bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytical investigation of transient molecular-motor-assisted transport in elongated cells
Authors: Kuznetsov Andrey , Avramenko Andriy 
Published: March 2008

Abstract
This paper investigates analytically the molecular-motor-assisted transport between the cell nucleus and cell membrane in an elongated cell, which allows the formulation of governing equations in a cylindrical coordinate system. This problem is relevant to biomimetic transport systems as well as to many biological processes occurring in living cells, such as the viral infection of a cell. The obtained analytical solution is shown to agree well with a high-accuracy numerical solution of the same problem. The developed analytical technique extends the applicability of the generalized Fourier series method to a new type of problems involving intracellular transport of organelles.
Band structure and optical properties of antimony-sulfobromide: density functional calculation
Authors: Akkus Harun , Mamedov Amirullah , Kazempour Ali , Akbarzadeh Hadi 
Published: March 2008

Abstract
The electronic structure, linear, and non-linear optical properties of ferroelectric-semiconductor SbSBr are investigated in the non-polar (paraelectric) and polar (ferroelectric) phase, using the density functional methods in the generalized gradient approximation. The electronic band structure obtained shows that SbSBr has an indirect forbidden gap of 2.16 and 2.21 eV in the paraelectric and ferroelectric phase, respectively. The linear photon-energy dependent dielectric functions and some optical functions, such as absorption and extinction coefficients, refractive index, energy-loss function, reflectivity, and optical conductivity in both phases and photon-energy dependent second-order susceptibilities in the ferroelectric phase are calculated. Moreover, some important optical parameters, such as the effective number of valence electrons and the effective optical dielectric constant, are calculated in both phases.
Theoretical study of NO3− interacting with carbon nanotube
Authors: Guerini Silvete , Azevedo David , Lima Maria , Zanella Ivana , Filho Josué 
Published: March 2008

Abstract
This paper deals with quantum mechanical interaction of no
3− with (5,5) and (8,0) swcnts. To perform this we have made an ab initio calculation based on the density functional theory. In these framework the electronic density plays a central role and it was obtained of a self-consistent field form. It was observed through binding energy that NO3− molecule interacts with each nanotube in a physisorption regime. We propose these swcnts as a potential filter device due to reasonable interaction with NO3− molecule. Besides this type of filter could be reusable, therefore after the filtering, the swcnts could be separated from NO3− molecule.
Arbitrary /-state approximate solutions of the Hulthén potential through the exact quantization rule
Authors: Qiang Wen-Chao , Gao Yang , Zhou Run-Suo 
Published: March 2008

Abstract
In this paper, using the Exact Quantization Rule, we present approximate analytical solutions of the radial Schrödinger equation with non-zero l values for the Hulthén potential in the frame of an approximation to the centrifugal potential for any l states. The energy levels of all bound states can be easily calculated from the Exact Quantization Rule. Specifically, the normalized analytical wave functions are also obtained. Some energy eigenvalues are numerically calculated and compared with those obtained by other methods such as asymptotic iteration, supersymmetry, numerical integration methods, and the schroedinger Mathematica package.
Reflection of spin waves from a ferromagnetic multilayer with interfacial coupling of finite strength (reflection of spin waves from multilayer)
Authors: Gorobets Yuri , Reshetnyak Sergey 
Published: March 2008

Abstract
The reflection coefficient of bulk spin waves from a ferromagnetic multilayer with periodically modulated parameters of the exchange interaction, the uniaxial magnetic anisotropy and the saturation magnetization (a magnonic crystal) is calculated. The dependence of the reflection coefficient upon the spin wave frequency and the values of the bias magnetic field, the parameter of interfacial coupling, and the internal structure of the unit cell are investigated.
Exact analytical solutions for shallow impurity states in symmetrical paraboloidal and hemiparaboloidal quantum dots
Authors: Assaid M. , Aydi M’hamed , Feddi M. , Dujardin Françis 
Published: March 2008

