1,479 research outputs found

    Supporting and protecting device Patent

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    Supporting and protecting frame structure and plug for empty thrust chamber assembly, handling, and shippin

    Bound on the multiplicity of almost complete intersections

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    Let RR be a polynomial ring over a field of characteristic zero and let IRI \subset R be a graded ideal of height NN which is minimally generated by N+1N+1 homogeneous polynomials. If I=(f1,...,fN+1)I=(f_1,...,f_{N+1}) where fif_i has degree did_i and (f1,...,fN)(f_1,...,f_N) has height NN, then the multiplicity of R/IR/I is bounded above by i=1Ndimax{1,i=1N(di1)(dN+11)}\prod_{i=1}^N d_i - \max\{1, \sum_{i=1}^N (d_i-1) - (d_{N+1}-1) \}.Comment: 7 pages; to appear in Communications in Algebr

    Central band interosseus membrane reconstruction for longitudinal instability injuries of the forearm

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    Aims Acute and chronic injuries of the interosseus membrane can result in longitudinal instability of the forearm. Reconstruction of the central band of the interosseus membrane can help to restore biomechanical stability. Different methods have been used to reconstruct the central band, including tendon grafts, bone-ligament-bone grafts, and synthetic grafts. This Idea, Development, Exploration, Assessment, and Long-term (IDEAL) phase 1 study aims to review the clinical results of reconstruction using a synthetic braided cross-linked graft secured at either end with an Endobutton to restore the force balance between the bones of the forearm. Methods An independent retrospective review was conducted of a consecutive series of 21 patients with longitudinal instability injuries treated with anatomical central band reconstruction between February 2011 and July 2019. Patients with less than 12 months’ follow-up or who were treated acutely were excluded, leaving 18 patients in total. Preoperative clinical and radiological assessments were compared with prospectively gathered data using range of motion and the abbreviated version of the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) functional outcome score. Results Of the 18 patients (nine male, nine female) who met the inclusion criteria, the median follow-up was 8.5 years (interquartile range (IQR) 5.6 to 10). Their mean age was 49 years (SD 11). The mean extension improved significantly from 38° (SD 15°) to 24° (SD 9°) (p = 0.027), with a mean flexion-extension arc change from 81° (SD 27°) to 93° (SD 30°) (p = 0.172) but with no forearm rotational improvement (p = 0.233) at latest follow-up. The QuickDASH functional score improved significantly from 80 (SD 14) to 52 (SD 26) following reconstruction (p = 0.031), but generally the level of disability remains high. Radiological assessment showed no progression of proximal migration of the radius, with a stable interbutton distance and ulnar variance from immediate postoperative radiograph to the latest follow-up. Conclusion Central band interosseus membrane reconstruction using a synthetic braided cross-linked graft can improve patient-rated arm function and range of motion, but significant functional deficits remain in patients with chronic injuries.</p

    Symmetric Groups and Quotient Complexity of Boolean Operations

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    The quotient complexity of a regular language L is the number of left quotients of L, which is the same as the state complexity of L. Suppose that L and L' are binary regular languages with quotient complexities m and n, and that the transition semigroups of the minimal deterministic automata accepting L and L' are the symmetric groups S_m and S_n of degrees m and n, respectively. Denote by o any binary boolean operation that is not a constant and not a function of one argument only. For m,n >= 2 with (m,n) not in {(2,2),(3,4),(4,3),(4,4)} we prove that the quotient complexity of LoL' is mn if and only either (a) m is not equal to n or (b) m=n and the bases (ordered pairs of generators) of S_m and S_n are not conjugate. For (m,n)\in {(2,2),(3,4),(4,3),(4,4)} we give examples to show that this need not hold. In proving these results we generalize the notion of uniform minimality to direct products of automata. We also establish a non-trivial connection between complexity of boolean operations and group theory

    Realigning the Clean Water Act: Comprehensive Treatment of Nonpoint Source Pollution

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    Nonpoint source pollution is the biggest threat to water quality in the United States today. This Article argues for stronger federal controls over nonpoint source pollution. It begins by examining the history of water quality regulation in the United States, including the passage and amendment of the Clean Water Act and the evolving definition of “navigable waters” over time. The Article then discusses recent rulemaking and litigation developments, including the Clean Water Rule, the Navigable Waters Protection Rule, and the County of Maui, Hawaii v. Hawaii Wildlife Fund case. It offers three recommendations. First, the Article calls for a congressional amendment to the Clean Water Act to require binding controls on nonpoint source pollution. Second, recognizing that an amendment to the Clean Water Act may not be politically viable, it offers an approach for controlling nonpoint source pollution through an amendment to the Safe Drinking Water Act. Finally, it identifies tools that interested states, local governments, and citizens’ groups can utilize to take action on nonpoint source pollution under existing law. This Article concludes that reductions in nonpoint source pollution will lead to significant improvements in the water quality of our nation’s lakes, rivers, wetlands, and coastal areas, to the benefit of human and environmental health

    Acute pulmonary hypertension caused by tumor embolism: a report of two cases.

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    Acute pulmonary hypertension leading to right ventricular failure and circulatory collapse is usually caused by thromboembolic obstruction of the pulmonary circulation. However, in rare instances, other causes can be associated with a similar clinical presentation. We present and discuss the clinical histories of two patients with acute right ventricular failure due to an atypical cause of pulmonary hypertension, disseminated pulmonary tumor embolism

    Conservation Easements: A Tool For Preserving Wildlife Habitat on Private Lands

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    Conservation easements are an essential tool for conserving private lands, and they have great potential for enhancing wildlife habitat and biodiversity. Private land conservation in the United States is likely to increase in the coming years, in light of Executive Order No. 14,008, issued by President Joseph Biden on January 27, 2021, which set a goal of conserving at least 30% of U.S. lands and waters by 2030 (Executive Office of the President 2021). There is, therefore, a need to evaluate the effect of conservation easements on wildlife habitat and biodiversity and to make recommendations for further enhancing the effectiveness of easements. Herein we propose a shift from primarily negative clauses and restrictive language to a more affirmative approach, developing language to proactively improve management of properties under conservation easement in order to maximize benefits to wildlife and ecosystems. In addition, we identify areas for further research on landowner perceptions and experiences regarding conservation easements

    Spatially dispersive finite-difference time-domain analysis of sub-wavelength imaging by the wire medium slabs

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    In this paper, a spatially dispersive finite-difference time-domain (FDTD) method to model wire media is developed and validated. Sub-wavelength imaging properties of the finite wire medium slabs are examined. It is demonstrated that the slab with its thickness equal to an integer number of half-wavelengths is capable of transporting images with sub-wavelength resolution from one interface of the slab to another. It is also shown that the operation of such transmission devices is not sensitive to their transverse dimensions, which can be made even comparable to the wavelength. In this case, the edge diffractions are negligible and do not disturb the image formation.Comment: 14 pages, 13 figures, submitted to Optics Expres
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