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Business, Economics, Finance and Accounting3%
5 Other Domains9%
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38 Other Subdomains86%

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    • Selected Abstracts

    Compression and Importance Sampling of Near-Field Light Sources

    COMPUTER GRAPHICS FORUM, Issue 8 2008
    Albert Mas
    I.3.7 Computer Graphics: Three-Dimensional Graphics and Realism Abstract This paper presents a method for compressing measured datasets of the near-field emission of physical light sources (represented by raysets). We create a mesh on the bounding surface of the light source that stores illumination information. The mesh is augmented with information about directional distribution and energy density. We have developed a new approach to smoothly generate random samples on the illumination distribution represented by the mesh, and to efficiently handle importance sampling of points and directions. We will show that our representation can compress a 10 million particle rayset into a mesh of a few hundred triangles. We also show that the error of this representation is low, even for very close objects. [source]

    Tangible Heritage: Production of Astrolabes on a Laser Engraver

    COMPUTER GRAPHICS FORUM, Issue 8 2008
    G. Zotti
    I.3.5 [Computer Graphics]: Computational geometry and object modelling , geometric algorithms, languages and systems; I.3.8 [Computer Graphics]: Applications Abstract The astrolabe, an analog computing device, used to be the iconic instrument of astronomers during the Middle Ages. It allowed a multitude of operations of practical astronomy which were otherwise cumbersome to perform in an epoch when mathematics had apparently almost been forgotten. Usually made from wood or sheet metal, a few hundred instruments, mostly from brass, survived until today and are valuable museum showpieces. This paper explains a procedural modelling approach for the construction of the classical kinds of astrolabes, which allows a wide variety of applications from plain explanatory illustrations to three-dimensional (3D) models, and even the production of working physical astrolabes usable for public or classroom demonstrations. [source]

    Centrality Based Visualization of Small World Graphs

    COMPUTER GRAPHICS FORUM, Issue 3 2008
    F. Van Ham
    Abstract Current graph drawing algorithms enable the creation of two dimensional node-link diagrams of huge graphs. However, for graphs with low diameter (of which "small world" graphs are a subset) these techniques begin to break down visually even when the graph has only a few hundred nodes. Typical algorithms produce images where nodes clump together in the center of the screen, making it hard to discern structure and follow paths. This paper describes a solution to this problem, which uses a global edge metric to determine a subset of edges that capture the graph's intrinsic clustering structure. This structure is then used to create an embedding of the graph, after which the remaining edges are added back in. We demonstrate applications of this technique to a number of real world examples. [source]

    Clustering revealed in high-resolution simulations and visualization of multi-resolution features in fluid,particle models

    CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 2 2003
    Krzysztof Boryczko
    Abstract Simulating natural phenomena at greater accuracy results in an explosive growth of data. Large-scale simulations with particles currently involve ensembles consisting of between 106 and 109 particles, which cover 105,106 time steps. Thus, the data files produced in a single run can reach from tens of gigabytes to hundreds of terabytes. This data bank allows one to reconstruct the spatio-temporal evolution of both the particle system as a whole and each particle separately. Realistically, for one to look at a large data set at full resolution at all times is not possible and, in fact, not necessary. We have developed an agglomerative clustering technique, based on the concept of a mutual nearest neighbor (MNN). This procedure can be easily adapted for efficient visualization of extremely large data sets from simulations with particles at various resolution levels. We present the parallel algorithm for MNN clustering and its timings on the IBM SP and SGI/Origin 3800 multiprocessor systems for up to 16 million fluid particles. The high efficiency obtained is mainly due to the similarity in the algorithmic structure of MNN clustering and particle methods. We show various examples drawn from MNN applications in visualization and analysis of the order of a few hundred gigabytes of data from discrete particle simulations, using dissipative particle dynamics and fluid particle models. Because data clustering is the first step in this concept extraction procedure, we may employ this clustering procedure to many other fields such as data mining, earthquake events and stellar populations in nebula clusters. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Estimating Diversity in Unsampled Habitats of a Biogeographical Province

    CONSERVATION BIOLOGY, Issue 3 2003
    Michael L. Rosenzweig
    A number of methods have been developed to overcome sample-size limits within a single habitat. We evaluated six of these methods to see whether they could also compensate for incomplete habitat samples. We applied them to the butterfly species of the 110 ecoregions of Canada and the United States. Two of the methods use the frequency of species that occur in a few of the sampled ecoregions. These two methods did not work. The other four methods estimate the asymptote of the species-accumulation curve ( the graph of "number of species in a set of samples" versus "number of species occurrences in those samples" ). The asymptote of this curve is the actual number of species in the system. Three of these extrapolation estimators produced good estimates of total diversity even when limited to 10% of the ecoregions. Good estimates depend on sampling ecoregions that are hyperdispersed in space. Clustered sampling designs ruin the usefulness of the three successful methods. To ascertain their generality, our results must be duplicated at other scales and for other taxa and in other provinces. Resumen: La estimación del número de especies en una provincia biogeográfica puede ser problemático. Se ha desarrollado un número de métodos para superar los límites del tamaño de muestra dentro de un solo hábitat. Evaluamos seis de estos métodos para ver si podrían compensar por muestras incompletas de hábitat. Aplicamos estos métodos a especies de mariposas de las 110 ecoregiones de Canadá y los Estados Unidos. Dos de los métodos usan la frecuencia de las especies que ocurren en algunas de las ecoregiones muestreadas. Estos dos métodos no sirvieron. Los otros cuatro métodos estimaron la asíntota de la curva de acumulación de especies ( la gráfica de "el número de especies en un juego de muestras" contra el "número de ocurrencias de especies en éstas muestras" ). La asíntota de ésta curva es el número real de especies en el sistema. Tres de éstos estimadores de extrapolación produjeron buenas estimaciones de la diversidad total aún cuando se limitaron al 10% de las ecoregiones. Las buenas estimaciones dependen del muestreo de ecoregiones altamente dispersas en el espacio. Los diseños de muestreos en agrupamientos arruinan la utilidad de los tres métodos exitosos. Para asegurar su generalidad, nuestros resultados deben ser duplicados a otras escalas y para otros taxones en otras provincias. [source]