Abstract
The problem of a shallow donor impurity located at the centre of a symmetrical paraboloidal quantum dot (SPQD) is solved exactly. The Schrödinger equation is separated in the paraboloidal coordinate system. Three different cases are discussed for the radial-like equations. For a bound donor, the energy is negative and the solutions are described by Whittaker functions. For a non-bound donor, the energy is positive and the solutions become coulomb wave functions. In the last case, the energy is equal to zero and the solutions reduce to Bessel functions. Using the boundary conditions at the dot surfaces, the variations of the donor kinetic and potential energies versus the size of the dot are obtained. The problem of a shallow donor impurity in a Hemiparaboloidal Quantum dot (HPQD) is also studied. It is shown that the wave functions of a HPQD are specific linear combinations of those of a SPQD.
Role of optical techniques in combined use of selected methods of medical imaging
Authors: Cysewska-Sobusiak A. , Wiczyński G. , Krawiecki Z. , Sowier A. 
Published: March 2008

AbstractThe subject matter of this paper concerns advanced techniques of imaging used in diagnosis and minimally invasive procedures applied in non-operable cases of the digestive tract tumour therapy. The role of optical techniques in current medical imaging is significant. Optical properties of transilluminated or illuminated tissues and organs depend on strong light absorption and scattering. Numerous issues related to the result interpretation still remain unsolved. Effectiveness and precision can be especially improved when some combined methods of imaging are used. Videoendoscopy imaging, X-ray imaging, and endoscopic ultrasound imaging are three complementary methods applied during the interventions described in this work. All interventions have concerned with the upper part of the digestive tract. Especially, interdisciplinary issues of combined medical imaging are presented using some examples of a modern approach to imaging of esophagus and biliary stenting. The selected examples of effects obtained during interventions assisted by combined imaging of the operation site are presented. The operator can have great control over the appearance of desirable effects as well as undesirable complications in order to work comfortably and safe.
K-Radical classes and product radical classes of MV-algebras
Authors: Jakubík Ján 
Published: March 2008

Abstract
For an MV-algebra let J
0() be the system of all closed ideals of ; this system is partially ordered by the set-theoretical inclusion. A radical class X of MV-algebras will be called a K-radical class iff, whenever ∈ X and is an MV-algebra with J
0() ≅ J
0(), then ∈ X. An analogous notation for lattice ordered groups was introduced and studied by Conrad. In the present paper we show that there is a one-to-one correspondence between K-radical classes of MV-algebras and K-radical classes of abelian lattice ordered groups. We also prove an analogous result for product radical classes of MV-algebras; product radical classes of lattice ordered groups were studied by Ton.
A note on the multiplicity in factor ring
Authors: Boďa Eduard 
Published: March 2008

Abstract
Let (R,m) = k[x
1,..., x
n](x
1,...,x
n) be a local polynomial ring (k being an algebraically closed field), and Q:= (F
1,..., F
r)R be a primary ideal in R with respect to a maximal ideal m ⊂ R. In this short note we give a formula for the multiplicity e
0 (QR/(F
1)R, R/(F
1)R).
Fundamental group of tiles associated to quadratic canonical number systems
Authors: Loridant Benoit 
Published: March 2008

Abstract
If A is a 2 × 2 expanding matrix with integral coefficients, and ⊂ ℤ2 a complete set of coset representatives of ℤ2/Aℤ2 with |det(A)| elements, then the set ℐ defined by Aℐ = ℐ + is a self-affine plane tile of ℝ2, provided that its two-dimensional Lebesgue measure is positive.
It was shown by Luo and Thuswaldner that the fundamental group of such a tile is either trivial or uncountable.
To a quadratic polynomial x
2 + Ax + B, A, B ∈ ℤ such that B ≥ 2 and −1 ≤ A ≤ B, one can attach a tile ℐ. Akiyama and Thuswaldner proved the triviality of the fundamental group of this tile for 2A < B + 3, by showing that a tile of this class is homeomorphic to a closed disk. The case 2A ≥ B + 3 is treated here by using the criterion given by Luo and Thuswaldner.
What determines emergence and net recruitment in an early succession plant community? Disentangling biotic and abiotic effects
Authors: Luzuriaga Arantzazu L. , Escudero Adrián 
Published: March 2008

