Non-positive Correlation Research Articles

Impact of rotor–stator axial spacing on the gas–liquid–solid flow characteristics of a multiphase rotodynamic pump based on the Euler multi-fluid model

Multiphase rotodynamic pumps are used by the oil and gas industry to transport mixed media in pipelines. The characteristics of gas–liquid–solid flow in such pumps are significantly affected by the rotor–stator axial spacing so that further investigation is required. Based on the Euler multi-fluid model, the Computational Fluid Dynamics simulations were conducted in this study on the gas–liquid–solid multiphase rotodynamic pump at the rotor–stator axial spacings of 8, 10, 12, 14, and 16 mm, respectively. Changes in the pump's characteristics of external, multiphase flow, and pressure fluctuation were systematically analyzed by using ANSYS-CFX. The results showed that, an overall decreasing trend for the efficiency and head of the multiphase rotodynamic pump were demonstrated with increases in the rotor–stator axial spacing from 8 to 16 mm, which can be categorized into plummets I, moderation, and plummets II. As the rotor–stator axial spacing increased, the pressurization decreased from the inlet to outlet of guide vane while the aggregation of gas and solid increased. Additionally, vorticity increased and vortex structure was found to be more significant. As a result, the overall performance of the multiphase rotodynamic pump deteriorated. The pressure fluctuation in the multiphase rotodynamic pump was determined by the rotor–stator interaction and multiphase flow under gas–liquid–solid flow conditions, resulting in a non-positive correlation between the pressure fluctuation and the pump's external and internal flow characteristics. The location of maximum pressure fluctuation in the multiphase rotodynamic pump was changed from the impeller outlet to the guide vane inlet with increases in rotor–stator axial spacing.

Research on the effect of the variation of laser power on the contour control and performance control of laser cladding Ni60CuMo/IN718 coating on RuT300

To improve the wear resistance of Vermicular cast iron (RuT300) surface and overcome the crack inhibition bottleneck of high-hardness coating, a Ni60CuMo/IN718 composite coating was fabricated on RuT300 surface. Results indicate the cracking-free coating with a maximum hardness of 475 HV0.5 at 800 W. In addition, the hard phases MC (M=Nb, Ti), Cr7C3, CrB and the self-lubricating phase Cu3.8Ni were in-situ synthesized in the coating. Increasing laser power raised C content from substrate in the molten pool, providing more C elements for in-situ synthesized Cr7C3. Along with the consumption of Cr by carbide generation, the Cr content used for in-situ synthesized CrB decreases. Moreover, the hardness of Cr7C3 is lower than that of CrB, and the low-hardness Fe in the substrate intensifies the coatings dilution with the increasing power. Therefore, these effects result in a non-positive correlation between the increase of laser power and the coatings hardness. Due to the better anti-wear effect of the high hardness coating, the hardest coatings have the lowest wear rates at room temperature (RT). Abrasive wear is the primary wear mechanism for these coatings at RT. Fe2O3 generated by high temperature friction plays a lubricating effect, but the coating with the low hardness softened by high temperature is not conducive to the compaction and forming of the oxide film. As a result, coatings that produce a moderate oxide film at 300 °C and 500 °C have a lower wear rate in the same environment. The main wear mechanism for the coatings is oxidative wear.

Experimental Study on Dense Settlement of Full-Tail Mortar under Mechanical Vibration

There are some problems in the application of slurry preparation technology, such as wide fluctuation range of underflow concentration, long settling time and low efficiency of solid–liquid separation. This is an important basis for researching the thick settling law of tailings slurry under the action of mechanical vibration and its influencing factors to solve these problems. To this end, a small vibration thickening testing machine and vibrating rod were designed and developed. Physical simulation experiments were conducted to analyze the settling characteristics of tailings slurry under different vibration duration, start time, vibration frequency, and vibration inertia single factors. The results show that: (1) Mechanical vibration can effectively accelerate the settling speed of tailings particles, but the relationship between them is a non-positive correlation, and mechanical vibration time control with in 5 mins is the best. With the delay of starting the vibration time, the final mass concentration first increases and then decreases. (2) As the vibration frequency increases, the final mass concentration of tailings settlement first increases and then decreases. When the eccentric vibrator speed is 6000 r/min, the best slurry settlement effect is achieved. (3) When the vibration inertia of the eccentric oscillator is 0.158 g·cm2 and the final mass concentration reaches 70.1%, the settling time only takes 210 min. (4) The lower the slurry concentration, the faster the settling speed. As the initial concentration increases, the final thickening time is also gradually prolonged. The research results provide some insights for the rapid thickening technology of rake-free paste thickeners.