    A decade of hypocretins: past, present and future of the neurobiology of arousal

    ACTA PHYSIOLOGICA, Issue 3 2010
    L. De Lecea
    Abstract In 1998, two groups independently identified the hypocretins, also known as orexins, as two hypothalamic peptides derived from the same precursor expressed in a few thousand neurones restricted to the perifornical area. A decade later, an amazing set of discoveries has demonstrated a key role for this neurotransmitter system in arousal and beyond. Here I review some of the experiments that led to these discoveries and the implications in the neurobiology of the hypothalamus and our understanding of brain arousal. [source]

    Spectroscopic Diagnostics of Pulsed arc Plasmas for Particle Generation

    CONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2008
    K. Behringer
    Abstract Pulsed arc plasmas were diagnosed by means of emission spectroscopy. A capacitor was discharged through argon and hydrogen leading to a few cycles of damped current oscillation with ,120 ,s period and 5-12 kA maximum current. Spectroscopic measurements in the visible range were carried out in order to characterise the electron temperature and density in the arc channel as well as electron and gas temperatures in the afterglow plasmas. Spectra were integrated over 10 ,s time windows and shifted in time from pulse to pulse. The plasmas also contained substantial fractions of electrode material (brass), namely copper and zinc. The electron density was measured in the conventional way from the broadening of H, or from the Ar I Stark width. In the arc channel, it ranged from about 3 · 1022 to 2 · 1023 m,3. The broadening of Zn II lines could also be used. Ratios of Ar I to Ar II and of Zn I to Zn II line intensities were analysed for the electron temperature. Line pairs were found which lay conveniently close in one frame of the spectrometer allowing automatic on-line analysis without relying on reproducibility. Atomic physics models including opacity were developed for Ar II and Zn II in order to check the existence of a Boltzmann distribution of their excited states. These calculations showed that the observed levels were in fact close to thermodynamic equilibrium, in particular, if the resonance lines were optically thick. Electron temperature measurements yielded values between 14000 K and 21000 K. The gas temperature in the afterglow, where particles should have formed, was derived from the rotational and vibrational temperatures of C2 molecular bands. Ratios between Cu I line intensities yielded the electron temperatures. Both were found to be a few 1000 K. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Analysis of Particle Pumping Using SOLDOR/NEUT2D Code in the JT-60U Tokamak

    CONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2008
    H. Kawashima
    Abstract In order to understand the particle pumping on JT-60U, we analyze the roles of atomic and molecular processes using SOLDOR/NEUT2D code. A case of short strike point distance shows that most of neutrals produced on the targets go toward the exhaust slot directly. Whereas, neutrals are scattered in the spherically at random for the long distance case by collision processes and a few of them go toward the slot. It is clarified that the incident neutrals to the slot at low ne/high Te divertor plasma condition are dominated by atoms. Those at high ne/low Te condition are dominated by molecules due to elastic collision. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Utility of CD26 in flow cytometric immunophenotyping of T-cell lymphomas in tissue and body fluid specimens,

    CYTOMETRY, Issue 6 2008
    Diane M. Pierson
    Abstract Background CD26 is expressed by most CD4+ T cells in normal peripheral blood specimens. Neoplastic T cells are frequently CD26, in mycosis fungoides/Sezary syndrome involving the peripheral blood. However, CD26 expression by reactive and neoplastic T cells in solid tissues and body fluids has not been fully characterized by flow cytometry (FC). Methods Solid tissue and body fluid specimens were assayed for CD26 expression using four-color FC immunophenotyping, by qualitative assessment of population clusters, and by quantitation with comparison with isotype controls. Benign T cells were studied in reactive tissues and in the background of other malignancies. Results Many T-cell lymphomas were dim or negative for CD26, whereas a few were brightly positive. In the majority of T-cell lymphomas, CD26 expression could potentially help identify aberrant population clusters. T cells in reactive tissue specimens and tumor-infiltrating T cells were commonly dim to negative for CD26. Conclusions Both T-cell lymphomas and reactive T cells in tissue and body fluid specimens often show low levels of CD26 expression. Therefore, quantitative methods may not reliably distinguish benign from neoplastic T cells in these specimens. However, CD26, in combination with other T-cell markers, can be helpful for identifying aberrant population clusters in T-cell lymphomas. © 2008 Clinical Cytometry Society [source]

