Electric mobility of bivalent cations in the presence of an anionic polysaccharide.

The electrophoretic mobilities of bivalent cations (Ca⁺⁺ and Sr⁺⁺) were measured in the presence of a linear anionic polysaccharide extracted from cartilage—chondroitin sulfate. The experimental results were analyzed according to Manning's treatment which involves only the charge-density parameter ξ related to the structure of the polyion and the charge of the counterion. The comparison between the electrophoretic mobility and the self-diffusion coefficient enabled us to determine the apparent charge of the counterions in the different domains of concentration.     

A three‐dimensional numerical model investigation of the impact of submerged macrophytes on flow dynamics in a large fluvial lake

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Studies of DNA Organization in Hydrated Spermidine-Condensed DNA Toruses and Spermidine-DNA Fibres

Abstract

We have investigated in vitro spermidine-condensed DNA preparations by both biochemical and freeze-etch electron microscopic approaches. These studies lead us to the conclusion that the reversibly condensed preparations, qualitatively described by Manning's counterion condensation theory, contain disk-like torus structures largely comprised of unidirectional, circumferentially wrapped DNA. Stereoscopic measurements on stereomicrographs of DNA torus and fibre objects have demonstrated the feasibility of directly measuring DNA writhe or, for that matter, mapping any secondary, tertiary or quaternary structure features of a hydrated macromolecular array in which the features can be differentially highlighted by low replica metal shadow levels.     

Comparison of Poisson-Boltzmann and condensation model expression for the colligative properties of cylindrical polyions

Closed-form expression have been derived for the polyelectrolyte contribution to the colligative properties of solutions containing rodlike polyions in the presence of excess added salt. The derivations are based on: the conventional Poisson-Boltzmann equation for cylindrical symmetry; the thermodynamics of the cell model developed by Marcus [J. Chem. Phys. 23 , 1057–1068 (1955)]; and an equation derived from the cylindrical Poisson-Boltzmann cell model by Anderson and Record [Biophys. Chem. 11 , 353–360 (1980)]. Subject to the inherent limitations of the Poisson-Boltzmann approximation [Fixman (1979) J. Chem. Phys. 70 , 4995–5005], the resulting expressions are nevertheless applicable outside the “limit of infinite dilution.” They conform over a range of salt concentrations to the limiting laws deduced by Manning from the hypothesis of counterion condensation [J. Chem. Phys. 51 , 924–933 (1969)]. This hypothesis is found to be compatible with the Poisson-Boltzmann cell model but is not required in the derivation of the thermodynamic coefficients presented here. It is demonstrated that the magnitude of the polyion axial charge density plays a critical role in determining the low-salt limiting forms of the colligative properties obtained from the Poisson-Boltzmann equation, in close analogy with Manning's model.     

Thermodynamic stability of the ordered conformations of carrageenan polyelectrolytes

Manning's counterion condensation theory has been applied to the temperature-induced conformational transition of κ- and ι-carrageenan in the solution and gel states. The formalism of the theory has been extended to transitions between conformations with charge densities below or across the counterion condensation threshold. Measurements of the dependence of the melting temperature on ionic strength, and of the enthalpy of melting, are interpreted with the theory as indicating that the conformational transition is intramolecular and that side-by-side dimerization of chains gives rise to the gel structure.     

Salt Dependence of DNA Structural Stabilities in Solution. Theoretical Predictions Versus Experiments

Abstract

The predictions of currently available theories for treating DNA-diffuse ionic cloud free energy contributions to conformational stability have been tested against experimental data for salt induced B-Z and B-A transitions. The theories considered are (i) Manning's counterion condensation approach (CC), (ii) the idealized Poisson-Boltzmann approximation (PB), and (iii) the potentials of mean force (PMF) approach proposed by Soumpasis. As far as we can judge from comparison with the set of experimental data currently available, it is found that only the latter theory yields satisfactory quantitative results for the dependence of the B-Z and B-A relative stabilities on monovalent salt concentration. The correct application of the PB and CC theories does not yield very low salt Z-B transitions, in contradiction to earlier assertions. At low salt concentrations the PB theory is qualitatively correct in predicting that the B form is electrostatically more favorable than both the A and B forms, whereas the CC theory is qualitatively wrong predicting that Z-DNA is more stable than both B and A DNA.     

The effect of counter-ion substitution on the transport properties of polyelectrolyte solutions

The effects of counter-ion substitution in aqueous polyelectrolyte solutions (chondroitin sulfate) on the two main transport phenomena of the ionic species, self-diffusion and electrical mobility, were studied experimentally by tracer methods and dynamic light scattering. The data were analyzed with respect to counter-ion condensation and stoichiometric substitution of low-ionic counterions by high-ionic charge ones and compared to Manning's theory. Substitution effects on the apparent charge of the macro-ion were derived from the transport data using an extended Nernst-Einstein relationship and discussed in the light of the condensation effect in polyelectrolyte solutions. The effective charge of the polyion (i.e., its residual charge after condensation of counter-ions) and the charge difference between the substituting counter-ions appear determinant in the mechanism of substitution.     

