bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exchange Constant in Fe–Cr Films from Spin-Wave Resonance Spectra
Authors: Rossing Thomas , Phillips T. G. 
Published: February 2004

Spin-wave spectra at 34 GHz have been observed in a series of iron-chromium films of varying composition. The spacing of the modes generally varies with the square of the spin wavevector k with the usual small distortion towards a linear spacing of the first few modes. In addition there is a region at the high mode number end of the spectrum which contains dependence on k4 or higher powers. The magnitude of these higher-order terms in the dispersion relation appears to be correlated with increasing chromium content.
The value of D determined from the k2 portion of the spectrum decreases with Cr content in approximate agreement with the value of D found by neutron-scattering experiments. The decrease of D and the increase of the k4 term with Cr content appear to be in qualitative agreement with the predictions of the itinerant electron model of spin waves in the iron group metals.
Motion of the Magnetic Moment of Thin Magnetic Films in a hf Rotating Field
Authors: Salanskii N. M. , Polskii A. I. 
Published: February 2004

This paper is devoted to some spectral investigation of the signal induced by the magnetic-moment motion of thin anisotropic Permalloy films. Film switching was carried out by a rotating field of frequency f=6 Mc/sec. The signal induced by magnetic-moment motion was detected by a measuring coil. Three spectral signal regions may be marked out, depending on the magnitude of the constant and hf rotating fields in the film plane: rotation frequencies, subharmonic oscillations, and higher harmonics.
Rotation-frequency signal-amplitude measurement settled three kinds of magnetic-moment motion depending on the field magnitude: oscillating, partial, and full rotation. There is a continuous spectrum noise near the rotation frequency in the case of partial rotation. A physical model of this spectrum is discussed.
Subharmonic oscillations with ¼, ½, ¾ frequency rotations were also detected. These oscillations arise in the presence of the constant field when the rotating field corresponds to partial rotation.
In the experiments with rotating fields corresponding to full magnetic-moment motion, amplitude harmonic relations are nearly with coherent rotation theory.
Status of Magneto-optical Experiments on Ordered Rare Earth Compounds
Authors: Leask M. J. M. 
Published: February 2004

Rare-earth compounds of interest in this field have ordering temperatures typically in the range 1°−4°K. This in turn implies internal fields of order 10 kOe, and therefore a potentially amenable experimental situation.
A number of such systems have been studied recently, where the magneto-optic effects due to the magnetic order have been studied for both the host rare-earth ion, and for small amounts of other rare-earth ions introduced as probes into the systems. The following are some of the general conclusions to be drawn from this work: (i) the relative sucess of a ``one-ion''-essentially molecular field-picture in explaining effects observed both as a function of temperature and as a function of externally applied field, (ii) the considerable difference between effects seen by host ions and effects seen by probe ions, (iii) observation of magnetic effects at temperatures above the ordering temperature, therefore attributable to magnetic short-range order in the system, and (iv) the considerable difference in detail between short-range-order effects seen in different systems.
Expansion of the Inhomogeneous Symplectic Lie Algebras T(2n)+ lim ←Sp(n) to Sp(n+2)
Authors: Nagel John G. , Shah K. Tahir 
Published: February 2004

We show that the semidirect sum G(n+N)≅T(Nn)+ lim ←Sp(n), with T(Nn) the ideal, can be expanded to Sp(n + N) iff N = 2. We derive a general formula for invariants of T(2n)+ lim ←Sp(n) and, besides, two general formulas for invariants of ISO(n1, n2).
As a conclusion we find that an expansion E(G) of an arbitrary Lie algebra G, in general, is not isomorphic to a deformation D(G) of G, but that there exists a Lie algebra G′ ⊇ G and a deformation D(G′) of G′ such that E(G) ≅ D(G′).
Quantum Corrections to the Second Virial Coefficient for a Square-Well Potential
Authors: Theumann Alba 
Published: February 2004