    An electro-optic monitor of the behavior of Chlamydomonas reinhardtii cilia

    CYTOSKELETON, Issue 2 2005
    Keith Josef
    Abstract The unicellular green alga Chlamydomonas reinhardtii steers through water with a pair of cilia (eukaryotic flagella). Long-term observation of the beating of its cilia with controlled stimulation is improving our understanding of how a cell responds to sensory inputs. Here we describe how to record ciliary motion continuously for long periods. We also report experiments on the network of intracellular signaling that connects the environment inputs with response outputs. Local spatial changes in ciliary response on the time scale of the underlying biochemical dynamics are observed. Near-infrared light monitors the cells held by a micropipette. This condition is tolerated well for hours, not interfering with ciliary beating or sensory transduction. A computer integrates the light stimulation of the eye of Chlamydomonas with the ciliary motion making possible long-term correlations. Measures of ciliary responses include the beating frequency, stroke velocity, and stroke duration of each cilium, and the relative phase of the cis and trans cilia. The stationarity and dependence of the system on light intensity was investigated. About 150,000,000 total beat cycles and up to 8 h on one cell have been recorded. Each beat cycle is resolved so that each asynchronous beat is detected. Responses extend only a few hundred milliseconds, but there is a persistence of momentary changes that last much longer. Interestingly, we see a response that is linear with absolute light intensity as well as different kinds of response that are clearly nonlinear, implying two signaling pathways from the cell body to the cilia. Cell Motil. Cytoskeleton 61:83,96, 2005. © 2005 Wiley-Liss, Inc. [source]

    The ,II isotype of tubulin is present in the cell nuclei of a variety of cancers

    CYTOSKELETON, Issue 2 2004
    I-Tien Yeh
    Abstract Tubulin, the subunit protein of microtubules, has generally been thought to be exclusively a cytoplasmic protein in higher eukaryotes. We have previously shown that cultured rat kidney mesangial cells contain the ,II isotype of tubulin in their nuclei in the form of an ,,II dimer [Walss et al., 1999: Cell Motil. Cytoskeleton 42:274,284, 1999]. More recently, we examined a variety of cancerous and non-cancerous cell lines and found ,II in the nuclei of all of the former and only a few of the latter (Walss-Bass et al., 2002: Cell Tissue Res. 308:215,223]. In order to determine if ,II -tubulin occurs in the nuclei of actual cancers as well as in cancer cell lines, we used the immunoperoxidase method to look for nuclear ,II in a variety of tumors excised from 201 patients. We found that 75% of these tumors contain ,II in their nuclei. Distribution of nuclear ,II was highly dependent on the type of cancer, with 100% of the colon and prostate cancers, but only 19% of the skin tumors, having nuclear ,II. Nuclear ,II was particularly marked in tumors of epithelial origin, of which 83% showed nuclear ,II, in contrast to 54% in tumors of non-epithelial origin. In many cases, ,II staining occurred very strongly in the nuclei and not in the cytoplasm; in other cases, ,II was present in both. In many cases, particularly metastases, otherwise normal cells adjacent to the tumor also showed nuclear ,II, suggesting that cancer cells may influence nearby cells to synthesize ,II and localize it to their nuclei. Our results have implications for the diagnosis, biology, and chemotherapy of cancer. Cell Motil. Cytoskeleton 57:96,106, 2004. © 2004 Wiley-Liss, Inc. [source]

    Bone replacement following dental trauma prior to implant surgery , present status

    DENTAL TRAUMATOLOGY, Issue 1 2009
    Mats Hallman
    Although autogenous bone grafts is considered the ,gold standard', this may be associated with patient morbidity and graft resorption. Consequently, the use of bone substitutes has increased. Today, a substantial number of biomaterials are available on the market, but only a few are well documented. The user should be aware that these biomaterials have different properties: resorbable or non-resorbable, time of resorption and resorption mechanism. The purpose of this review is to describe the function of various bone substitutes and indications for their use in reconstructive implant surgery and to give an overview of the current situation. [source]

    Panic disorder phenomenology in urban self-identified caucasian,non-hispanics and caucasian,hispanics

    DEPRESSION AND ANXIETY, Issue 1 2003
    Michael Hollifield M.D.
    Abstract The epidemiology of panic disorder is well known, but data about some phenomenological aspects are sparse. The symptom criteria for panic disorder were developed largely from rational expert consensus methods and not from empirical research. This fact calls attention to the construct validity of the panic disorder diagnosis, which may affect accuracy of epidemiological findings. Seventy self-identified Non-Hispanic,Caucasian (Anglo) and Hispanic,Caucasian (Hispanic) people who were diagnosed with DSM-III-R panic disorder with or without agoraphobia were invited to complete a Panic Phenomenological Questionnaire (PPQ), which was constructed for this study from the Hamilton Anxiety Scale Items and The DSM-III-R panic symptoms. Fifty (71%) subjects agreed to participate, and there was no response bias detected. Seven symptoms on the PPQ that are not in the DSM-IV diagnostic criteria were reported to occur with a high prevalence in this study. Furthermore, many symptoms that occurred with a high frequency and were reported to be experienced as severe are also not included in current nosology. A few of the DSM-IV criterion symptoms occurred with low prevalence, frequency, and severity. Cognitive symptoms were reported to occur with higher frequency and severity during attacks than autonomic or other symptoms. There were modest differences between ethnic groups with regard to panic attack phenomena. Further research using multiple empirical methods aimed at improving the content validity of the panic disorder diagnosis is warranted. This includes utilizing consistent methods to collect data that will allow for rational decisions about how to construct valid panic disorder criteria across cultures. Depression and Anxiety 18:7,17, 2003. © 2003 Wiley-Liss, Inc. [source]