Charge transport in the spatially correlated exponential random energy landscape: effect of the nonpositive correlation function.

Charge transport in amorphous semiconductors having spatially correlated exponential density of states (DOS) has been considered for the arbitrary behavior of the correlation function of random energies. Average carrier velocity is exactly calculated for the quasi-equilibrium (nondispersive) transport regime. For the symmetric exponential DOS with exponential tails for low and high energies and nonpositive correlation function the temperature of the transition to the dispersive transport regime depends on correlation properties and becomes greater than the traditional estimation based on the DOS decay energy kT = U0. Another new feature of the transport in the landscape having nonpositive correlation function is the decrease of the mobility with the field in the low field region and development of the universal mobility field dependence for stronger fields.

Observing correlations between dark matter accretion and galaxy growth: II. testing the impact of galaxy mass, star formation indicator, and neighbour colours

ABSTRACT A crucial question in galaxy formation is what role new accretion has in star formation. Theoretical models have predicted a wide range of correlation strengths between halo accretion and galaxy star formation. Previously, we presented a technique to observationally constrain this correlation strength for isolated Milky Way mass galaxies at z ∼ 0.12, based on the correlation between halo accretion and the density profile of neighbouring galaxies. By applying this technique to both observational data from the Sloan Digital Sky Survey and simulation data from the UniverseMachine, where we can test different correlation strengths, we ruled out positive correlations between dark matter accretion and recent star formation activity. In this work, we expand our analysis by (1) applying our technique separately to red and blue neighbouring galaxies, which trace different infall populations, (2) correlating dark matter accretion rates with Dn 4000 measurements as a longer-term quiescence indicator than instantaneous star-formation rates, and (3) analysing higher-mass isolated central galaxies with 1011.0 < M*/M⊙ < 1011.5 out to z ∼ 0.18. In all cases, our results are consistent with non-positive correlation strengths with ≳ 85 per cent confidence, which is most consistent with models where processes such as gas recycling dominate star formation in massive z = 0 galaxies.

Direct comparison of two kinds of linoleic acid-docetaxel derivatives: in vitro cytotoxicity and in vivo antitumor activity.

Rational designed lipid-drug derivatives provide a favorable approach to improve the druggability of highly hydrophobic prototypes. It has been regarded as common sense that good cytotoxicity is the guarantee of superior anticancer efficacy for candidate derivatives screening. However, does it apply to lipid-drug conjugate-based self-assembled nanoparticles? Here, we established the above two derivatives and a non-correlation between the cytotoxic activity in vitro and drug efficacy in vivo was found. The IC50 of DSL NPs (DTX-S-LA nanoparticles) and DL NPs (DTX-LA nanoparticles) were 4.02 and 209.6ng/mL (DTX equivalent concentration), respectively. However, DL NPs unexpectedly showed stronger tumor inhibition abilities than DSL NPs. To explain the non-positive correlation between cytotoxicity and anticancer efficacy, more experiments were carried out in depth. Remarkably, the drug release studies in blood and PK study both suggested that the DL NPs were more stable to remain the structural integrity in circulation, which resulted in more accumulation in tumor sites. As verified by the bio-distribution study, DL NPs performed a superior target effect than DSL NPs in tumors. Our data indicated that the biological fates of so-called smart bond inserted derivatives in vivo are complicated; thus, simple cytotoxicity is not enough for derivatives screening, and the comprehensive understanding of both in vitro and in vivo behaviors is essential.

Hb adaptation to hypoxia in high-altitude fishes: Fresh evidence from schizothoracinae fishes in the Qinghai-Tibetan Plateau

Uncovering the genetic basis of hypoxic adaptation is one of the most active research areas in evolutionary biology. Among air-breathing vertebrates, modifications of hemoglobin (Hb) play a pivotal role in mediating an adaptive response to high-altitude hypoxia. However, the relative contributions in water-breathing organisms are still unclear. Here, we tested the Hb concentration of fish at different altitudes. All species showed species-specific Hb concentration, which has a non-positive correlation with altitude. Moreover, we investigated the expression of Hb genes by the RNA-seq and quantitative real-time PCR (qRT-PCR), and Hb composition by two-dimensional electrophoresis (2-DE). The results showed that the multiple Hb genes and isoforms are co-expressed in schizothoracinae fishes endemic to the Qinghai-Tibetan Plateau (QTP). Phylogenetic analyses of Hb genes indicated that the evolutionary relationships are not easily reconciled with the organismal phylogeny. Furthermore, evidence of positive selection was found in the Hb genes of schizothoracinae fishes through the selection pressure analysis. We demonstrated that positively selected sites likely facilitated the functional divergence of Hb isoforms. Taken together, this study indicated that the long-term maintenance of high Hb concentration may be a disadvantage for physiologically acclimating to high altitude hypoxia. Meanwhile, the genetically based modification of Hb-O2 affinity in schizothoracinae fishes might facilitate the evolutionary adaptation to Tibetan aqueous environments.