The first two quantum corrections to the classical second virial coefficient are evaluated in the case that the intermolecular potential is V(r)=∞,0&lt;r≤a,=−U&lt;0,a&lt;r≤b,=0,r&gt;b.
The first terms of the expansion of B(T) in powers of λ = (h2/2πmkT)½ are B(T)=23πNa3eUβ[1+(√98)λ/a+(π)−1(λ/a)2]+23πNb3(1−eUβ+(√98)(λ/b)[1+eUβ−2e12UβI0(12Uβ)]+(π)−1(λ/b)2{12(eUβ−1)−38;(πUβ)12e12Uβ[3I12(12Uβ)+I52(12Uβ)]+[1+12(Uβ)−1]3eUβ(Uβ)−12 Erf [(Uβ)12]−[1−12(Uβ)−1]3(Uβ)−12 Erfi [(Uβ)12]−32(Uβ)−1×(1+eUβ)})+O(λ3).The contribution of the bound states to the first quantum correction is evaluated and the behavior of B1(b)/B1 vs T is plotted.
The Spin Spectrum of an Unstable Particle
Authors: Fleming Gordon N. 
Published: February 2004

A state vector (vector-valued distribution) of an unstable particle can be a 3-momentum eigenvector in at most one inertial frame as a consequence of the necessary width of the energy spectrum. We investigate this frame dependence of momentum eigenvectors of unstable particles and demonstrate that:
(i) It is compatible with the principle of relativity.
(ii) It leads to a distinction between two ways of defining the spin of the particle which are equivalent for stable particles.
(iii) One definition, called kinematical spin, yields a precise value, and is determined by considerations of detailed balancing and other means of counting the degeneracy of the momentum eigenvectors.
(iv) The second definition, called dynamical spin, need not yield a sharp value, is determined by the dynamics of the decay process, and is measured by observing angular distributions of decay products.
It is shown that an unstable particle with vanishing kinematical spin (pion) may have a small admixture of non-isotropic angular distribution of unpolarized decay products in the rest frame of the decay products. The order of magnitude of the effect is estimated and the coupling between the mass and spin spectrum is studied in the case of local interactions without derivative coupling.
Male Bias in Road-kills of Macropods
Authors: Coulson Graeme 
Published: February 2004

I determined the sex of a total of 251 road-kills of six macropod species in southern Australia over a 13-year period. There was a significant bias towards males in five species, ranging from 65 to 92% males, but there was no difference from parity in the red kangaroo, Macropus rufus. Male eastern grey kangaroos, M. giganteus, and male western grey kangaroos, M. fuliginosus, probably behave in ways that expose them to vehicles more than females. Male-biased road-kills of swamp wallabies, Wallabia bicolor, may reflect skewed population sex ratios. There are insufficient data on the behaviour and population structure of the red-necked wallaby, M. rufogriseus, and rufous-bellied pademelon, Thylogale billardierii, to determine which explanation is responsible for male-biased road mortality in these species.
Diet, nutrition and the prevention of excess weight gain and obesity
Authors: BA Swinburn , I Caterson , JC Seidell , WPT James 
Published: February 2004

AbstractObjective:To review the evidence on the diet and nutrition causes of obesity and to recommend strategies to reduce obesity prevalence.Design:The evidence for potential aetiological factors and strategies to reduce obesity prevalence was reviewed, and recommendations for public health action, population nutrition goals and further research were made.Results:Protective factors against obesity were considered to be: regular physical activity (convincing); a high intake of dietary non-starch polysaccharides (NSP)/fibre (convincing); supportive home and school environments for children (probable); and breastfeeding (probable). Risk factors for obesity were considered to be sedentary lifestyles (convincing); a high intake of energy-dense, micronutrient-poor foods (convincing); heavy marketing of energy-dense foods and fast food outlets (probable); sugar-sweetened soft drinks and fruit juices (probable); adverse social and economic conditions—developed countries, especially in women (probable).A broad range of strategies were recommended to reduce obesity prevalence including: influencing the food supply to make healthy choices easier; reducing the marketing of energy dense foods and beverages to children; influencing urban environments and transport systems to promote physical activity; developing community-wide programmes in multiple settings; increased communications about healthy eating and physical activity; and improved health services to promote breastfeeding and manage currently overweight or obese people.Conclusions:The increasing prevalence of obesity is a major health threat in both low- and high income countries. Comprehensive programmes will be needed to turn the epidemic around.
Diet, nutrition and the prevention of hypertension and cardiovascular diseases
Authors: Reddy K Srinath , Katan Martijn B 
Published: February 2004

