100,642 research outputs found

    Letter, [Author unclear] to Paulina T. Merritt

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    Handwritten letter to Paulina Merritt from an unknown author, October 1, 1876.

    Tree Rings of Pinus ponderosa and Juniperus virginiana Show Different Responses to Stand Density and Water Availability in the Nebraska Grasslands

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    Changes in climate, land use and management have led to an increase in woody species encroachment into grasslands, threatening key ecosystem services and resilience. This study uses dendroecological techniques to investigate acclimation strategies of two native woody species, Juniperus virginiana and Pinus ponderosa, to spatial and temporal variability in precipitation and stand density in Nebraska (NE). Two locations in Eastern NE and one in Western NE, were selected and tree cores for ring-width measurements were collected. Stable Isotope ratios of carbon were analysed to investigate water use efficiency (WUE), and stable isotope ratios of oxygen were used to understand stomatal conductance and control. Our results showed trees in dense stands exhibited less intra-specific variability in response to climate and narrower tree rings than sparse open stands, with P. ponderosa being more responsive to density and climate variability than J. virginiana. Populations in the drier Sandhills grasslands of Western NE were more dependent on intra- and inter-annual precipitation and generally more impacted by drought events than those in the East. Eastern NE trees were less limited by drought and displayed lower WIT relative to Western location, even though temperatures were slightly higher, but this was compensated for by the overall higher precipitation levels in the East. Generally, above average winter temperatures were positively correlated with ring widths, while temperature extremes during the growing season were negatively correlated. Although years of extreme drought events were visible in the tree-ring width patterns for both species independent of stand density and location, it seems that once the trees are established and have access to soil moisture, the current climate variability and extremes in NE do not limit or cause a permanent it decline in growth of either species

    Handwritten biographical information on Paulina T. McClung Merritt

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    A handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.

    Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.

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    IFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells

    Dispelling the Myths Behind First-author Citation Counts

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    We conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more sophisticated methods

    Pelevin’s Trinity in the novel “t”: author – protagonist – reader

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    The article attempts to interpret Pelevin's artistic strategy in the novel "T" by exploring its subject organization and addressing the key problems of the author, the protagonist, and the reader as they are seen by the researcher. The article analyzes the peculiarities of constructing the narrative reality in the novel "T", and goes on to discuss Pelevin's philosophic models of the development of the humankind, and the emergence of his new anthropology

    Increasing atmospheric CO2 concentrations outweighs effects of stand density in determining growth and water use efficiency in Pinus ponderosa of the semi-arid grasslands of Nebraska (U.S.A.)

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    This study investigated the impacts of environmental (e.g., climate and CO2 level) and ecological (e.g., stand density) factors on the long-term growth and physiology of ponderosa pine (Pinus ponderosa) in a semi-arid north American grassland. We hypothesized that ponderosa pine long-term growth patterns were positively influenced by an increase in atmospheric CO2 concentrations and a decrease in stand density. To test this hypothesis, comparison of long-term trends in tree-ring width and carbon and oxygen stable isotopic composition of trees growing in dense and sparse forest stands were carried out at two sites located in the Nebraska National Forest. Results indicated that tree-ring growth increased over time, more at the sparse than at the dense stands. In addition, the carbon and oxygen isotopic ratios showed long-term increases in intrinsic water use efficiency (WUEi), with little difference between dense and sparse stands. We found a clear trend over time in ponderosa pine tree growth and WUEi, mechanistically linked to long-term changes in global CO2 concentration. The study also highlighted that global factors tend to outweigh local effects of stand density in determining long-term trends in ponderosa pine growth. Finally, we discuss the implications of these results for woody encroachment into grasslands of Nebraska and we underlined how the use of long-term time series is crucial for understanding those ecosystems and to guarantee their conservation

    Measuring industry-science links through inventor-author relations: A profiling method

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    In this pilot study we examine the performance of text-based profiling in recovering a set of validated inventor-author links. In a first step we match patents and publications solely based on their similarity in content. Next, we compare inventor and author names on the highest ranked matches for the occurrence of name matches. Finally, we compare these candidate matches with the names listed in a validated set of inventor-author names. Our text-based profile methodology performs significantly better than a random matching of patents and publications, suggesting that text-based profiling is a valuable complementary tool to the name searches used in previous studies.innovation; industry-science links; text-based profiling;

    Hepatitis C Infection Associated with Acquired Pure Red Cell Aplasia

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    Acquired pure red cell aplasia is a rare bone marrow failure disorder characterized by many underlying etiologies. The hallmark bone marrow feature is the near absence of erythroid precursors that otherwise exhibit normal cellularity, which has been attributed to both immune- and cellular-mediated mechanisms. Besides being merely speculative and considering the rarity of the disorder, the description of acquired pure red cell aplasia clinical associations represents a unique occasion to improve our current clinical knowledge of the disease, reveal clues on its pathogenesis, and guide therapeutic decisions. The varied clinical scenarios and common acquired pure red cell aplasia associated conditions (i.e., thymoma, T cell/NK-cell large granular lymphocyte leukemia, B cell dyscrasia) suggest a heterogeneity of pathogenic routes. Viral etiologies must always be considered and worked up in the initial assessment of newly diagnosed acquired pure red cell aplasia patients. In this report, we present two cases of hepatitis-C-related acquired pure red cell aplasia and successful use of anti-viral strategies in the achievement of a complete response
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