Nuclear symmetry energy from neutron skins and pure neutron matter in a Bayesian framework

We present an inference of the nuclear symmetry energy magnitude $J$, the slope $L$, and the curvature ${K}_{\mathrm{sym}}$ from combining neutron skin data on calcium, lead and tin isotopes, and our best theoretical information about pure neutron matter. A Bayesian framework is used to consistently incorporate prior knowledge of the pure neutron matter equation of state from chiral effective field theory calculations. Neutron skins are modeled in a fully quantum Skyrme-Hartree-Fock approach using an extended Skyrme energy-density functional which allows for independent variation of $J$, $L$, and ${K}_{\mathrm{sym}}$ without affecting the symmetric nuclear matter equation of state. The effect of using neutron skin data obtained with different physical probes is quantified. We argue that, given the existing data, combining the errors in quadrature is the more appropriate way to obtain unified errors for each nuclide, and in doing so we obtain 95% credible values of $J=31.3\begin{array}{c}+4.2\\ \ensuremath{-}5.9\end{array}\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$, $L=40\begin{array}{c}+34\\ \ensuremath{-}26\end{array}\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$, and ${K}_{\ensuremath{\tau}}=L\ensuremath{-}6{K}_{\mathrm{sym}}=\ensuremath{-}444\begin{array}{c}+100\\ \ensuremath{-}84\end{array}\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ using uninformative priors in $J$, $L$, and ${K}_{\mathrm{sym}}$, and $J=31.9\begin{array}{c}+1.3\\ \ensuremath{-}1.3\end{array}\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$, $L=37\begin{array}{c}+9\\ \ensuremath{-}8\end{array}\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$, and ${K}_{\ensuremath{\tau}}=\ensuremath{-}480\begin{array}{c}+25\\ \ensuremath{-}26\end{array}\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ using pure neutron matter (PNM) priors. We also show that the nonpositive correlation between $J$ and $L$ induced by neutron skin data is consistent with the nuclear droplet model. Neutron skin data alone are shown to place limits on the symmetry energy parameters as stringent as those obtained from chiral effective field theory alone, and when combined the 95% credible intervals are reduced by a factor of 4--5. It is also shown that the majority of nuclear interactions used in the literature have subsaturation density dependencies that are inconsistent with the combination of PNM priors and neutron skin data. We show measurements of lead and calcium neutron skins from upcoming parity-violating electron scattering experiments at Jefferson Lab and Mainz Superconducting Accelerator should obtain total error ranges $\mathrm{\ensuremath{\Delta}}L\ensuremath{\approx}50\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ and $\mathrm{\ensuremath{\Delta}}{K}_{\ensuremath{\tau}}\ensuremath{\approx}240\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ for uninformative priors and $\mathrm{\ensuremath{\Delta}}L\ensuremath{\approx}30\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ and $\mathrm{\ensuremath{\Delta}}{K}_{\ensuremath{\tau}}\ensuremath{\approx}100\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ for PNM priors at 67% credible bounds. Ahead of those experiments, we make predictions based on existing data on neutron skins of tin alone for the neutron skins of calcium and lead of $0.166\ifmmode\pm\else\textpm\fi{}0.008$ fm and $0.169\ifmmode\pm\else\textpm\fi{}0.014$ fm, respectively, using uninformative priors and $0.167\ifmmode\pm\else\textpm\fi{}0.008$ fm and $0.172\ifmmode\pm\else\textpm\fi{}0.015$ fm, respectively, using PNM priors.