AbstractCardiovascular diseases (CVD) are growing contributors to global disease burdens, with epidemics of CVD advancing across many regions of the world which are experiencing a rapid health transition. Diet and nutrition have been extensively investigated as risk factors for major cardiovascular diseases like coronary heart disease (CHD) and stroke and are also linked to other cardiovascular risk factors like diabetes, high blood pressure and obesity. The interpretation of evidence needs to involve a critical appraisal of methodological issues related to measurement of exposures, nature of outcome variables, types of research design and careful separation of cause, consequence and confounding as the basis for observed associations.Adequate evidence is available, from studies conducted within and across populations, to link several nutrients, minerals, food groups and dietary patterns with an increased or decreased risk of CVD. Dietary fats associated with an increased risk of CHD includetrans–fats and saturated fats, while polyunsaturated fats are known to be protective. Dietary sodium is associated with elevation of blood pressure, while dietary potassium lowers the risk of hypertension and stroke. Regular frequent intake of fruits and vegetables is protective against hypertension, CHD and stroke. Composite diets (such as DASH diets, Mediterranean diet, ‘prudent’ diet) have been demonstrated to reduce the risk of hypertension and CHD. Sufficient knowledge exists to recommend nutritional interventions, at both population and individual levels, to reduce cardiovascular risk. That knowledge should now be translated into policies which promote healthy diets and discourage unhealthy diets. This requires coordinated action at the level of governments, international organizations, civil society and responsible sections of the food industry.
Directed evolution relieves product inhibition and confers in vivo function to a rationally designed tyrosine aminotransferase
Authors: Rothman Steven C. , Voorhies Mark , Kirsch Jack F. 
Published: February 2004

AbstractThe Escherichia coli aspartate (AATase) and tyrosine (TATase) aminotransferases share 43% sequence identity and 72% similarity, but AATase has only 0.08% and 0.01% of the TATase activities (kcat/Km) for tyrosine and phenylalanine, respectively. Approximately 5% of TATase activity was introduced into the AATase framework earlier both by rational design (six mutations, termed HEX) and by directed evolution (9–17 mutations). The enzymes realized from the latter procedure complement tyrosine auxotrophy in TATase deficient E. coli. HEX complements even more poorly than does wild‐type AATase, even though the (kcat/Km) value for tyrosine exhibited by HEX is similar to those of the enzymes found from directed evolution. HEX, however, is characterized by very low values of Km and KD for dicarboxylic ligands, and by a particularly slow release for oxaloacetate, the product of the reaction with aspartate and a TCA cycle intermediate. These observations suggest that HEX exists largely as an enzyme–product complex in vivo. HEX was therefore subjected to a single round of directed evolution with selection for complementation of tyrosine auxotrophy. A variant with a single amino acid substitution, A293D, exhibited substantially improved TATase function in vivo. The A293D mutation alleviates the tight binding to dicarboxylic ligands as Kms for aspartate and α‐ketoglutarate are >20‐fold higher in the HEX + A293D construct compared to HEX. This mutation also increased kcat/KmTyr threefold. A second mutation, I73V, elicited smaller but similar effects. Both residues are in close proximity to Arg292 and the mutations may function to modulate the arginine switch mechanism responsible for dual substrate recognition in TATases and HEX.
Enterococcus faecalis mevalonate kinase
Authors: Hedl Matija , Rodwell Victor W. 
Published: February 2004

