3,218 research outputs found

    The antibody loci of the domestic goat (Capra hircus)

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    The domestic goat (Capra hircus) is an important ruminant species both as a source of antibody-based reagents for research and biomedical applications and as an economically important animal for agriculture, particularly for developing nations that maintain most of the global goat population. Characterization of the loci encoding the goat immune repertoire would be highly beneficial for both vaccine and immune reagent development. However, in goat and other species whose reference genomes were generated using short-read sequencing technologies, the immune loci are poorly assembled as a result of their repetitive nature. Our recent construction of a long-read goat genome assembly (ARS1) has facilitated characterization of all three antibody loci with high confidence and comparative analysis to cattle. We observed broad similarity of goat and cattle antibody-encoding loci but with notable differences that likely influence formation of the functional antibody repertoire. The goat heavy-chain locus is restricted to only four functional and nearly identical IGHV genes, in contrast to the ten observed in cattle. Repertoire analysis indicates that light-chain usage is more balanced in goats, with greater representation of kappa light chains (~ 20-30%) compared to that in cattle (~ 5%). The present study represents the first characterization of the goat antibody loci and will help inform future investigations of their antibody responses to disease and vaccination

    Forest structure, stand composition, and climate-growth response in montane forests of Jiuzhaigou National Nature Reserve, China.

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    Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1) whether the forest appears in transition toward increased hardwood composition; 2) if conifers appear stressed by recent climate change relative to hardwoods; and 3) how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20(th) century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix) strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth

    The Manly Art of Observation and Deduction

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    The Survival of the Derivative Suit: An Evaluation and a Proposal for Legislative Reform

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    The shareholder derivative suit today faces extinction. Long considered the chief regulator of corporate management, and a recognized form of litigation in American courts at least since 1855, it now confronts the second great challenge of its history. Thirty-odd years ago, commentators foresaw the derivative suit\u27s demise when state legislatures began adopting security-for-expenses statutes to curb the abuses of strike suit litigation. These reports of its death proved exaggerated, however, as plaintiffs discovered various tactics by which to outflank these statutes. As a result, by the late 1960\u27s, the crisis was past, and a revival in the action\u27s popularity was duly noted by leading academics. Today, the new threat is judicial, rather than legislative, and if the prophecies of doom are again to prove false, countervailing legislation may be necessary. In the aftermath of the Supreme Court\u27s decision in Burks v. Lasker, a number of courts have upheld the capacity of disinterested directors, in the exercise of their business judgment, to terminate a derivative suit on the grounds that it is adverse to the corporation\u27s best interests. As a practical consequence of this extension of the business judgment rule, a veto power over derivative actions may now rest with a corporation\u27s often only nominally independent directors. What has caused this transition? Curiously, no court has explicitly reevaluated the derivative suit, condemned it on policy grounds, cited any new consideration, or even reached any legal conclusion that could be described as original. Rather, the basic process has been a triumph of legal formalism: in theory, the derivative action asserts a corporate right, and hence, as a matter of formal logic, the right should be one that the board can waive or compromise. Such a conclusion has the force of logic, but not of experience. Realism suggests that an unqualified recognition of such a power may make the derivative suit an endangered species of legal action

    Representing Interests and Interest Group Representation

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    Interest groups and other “group concepts” of politics dominated explanations of American government and policy-making in the 1950s and early 1960s and, as filtered through the concept of pluralism, have provided what is arguably the most lasting and perhaps the most persuasive theorizing on political decision-making in the United States. Representing Interests and Interest Group Representation explores both the strengths and weaknesses of the current research on interest groups. It points to what needs to be done, the major intellectual concerns that should guide the research, and some of the more productive ways to approach the significant research questions.https://ideaexchange.uakron.edu/representing_interests/1000/thumbnail.jp

    The evolution of the natural killer complex; a comparison between mammals using new high-quality genome assemblies and targeted annotation.

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    Natural killer (NK) cells are a diverse population of lymphocytes with a range of biological roles including essential immune functions. NK cell diversity is in part created by the differential expression of cell surface receptors which modulate activation and function, including multiple subfamilies of C-type lectin receptors encoded within the NK complex (NKC). Little is known about the gene content of the NKC beyond rodent and primate lineages, other than it appears to be extremely variable between mammalian groups. We compared the NKC structure between mammalian species using new high-quality draft genome assemblies for cattle and goat; re-annotated sheep, pig, and horse genome assemblies; and the published human, rat, and mouse lemur NKC. The major NKC genes are largely in the equivalent positions in all eight species, with significant independent expansions and deletions between species, allowing us to propose a model for NKC evolution during mammalian radiation. The ruminant species, cattle and goats, have independently evolved a second KLRC locus flanked by KLRA and KLRJ, and a novel KLRH-like gene has acquired an activating tail. This novel gene has duplicated several times within cattle, while other activating receptor genes have been selectively disrupted. Targeted genome enrichment in cattle identified varying levels of allelic polymorphism between the NKC genes concentrated in the predicted extracellular ligand-binding domains. This novel recombination and allelic polymorphism is consistent with NKC evolution under balancing selection, suggesting that this diversity influences individual immune responses and may impact on differential outcomes of pathogen infection and vaccination

    Bending and shear stresses developed by the instantaneous arrest of the root of a cantilever beam rotating with constant angular velocity about a transverse axis through the root

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    A theoretical investigation was made of the behavior of a cantilever beam in rotational motion about a transverse axis through the root determining the stresses, the deflections, and the accelerations that occur in the beam as a result of the arrest of motion. The equations for bending and shear stress reveal that, at a given percentage of the distance from root to tip and at a given trip velocity, the bending stresses for a particular mode are independent of the length of the beam and the shear stresses vary inversely with the length. When examined with respect to a given angular velocity instead of a given tip velocity, the equations reveal that the bending stress is proportional to the length of the beam whereas the shear stress is independent of the length. Sufficient experimental verification of the theory has previously been given in connection with another problem of the same type

    Lack of self-averaging of the specific heat in the three-dimensional random-field Ising model

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    We apply the recently developed critical minimum energy subspace scheme for the investigation of the random-field Ising model. We point out that this method is well suited for the study of this model. The density of states is obtained via the Wang-Landau and broad histogram methods in a unified implementation by employing the N-fold version of the Wang-Landau scheme. The random-fields are obtained from a bimodal distribution (hi=±2h_{i}=\pm2), and the scaling of the specific heat maxima is studied on cubic lattices with sizes ranging from L=4L=4 to L=32L=32. Observing the finite-size scaling behavior of the maxima of the specific heats we examine the question of saturation of the specific heat. The lack of self-averaging of this quantity is fully illustrated and it is shown that this property may be related to the question mentioned above.Comment: 8 pages, 7 figures, extended version with two new figures, version as accepted for publication to Physical Review

    Regularized Electron Flux Spectra in the 2002 July 23 Solar Flare

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    By inverting the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) hard X-ray photon spectrum with the Tikhonov regularization algorithm, we infer the effective mean electron source spectrum for a time interval near the peak of the 2002 July 23 event. This inverse approach yields the smoothest electron flux spectrum consistent with the data while retaining real features, such as local minima, that cannot be found with forward model-fitting methods that involve only a few parameters. A significant dip in the recovered mean source electron spectrum near E = 55 keV is noted, and its significance briefly discussed
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