Comparative study of fungal stability between Metarhizium strains after successive subculture

BackgroundMetarhizium species are considered one of the most outstanding powerful biological control agents that have been commercialized as biopesticides against various agricultural pests. Fungal stability with successive in vitro cultivation is a desirable trait for a large-scale production of fungal biopesticide.Main bodyThe new Egyptian strain Metarhizium anisopliae AUMC 3262 exhibited auspicious results when compared to Metarhizium brunneum ARSEF 4556 and M. brunneum V275 based on the variations of fungal characteristics, and essential quality control parameters (radial growth rate, conidial yield, viability, and virulence) after repeated in vitro subculturing. Changes in morphological characteristics were noted at both AUMC 3262 and ARSEF 4556. Following the 5th subculture, decreased conidial yield was noted, though radial growth remained stable, confirming that there is a non-positive correlation between conidial yield and radial growth rate for these species. In contrast, V275 showed a high morphological stability, conidial yield, and radial growth rate after repeated subculture. The three tested strains manifested high viability up to 100% and displayed the same pattern of Pr1 production. A slight variation was recorded in the median lethal time (LT50) values against the great wax moth, Galleria mellonella (L.), larvae between different subcultures of the tested Metarhizium strains.ConclusionThe new Egyptian strain AUMC 3262 showed a high stability with a slight difference in some parameters after the successive subculture compared to both ARSEF4556 and V275.

Strategic interactions inenvironmental regulation enforcement: evidence from Chinese cities.

Environmental regulation policy is the main means of pollution control and emission reduction and plays an irreplaceable role in environmental governance. However, due to the competitive behavior of economic development, the local government cannot effectively use the efficiency of environmental regulation to reduce the emission of environmental pollution. Taking 284 prefecture-level cities in China from 2005 to 2016 as samples, this paper studies the strategic interaction of environmental regulation enforcement by local governments under different circumstances and its impact on environmental pollution, so as to provide reference for national overall environmental governance planning. Through the research, it is found that the strategic interaction of environmental regulation enforcement among Chinese cities is characterized by the race-to-the-top. And the strategic interaction of environmental regulation enforcement among cities of the same economic level has the strongest impact. Besides, the impact of environmental regulation on environmental pollution has different intensity in different scenarios, showing a non-positive correlation. Most importantly, the Pollution Paradise exists in some cities under special circumstances.

Organic Single-Crystal Transistor with Unique Photo Responses and Its Application as Light-Stimulated Synaptic Devices.

Tremendous progress has been achieved on organic transistor-based photodetectors; however, because of the nonpositive correlation relationship between the photo/dark current ratio (P) and the gate voltage, the claimed best P, R (photoresponsivity), and D* (detectivity) can hardly be obtained simultaneously at a given gate voltage, which severely compromises the device performance. Here, a light and voltage dually gated transistor based on an organic semiconducting single crystal of 2,6-dithienylanthracene (DTAnt) is developed. Attributing to its very low on/off ratio in the dark and the remarkable increment of mobilities under illumination, this phototransistor shows good performance with a P of 3.83 × 103, R of 1.32 A W-1, and D* of 1.94 × 1012 Jones achieved simultaneously at Vg = -100 V. Besides, the good reversibility and repeatability of its light-responsive behavior allows for the construction of an artificial photonic neuromorphic device with demonstrated synaptic functions, including excitatory postsynaptic current, short/long-term memory , and pair-pulse facilitation/depression.

Assessing impacts of climate change and human activities on the abnormal correlation between actual evaporation and atmospheric evaporation demands in southeastern China

Generally, atmospheric evaporation demand (AED) shows a positive correlation with actual evaporation (AE) in the Yangtze River basin. In order to explore whether and why abnormal correlation exits in its five sub-basins, the temporal changes between AED and AE were compared, and then the impacts of climate change and human activities on abnormal correlations were assessed using the sensitivity method of Penman equation and the decomposition method of Budyko equation. The results indicated: (1) Pan evaporation and potential evaporation (indicators of AED) decreased at rates of up to -0.04 and -0.06 mm d−1 decade−1, respectively. In contrast, the water budget-derived evaporation (an indicator of AE) increased at the rate of 0.09 mm d−1 decade−1 in the Fuhe River basin and remained stable in other basins. Abnormal correlations (nonpositive correlations) were observed. (2) Decreasing net radiation and wind speed were major climate factors resulting in simultaneous temporal decreases in AED and AE. In contrast, afforestation was a major human factor leading to an increase in annual AE of 78 mm, but had no effect on AED. Afforestation was the primary driving force of the abnormal correlation. These results could provide water-energy guidance for urban climate change mitigation and flood/drought disaster management.