A ligand binding model of counterion condensation to finite length polyelectrolytes

A ligand binding model of counterion association in finite length polyelectrolytes is presented. This model introduces counterion condensation features into a binding formalism. It agrees well with the predictions of other finite length models and is consistent with experimental data on helix–coil melting transitions for short nucleic acid oligomers. This model uses a discrete charge distribution for the polyelectrolyte. An expression for the electrostatic self-energy of finite length polyelectrolytes is derived using the Euler–Maclaurin sum formula. This sum is shown to be accurate over a wide range of salt concentrations. This electrostatic term is used in an energy minimization analysis. The energy minimization is solved analytically using a Lagrange inversion formula. This general procedure gives a rapidly convergent series and requires no assumptions with regard to “limiting law” behavior. However, when used in the Manning minimization formalism [(1977) Biophysical Chemistry, 24 , 2086], the volume of the condensed phase becomes unrealistically large at low ionic strength. The ligand binding model does not have a condensed phase volume as a parameter. It provides a single expression that agrees both with Manning's theory and with the theory of Ramanathan and Woodbury [(1982) Journal of Chemical Physics 77 , 4133] under the respective conditions of these theories.     

Advocating the Advocates

Abstract

Charles Fowler. Can We Rescue the Arts for America's Children? Coming to Our Senses—10 Years Later. New York: American Council for the Arts, 1988. 181 pages. $14.95 paperback.     

Deep Convolution Neural Network Based System for Early Diagnosis of Alzheimer's Disease

ObjectivesAlzheimer's Disease (AD) is the most general type of dementia. In all leading countries, it is one of the primary reasons of death in senior citizens. Currently, it is diagnosed by calculating the MSME score and by the manual study of MRI Scan. Also, different machine learning methods are utilized for automatic diagnosis but existing has some limitations in terms of accuracy. So, main objective of this paper to include a preprocessing method before CNN model to increase the accuracy of classification.Materials and methodIn this paper, we present a deep learning-based approach for detection of Alzheimer's Disease from ADNI database of Alzheimer's disease patients, the dataset contains fMRI and PET images of Alzheimer's patients along with normal person's image. We have applied 3D to 2D conversion and resizing of images before applying VGG-16 architecture of Convolution neural network for feature extraction. Finally, for classification SVM, Linear Discriminate, K means clustering, and Decision tree classifiers are used.ResultsThe experimental result shows that the average accuracy of 99.95% is achieved for the classification of the fMRI dataset, while the average accuracy of 73.46% is achieved with the PET dataset. On comparing results on the basis of accuracy, specificity, sensitivity and on some other parameters we found that these results are better than existing methods.Conclusionsthis paper, suggested a unique way to increase the performance of CNN models by applying some preprocessing on image dataset before sending to CNN architecture for feature extraction. We applied this method on ADNI database and on comparing the accuracies with other similar approaches it shows better results.     

Catalytic influence of heparin on auramine O hydrolysis: A basis for differentiating heparin from other glycosaminoglycans based on its properties as a polyelectrolyte

The basis for heparin's ability to accelerate the conversion of auramine O (AuO) to Michlers ketone [P. Band & A. Lukton (1982) Anal. Biochem. 120 , 19–24] is here explained in terms of well-known polyelectrolyte phenomena. Acceleration of this acidcatalyzed hydrolysis appears to be due to colocalization of the cationic dye and hydronium ion within the microenvironment of heparin's electrostatic domain. The dependence of reaction rate on polymer, dye, and hydronium ion concentration, ionic strength, and various ratios of these parameters is consistent with what others have observed for polyelectrolyte catalysts. Dextran sulfate, polyvinyl sulfate, and polyanethole sulfonate likewise accelerate this reaction, thus precluding any explanation of the catalysis in terms of a specific catalytic site. A striking aspect about the polyanion–AuO system is the inability of all other natural glycosaminoglycans tested to catalyze this reaction, despite their analogous polyanionic nature. Manning's limiting laws describing counterion condensation in polyelectrolyte solutions provide a simple context within which to interpret these results. Calculation of the structural linear charge density parameter, ξ, based on analytically determined sulfate-to-hexosamine ratios, reveals that heparin is unique among the glycosaminoglycans in possessing an ξ value greater than unity under the conditions described. Thus, heparin's differential ability to catalyze AuO hydrolysis is a reflection of the fact that only heparin is sulfated to an extent great enough to maintain ξ > 1, even when the negative charge of carboxylate groups is neutralized. It is proposed that this distinction may be important to the unique biochemical attributes of heparin and that such considerations may prove useful in establishing structure–function relationships when comparing different glycosaminoglycan classes.     

