Chaotic pulses for discrete reaction diffusion systems

Existence and dynamics of chaotic pulses on a one-dimensional lattice are discussed. Traveling pulses arise typically in reaction diffusion systems like the FitzHugh-Nagumo equations. Such pulses annihilate when they collide with each other. A new type of traveling pulse has been found recently in many systems where pulses bounce off like elastic balls. We consider the behavior of such a localized pattern on one-dimensional lattice, i.e., an infinite system of ODEs with nearest interaction of diffusive type. Besides the usual standing and traveling pulses, a new type of localized pattern, which moves chaotically on a lattice, is found numerically. Employing the strength of diffusive interaction as a bifurcation parameter, it is found that the route from standing pulse to chaotic pulse is of intermittent type. If two chaotic pulses collide with appropriate timing, they form a periodic oscillating pulse called a molecular pulse. Interaction among many chaotic pulses is also studied numerically

Implementation of earlier antibiotic administration in patients with severe sepsis and septic shock in Japan: a descriptive analysis of a prospective observational study.

BACKGROUND: Time to antibiotic administration is a key element in sepsis care; however, it is difficult to implement sepsis care bundles. Additionally, sepsis is different from other emergent conditions including acute coronary syndrome, stroke, or trauma. We aimed to describe the association between time to antibiotic administration and outcomes in patients with severe sepsis and septic shock in Japan. METHODS: This prospective observational study enrolled 1184 adult patients diagnosed with severe sepsis based on the Sepsis-2 criteria and admitted to 59 intensive care units (ICUs) in Japan between January 1, 2016, and March 31, 2017, as the sepsis cohort of the Focused Outcomes Research in Emergency Care in Acute Respiratory Distress Syndrome, Sepsis and Trauma (FORECAST) study. We compared the characteristics and in-hospital mortality of patients administered with antibiotics at varying durations after sepsis recognition, i.e., 0-60, 61-120, 121-180, 181-240, 241-360, and 361-1440 min, and estimated the impact of antibiotic timing on risk-adjusted in-hospital mortality using the generalized estimating equation model (GEE) with an exchangeable, within-group correlation matrix, with "hospital" as the grouping variable. RESULTS: Data from 1124 patients in 54 hospitals were used for analyses. Of these, 30.5% and 73.9% received antibiotics within 1 h and 3 h, respectively. Overall, the median time to antibiotic administration was 102 min [interquartile range (IQR), 55-189]. Compared with patients diagnosed in the emergency department [90 min (IQR, 48-164 min)], time to antibiotic administration was shortest in patients diagnosed in ICUs [60 min (39-180 min)] and longest in patients transferred from wards [120 min (62-226)]. Overall crude mortality was 23.4%, where patients in the 0-60 min group had the highest mortality (28.0%) and a risk-adjusted mortality rate [28.7% (95% CI 23.3-34.1%)], whereas those in the 61-120 min group had the lowest mortality (20.2%) and risk-adjusted mortality rates [21.6% (95% CI 16.5-26.6%)]. Differences in mortality were noted only between the 0-60 min and 61-120 min groups. CONCLUSIONS: We could not find any association between earlier antibiotic administration and reduction in in-hospital mortality in patients with severe sepsis