AbstractGram‐positive pathogens synthesize isopentenyl diphosphate, the five‐carbon precursor of isoprenoids, via the mevalonate pathway. The enzymes of this pathway are essential for the survival of these organisms, and thus may represent possible targets for drug design. To extend our investigation of the mevalonate pathway in Enterococcus faecalis, we PCR‐amplified and cloned into pET‐28b the mvaK1 gene thought to encode mevalonate kinase, the fourth enzyme of the pathway. Following transformation of the construct EFK1‐pET28b into Escherichia coli BL21(DE3) cells, the expressed C‐terminally hexahistidine‐tagged protein was purified on a nickel affinity support to apparent homogeneity. The purified protein catalyzed the divalent ion‐dependent phosphorylation of mevalonate to mevalonate 5‐phosphate. The specific activity of the purified kinase was 24 μmole/min/mg protein. Based on sedimentation velocity data, E. faecalis mevalonate kinase exists in solution primarily as a monomer with a mass of 32.2 kD. Optimal activity occurred at pH 10 and at 37°C. ΔHa was 22 kcal/mole. Kinetic analysis suggested that the reaction proceeds via a sequential mechanism. Km values were 0.33 mM (mevalonate), 1.1 mM (ATP), and 3.3 mM (Mg2+). Unlike mammalian mevalonate kinases, E. faecalis mevalonate kinase utilized all tested nucleoside triphosphates as phosphoryl donors. ADP, but not AMP, inhibited the reaction with a Ki of 2.7 mM.
Correlation between sequence hydrophobicity and surface‐exposure pattern of database proteins
Authors: Moelbert Susanne , Emberly Eldon , Tang Chao 
Published: February 2004

AbstractHydrophobicity is thought to be one of the primary forces driving the folding of proteins. On average, hydrophobic residues occur preferentially in the core, whereas polar residues tend to occur at the surface of a folded protein. By analyzing the known protein structures, we quantify the degree to which the hydrophobicity sequence of a protein correlates with its pattern of surface exposure. We have assessed the statistical significance of this correlation for several hydrophobicity scales in the literature, and find that the computed correlations are significant but far from optimal. We show that this less than optimal correlation arises primarily from the large degree of mutations that naturally occurring proteins can tolerate. Lesser effects are due in part to forces other than hydrophobicity, and we quantify this by analyzing the surface‐exposure distributions of all amino acids. Lastly, we show that our database findings are consistent with those found from an off‐lattice hydrophobic–polar model of protein folding.
Combination of multiple alignment analysis and surface mapping paves a way for a detailed pathway reconstruction—The case of VHL (von Hippel‐Lindau) protein and angiogenesis regulatory pathway
Authors: Sikora Sergey , Godzik Adam 
Published: February 2004

AbstractUsing the tumor suppressor VHL protein as an example, we show that detailed analysis of conservation versus variation pattern in the multiple alignment can be coupled with the genomic pathway/complex conservation analysis to provide a more complete picture of the entire interaction/regulatory network. Results from the present study have allowed us to hypothesize that two additional proteins are involved in the VHL‐mediated regulation of angiogenesis. Detailed modeling also has led to a prediction of the possible interaction mode between the known and the proposed parts of the VHL complex. To aid in an analysis of the VHL protein regulation of HIF‐1α degradation, an important and only partially understood process that directly influences angiogenesis, we performed a comprehensive search for the orthologs of the VHL as well as for VHL‐interacting proteins in all the available eukaryotic genomes. Analysis of a multiple alignment of thus identified VHL orthologs reveals an unusually high degree of conservation of the surface amino acid residues that almost exactly correspond to positions mutated in the VHL disease‐associated tumors. In addition, these positions form well‐defined clusters in three‐dimensional space, and presence or absence of individual clusters correlates with the presence or absence of pathway elements in different genomes. We have also shown that relation trees derived from the multiple sequence alignment, functional surface‐mapping, and HIF‐1α degradation pathway structure are in complete agreement, linking the functional and structural evolution of the VHL protein and VHL‐dependent HIF‐1α degradation complex.
The solution structure of the pH‐induced monomer of dynein light‐chain LC8 from Drosophila
Authors: Makokha Moses , Huang Yuanpeng Janet , Montelione Gaetano , Edison Arthur S. , Barbar Elisar 
Published: February 2004