Investigation on oligo- and polygalacturonic acids by potentiometry and circular dichroism

The potentiometric data concerning the dependence of the apparent pK with the degree of neutralization and the nature of counterions (Na or Ca) of galacturonic oligomers and polymers are discussed. They are characterized by an apparent charge density λ_app which predicts their electrostatic behavior. The calculated osmotic coefficients from Katchalsky and Manning's theories are in good agreement with the experimental data obtained by potentiometry. The dependence of the osmotic coefficient (?_Ca) as a function of the polymer concentration is established by potentiometry and interpreted in terms of a multichain aggregation. In addition, it is proven that no Ca²⁺ is ever fixed in excess of stoichiometry. The dependence of CD spectra obtained under the same conditions as the pK measurements shows analogies between the two sets of results. The CD data, in agreement with ¹³C-nmr measurements, suggest that in dilute solutions the polymer adopts two conformations: one (acidic form) which may be represented by threefold screw symmetry and a second (Na or Ca form) which can be related to a twofold screw symmetry. The twofold screw symmetry is known to allow the formation of cooperative “egg-box” fixation of Ca without conformation change.     

La Flora Delle Gole di Popoli (Pescara)

Abstract

Flora of Popoli's gorges (Central Italy). — The results of floristic research developed from 1967 to 1969 at the Popoli's gorges (province of Pescara, in Abruzzo, Central Italy) are reported. Short accounts on the geographic position, on the geology and climate of the gorges are given, together with the floristic index of 696 entities, 4 of which are new for Abruzzo. For each species the biological and the phytogeographical categories are indicated; and for the whole of the flora the biological spectrum. This shows that this flora is a submediterranean one, with altitude influences. Critical remarks are developed about the taxonomy and distribution in the region of Abruzzo of several species wich looked particularly significant to the author.     

Nucleosomal Positioning and Genetic Divergence Study Based on DNA Flexibility Map

Abstract

Based on worm like chain model, DNA structural parameters—tilt, roll and rise, derived from crystallographic database have been used to determine the flexibility of DNA that regulates the nucleosomal translational positioning. Theoretically derived data has been compared to the experimental values available in Ioshikhes and Trifonov's database. The methodology has been extended to determine the flexibility of 18S rRNA genome in eukarya, where yeast shows a distinct difference when compared with mammals like human, mouse and rabbit.     

The image of loss: Jalal Toufic's filmic Beirut

Jalal Toufic's cinematic and literary pieces form a unique corpus within contemporary Arab filmmaking. His esthetic vision—built around a sublime understanding of image as loss—not only connects with the current ruins of the Lebanon he films, but also resonates with the classical tradition of the nasib in Arabic poetry.     

Ceramic sculpture of Russell Aitken

Abstract

Pongioli's blowing, and the scraping of the anonymous fiddlers had shaken the air in the great hall. This moved the air in Lord Edward's membrana tympani; the interlocked malleus, incus, and stirrup bones were set in motion so as to agitate the membrana of the oval window and raise an infinitesimal storm in the fluid of the labyrinth. The hairy endings of the auditory nerve shuddered like weeds in a rough sea; a vast number of obscure miracles were performed in the brain, and Lord Edward ecstatically whispered ‘Bach!’—Aldous Huxley, Point Counterpoint

Music is the supreme mystery of human knowledge.—Claude Levi-Strauss     

Note Sui Grani a Spighe Ramificate

Resumé

Chez les Blés branchus de l'espèce «turgidum» (Triticum turgidum compositum), il existe des sortes à thermostade plutôt froid (Blés d'hiver ou de semi-hiver) et des sortes à thermostade chaud, tièe ou «indifférent» (Blés de printemps).

Les Blés branchus de l'espèce «turgidum» apparaissent comme étant des plantes à photostade de jour long.

La plus ou moins grande rapidité de l'accomplissement du photostade, par rapport à la rapidité de l'assimilation des matières plastiques, détermine la structure, — non ramifiée ou ramifiée — de l'épi.     

Construction of a prognostic signature in Ewing's sarcoma: Based on metabolism-related genes

ObjectiveBy combining the expression profiles of metabolism-related genes (MRGS) with clinical information, the expression quantities of MRGS and the influence on development and prognosis were systematically analyzed, so as to provide a theoretical basis for the clinical study on the prognosis of Ewing's sarcoma.MethodsMRGs expression profiles of 64 patients with Ewing's sarcoma were obtained from GEO dataset. Univariate Cox regression analysis was used to identify metabolization-related differentially expressed genes (DEGs) related with prognosis in Ewing's sarcoma patients. Then, multivariate Cox analysis was used to calculate novel prognostic markers based on metabolism-related DEGs. Besides, We validate the model using ICGC datasets. Finally, the new prognostic index was verified on the basis of the prognostic models.ResultsMultivariate Cox regression analysis identified 74 metabolization-related DEGs, 25 of which were associated with Ewing's sarcoma patients' overall survival. Subsequently, we used 25 DEGs to construct metabolism-related prognostic signature for patients with Ewing's sarcoma. Based on the 18 DEGs regression coefficient, we propose the formula of each patient's risk score, and then divided the patients into high-risk group and low-risk group. The results indicated that the survival rate and survival time were higher in the low-risk group and lower in the high-risk group. Multivariate Cox analysis showed that risk score index was an independent prognostic factor for Ewing's sarcoma.ConclusionThe experimental results suggest that the 18 metabolism-related DEGs marker may be effective in predicting the prognosis of Ewing's sarcoma to some extent, helping to individualize treatment of patients at different risks.