    Short-Term Side Effects of Fractional Photothermolysis

    DERMATOLOGIC SURGERY, Issue 2005
    Galen H. Fisher MD
    Objective:. To ascertain the immediate and short-term side effects of fractional photothermolysis for the treatment of a variety of skin disorders involving the face, neck, chest, and hands. Methods. Physician-administered questionnaires were given during 60 follow-up visits for fractional photothermolysis treatment for a variety of facial skin disorders in patients with skin types ranging from I to IV. The questionnaire addressed 14 possible side effects, pain, and limitation of social activities. In addition, all patients were asked about any additional side effects not mentioned in the survey. An analysis of the data was performed once 60 surveys had been collected. Results. All patients (100%) undergoing fractional photothermolysis had transient post-treatment erythema. Other frequently reported post-treatment side effects were transient and included facial edema (82%), dry skin (86.6%), flaking (60%), a few (one to three) small, superficial scratches (46.6%), pruritis (37%), and bronzing (26.6%). Other more rarely reported effects included transient increased sensitivity (10%) and acneiform eruption (10%). Most patients reported that the pain level was easily tolerated, with an average pain score of 4.6 on a scale of 10. Most patients (72%) reported limiting social engagements for an average of 2 days after treatment. There were no long-lasting adverse events noted in our survey. Conclusion. Fractional photothermolysis to treat dermatologic conditions on the face, neck, chest, and hands is a well-tolerated and safe procedure with several immediate, and slightly delayed, post-treatment side effects. In our experience, these side effects were transient and limited to erythema, edema, dry skin, flaking skin, superficial scratches, pruritis, increased sensitivity, and acneiform eruption. Importantly, we did not see the development of post-treatment scarring, herpetic activation, hypopigmentation, hyperpigmentation, persistent erythema, persistent edema, or infection. [source]

    Ectopic germline cells in embryos of Xenopus laevis

    DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 7 2007
    Kohji Ikenishi
    Whether all descendants of germline founder cells inheriting the germ plasm can migrate correctly to the genital ridges and differentiate into primordial germ cells (PGCs) at tadpole stage has not been elucidated in Xenopus. We investigated precisely the location of descendant cells, presumptive primordial germ cells (pPGCs) and PGCs, in embryos at stages 23,48 by whole-mount in situ hybridization with the antisense probe for Xpat RNA specific to pPGCs and whole-mount immunostaining with the 2L-13 antibody specific to Xenopus Vasa protein in PGCs. Small numbers of pPGCs and PGCs, which were positively stained with the probe and the antibody, respectively, were observed in ectopic locations in a significant number of embryos at those stages. A few of the ectopic PGCs in tadpoles at stages 44,47 were positive in TdT-mediated dUTP digoxigenin nick end labeling (TUNEL) staining. By contrast, pPGCs in the embryos until stage 40, irrespective of their location and PGCs in the genital ridges of the tadpoles at stages 43,48 were negative in TUNEL staining. Therefore, it is evident that a portion of the descendants of germline founder cells cannot migrate correctly to the genital ridges, and that a few ectopic PGCs are eliminated by apoptosis or necrosis at tadpole stages. [source]

    Brain dysmorphology in individuals with severe prenatal alcohol exposure

    DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 3 2001
    Sarah L Archibald MA
    Our previous studies revealed abnormalities on structural MRI (sMRI) in small groups of children exposed to alcohol prenatally. Microcephaly, disproportionately reduced basal ganglia volume, and abnormalities of the cerebellar vermis and corpus callosum were demonstrated. The present study used sMRI to examine in detail the regional pattern of brain hypoplasia resulting from prenatal exposure to alcohol using a higher resolution imaging protocol and larger sample sizes than reported previously. Fourteen participants (mean 11.4 years; eight females, six males) with fetal alcohol syndrome (FAS) and 12 participants (mean 14.8 years; four females, eight males) with prenatal exposure to alcohol (PEA) but without the facial features of FAS were compared to a group of 41 control participants (mean 12.8 years, 20 females, 21 males). Findings of significant microcephaly and disproportionately reduced basal ganglia volumes in the FAS group were confirmed. Novel findings were that in FAS participants, white matter volumes were more affected than gray matter volumes in the cerebrum, and parietal lobes were more affected than temporal and occipital lobes. Among subcortical structures, in contrast to the disproportionate effects on caudate nucleus, the hippocampus was relatively preserved in FAS participants. Differences between the PEA group and controls were generally non-significant; however, among a few of the structures most affected in FAS participants, there was some evidence for volume reduction in PEA participants as well, specifically in basal ganglia and the parietal lobe. There were no group differences in cerebral volume asymmetries. Severe prenatal alcohol exposure appears to produce a specific pattern of brain hypoplasia. [source]

    Respiratory units of motor production and song imitation in the zebra finch

    DEVELOPMENTAL NEUROBIOLOGY, Issue 2 2002
    Michele Franz
    Abstract Juvenile male zebra finches (Taeniopygia guttata) learn a stereotyped song by imitating sounds from adult male tutors. Their song is composed of a series of syllables, which are separated by silent periods. How acoustic units of song are translated into respiratory and syringeal motor gestures during the song learning process is not well understood. To learn about the respiratory contribution to the imitation process, we recorded air sac pressure in 38 male zebra finches and compared the acoustic structures and air sac pressure patterns of similar syllables qualitatively and quantitatively. Acoustic syllables correspond to expiratory pressure pulses and most often (74%) entire syllables are copied using similar air sac pressure patterns. Even notes placed within different syllables are generated with similar air sac pressure patterns when only segments of syllables are copied (9%). A few of the similar syllables (17%) are generated with a modified pressure pattern, typically involving addition or deletion of an inspiration. The high similarity of pressure patterns for like syllables indicates that generation of particular sounds is constrained to a narrow range of air sac pressure conditions. Following presentation of stroboscope flashes, song was typically interrupted at the end of an expiratory pressure pulse, confirming that expirations and, therefore, syllables are the smallest unit of motor production of song. Silent periods, which separate syllables acoustically, are generated by switching from expiration to inspiration. Switching between respiratory phases, therefore, appears to play a dominant role in organizing the stereotyped motor program for song production. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 129,141, 2002 [source]

