5,392 research outputs found

    Low-temperature structural transition in FeCr_2S_4

    Full text link
    Transmission electron microscopy studies of [110] and [111] oriented FeCr_2S_4 single crystals at different temperatures reveal a structural transition at low temperatures indicating a cubic-to-triclinic symmetry reduction within crystallographic domains. The overall crystal symmetry was found to be reduced from Fd3m to F-43m. The triclinic distortions were suggested to result from the combined actions of tetragonal distortions due to the Jahn-Teller active Fe^2+ ions and trigonal distortions due to a displacement of the Cr^3+ ions in the direction.Comment: 4 pages, 8 figure

    Formulating a Strategy for Securing High-Speed Rail in the United States, Research Report 12-03

    Get PDF
    This report presents an analysis of information relating to attacks, attempted attacks, and plots against high-speed rail (HSR) systems. It draws upon empirical data from MTI’s Database of Terrorist and Serious Criminal Attacks Against Public Surface Transportation and from reviews of selected HSR systems, including onsite observations. The report also examines the history of safety accidents and other HSR incidents that resulted in fatalities, injuries, or extensive asset damage to examine the inherent vulnerabilities (and strengths) of HSR systems and how these might affect the consequences of terrorist attacks. The study is divided into three parts: (1) an examination of security principles and measures; (2) an empirical examination of 33 attacks against HSR targets and a comparison of attacks against HSR targets with those against non-HSR targets; and (3) an examination of 73 safety incidents on 12 HRS systems. The purpose of this study is to develop an overall strategy for HSR security and to identify measures that could be applied to HSR systems currently under development in the United States. It is hoped that the report will provide useful guidance to both governmental authorities and transportation operators of current and future HSR systems

    Composite vertices that lead to soft form factors

    Get PDF
    The momentum-space cut-off parameter Λ\Lambda of hadronic vertex functions is studied in this paper. We use a composite model where we can measure the contributions of intermediate particle propagations to Λ\Lambda. We show that in many cases a composite vertex function has a much smaller cut-off than its constituent vertices, particularly when light constituents such as pions are present in the intermediate state. This suggests that composite meson-baryon-baryon vertex functions are rather soft, i.e., they have \Lambda considerably less than 1 GeV. We discuss the origin of this softening of form factors as well as the implications of our findings on the modeling of nuclear reactions.Comment: REVTex, 19 pages, 5 figs(to be provided on request

    Sex adjusted standardized prevalence ratios for celiac disease and other autoimmune diseases in patients with postural orthostatic tachycardia syndrome (POTS) : a systematic review and meta-analysis

    Get PDF
    Standardised sex-adjusted prevalence ratios (SSPRs) have not been published for any autoimmune diseases (ADs) in patients with Postural Orthostatic Tachycardia Syndrome (POTS), who are predominantly young females. We performed a systematic review according to PRISMA guidelines of POTS cohorts reporting the prevalence of at least one AD. Only four studies were found: two providing data on celiac disease; and two with data on ‘any AD’, Hashimoto’s thyroiditis, rheumatoid arthritis, systemic lupus erythematosus (SLE), Sjogren ¨ ’s syndrome and celiac disease and (one study) antiphospholipid syndrome. All studies were assessed as being at high risk of bias for estimating AD prevalence in POTS patients, with under-reporting of ADs likely due to the lack of rigorous prospective screening for ADs. A literature search found a ‘gold standard’ general population (GP) comparator only for celiac disease in the United States, leading to a pooled SSPR in POTS patients of 2.75 with 95% confidence interval (1.06–4.40). The lack of recent high-quality studies on GP prevalence for the other ADs was noteworthy. Exploratory pooled SSPRs were calculated for ‘any AD’ and for the other five ADs using GP comparator data from a comprehensive review. All pooled SSPRs were greater than one and statistically significant, implying a higher prevalence of these ADs, and any AD, in POTS patients. The magnitude of the exploratory SSPRs was very large for SLE, Sjogren ¨ ’s syndrome and antiphospholipid syndrome, perhaps reflecting the use of non-gold standard GP comparators, which may underestimate AD prevalence. Further research in a large POTS cohort with an appropriately age- and sex-matched GP control group is recommended, to confirm the SSPR for celiac disease and to determine whether SLE, Sjogren’s syndrome and antiphospholipid syndrome are indeed many times more prevalent in POTS patients than in the GP. The findings are consistent with POTS itself being an AD

