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71.
Andrea Avena-Koenigsberger Joaquín Go?i Ricard Solé Olaf Sporns 《Journal of the Royal Society Interface》2015,12(103)
The structure of complex networks has attracted much attention in recent years. It has been noted that many real-world examples of networked systems share a set of common architectural features. This raises important questions about their origin, for example whether such network attributes reflect common design principles or constraints imposed by selectional forces that have shaped the evolution of network topology. Is it possible to place the many patterns and forms of complex networks into a common space that reveals their relations, and what are the main rules and driving forces that determine which positions in such a space are occupied by systems that have actually evolved? We suggest that these questions can be addressed by combining concepts from two currently relatively unconnected fields. One is theoretical morphology, which has conceptualized the relations between morphological traits defined by mathematical models of biological form. The second is network science, which provides numerous quantitative tools to measure and classify different patterns of local and global network architecture across disparate types of systems. Here, we explore a new theoretical concept that lies at the intersection between both fields, the ‘network morphospace’. Defined by axes that represent specific network traits, each point within such a space represents a location occupied by networks that share a set of common ‘morphological’ characteristics related to aspects of their connectivity. Mapping a network morphospace reveals the extent to which the space is filled by existing networks, thus allowing a distinction between actual and impossible designs and highlighting the generative potential of rules and constraints that pervade the evolution of complex systems. 相似文献
72.
A surface acoustic wave-based sample delivery and ionization method that requires minimal to no sample pretreatment and that can operate under ambient conditions is described. This miniaturized technology enables real-time, rapid, and high-throughput analysis of trace compounds in complex mixtures, especially high ionic strength and viscous samples that can be challenging for conventional ionization techniques such as electrospray ionization. This technique takes advantage of high order surface acoustic wave (SAW) vibrations that both manipulate small volumes of liquid mixtures containing trace analyte compounds and seamlessly transfers analytes from the liquid sample into gas phase ions for mass spectrometry (MS) analysis. Drugs in human whole blood and plasma and heavy metals in tap water have been successfully detected at nanomolar concentrations by coupling a SAW atomization and ionization device with an inexpensive, paper-based sample delivery system and mass spectrometer. The miniaturized SAW ionization unit requires only a modest operating power of 3 to 4 W and, therefore, provides a viable and efficient ionization platform for the real-time analysis of a wide range of compounds. 相似文献
73.
The effects of the presence of chlorinated species on soot formation have been studied in laminar diffusion flames burning
chlorinated hydrocarbons. Measurements have been made of the structure of a chlorinated laminar, diffusion flame that is stabilized
in a stagnation point flow around a porous cylinder. Comparisons have been made between a pure methane flame and a flame of
50% methane and 50% methyl chloride. Temperature profiles were obtained with a thermocouple. Laser Doppler velocimetry was
used to measure the velocity of the gas along the streamline. Laser extinction and scattering techniques were employed to
characterize the soot aerosol. It was found that the addition of the methyl chloride to methane caused soot production, as
measured by the soot volume fraction, to increase by at least an order of magnitude. 相似文献
74.
75.
RC Go LW Duke LE Harrell H Cody SS Bassett MF Folstein MS Albert JL Foster NA Sharrow D Blacker 《Canadian Metallurgical Quarterly》1997,10(4):161-167
Eating disorders are an increasing problem for society and the medical professions. The dental practitioner has an important role both in identifying the illnesses and in minimising its affects on the dentition. This paper highlights the features of the most common eating disorders and discusses the possible role of the dental profession in the long-term care of patients suffering from the problem. 相似文献
76.