Suppression of propane cup-burner flame with HFO-1336mzz(Z) and its thermal stability study

Cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) conforms the most of necessary requirements as an environment-friendly extinguishant. However, its fire suppression performance has not been investigated. In this study, the fire suppression effectiveness of HFO-1336 was evaluated by a cup burner apparatus. The extinguishing concentration indicates nonpositive correlation with the fuel flow. On the other hand, to characterize the heat release of the reaction kernel, the temperature of the flame base was measured. The results showed that the temperature increased with HFO-1336 loading in the range of 2–5 %, while decreased as the concentration exceeded 5 %. In addition, the thermal decomposition properties of HFO-1336 were investigated over a temperature range of 100–800 ℃ and the products were analyzed by GC–MS. According to the detected products, the possible decomposition pathways were proposed and the extinguishing mechanism were discussed.

Influence of sediment media with different particle sizes on the nucleation of gas hydrate

In order to identify the effect of the particle size of sediment media on the nucleation of gas hydrate (hereinafter referred to as hydrate), we conducted gas hydrate nucleation kinetics experiments on six types of sediment media by using the high-pressure visualized reactor to measure the nucleation induction time of hydrates in sediment media with different particle sizes, based on the size of hydrate-bearing sediments in the Shenhu sea area of the South China Sea. Besides, the nucleation pattern of hydrates in sediment media was analyzed using the probability distribution function. Then, considering the effect of capillarity on the liquid-gas interfacial tension in the pores of sediments, a theoretical model for the pore radius of sediment-nucleation induction time of hydrates was established based on the Kashchiev model in combination with the Arrhenius equation. Finally, the calculation results of the theoretical model were compared with the experimental results. The following results were obtained. First, sediment media with larger particle sizes can help effectively shorten the nucleation induction time of hydrate and increase the concentration degree of induction time. Second, it is deduced from the theoretical model formula that, due to the interfacial tension of pores in the sediment, the nucleation induction time of hydrate increases and then decreases with the increase of sediment particle size, and there is a critical particle size. Third, there is a non-positive correlation between the sediment particle size and the change of hydrate formation difficulty. Within a certain range, the hydrate formation difficulty decreases gradually with the increase of sediment particle size. The research results provide a technical support for the exploration of marine gas hydrate deposits.

Relations of vegetation and water indices to volumetric soil water content in the Pantanal of Mato Grosso, Brazil

ABSTRACTThe measurement of the spatial distribution of volumetric soil water content in the Pantanal is highly difficult, but it can be performed indirectly from vegetation and water indices estimated by remote sensors. Thus, we assessed the relationship between volumetric soil water content (VSWC) and indices of the vegetation and water by TM Landsat 5 images in pasture and forest in the Pantanal of State of Mato Grosso. The VSWC was measured daily by a TDR on a non-flooded pasture in the Fazenda Miranda (FMI) and on a floodplain monodominant area of Vochysia divergens Pohl in the RPPN SESC Pantanal, locally known as Cambarazal (Cam). The VSWC in FMI was significantly correlated with the local rainfall, but it was 5 months delayed with rainfall in Cam. The temporal dynamics of vegetation and water indices were significantly correlated with VSWC. However, some spectral indices were negatively correlated with VSWC in Cam. It suggested different responses to VSWC in each study site. As the vegetation in FMI is water limited, the biomass increased directly with the VSWC during the wet season. The combined effect of the presence of dense woody vegetation and the occurrence of flooding in Cam influenced on the non-positive correlation between VSWC and vegetation and water indices. This article demonstrates the need for further research on the relationship of VSWC and spectra indices in the Pantanal.

Looming large in others' eyes: racial stereotypes illuminate dual adaptations for representing threat versus prestige as physical size

We hypothesize that, paralleling the evolution of human hierarchies from social structures based on dominance to those based on prestige, adaptations for representing status are derived from those for representing relative fighting capacity. Because both violence and status are important adaptive challenges, the mind contains the ancestral representational system as well as the derived system. When the two representational tasks conflict, owing to the exigent nature of potential violence, the former should take precedence over the latter. Indeed, separate literatures indicate that, despite the fact that threatening traits are generally deleterious to prestige, both threatening individuals and high-status individuals are conceptually represented as physically large. We investigated the interplay between size-based representations of threat versus prestige by examining racial danger stereotypes. In three studies, we demonstrate that (a) judgments of status only positively correlate with envisioned body size for members of groups stereotyped as safe, (b) group-based inferences of interpersonal threat are mediated by representations of physical size, (c) controlling for perceived threatening aggressiveness reduces or reverses non-positive correlations between status and size, and (d) individuating information about relative threat or status attenuates the influence of group danger stereotypes. These results support our proposal that ancestral threat-representation mechanisms and derived mechanisms for representing social rank coexist – and sometimes compete – in the mind.