    Channel Modeling and Analysis for Radio Wave Propagation in Vehicular Ad Hoc Network

    Full text link
    VANET is the basic technology of Vehicle Infrastructure Integration (VII). Vehicular Ad Hoc Network (VANET) is the network that is connecting a vehicle to the infrastructure (V2I) and vehicle to vehicle (V2V) via wireless manner to convey the information between them. Therefore analyzing influence such channels on the VANET system performance is crucial. This paper is conducted to model and analyze the channel for radio wave propagation with considering free space, two ray ground reflection and single knife edge diffraction. The received power, path loss and effect state of the communication sides whether is in moving stable are discussed. The direction of moving of the vehicles and location of obstacles are also taken into account for calculating the received power and path loss

    INTEGRATION OF PHOTOGRAMMETRY AND PORTABLE MOBILE MAPPING TECHNOLOGY FOR 3D MODELING OF CULTURAL HERITAGE SITES: THE CASE STUDY OF THE BZIZA TEMPLE

    Get PDF
    Abstract. In this paper, we present a multi-sensor approach employed to obtain the 3D model of the Roman temple of Bziza (Lebanon) and its surroundings, a work carried out as part of the archaeological Northern Lebanon Project (NoLeP). The integration of photogrammetry and portable mobile mapping technology was tested to overcome the weaknesses of each individual surveying method, with the aim of producing a complete and realistic 3D reconstruction of the whole site, as well as capturing at high-resolution the architectural features of the main structure. Moreover, this case study serves to further investigate the accuracy that can be reached with mobile laser scanners, highlighting benefits and limitations of this rapid and efficient mapping technique also in the field of Cultural Heritage documentation

    A variant of nonsmooth maximum principle for state constrained problems

    Full text link
    We derive a variant of the nonsmooth maximum principle for problems with pure state constraints. The interest of our result resides on the nonsmoothness itself since, when applied to smooth problems, it coincides with known results. Remarkably, in the normal form, our result has the special feature of being a sufficient optimality condition for linearconvex problems, a feature that the classical Pontryagin maximum principle had whereas the nonsmooth version had not. This work is distinct to previous work in the literature since, for state constrained problems, we add the Weierstrass conditions to adjoint inclusions using the joint subdifferentials with respect to the state and the control. Our proofs use old techniques developed in [16], while appealing to new results in [7].Comment: 6 pages, No figures, Conference Proceeding

    The ‘Galilean Style in Science’ and the Inconsistency of Linguistic Theorising

    Get PDF
    Chomsky’s principle of epistemological tolerance says that in theoretical linguistics contradictions between the data and the hypotheses may be temporarily tolerated in order to protect the explanatory power of the theory. The paper raises the following problem: What kinds of contradictions may be tolerated between the data and the hypotheses in theoretical linguistics? First a model of paraconsistent logic is introduced which differentiates between week and strong contradiction. As a second step, a case study is carried out which exemplifies that the principle of epistemological tolerance may be interpreted as the tolerance of week contradiction. The third step of the argumentation focuses on another case study which exemplifies that the principle of epistemological tolerance must not be interpreted as the tolerance of strong contradiction. The reason for the latter insight is the unreliability and the uncertainty of introspective data. From this finding the author draws the conclusion that it is the integration of different data types that may lead to the improvement of current theoretical linguistics and that the integration of different data types requires a novel methodology which, for the time being, is not available

    The ‘Galilean Style in Science’ and the Inconsistency of Linguistic Theorising

    Get PDF
    Chomsky’s principle of epistemological tolerance says that in theoretical linguistics contradictions between the data and the hypotheses may be temporarily tolerated in order to protect the explanatory power of the theory. The paper raises the following problem: What kinds of contradictions may be tolerated between the data and the hypotheses in theoretical linguistics? First a model of paraconsistent logic is introduced which differentiates between week and strong contradiction. As a second step, a case study is carried out which exemplifies that the principle of epistemological tolerance may be interpreted as the tolerance of week contradiction. The third step of the argumentation focuses on another case study which exemplifies that the principle of epistemological tolerance must not be interpreted as the tolerance of strong contradiction. The reason for the latter insight is the unreliability and the uncertainty of introspective data. From this finding the author draws the conclusion that it is the integration of different data types that may lead to the improvement of current theoretical linguistics and that the integration of different data types requires a novel methodology which, for the time being, is not available
    • …
    corecore