3,091 research outputs found

    Shock Pulse Filtering Evaluation on Package Size and Cost

    Get PDF
    Distribution packaging design often relies on cushion curves to determine required material thickness needed for product protection during shipment. The material thickness chosen based on cushion curves establishes overall package size, a key determiner of logistics costs. Cushion curves are constructed by dropping a mass onto a cushion, and interpreting the resulting shock pulse deceleration. The reported deceleration can be highly influenced by applying a “filter” to the shock pulse, a useful standar d prac - tice that removes unwanted high frequency elements superimposed on top of the basic shock pulse shape. Standard test methods for generating cushion curves generally do not require reporting what filter was used, or whether the filter influenced the resulting cushion curve information. This paper demonstrates quantitatively how shock pulse filtering influences cushion curves and cushion thickness, which in turn affects logistics costs

    Global MHD simulation of flux transfer events at the high-latitude magnetopause observed by the cluster spacecraft and the SuperDARN radar system

    Get PDF
    A global magnetohydrodynamic numerical simulation is used to study the large-scale structure and formation location of flux transfer events (FTEs) in synergy with in situ spacecraft and ground-based observations. During the main period of interest on the 14 February 2001 from 0930 to 1100 UT the Cluster spacecraft were approaching the Northern Hemisphere high-latitude magnetopause in the postnoon sector on an outbound trajectory. Throughout this period the magnetic field, electron, and ion sensors on board Cluster observed characteristic signatures of FTEs. A few minutes delayed to these observations the Super Dual Auroral Radar Network (SuperDARN) system indicated flow disturbances in the conjugate ionospheres. These “two-point” observations on the ground and in space were closely correlated and were caused by ongoing unsteady reconnection in the vicinity of the spacecraft. The three-dimensional structures and dynamics of the observed FTEs and the associated reconnection sites are studied by using the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme (BATS-R-US) MHD code in combination with a simple open flux tube motion model (Cooling). Using these two models the spatial and temporal evolution of the FTEs is estimated. The models fill the gaps left by measurements and allow a “point-to-point” mapping between the instruments in order to investigate the global structure of the phenomenon. The modeled results presented are in good correlation with previous theoretical and observational studies addressing individual features of FTEs

    Extended microsatellite analysis in microsatellite stable, MSH2 and MLH1 mutation-negative HNPCC patients: Genetic reclassification and correlation with clinical features

    Get PDF
    Background: Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disorder predisposing to predominantly colorectal cancer (CRC) and endometrial cancer frequently due to germline mutations in DNA mismatch repair (MMR) genes, mainly MLH1, MSH2 and also MSH6 in families seen to demonstrate an excess of endometrial cancer. As a consequence, tumors in HNPCC reveal alterations in the length of simple repetitive genomic sequences like poly-A, poly-T, CA or GT repeats (microsatellites) in at least 90% of the cases. Aim of the Study: The study cohort consisted of 25 HNPCC index patients ( 19 Amsterdam positive, 6 Bethesda positive) who revealed a microsatellite stable (MSS) - or low instable (MSI-L) - tumor phenotype with negative mutation analysis for the MMR genes MLH1 and MSH2. An extended marker panel (BAT40, D10S197, D13S153, D18S58, MYCL1) was analyzed for the tumors of these patients with regard to three aspects. First, to reconfirm the MSI-L phenotype found by the standard panel; second, to find minor MSIs which might point towards an MSH6 mutation, and third, to reconfirm the MSS status of hereditary tumors. The reconfirmation of the MSS status of tumors not caused by mutations in the MMR genes should allow one to define another entity of hereditary CRC. Their clinical features were compared with those of 150 patients with sporadic CRCs. Results: In this way, 17 MSS and 8 MSI-L tumors were reclassified as 5 MSS, 18 MSI-L and even 2 MSI-H ( high instability) tumors, the last being seen to demonstrate at least 4 instable markers out of 10. Among all family members, 87 malignancies were documented. The mean age of onset for CRCs was the lowest in the MSI-H-phenotyped patients with 40.5 +/- 4.9 years (vs. 47.0 +/- 14.6 and 49.8 +/- 11.9 years in MSI-L- and MSS-phenotyped patients, respectively). The percentage of CRC was the highest in families with MSS-phenotyped tumors (88%), followed by MSI-L-phenotyped ( 78%) and then by MSI-H-phenotyped (67%) tumors. MSS tumors were preferentially localized in the distal colon supposing a similar biologic behavior like sporadic CRC. MSH6 mutation analysis for the MSI-L and MSI-H patients revealed one truncating mutation for a patient initially with an MSS tumor, which was reclassified as MSI-L by analyzing the extended marker panel. Conclusion: Extended microsatellite analysis serves to evaluate the sensitivity of the reference panel for HNPCC detection and permits phenotype confirmation or upgrading. Additionally, it confirms the MSS status of hereditary CRCs not caused by the common mutations in the MMR genes and provides hints to another entity of hereditary CRC. Copyright (C) 2004 S. Karger AG, Basel

