Using a recently realized ''addressable catalyst surface'' [Science 294, 134 (2001)] we study the interaction of chemical reaction waves with prescribed spatiotemporal fields. In particular, we study how a traveling chemical pulse is ''dragged'' by a localized, moving temperature heterogeneity as a function of its intensity and speed. The acceleration and eventual ''detachment'' of the wave from the heterogeneity is also explored through simulation and stability analysis. DOI: 10.1103/PhysRevLett.90.018302 PACS numbers: 82.40.Bj, 05.45.-a, 82.40.Np, 82.45.Jn As the elements of spontaneous pattern formation are progressively understood through theory, experimentation, and scientific computation [1], ways to purposefully interact with the coherent structures (pulses and fronts) that constitute the building blocks of spatiotemporal patterns are becoming the focus of extensive research [2,3]. In particular, the stabilization and control of various patterns [3-9] through local, nonlocal, or global feedback, and pattern formation in media with designed heterogeneities [10 -12] are the source of novel insights for spatiotemporal dynamics.To explore such phenomena, we have recently constructed an ''addressable catalyst'': A focused laser beam, manipulated through computer-controlled mirrors and capable of ''writing'' spatiotemporal temperature heterogeneity patterns on a metal single crystal catalyst. The loop between this actuation and sensing (both resolved in space and time) through nonintrusive microscopies is then closed through the computer or the experimentalist herself/himself in real time. Our model system is the low-pressure catalytic oxidation of CO on Pt(110), a reaction exhibiting well-documented spatiotemporal patterns [13][14][15][16], and whose macroscopic modeling has reached an advanced level [17][18][19][20].In this Letter we study the interaction of reactive pulses with a single, spatially coherent but temporally mobile heterogeneity. In particular, we use a temperature heterogeneity, localized in space and steadily moving in time, to ''drag'' spontaneously isothermally forming reactive pulses and fronts with speeds differing from their natural speed. We examine the shapes acquired by these dragged waves and their limits of stability (that is, the range of dragging speeds for which they can exist). Through computer-aided analysis we examine the nature of the detachment instability, marking the loss of the ability of the heterogeneity to drag a pulse in 1D or 2D. Two possible paths to instability (depending on the linearized spectrum crossing) are detected. We explore the postdetachment transient dynamics and the interactions of a pulse with successive elements of a 1D periodic, constant speed array of identical heterogeneities. The theme of pulse dragging is currently also being explored in a variety of physically relevant Hamiltonian systems, or weakly perturbed dissipative variations thereof (targeted transfer of pulses in optical media or the motion/displacement of harmonic traps or optical l...

History of alcohol consumption may predict less depressive symptoms and more anxiety among Chinese patients living in a northeastern Chinese city with ESRD. EPO administration may reduce anxiety in patients with ESRD. Female patients were more prone to anxiety, whereas males were more likely to show symptoms of depression. These factors should be evaluated by nephrologists treating patients with ESRD.

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Background: The relationship between pretreatment C-reactive protein to albumin ratio (CAR) and colorectal cancer (CRC) prognosis has been extensively studied in various tumors. However, little is known on CAR and its association with prognosis in CRC. This study aims to investigate the prognostic value of pretreatment CAR in CRC. Methods: We conducted a systematic search of MEDLINE, EMBASE, and Cochrane Library databases for eligible studies evaluating the associations of CAR with survival and/or clinicopathology of CRC. Overall survival (OS), disease-free survival (DFS), relapse-free survival (RFS), and clinicopathological features were synthesized and compared. Results: Nine studies including 3431 patients were analyzed in this meta-analysis. Pooled results showed that elevated pretreatment CAR was associated with poor OS (pooled hazards ratio [HR]: 2.18, 95% confidence interval [CI]: 1.70-2.78, P < .001) and DFS/RFS (pooled HR: 2.36, 95% CI: 1.40-3.98, P < .001). Moreover, elevated pretreatment CARs were correlated with male patients, large tumor diameter, late III-IV tumor node metastasis stage tumors, high serum carcinoembryonic antigen and carbohydrate antigen 19-9, and presence of lymphatic invasion and venous invasion. Conclusion: Elevated pretreatment CAR could be an adverse prognostic indicator in patients with CRC.

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We review the Langmuir–Hinshelwood model for the heterogeneous catalytic oxidation of carbon monoxide on thin (≈3000 Å) platinum catalysts. Our ultimate goal is to model observed thermo-mechano-chemical oscillations on a thin Pt (110) crystal under low pressure/vacuum conditions. Here we consider only the thermochemical aspects. We supplement the reaction-diffusion model of chemical kinetics by a heat balance equation for the catalyst surface, derived from the energetics of the reaction, adsorption, and desorption processes, and including radiation and conduction to the supporting environment. From the resulting distributed system a four-dimensional lumped ordinary differential equation is derived, which we study via dynamical systems theory, making use of time scale separation, and deriving reduced two-dimensional models. We show that key types of dynamics of the isothermal reaction persist, including multiple equilibria and periodic oscillations, but with the varying catalyst temperature “slaved” to the chemistry. We show how the stability of the periodic orbit branch changes as the catalyst’s area and thickness change, we verify that the lumped models capture the dominant dynamics of the distributed system, and we outline the major differences.

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The protective effect of erythropoietin (EPO) on tissues following ischemia and reperfusion injuries remains poorly understood. We aimed to investigate the effect of EPO in preventing endotoxin-induced organ damage. Rat model of multiple organ failure (MOF) was established by tail vein injection of 10 mg/kg lipopolysaccharide (LPS). Recombinant human EPO treatment (5000 U/kg) was administered by tail vein injection at 30 min after LPS challenge. Twenty-four h after EPO treatment, changes in serum enzyme levels, including aspartate aminotransferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN) and creatinine (Cr), were evaluated by biochemical analysis. Serum levels of tumor necrosis factor-α (TNF-α) were determined by using immunoradiometric assay. Histological examination of tissue sections was carried out by hematoxylin and eosin staining, while ultrastructure evaluation of organ tissues was assessed by transmission electron microscopy. Protein expression levels were detected by using Western blotting. EPO treatment showed a modest effect in preventing LPS-induced elevation of AST, ALT, BUN, Cr, and TNF-α levels, and in protecting against LPS-induced tissue degeneration and injured ultrastructure in the lung, liver, and kidney. Moreover, LPS promoted phosphorylation of alanine aminotransferase (AKT) and increased nuclear factor-κB (NF-κB) activation in the lung, liver, and kidney (P<0.05 vs. control). However, EPO treatment significantly decreased the LPS-induced pAKT up-regulation in these tissues (P<0.05 vs. LPS treatment alone). The present study demonstrates that EPO may play a protective role against LPS-induced MOF by reducing the inflammatory response and tissue degeneration, possibly via the phosphatidylinositol 3-kinase/AKT and NF-κB signaling pathways.