of the initially flat sheet and the final confinement fully specify the resulting crumpled state. Instead, the internal geometry and mechanical properties of the crumpled ball may reflect the history of its preparation. Our X-ray microtomography experiments reveal that the internal three-dimensional geometry of a crumpled ball is in many respects isotropic and homogeneous. In these respects, crumpling recapitulates other classic nonequilibrium problems such as turbulence, where a system driven by long-wavelength, low-symmetry, forcing shows only rather subtle fingerprints of the forcing mechanism. However, we find local nematic ordering of the sheet into parallel stacks. The layering proceeds radially inward from the outer surface. The extent of this layering increases with the volume fraction, or degree of compression.