    Nicotinic synapses formed between chick ciliary ganglion neurons in culture resemble those present on the neurons in vivo

    DEVELOPMENTAL NEUROBIOLOGY, Issue 4 2001
    Min Chen
    Abstract We studied nicotinic synapses between chick ciliary ganglion neurons in culture to learn more about factors influencing their formation and receptor subtype dependence. After 4,8 days in culture, nearly all neurons displayed spontaneous excitatory postsynaptic currents (sEPSCs), which occurred at about 1 Hz. Neurons treated with tetrodotoxin displayed miniature EPSCs (mEPSCs), but these occurred at low frequency (0.1 Hz), indicating that most sEPSCs are actually impulse driven. The sEPSCs could be classified by decay kinetics as fast, slow, or biexponential and, reminiscent of the situation in vivo, were mediated by two major nicotinic acetylcholine receptor (AChR) subtypes. Fast sEPSCs were blocked by ,-bungarotoxin (,Bgt), indicating dependence on ,Bgt-AChRs, most of which are ,7 subunit homopentamers. Slow sEPSCs were unaffected by ,Bgt, and were blocked instead by the ,3/,2-selective ,-conotoxin-MII (,CTx-MII), indicating dependence on ,3*-AChRs, which lack ,7 and contain ,3 subunits. Biexponential sEPSCs were mediated by both ,Bgt- and ,3*-AChRs because they had fast and slow components qualitatively similar to those comprising simple events, and these were reduced by ,Bgt and blocked by ,CTx-MII, respectively. Fluorescence labeling experiments revealed both ,Bgt- and ,3*-AChR clusters on neuron somata and neurites. Colabeling with antisynaptic vesicle protein antibody suggested that some ,3*-AChR clusters, and a few ,Bgt-AChR clusters are associated with synaptic sites, as is the case in vivo. These findings demonstrate the utility of ciliary ganglion neuron cultures for studying the regulation of nicotinic synapses, and suggest that mixed AChR subtype synapses characteristic of the neurons in vivo can form in the absence of normal inputs or targets. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 265,279, 2001 [source]

    A role for innate immunity in type 1 diabetes?

    DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2003
    H. Beyan
    Abstract Two arms of the immune system, innate and adaptive immunity, differ in their mode of immune recognition. The innate immune system recognizes a few highly conserved structures on a broad range of microorganisms. On the other hand, recognition of self or autoreactivity is generally confined to the adaptive immune response. Whilst autoimmune features are relatively common, they should be distinguished from autoimmune disease that is infrequent. Type 1 diabetes is an immune-mediated disease due to the destruction of insulin secreting cells mediated by aggressive immune responses, including activation of the adaptive immune system following genetic and environmental interaction. Hypotheses for the cause of the immune dysfunction leading to type 1 diabetes include self-reactive T-cell clones that (1) escape deletion in the thymus, (2) escape from peripheral tolerance or (3) escape from homeostatic control with an alteration in the immune balance leading to autoimmunity. Evidence, outlined in this review, raises the possibility that changes in the innate immune system could lead to autoimmunity, by either priming or promoting aggressive adaptive immune responses. Hostile microorganisms are identified by genetically determined surface receptors on innate effector cells, thereby promoting clearance of these invaders. These innate effectors include a few relatively inflexible cell populations such as monocytes/macrophages, dendritic cells (DC), natural killer (NK) cells, natural killer T (NKT) cells and ,, T cells. Recent studies have identified abnormalities in some of these cells both in patients with type 1 diabetes and in those at risk of the disease. However, it remains unclear whether these abnormalities in innate effector cells predispose to autoimmune disease. If they were to do so, then modulation of the innate immune system could be of therapeutic value in preventing immune-mediated diseases such as type 1 diabetes. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    The effects of green tree retention and subsequent prescribed burning on ground beetles (Coleoptera: Carabidae) in boreal pine-dominated forests

    ECOGRAPHY, Issue 5 2006
    Petri Martikainen
    We studied how two methods to promote biodiversity in managed forests, i.e. green tree retention and prescribed fire, affect the assemblages of carabid beetles. Our experiment consisted of 24 study sites, each 3,5 ha in size, which had been prepared according to factorial design. Each of the eight treatment combinations determined by the two factors explored , tree retention level (0, 10, 50 m3/ha,1 and uncut controls) and prescribed use of fire (yes/no) , was replicated three times. We sampled carabids using pitfall traps one year after the treatments. Significantly more individuals were caught in most of the burned sites, but this difference was partially reflective of the trap-catches of Pterostichus adstrictus. The fire did not increase no. of P. adstrictus in the uncut sites as much as in the other sites. Species richness was significantly affected by both factors, being higher in the burned than in the unburned sites and in the harvested than in the unharvested sites. Many species were concentrated in the groups of retention trees in the burned sites, but only a few were in the unburned sites. The species turnover was greater in the burned than in the unburned sites, as indicated by the NMDS ordinations. Greater numbers of smaller sized species and proportion of brachypterous species were present in the burned sites. Fire-favored species, and also the majority of other species that prefer open habitats were more abundantly caught in the burned sites than in the unburned sites. Dead wood or logging waste around the traps did not correlate with the occurrence of species. We conclude that carabids are well adapted to disturbances, and that frequent use of prescribed fire is essential for the maintenance of natural assemblages of carabid beetles in the boreal forest. Small retention tree groups can not maintain assemblages of uncut forest, but they can be important by providing food, shelter and breeding sites for many species, particularly in the burned sites. [source]