AbstractQuestion: How do different regeneration scenarios shape species composition at two stages of plant community establishment (emergence and net recruitment) in an early succession?Location: Northern Spain.Methods: In a recently ploughed field, we created eight regeneration scenarios with light, water and nitrogen availability (five replicates each). Seedlings of all species were monitored from emergence to death during one year. Abiotic and biotic variables were measured per quadrat, i.e. soil texture, nutrient contents, seed bank densities and composition, neighbour plant species densitiy and cover. We used partial ordination methods in order to separate the effect of each environmental variable on species composition during emergence and adult net recruitment.Results: Light treatment determined annual plant density at time of emergence and recruitment, while water addition controlled the recruitment of perennials. Resource levels explained the emerged species composition; this effect was not translated into the recruited species composition. N‐addition and N + water addition were strongly associated to species abundances at the time of emergence. Seedling composition in summer was correlated with seed abundance of Cerastium spp. Neighbour species density and cover (mainly Arrhenatherum bulbosum, Agropyron repens and Picris echioides) explained significant fractions of species composition in the emergence and recruitment of the different cohorts. Interactions between species seem to vary in intensity among cohorts and in the key plant species that determined species abundance along succession.Conclusions: Our scenarios exerted contrasting and multilevel effects on the development of our early succession community. Resource availability differently affected plant density and species composition at different life stages. It is relevant to consider different life stages in plant community studies. However, regeneration conditions and other abiotic factors are not enough to explain how community composition varies.
A new and improved MILP formulation to optimize observability, redundancy and precision for sensor network problems
Authors: Kelly Jeffrey D. , Zyngier Danielle 
Published: March 2008

AbstractNew mathematical formulations of observability, redundancy, and an improved formulation for precision are provided which can be explicitly and analytically solved using mixed integer linear programming (MILP). By using the Schur complement found at the heart of both Gaussian elimination and Cholesky factorization for direct block matrix reduction and the variable classification and covariance calculations found in the reconciliation, regression, and regularization approach of Kelly, it is possible to efficiently optimize the overall instrumentation cost considering both estimability and variability as constraints during the branch‐and‐bound search of the MILP. Two illustrative examples are highlighted which minimize the cost of sensor placement subject to software and hardware redundancy of the measured variables, observability of the unmeasured variables, and their precision (i.e., inverse of their variance). This formulation is well suited to the problems of designing as well as retrofitting sensor locations in arbitrary networks. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Nicotine and lung development
Authors: Maritz Gert S. 
Published: March 2008

AbstractNicotine is found in tobacco smoke. It is a habit forming substance and is prescribed by health professionals to assist smokers to quit smoking. It is rapidly absorbed from the lungs of smokers. It crosses the placenta and accumulates in the developing fetus. Nicotine induces formation of oxygen radicals and at the same time also reduces the antioxidant capacity of the lungs. Nicotine and the oxidants cause point mutations in the DNA molecule, thereby changing the program that controls lung growth and maintenance of lung structure. The data available indicate that maternal nicotine exposure induces a persistent inhibition of glycolysis and a drastically increased cAMP level. These metabolic changes are thought to contribute to the faster aging of the lungs of the offspring of mothers that are exposed to nicotine via the placenta and mother's milk. The lungs of these animals are more susceptible to damage as shown by the gradual deterioration of the lung parenchyma. The rapid metabolic and structural aging of the lungs of the animals that were exposed to nicotine via the placenta and mother's milk, and thus during phases of lung development characterized by rapid cell division, is likely due to “programming” induced by nicotine. It is, therefore, not advisable to use nicotine during gestation and lactation. Birth Defects Research (Part C) 84:45–53, 2008. © 2008 Wiley‐Liss, Inc.
Nicotine and brain development
Authors: Dwyer Jennifer B. , Broide Ron S. , Leslie Frances M. 
Published: March 2008