A Fagot-Campagna RG Nelson WC Knowler DJ Pettitt DC Robbins O Go TK Welty ET Lee BV Howard 《Canadian Metallurgical Quarterly》1998,41(9):1002-1009
Animal studies suggest that lipids are risk factors for kidney diseases. Some prospective studies and clinical trials have reported predictive effects of lipoproteins on different stages of diabetic nephropathy in humans. We examined lipoprotein abnormalities to determine if they predict abnormal urinary excretion of albumin (> or = 30 mg albumin/g creatinine), using logistic regression. We followed 671 American Indians (211 men, 460 women) with Type II diabetes for a mean of 3.9 years (range 1.7-6.2). Participants were aged 45-74 years. They had normal excretion of albumin and normal serum creatinine at baseline. 67 men and 144 women developed abnormal excretion of albumin. In models controlled for age, treatment with oral hypoglycaemic agents or insulin, HbA1c, study site, degree of Indian heritage, mean arterial blood pressure, albumin excretion at baseline and duration of diabetes, a high HDL cholesterol was a protector for abnormal excretion of albumin in women [odds ratio (OR) comparing the 90th with the 10th percentile = 0.56, 95% confidence interval (CI) = 0.32-0.98], but not in men (OR = 1.5, 95% CI = 0.66-3.4). Further adjustment for obesity, insulin concentration, alcohol consumption or physical activity did not change the results. There was a tendency for high values of VLDL and total triglyceride and small LDL size to predict abnormal excretion of albumin in women only. We conclude that low HDL cholesterol was a risk factor for abnormal excretion of albumin in women, but not in men. Sex hormones may be responsible for sex differences in the association between HDL cholesterol and abnormal excretion of albumin. 相似文献
77.
Computed tomography remains the imaging modality of choice in the detection of two processes: acute intracranial hemorrhage and calcification; however, in the subacute and chronic stages of hemorrhage, MR imaging is more sensitive in aging and staging hemorrhage. FLAIR imaging increases the sensitivity of MR imaging in the detection of subarachnoid hemorrhage. The signal characteristics of calcification on MR imaging is variable, especially on T1-weighted images decreasing its detectability. CT is superior to MR imaging in the detection of calcification. A number of factors including slice thickness, as well as window width and level may affect the detectability of calcification on CT. 相似文献
78.
79.
The antimalarial drug mefloquine binds avidly to phospholipids in biomembranes. The thermodynamics of the partitioning process in dimyristoylphosphatidylcholine (DMPC) bilayers was investigated to give some insight into the drug-phospholipid interaction. Thermodynamic parameters for the partition equilibria were evaluated from the equilibrium partition coefficients measured as a function of temperature. Negative values of delta H and delta S were obtained for the transfer of mefloquine from the aqueous to the gel phase of the phospholipid. The partitioning is enthalpy controlled which suggests that mefloquine interacts strongly with the phospholipid phase. In contrast, the partitioning of mefloquine into the liquid crystalline phase of DMPC is entropy controlled which is typical of a hydrophobic interaction between mefloquine and the aqueous phase. The partitioning of mefloquine into the bulk solvents octanol and hexane were found to be enthalpy and entropy controlled, respectively. The enthalpy dominated partitioning of mefloquine into gel phase DMPC and octanol is attributed to the occurrence of hydrogen bonding and van der Waals interactions between solute and solvent. The flat shape of mefloquine may further aid its interaction with the orderly domains of the lipidic/organic phase. This is apparent from a comparison of the partitioning characteristics of another structurally related but conformationally different molecule, quinine into DMPC and octanol. 相似文献
80.
Peptides representing a sequence of 23 amino acid residues at the N terminus of human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp41 bind and subsequently induce fusion of large unilamellar vesicles (LUV), an activity presumably related to gp41 function in viral infection. These in vitro effects can be modulated by several factors that are known to affect HIV-1 infectivity and gp41-mediated virus-cell fusion. Peptide-induced membrane fusion but not peptide binding can be inhibited by two factors known to block gp41 activity: a polar amino acid substitution V --> E in position 2 and the presence of the N-terminal hexapeptide of gp41 in addition to the parent sequence. Whereas inclusion of the alternative gp120 receptor galactosylceramide in membranes has virtually no effect, membrane cholesterol stimulates fusion activity. In view of its putative physiological relevance, we have used the fusion activity of the peptides as a tool to evaluate the inhibitory effect of antivirals that might target this sequence. We describe three dissimilar effects: Amphotericin B inhibits in a cholesterol-independent way peptide-induced fusion but not binding, human serum albumin inhibits binding and consequently fusion, and dextran sulfate (M(r) 5000) does not affect either binding or fusion. 相似文献