    Hierarchy of exchange interactions in the triangular-lattice spin-liquid YbMgGaO4_{4}

    Full text link
    The spin-1/2 triangular lattice antiferromagnet YbMgGaO4_{4} has attracted recent attention as a quantum spin-liquid candidate with the possible presence of off-diagonal anisotropic exchange interactions induced by spin-orbit coupling. Whether a quantum spin-liquid is stabilized or not depends on the interplay of various exchange interactions with chemical disorder that is inherent to the layered structure of the compound. We combine time-domain terahertz spectroscopy and inelastic neutron scattering measurements in the field polarized state of YbMgGaO4_{4} to obtain better microscopic insights on its exchange interactions. Terahertz spectroscopy in this fashion functions as high-field electron spin resonance and probes the spin-wave excitations at the Brillouin zone center, ideally complementing neutron scattering. A global spin-wave fit to all our spectroscopic data at fields over 4T, informed by the analysis of the terahertz spectroscopy linewidths, yields stringent constraints on gg-factors and exchange interactions. Our results paint YbMgGaO4_{4} as an easy-plane XXZ antiferromagnet with the combined and necessary presence of sub-leading next-nearest neighbor and weak anisotropic off-diagonal nearest-neighbor interactions. Moreover, the obtained gg-factors are substantially different from previous reports. This works establishes the hierarchy of exchange interactions in YbMgGaO4_{4} from high-field data alone and thus strongly constrains possible mechanisms responsible for the observed spin-liquid phenomenology

    Does the KARMEN time anomaly originate from a beam-correlated background?

    Get PDF
    The time anomaly of neutrino events observed in the KARMEN detector at the ISIS facility is discussed. We show that beam-correlated neutron events are not completely suppressed by the KARMEN lower energy cut and could cause the observed deviation of the measured time distribution from an exponential curve with tau = 2.2 microseconds.Comment: 12 pages including figure captions, 2 figures, 1 tabl

    The reaction npppπ{n} {p} \to {p} {p} \pi^{-} from threshold up to 570 MeV

    Full text link
    The reaction npppπ{n} {p} \to {p} {p} \pi^{-} has been studied in a kinematically complete measurement with a large acceptance time-of-flight spectrometer for incident neutron energies between threshold and 570 MeV. The proton-proton invariant mass distributions show a strong enhancement due to the pp(1S0^{1}{S}_{0}) final state interaction. A large anisotropy was found in the pion angular distributions in contrast to the reaction ppppπ0{p}{p} \to {p}{p} \pi^{0}. At small energies, a large forward/backward asymmetry has been observed. From the measured integrated cross section σ(npppπ)\sigma({n}{p} \to {\rm p}{p} \pi^{-}), the isoscalar cross section σ01\sigma_{01} has been extracted. Its energy dependence indicates that mainly partial waves with Sp final states contribute. Note: Due to a coding error, the differential cross sections dσ/dMpp{d \sigma}/{d M_{pp}} as shown in Fig. 9 are too small by a factor of two, and inn Table 3 the differential cross sections dσ/dΩπ{d \sigma}/{d \Omega_{\pi}^{*}} are too large by a factor of 10/2π10/2\pi. The integrated cross sections and all conclusions remain unchanged. A corresponding erratum has been submitted and accepted by European Physics Journal.Comment: 18 pages, 16 figure

    Analysing powers for the reaction npppπ\vec{\rm n} {\rm p} \to {\rm p} {\rm p} \pi^{-} and for np elastic scattering from 270 to 570 MeV

    Full text link
    The analysing power of the reaction npppπ{\rm n}{\rm p} \to {\rm p}{\rm p} \pi^{-} for neutron energies between threshold and 570 MeV has been determined using a transversely polarised neutron beam at PSI. The reaction has been studied in a kinematically complete measurement using a time-of-flight spectrometer with large acceptance. Analysing powers have been determined as a function of the c.m. pion angle in different regions of the proton-proton invariant mass. They are compared to other data from the reactions npppπ{\rm n}{\rm p} \to {\rm p}{\rm p} \pi^{-} and ppppπ0{{\rm p}{\rm p} \to {\rm p}{\rm p} \pi^{0}}. The np elastic scattering analysing power was determined as a by-product of the measurements.Comment: 12 pages, 6 figures, subitted to EPJ-
    corecore