    Distributional effects of WTO agricultural reforms in rich and poor countries

    ECONOMIC POLICY, Issue 50 2007
    Thomas W. Hertel
    SUMMARY WTO agricultural reforms Rich countries' agricultural trade policies are the battleground on which the future of the WTO's troubled Doha Round will be determined. Subject to widespread criticism, they nonetheless appear to be almost immune to serious reform, and one of their most common defences is that they protect poor farmers. Our findings reject this claim. The analysis conducted here uses detailed data on farm incomes to show that major commodity programmes are highly regressive in the US, and that the only serious losses under trade reform are among large, wealthy farmers in a few heavily protected sub-sectors. In contrast, analysis using household data from 15 developing countries indicates that reforming rich countries' agricultural trade policies would lift large numbers of developing country farm households out of poverty. In the majority of cases these gains are not outweighed by the poverty-increasing effects of higher food prices among other households. Agricultural reforms that appear feasible, even under an ambitious Doha Round, achieve only a fraction of the benefits for developing countries that full liberalization promises, but protect the wealthiest US farms from most of the rigors of adjustment. Finally, the analysis conducted here indicates that maximal trade-led poverty reductions occur when developing countries participate more fully in agricultural trade liberalization. , Thomas W. Hertel, Roman Keeney, Maros Ivanic and L. Alan Winters [source]

    Renewable Copper and Silver Amalgam Film Electrodes of Prolonged Application for the Determination of Elemental Sulfur Using Stripping Voltammetry

    ELECTROANALYSIS, Issue 7 2008
    Robert Piech
    Abstract New, renewable copper (Hg(Cu)FE) and silver (Hg(Ag)FE) based amalgam film electrodes applied for the determination of elemental sulfur using differential pulse cathodic stripping voltammetry are presented. With surface areas adjustable from 1 to 12,mm2, both electrodes are characterized by very good surface reproducibility (,2%) and long-term stability (a few thousand measurement cycles). The mechanical refreshing of the amalgam film takes about 1,2 seconds. The effects of various factors such as instrumental parameters and the supporting electrolyte composition were optimized. Interferences from sulfides are easily removed by the addition of acid, and bubbling with argon, for Hg(Ag)FE. In the case of Hg(Cu)FE, sulfides did not interfere. The calibration graph is linear within the studied range from 16,ng L,1 to 4.8,,g L,1 for Hg(Cu)FE, and up to 6.4,,g L,1 for Hg(Ag)FE (tacc=15,s). The correlation coefficients for the two electrodes were at least 0.997. The detection limits for a low concentration of S(0) and tacc=60,s are as low as 14,ng L,1 for Hg(Cu)FE and 4,ng L,1 for Hg(Ag)FE. The proposed method was successfully applied and validated by studying the recovery of S(0) from spiked river water. [source]

    Can late summer Landsat data be used for locating Asian migratory locust, Locusta migratoria migratoria, oviposition sites in the Amudarya River delta, Uzbekistan?

    ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2008
    Ramesh Sivanpillai
    Abstract Existing survey methods for assessing the Asian migratory locust, Locusta migratoria migratoria L. (Orthoptera: Acrididae), infestation risk in the Amudarya River delta, Uzbekistan, are largely constrained by economic resources and site accessibility. The surveys are restricted to a few easily accessible areas, which leads to a misinterpretation of the threat of locust infestation. This often results in indiscriminate blanket treatments of vast areas of wetlands with broad-spectrum insecticides, which may adversely impact non-target fauna and flora. In order to minimize the bias during surveys, one approach would be to allocate the sampling locations based on the distribution of the primary food and shelter plant of the locusts, the common reed, Phragmites australis (Cav.) Trin. ex Steud (Poaceae). In this study, we evaluated the utility of satellite-based remotely sensed data (Landsat TM) acquired in August 2006 to characterize reed distribution in the delta and identify potential locust oviposition sites. The overall accuracy of the Landsat data to map land cover classes in the delta was 84%. The Landsat TM data identified 90% of the reeds, but it was less useful in identifying areas where other vegetations (shrubs and grasses) were mixed with reeds. During the following summer field survey in June 2007, we identified 37 sites that were infested with early-instar locusts. The low migration capacity of young nymphs in dense reed vegetation allowed us to presume that these sites were used for oviposition in the previous summer. Twenty-eight (74%) of these 37 sites had reeds in the previous year. Results from these studies demonstrate that reed distribution maps derived from satellite data could be used for targeting locust egg-pod survey locations, in order to minimize sampling bias while predicting locust infestation risks for the following season. [source]