AbstractPreclinical studies, using primarily rodent models, have shown acetylcholine to have a critical role in brain maturation via activation of nicotinic acetylcholine receptors (nAChRs), a structurally diverse family of ligand‐gated ion channels. nAChRs are widely expressed in fetal central nervous system, with transient upregulation in numerous brain regions during critical developmental periods. Activation of nAChRs can have varied developmental influences that are dependent on the pharmacologic properties and localization of the receptor. These include regulation of transmitter release, gene expression, neurite outgrowth, cell survival, and synapse formation and maturation. Aberrant exposure of fetal and neonatal brain to nicotine, through maternal smoking or nicotine replacement therapy (NRT), has been shown to have detrimental effects on cholinergic modulation of brain development. These include alterations in sexual differentiation of the brain, and in cell survival and synaptogenesis. Long‐term alterations in the functional status and pharmacologic properties of nAChRs may also occur, which result in modifications of specific neural circuitry such as the brainstem cardiorespiratory network and sensory thalamocortical gating. Such alterations in brain structure and function may contribute to clinically characterized deficits that result from maternal smoking, such as sudden infant death syndrome and auditory‐cognitive dysfunction. Although not the only constituent of tobacco smoke, there is now abundant evidence that nicotine is a neural teratogen. Thus, alternatives to NRT should be sought as tobacco cessation treatments in pregnant women. Birth Defects Research (Part C) 84:30–44, 2008. © 2008 Wiley‐Liss, Inc.
Cell‐based assays in GPCR drug discovery
Authors: Siehler Sandra 
Published: March 2008

AbstractG protein‐coupled receptors (GPCRs) transmit extracellular signals into the intracellular space, and play key roles in the physiological regulation of virtually every cell and tissue. Characteristic for the GPCR superfamily of cell surface receptors are their seven transmembrane‐spanning α‐helices, an extracellular N terminus and intracellular C‐terminal tail. Besides transmission of extracellular signals, their activity is modulated by cellular signals in an auto‐ or transregulatory fashion. The molecular complexity of GPCRs and their regulated signaling networks triggered the interest in academic research groups to explore them further, and their drugability and role in pathophysiology triggers pharmaceutical research towards small molecular weight ligands and therapeutic antibodies. About 30% of marketed drugs target GPCRs, which underlines the importance of this target class. This review describes current and emerging cellular assays for the ligand discovery of GPCRs.
Transcatheter treatment for systemic‐to‐pulmonary artery shunt obstruction in infants and children
Authors: Gillespie Matthew J. , Rome Jonathan J. 
Published: March 2008

AbstractSystemic‐to‐pulmonary artery shunt occlusion is a life‐threatening complication in patients with shunt‐dependent pulmonary blood flow. In the current era, the definitive diagnosis of shunt obstruction, and interventions to re‐establish shunt patency are performed in the catheterization laboratory, rather than the operating room. This review summarizes the various transcatheter techniques used by the interventionalist to re‐establish flow through occluded shunts. © 2008 Wiley‐Liss, Inc.
Carotid sheath rescue with a distal filter retrieval catheter
Authors: Chiam Paul T. L. , Roubin Gary S. 
Published: March 2008

AbstractSheath placement prior to carotid artery stenting is usually uncomplicated, and provides sufficient support for the procedure. In certain patients, especially those with unfavorable arch anatomy, tortuous vessels, and heavily calcified lesions, the sheath backs out into the aortic arch with compromise of wire and embolic protection device (EPD) position, and risk of “dragging” the EPD back through the lesion. A novel use of the distal filter retrieval catheter to “rescue” a prolapsed guide sheath is described. Use of the filter retrieval catheter as a “body” to retrack the sheath but not recapturing the deployed filter is a useful technique, since the equipment is already available. This avoided the need to pull a retrieved filter through a severe undilated carotid stenosis, reducing the amount of manipulations needed to reposition the sheath and thus reducing the risk of embolic events. © 2008 Wiley‐Liss, Inc.
Synthesis, Characterization, and Remarkable Biological Properties of Cyclodextrins Bearing Guanidinoalkylamino and Aminoalkylamino Groups on Their Primary Side
Authors: Mourtzis Nikolaos , Paravatou Maria , Mavridis Irene M. , Roberts Michael L. , Yannakopoulou Konstantina 
Published: March 2008

