1,063 research outputs found

    Construction of Parflux Mark II sediment trap : engineering report

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    A large, open ocean applicable sediment trap has been developed at the Woods Hole Oceanographic Institution in order to assess the fluxes of particles sinking through the deep water column, under the sponsorship of the National Science Foundation. PARFLUX Mark II trap, 1978-79 version for PARFLUX phase 1 program, has been successfully developed and has gathered much meaningful data. A trap opening is 1.5 m2 and consists of 94 hexagonal buffer cells with the nominal form ratio of 2. Sediment particles are concentrated to the receiving cup located at the bottom of the funnel-shaped trap. Two types of receiving cups have been developed; a trap with Type S cup is open at both ends as it sinks to the designated depth. Twenty-four hours after the deployment the receiving cup moves into alignment with the funnel to store the sediment. At the end of deployment a spring mechanism activated by a quartz oscillator based electrical timer-release retracts the receiving cup, seals the collected sample and leave the funnel open at both ends while the trap ascends for recovery. Type C mechanism is installed with a shutter which seals the cup during recovery; this type involves a simple mechanism with less moving parts. Sodium azide/sodium chloride solution is diffused through a series of membrane filters to keep the cup contents in an aseptic condition. Since October 1976 to December 1979, we have deployed and recovered 24 traps successfully along with several moorings as deep as 5,600 m for as long as 112 days. This reports the engineering detail and lists the required parts to assist the construction, operation and maintenance of the PARFLUX Mark II sediment trap.Prepared for the National Science Foundation under Grants OCE 76-82063 and OCE 77-27004

    Asymptotic function for multi-growth surfaces using power-law noise

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    Numerical simulations are used to investigate the multiaffine exponent αq\alpha_q and multi-growth exponent ÎČq\beta_q of ballistic deposition growth for noise obeying a power-law distribution. The simulated values of ÎČq\beta_q are compared with the asymptotic function ÎČq=1q\beta_q = \frac{1}{q} that is approximated from the power-law behavior of the distribution of height differences over time. They are in good agreement for large qq. The simulated αq\alpha_q is found in the range 1q≀αq≀2q+1\frac{1}{q} \leq \alpha_q \leq \frac{2}{q+1}. This implies that large rare events tend to break the KPZ universality scaling-law at higher order qq.Comment: 5 pages, 4 figures, to be published in Phys. Rev.

    Scaling of impact fragmentation near the critical point

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    We investigated two-dimensional brittle fragmentation with a flat impact experimentally, focusing on the low impact energy region near the fragmentation-critical point. We found that the universality class of fragmentation transition disagreed with that of percolation. However, the weighted mean mass of the fragments could be scaled using the pseudo-control parameter multiplicity. The data for highly fragmented samples included a cumulative fragment mass distribution that clearly obeyed a power-law. The exponent of this power-law was 0.5 and it was independent of sample size. The fragment mass distributions in this regime seemed to collapse into a unified scaling function using weighted mean fragment mass scaling. We also examined the behavior of higher order moments of the fragment mass distributions, and obtained multi-scaling exponents that agreed with those of the simple biased cascade model.Comment: 6 pages, 6 figure

    Multiple Interactions in Two-Photon Collisions

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    We compute cross sections for events where two pairs of partons scatter off each other in the same γγ\gamma\gamma reaction, giving rise to at least 3 high--{\mbox{pTp_T^{}}} jets. Unlike in {\mbox{ppˉp \bar p}}\ collisions we find the signal to lie well above the background from higher order QCD processes. If the usual ``eikonaliztion" assumption is correct, the signal should be readily observable at LEP2, and might already be detectable in data taken at TRISTAN.Comment: 8 pages, plain LaTeX, 2 figures (not included). A compressed PS file of the entire paper, including figures, can be obtained via anonymous ftp from ftp://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-921.ps.

    Classification of KPZQ and BDP models by multiaffine analysis

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    We argue differences between the Kardar-Parisi-Zhang with Quenched disorder (KPZQ) and the Ballistic Deposition with Power-law noise (BDP) models, using the multiaffine analysis method. The KPZQ and the BDP models show mono-affinity and multiaffinity, respectively. This difference results from the different distribution types of neighbor-height differences in growth paths. Exponential and power-law distributions are observed in the KPZQ and the BDP, respectively. In addition, we point out the difference of profiles directly, i.e., although the surface profiles of both models and the growth path of the BDP model are rough, the growth path of the KPZQ model is smooth.Comment: 11 pages, 6 figure

    Complex interplay between ÎČ-catenin signalling and Notch effectors in intestinal tumorigenesis

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    International audienceAims The activation of ÎČ-catenin signalling is a key step in intestinal tumorigenesis. Interplay between the ÎČ-catenin and Notch pathways during tumorigenesis has been reported, but the mechanisms involved and the role of Notch remain unclear. Methods Notch status was analysed by studying expression of the Notch effector Hes1 and Notch ligands/receptors in human colorectal cancer (CRC) and mouse models of Apc mutation. A genetic approach was used, deleting the Apc and RBP-J or Atoh1 genes in murine intestine. CRC cell lines were used to analyse the control of Hes1 and Atoh1 by ÎČ-catenin signalling. Results Notch signalling was found to be activated downstream from ÎČ-catenin. It was rapidly induced and maintained throughout tumorigenesis. Hes1 induction was mediated by ÎČ-catenin and resulted from both the induction of the Notch ligand/receptor and Notch-independent control of the Hes1 promoter by ÎČ-catenin. Surprisingly, the strong phenotype of unrestricted proliferation and impaired differentiation induced by acute Apc deletion in the intestine was not rescued by conditional Notch inactivation. Hyperactivation of ÎČ-catenin signalling overrode the forced differention induced by Notch inhibition, through the downregulation of Atoh1, a key secretory determinant factor downstream of Notch. This process involves glycogen synthase kinase 3 ÎČ (GSK3ÎČ) and proteasome-mediated degradation. The restoration of Atoh1 expression in CRC cell lines displaying ÎČ-catenin activation was sufficient to increase goblet cell differentiation, whereas genetic ablation of Atoh1 greatly increased tumour formation in Apc mutant mice. Conclusion Notch signalling is a downstream target of ÎČ-catenin hyperactivation in intestinal tumorigenesis. However, its inhibition had no tumour suppressor effect in the context of acute ÎČ-catenin activation probably due to the downregulation of Atoh1. This finding calls into question the use of Îł-secretase inhibitors for the treatment of CRC and suggests that the restoration of Atoh1 expression in CRC should be considered as a therapeutic approach

    The Impact of Menthol Cigarettes on Smoking Initiation among Non-Smoking Young Females in Japan

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    Japan presents an excellent case-study of a nation with low female smoking rates and a negligible menthol market which changed after the cigarette market was opened to foreign competition. Internal tobacco industry documents demonstrate the intent of tobacco manufacturers to increase initiation among young females through development and marketing of menthol brands. Japanese menthol market share rose rapidly from less than 1% in 1980 to 20% in 2008. Menthol brand use was dominated by younger and female smokers, in contrast with non-menthol brands which were used primarily by male smokers. Nationally representative surveys confirm industry surveys of brand use and provide further evidence of the end results of the tobacco industry’s actions—increased female smoking in Japan. These findings suggest that female populations may be encouraged to initiate into smoking, particularly in developing nations or where female smoking rates remain low, if the tobacco industry can successfully tailor brands to them. The Japanese experience provides a warning to public health officials who wish to prevent smoking initiation among young females
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