    Photomutagenicity of thiabendazole, a postharvest fungicide, in bacterial assays

    ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2003
    Mie Watanabe-Akanuma
    Abstract We investigated the photomutagenicity of thiabendazole (TBZ), a postharvest fungicide commonly used on imported citrus fruits. Using UVA light (320,400 nm), we irradiated bacterial cultures with or without TBZ in a 24-well multiplate. UVA-irradiation without TBZ was not mutagenic to the tester strains, nor was unirradiated TBZ. TBZ was strongly photomutagenic in Escherichia coli WP2uvrA and WP2uvrA/pKM101 strains, weakly photomutagenic in Salmonella typhimurium TA100 and TA98, and not photomutagenic in S. typhimurium TA1535 and TA1538. The photomutagenicity of TBZ was more evident in WP2uvrA/pKM101, which carries the trpE65 ochre mutation (TAA), than in TA100, which carries the hisG46 missense mutation (CCC). In E. coli WP3101,WP3106 and the corresponding pKM101-containing strains, photoactivated TBZ induced predominantly G:C,A:T transitions and A:T,T:A transversions. In the plasmid-containing strains only, TBZ induced a moderate number of A:T,G:C transitions and a few A:T,C:G and G:C,T:A transversions. The observation that UVA-irradiated TBZ mutated both G:C and A:T basepairs may explain why WP2uvrA/pKM101 was more sensitive to its mutagenicity than TA100. TBZ that was irradiated before it was added to the WP2uvrA/pKM101 cells was not photomutagenic, which suggests that the photomutagenic products of TBZ were unstable or rapidly reacted with other molecules before being incorporated into cells. Environ. Mol. Mutagen. 41:92,98, 2003. © 2003 Wiley-Liss, Inc. [source]

    Widespread occurrence of an intranuclear bacterial parasite in vent and seep bathymodiolin mussels

    ENVIRONMENTAL MICROBIOLOGY, Issue 5 2009
    Frank U. Zielinski
    Summary Many parasitic bacteria live in the cytoplasm of multicellular animals, but only a few are known to regularly invade their nuclei. In this study, we describe the novel bacterial parasite "Candidatus Endonucleobacter bathymodioli" that invades the nuclei of deep-sea bathymodiolin mussels from hydrothermal vents and cold seeps. Bathymodiolin mussels are well known for their symbiotic associations with sulfur- and methane-oxidizing bacteria. In contrast, the parasitic bacteria of vent and seep animals have received little attention despite their potential importance for deep-sea ecosystems. We first discovered the intranuclear parasite "Ca. E. bathymodioli" in Bathymodiolus puteoserpentis from the Logatchev hydrothermal vent field on the Mid-Atlantic Ridge. Using primers and probes specific to "Ca. E. bathymodioli" we found this intranuclear parasite in at least six other bathymodiolin species from vents and seeps around the world. Fluorescence in situ hybridization and transmission electron microscopy analyses of the developmental cycle of "Ca. E. bathymodioli" showed that the infection of a nucleus begins with a single rod-shaped bacterium which grows to an unseptated filament of up to 20 ,m length and then divides repeatedly until the nucleus is filled with up to 80 000 bacteria. The greatly swollen nucleus destroys its host cell and the bacteria are released after the nuclear membrane bursts. Intriguingly, the only nuclei that were never infected by "Ca. E. bathymodioli" were those of the gill bacteriocytes. These cells contain the symbiotic sulfur- and methane-oxidizing bacteria, suggesting that the mussel symbionts can protect their host nuclei against the parasite. Phylogenetic analyses showed that the "Ca. E. bathymodioli" belongs to a monophyletic clade of Gammaproteobacteria associated with marine metazoans as diverse as sponges, corals, bivalves, gastropods, echinoderms, ascidians and fish. We hypothesize that many of the sequences from this clade originated from intranuclear bacteria, and that these are widespread in marine invertebrates. [source]

    Widespread capacity to metabolize polychlorinated biphenyls by diverse microbial communities in soils with no significant exposure to PCB contamination

    ENVIRONMENTAL MICROBIOLOGY, Issue 8 2007
    Alexandre J. Macedo
    Summary The purpose of this work was to determine the extent of microbial metabolic potential for polychlorinated biphenyls (PCBs) in soils that have had no previous exposure to this class of xenobiotic pollutants. Soil and sediment samples of distinct characteristics from six sites in Germany were used to inoculate PCB oil (Aroclor 1242) microdroplets. All samples yielded multispecies biofilms, as revealed by single-strand conformation polymorphism (SSCP) analyses of polymerase chain reaction (PCR) analysis of 16S rRNA genes, and sequence analysis of the main amplicons. Microbes representing 20 different operational taxonomic units (OTUs) were identified in the biofilms, but only a few were common to all biofilms, namely those closely related to Aquabacterium sp., Caulobacter sp., Imtechium assamiensis, Nevskia ramosa, Parvibaculum lavamentivorans and Burkholderia sp. The PCB biofilm communities were always distinct from control biofilms developing from the same samples in the absence of PCB. All PCB droplet-grown biofilms degraded multiple PCB congeners but differed in the congener spectra they degraded. These findings reveal that microbial potential to degrade PCBs is widespread in soils that have not been subjected to PCB contamination, and that this potential is characteristic of consortia of very diverse phylogenetic composition. [source]

    Evolution of a chlorobenzene degradative pathway among bacteria in a contaminated groundwater mediated by a genomic island in Ralstonia