AbstractThe introduction of aminoalkylamino and guanidinoalkylamino substituents on the primary side of β‐ and γ‐cyclodextrin (CDs) resulted in a series of novel compounds that were extensively characterized by NMR spectroscopy and mass spectrometry. Bromination of the primary side of β‐ and γ‐CD, and reaction with neat alkylene diamines at a pressure of 7 atm afforded aminoalkylamino derivatives that were then guanylated at the primary amino group to give the corresponding guanidinoalkylamino‐CDs. These compounds are water soluble and display pKa values that allow them to be mostly protonated at neutral pH; for example, pK∼6.4 and pK∼9.5 for the aminoethylamino‐β‐CD and pK∼7.8 and pK∼11.0 for the guanidinoethylamino‐β‐CD. The title CDs are rigid, cyclic α‐D‐glucopyranose oligomers (heptamers or octamers) with branches that resemble lysine and arginine side chains that enable multiple interactions with suitable substrates. Thus, they bear similarities to known cell‐penetrating peptides. Indeed, the compounds were found to cross the membranes of HeLa cells and penetrate inside the cytoplasm quickly, the guadinylated ones within 15 min, as shown by fluorescence microscopy using fluorescein‐labeled derivatives. The toxicity of the compounds, measured by performing MTT tests, ranged from 50 to 300 μM. Furthermore, some of the aminated CDs could facilitate the transfection of DNA expressing the green fluorescent protein (GFP) in HEK 293T cells, with effectiveness comparable to the commercial agent Lipofectamine 2000. Circular dichroism, atomic force microscopy and electrophoresis experiments confirmed the strong interaction of the compounds with DNA. Because of their carbohydrate, non‐peptide nature the title compounds are not anticipated to be enzymatically labile or immunogenic, and thus they fulfill many of the criteria for non‐hazardous transport vectors in biological and pharmaceutical applications.
Properties of Alkali Metal Atoms Deposited on a MgO Surface: A Systematic Experimental and Theoretical Study
Authors: Finazzi Emanuele , Di Valentin Cristiana , Pacchioni Gianfranco , Chiesa Mario , Giamello Elio , Gao Hongjun , Lian Jichun , Risse Thomas , Freund Hans‐Joachim 
Published: March 2008

AbstractThe adsorption of small amounts of alkali metal atoms (Li, Na, K, Rb, and Cs) on the surface of MgO powders and thin films has been studied by means of EPR spectroscopy and DFT calculations. From a comparison of the measured and computed g values and hyperfine coupling constants (hfccs), a tentative assignment of the preferred adsorption sites is proposed. All atoms bind preferentially to surface oxide anions, but the location of these anions differs as a function of the deposition temperature and alkali metal. Lithium forms relatively strong bonds with MgO and can be stabilized at low temperatures on terrace sites. Potassium interacts very weakly with MgO and is stabilized only at specific sites, such as at reverse corners where it can interact simultaneously with three surface oxygen atoms (rubidium and cesium presumably behave in the same way). Sodium forms bonds of intermediate strength and could, in principle, populate more than a single site when deposited at room temperature. In all cases, large deviations of the hfccs from the gas‐phase values are observed. These reductions in the hfccs are due to polarization effects and are not connected to ionization of the alkali metal, which would lead to the formation of an adsorbed cation and a trapped electron. In this respect, hydrogen atoms behave completely differently. Under similar conditions, they form (H+)(e−) pairs. The reasons for this different behavior are discussed.
The Phenoxy/Phenol/Copper Cation: A Minimalistic Model of Bonding Relations in Active Centers of Mononuclear Copper Enzymes
Authors: Milko Petr , Roithová Jana , Schröder Detlef , Lemaire Joël , Schwarz Helmut , Holthausen Max C. 
Published: March 2008

AbstractThe “bare” complex [Cu(PhOH)(PhO)]+ with a phenol (PhOH) and a phenoxy (PhO) ligand bound to copper is studied both experimentally and computationally. The binding energies and structure of this complex are probed by mass spectrometry, infrared multi‐photon dissociation, and DFT calculations. Further, the monoligated complexes [Cu(PhO)]+ and [Cu(PhOH)]+ are investigated for comparison. DFT calculations on the [Cu(PhOH)(PhO)]+ complex predict that a phenolate anion interacts with copper(II) preferentially through the oxygen atom, and the bonding is associated with electron transfer to the metal center resulting in location of the unpaired electron at the aromatic moiety. Neutral phenol, on the other hand, interacts with copper preferentially through the aromatic ring. The same arrangements are also found in the monoligated complexes [Cu(PhO)]+ and [Cu(PhOH)]+. The calculations further indicate that the bond strength between the copper atom and the oxygen atom of the phenoxy radical is weakened by the presence of neutral phenol from 2.6 eV in bare [Cu(PhO)]+ to 2.1 eV in [Cu(PhOH)(PhO)]+.