STUDIE ON METALLÜBERGANG BEI DER SYNCHRONISIERTEN KONTROLLE DER DRAHTZUFÜHRUNG UND BEI STROM WELLENFORM

Za zavarivanje tankih limova s vrlo niskim unosom topline i minimalnim štrcanjem koristi se inačica MAG zavarivanje kratkim spojevima pri kojem se mijenja smjer gibanja elektrodne žice. Ako se takav stabilan prijenos može ostvariti u području globularnoga, tj. prijelaznog luka u zaštiti plina CO2, postiže se dodatna produktivnost. Za dane uvjete u ovom radu je opisan razvoj međuspremnika žice tzv. Buffer Position Control uređaja koji upravlja dodavanjem žice između motora koji gura i drugoga koji vuče žicu te može kompenzirati konstantnu brzinu dodavanja, uz primjenu tzv. Pulsed Dip Transfer Process, tj. kombinacije prijenosa metala impulsima i kratkim spojevima, čime se tijekom trajanja električnog luka stabilizira prijenos metalnih kapi za ravnu statičku značajku (CV-constant voltage). Primjenom takvoga valnog oblika struje poboljšava se prijenos topline u osnovni materijal. Dodatno su analizirana načela upravljanja procesom i utjecaj zavarivanja velikim brzinama na vrlo tankim limovima uz pojavu minimalnog štrcanja.A gas metal arc welding process that changes the wire feed direction according to the arc phenomena has been proposed and applied to a fi eld of the ultra-sheet plate joining on MAG welding process, due to the ultra-low spatter generation and the low heat input into the base metal in a current range of the short-circuit transfer mode. When such the welding process can realize the stable metal transfer in a current range of the globular transfer mode under the carbon dioxide shielding gas supplying, it can contribute the improvement of the further productivity. Under the circumstances, the authors have developed the Buffer Position Control which controls the interference reduction of the wire feed direction between the push feeder and the pull feeder and can compensate the constant mean wire feed rate, and the Pulsed Dip Transfer Process which forms the pulsatile output of the welding current during arc duration to stabilize the metal transfer by the constant voltage characteristic and improve the heat input to the base metal. In this paper, the principle of these controls and the effect of high speed welding with ultra-low spatter generation of the sheet metal joining will be presented.Beim Schweißen von dünnen Blechen mit einem sehr niedrigen Wärmeeintrag und mit minimalen Spritzen wird MAG Schweißen benutzt bei dem sich die Richtung der Drahtelektrode ändert. Falls sich so ein stabiler Metallübergang erreicht, im Bereich der globularen bzw. Übergehenden Lichtbogen beim CO2 Gas, kann man eine erweiterte Produktivität haben. Für die Konditionen in dieser Arbeit wurde die Entwicklung von dem Zwischendrahtbuffer beschrieben, der so genannter Buffer Position Control die die Drahtzufuhr reguliert zwischen dem Motor der den Draht schiebt und einen anderen Motor der den Draht zieht, und diese Bufferposition kann die konstante Drahtzufuhrgeschwindigkeit kompensieren und einen Pulsed Dip Transfer Process erreichen, bzw. eine Kombination des Metallübergangs mit Impulsen und Kurzlichtbogen wobei die statische Charakteristik des Lichtbogen gerade ist (CV-constant voltage). Mit der Anwendung so einer Strom Wellenform verbessert sich der Wärmeübergang in das Grundmaterial. Zusätzlich wurden die Prinzipen der Prozesskontrolle und der Einfl uss beim Schweißen mit hoher Geschwindigkeit an sehr dünnen Blechen mit minimalen Spritzen gezeigt

Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration

The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre absorbed with the growth factor. nHA–PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA–PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules

Ribozyme-mediated inactivation of mutant K-ras oncogene in a colon cancer cell line

Mutation of c-K-ras oncogene is an important step in progression of colon cancer. We used a hammerhead ribozyme (KrasRz) against mutated K-ras gene transcripts (codon 12, GTT) to inactivate mutant K-ras function in the colon cancer cell line SW480, harbouring a mutant K-ras gene. The β-actin promoter-driven KrasRz sequence (pHβ/KrasRz) was introduced into these cells (SW480/KrasRz), and we evaluated its effects on growth of the colon cancer. The gene expression of angiogenesis-related molecules (vascular endothelial growth factor and thrombospondin) was also estimated in SW480/KrasRz. KrasRz specifically and efficiently cleaved the mutant K-ras mRNA but not wild-type mRNA in vitro. SW480/KrasRz showed decreased growth rate under tissue culture conditions (P< 0.01, Dunnett’s test). The xenotransplantability of SW480/KrasRz (XeSW480/KrasRz) was significantly decreased in nude mice (P< 0.05, Fisher’s exact test). Tumour volume of the xenografts XeSW480/KrasRz was significantly smaller than that of XeSW480/DisKrasRz (P< 0.01, Dunnett’s test). Gene expression of VEGF was suppressed in SW480/KrasRz, while TSP1 gene expression was enhanced. The SW480/KrasRz cells showed apoptosis-related features including nuclear condensation and DNA fragmentation. These results suggested that the hammerhead ribozyme-mediated inactivation of the mutated K-ras mRNA induced growth suppression, apoptosis and alteration of angiogenic factor expression. © 2000 Cancer Research Campaig