    ENVIRONMENTAL MICROBIOLOGY, Issue 3 2003
    Tina Andrea Müller
    Summary The genetic structure of two Ralstonia spp., strain JS705 and strain JS745, isolated from the same groundwater aquifer, was characterized with respect to the degradation capacities for toluene and chlorobenzene degradation. Cosmid library construction, cloning, DNA sequencing and mating experiments indicated that the genes for chlorobenzene degradation in strain JS705 were a mosaic of the clc genes, previously described for Pseudomonas sp. strain B13, and a 5 kb fragment identical to strain JS745. The 5 kb fragment identical to both JS705 and JS745 was flanked in JS705 by one complete and one incomplete insertion (IS) element. This suggested involvement of the IS element in mobilizing the genes from JS745 to JS705, although insertional activity of the IS element in its present configuration could not be demonstrated. The complete genetic structure for chlorobenzene degradation in strain JS705 resided on a genomic island very similar to the clc element (Ravatn, R., Studer, S., Springael, D., Zehnder, A.J., van der Meer, J.R. 1998. Chromosomal integration, tandem amplification, and deamplification in Pseudomonas putida F1 of a 105-kilobase genetic element containing the chlorocatechol degradative genes from Pseudomonas sp. strain B13. J Bacteriol 180: 4360,4369). The unique reconstruction of formation of a metabolic pathway through the activity of IS elements and a genomic island in the chlorobenzene-degrading strain JS705 demonstrated how pathway evolution can occur under natural conditions in a few ,steps'. [source]

    Changes in the potential quantum yield of photosystem II and the integrity of cell membranes relative to the elemental content of the epilithic desert lichen Ramalina maciformis

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2002
    Jacob Garty
    Abstract The present study used the epilithic fruticose lichen Ramalina maciformis to investigate the occurrence of mineral elements, including heavy metals, at a distance of up to 50 km from the industrial region in Ramat Hovav in the Negev Desert, Israel. The major objective of this study was an analytical comparison of elemental content and physiological parameters of lichen vitality, apart from a test of the applicability of this specific lichen in investigations of air pollution. The Ca, Cr, Cu, K, Mg, Na, Pb, S, Sr, and Zn content of thalli from the unpolluted Tellalim site collected in August 1997, transferred to 24 biomonitoring sites, and retrieved in April 1998 was analyzed in comparison with the following parameters: The potential quantum yield of photosystem II (PSII), and the integrity of cell membranes. Transplanted thalli in several sites at Ramat Hovav accumulated large amounts of most of the elements. The K content of the transplants located in the polluted sites indicated a leakage of this element, because this content was lower than that of thalli in unpolluted sites. Calcium, Cu, Mn, and Na showed an inverse correlation with the K content of the lichen. Calcium, Cu, and Sr showed an inverse correlation with the Fv/Fm ratio expressing the potential quantum yield of PSII. Calcium, Cr, Cu, Mg, Na, S, and Sr showed a positive correlation with the electrical conductivity corresponding with cell-membrane disintegration. The present study demonstrated a meaningful connection between enlarged concentrations of certain elements and physiological phenomena. The capability of the lichen to detect air pollution was found to be satisfactory. The dispersion of airborne heavy metals was found, however, to be local and limited to a few hundred meters from the source of pollution. [source]

    Sediment chemical contamination and toxicity associated with a coastal golf course complex,

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2001
    Michael A. Lewis
    Abstract The increasing density of golf courses represents a potential source of sediment contamination to nearby coastal areas, the chemical and biological magnitude of which is almost unknown. The objective of this study was to determine the concentrations of contaminants and toxicities of sediments impacted by a coastal golf course complex. Sediment contaminant concentrations were determined at least twice during the two-year study period at 14 sampling stations. In addition, a combination of acute and chronic bioassays were conducted exposing four invertebrate test species to whole sediments and associated pore waters. Overall, the Florida, USA, golf course complex had a measurable impact on sediment chemical quality, particularly in near-field areas. Higher concentrations of several trace metals and organochlorine pesticides were detected in many golf course-associated sediments compared with reference areas; however, concentrations decreased seaward and only a few, primarily chlorinated pesticides, exceeded proposed sediment quality guidelines. Chromium, zinc, and mercury were detected more frequently than other trace metals. The DDT and associated metabolites, dieldrin and chlordane, were the more commonly detected organic contaminants. Acute toxicity was uncommon and occurred consistently for sediment collected from one coastal location. In contrast, chronic toxicity occurred at several study sites based on the response of Mysidopsis bahia. It was concluded that the impact of golf course runoff on sediment quality may be subtle and sensitive biological assessment methods, such as chronic toxicity tests, will be needed to detect adverse effects. [source]

    Distribution of degradation products of alkylphenol ethoxylates near sewage treatment plants in the lower Great Lakes, North America

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2000
    Erin R. Bennett
    Abstract Degradation of alkylphenol ethoxylate (APEO) surfactants in the environment leads to the formation of relatively hydrophobic compounds such as nonylphenol (NP), octylphenol (OP), nonylphenol monoethoxylate (NP1EO), and nonylphenol diethoxylate (NP2EO) that have been shown to have estrogenic activity. Previous studies have shown that sewage treatment plants (STPs) are point sources for these compounds in the aquatic environment. We collected sediment samples at several sites in the vicinity of STPs in Hamilton Harbour and in the Detroit River to determine the spatial distribution of the degradation products of APEOs. In addition, we deployed semipermeable membrane devices (SPMDs) and caged freshwater mussels (Elliptio complanata) at these locations to determine the distribution of these compounds in the dissolved phase and their potential to bioaccumulate in aquatic organisms. The NP, OP, NP1EO, and NP2EO were found at ,g/g (dry wt.) concentrations in sediments and accumulated to ng/g (wet wt.) concentrations in caged mussels near the STPs. However, in the Detroit River, the concentrations of these compounds declined to near background levels in the sediments, water column (i.e., SPMDs), and biota at stations about 1 km downstream from STPs. At stations in Hamilton Harbour, concentrations of APEO degradation products also declined markedly in sediments and SPMDs located a few hundred meters from the STP. These data indicate that degradation products of APEOs can be accumulated by biota near STPs. However, the environmental distribution of these compounds is localized to areas close to the point of discharge. [source]