Bernoulli Processes with Non-Positive Correlations

We deal with sequences of dependent Bernoulli variables with non positive correlations. Some special models for 1-dependent and 2-dependent 0–1 valued variables are analyzed, namely Bernoulli variables obtained by clipping a linear combination of iid variables. Formulas describing dependence of their correlation function on the clipping parameters are derived. The lower bound for the sum of autocorrelations of Bernoulli variables obtained by clipping a Gaussian process is provided.

Applying Spectral Decomposition in Value-at-Risk: Empirical Evidence from the Taiwan Stock Market

Controlling financial risk is an important issue for financial institutions. Value-at-risk is commonly used by practitioners to quantify risk and the Monte Carlo simulation is a popular method to calculate value-at-risk. Generally, the correlation matrix is decomposed by Cholesky decomposition in order to compute the value-at-risk of portfolio. However, it cannot be used to decompose a non-positive correlation matrix. This paper uses the spectral decomposition to solve the limitation of Cholesky method. The simulation results show that the Cholesky decomposition and the spectral decomposition have consistent results in the positive correlation case. For the non-positive case, the results of Monte Carlo simulation by spectral decomposition and other approaches are identical. Thus, we recommend that spectral decomposition is a better method to adopt in the value-at-risk approach for risk management.

Mean convergence theorems and weak laws of large numbers for weighted sums of random variables under a condition of weighted integrability

From the classical notion of uniform integrability of a sequence of random variables, a new concept of integrability (called h-integrability) is introduced for an array of random variables, concerning an array of constants. We prove that this concept is weaker than other previous related notions of integrability, such as Cesàro uniform integrability [Chandra, Sankhyā Ser. A 51 (1989) 309–317], uniform integrability concerning the weights [Ordóñez Cabrera, Collect. Math. 45 (1994) 121–132] and Cesàro α-integrability [Chandra and Goswami, J. Theoret. Probab. 16 (2003) 655–669]. Under this condition of integrability and appropriate conditions on the array of weights, mean convergence theorems and weak laws of large numbers for weighted sums of an array of random variables are obtained when the random variables are subject to some special kinds of dependence: (a) rowwise pairwise negative dependence, (b) rowwise pairwise non-positive correlation, (c) when the sequence of random variables in every row is φ-mixing. Finally, we consider the general weak law of large numbers in the sense of Gut [Statist. Probab. Lett. 14 (1992) 49–52] under this new condition of integrability for a Banach space setting.

Determination of a second-line chemotherapy agent for patients with colorectal cancer (CRC) after fluorouracil failure

3638 Background: Fluorouracil-based chemotherapy, such as with 5-FU/leucovorin, is standard as first-line chemotherapy for advanced CRCs. However, the best agent for chemotherapy after fluorouracil failure is still unknown. The primary objective of this study was to determine the best agent for second-line chemotherapy. Methods: Seventy-eight tumor specimens from CRC patients with no prior chemotherapy were obtained operatively and their sensitivity against five anticancer drugs, 5-FU, Mitomycin C, Cisplatine, Decetaxel and CPT-11, in an in vitro chemosensitivity test using CD-DST methods was analyzed. The chemosensitivity was expressed as the percentage T/C ratio, where T was the total volume of the treated group and C was that of the control group. Pearson's correlation coefficients were used to assess the relationship. P<0.05; statistically significant. A statistically significant correlation between two drugs was defined as a correlation of cross-resistance between them. Conversely, non-positive correlation was defined a correlation of no cross-resistance between them, with each of them having an independent spectrum. Results: Fifty-four specimens (colon, 30; rectum, 24) were successfully analyzed. The mean T/C ratios of 5-FU, Mitomycin C, Cisplatine, Decetaxel and CPT-11 were 79.1%, 69.9%, 81.2%, 59.4% and 63.8%, respectively. Although each of the agents has a different functional mechanism from that of 5-FU, with the exception CPT-11, all of them had a closely positive correlation with 5-FU. Conclusions: Only CPT-11 expressed an independent spectrum from 5-FU, thus indicating it to be the best agent for second-line chemotherapy after fluorouracil failure. No significant financial relationships to disclose.