AbstractThe structure of Drosophila LC8 pH‐induced monomer has been determined by NMR spectroscopy using the program AutoStructure. The structure at pH 3 and 30°C is similar to the individual subunits of mammalian LC8 dimer with the exception that a β strand, which crosses between monomers to form an intersubunit β‐sheet in the dimer, is a flexible loop with turnlike conformations in the monomer. Increased flexibility in the interface region relative to the rest of the protein is confirmed by dynamic measurements based on 15N relaxation. Comparison of the monomer and dimer structures indicates that LC8 is not a domain swapped dimer.
The Role of Serum Immunoglobulin E in the Pathogenesis of Plasmodium falciparum Malaria in Ivorian Children
Authors: Seka‐Seka J. , Brouh Y. , Yapo‐Crézoit A. C. , Atseye N. H. 
Published: February 2004

AbstractThe aim of the study was to determine the role of immunoglobulin E (IgE) in the pathogenesis of Plasmodium falciparum malaria in Ivorian children. The study comprised of 90 Ivorian children of both sexes, aged 6–72 months: 30 children suffering from severe malaria, 30 suffering from mild malaria and 30 in good heath (serving as the control population). The children underwent a total serum IgE test for the determination of haemoglobin and platelet level and parasite density. We noted a significant rise in IgE level in the children affected with malaria. The level was higher when the malaria was more severe, increasing from 84.61 kUI/l in the control children to 339.9 kUI/l in the children with mild malaria and 659.9 kUI/l in children with severe malaria. Among the comatose patients with severe malaria, the increase in IgE level was related to the level of deterioration of the consciousness. Moreover, we noted a negative correlation between IgE level and the level of haemoglobin and between the IgE level and platelet level. These results are in accordance with the results found in literature and confirm the use of IgE level as an indicator of P. falciparum malaria.
Generation of Amyloid A Protein by the Cell Lines from Amyloid‐Susceptible and ‐Resistant Mice
Authors: Ham D. , Skoryna S. C. 
Published: February 2004

AbstractIt has been proposed that impaired degradation is the cause of amyloid A (AA) formation in reactive amyloidosis (Ham et al., Scand J Immunol 1997; 45: 354–60). The current SDS‐PAGE of the culture medium showed that the macrophage cell line from the amyloid‐susceptible mouse strain (ANA1) degraded amyloid precursor protein serum amyloid A into the AA‐like amyloidogenic product of approximately 8.6 kDa but went no further, whereas cells from the resistant strain (A/J10) cleared the AA‐like derivates proceeding to approximately 7.7 kDa products within the incubation period. Degradation occurred in the chemically defined medium at a slower rate than in the medium with serum. This may imply that a lack of the serum components as well as impaired degradation could contribute to the development of amyloidosis.
Modification of the Inhibitory Amino Acid for Epitope Peptide Binding onto Major Histocompatibility Complex Class II Molecules Enhances Immunogenicity of the Antigen
Authors: Chang S.‐H. , Kim J. , Lee K.‐Y. , Kim H.‐J. , Chung Y. J. , Park C. U. , Kim B. S. , Jang Y.‐S. 
Published: February 2004

AbstractPreviously, the arginine at hen egg‐white lysozyme 61 (HEL 61) was characterized as inhibiting T‐lymphocyte stimulation due to the inefficient binding of the arginine‐containing epitope peptide to the corresponding major histocompatibility complex class II molecules in C57BL/6 mice. In this study, we produced recombinant HEL, with arginine or alanine at HEL 61, and compared its ability to induce immune responses in mice to see whether modification of an inhibitory amino acid could enhance the immunogenicity of an inefficient antigen. Immunization of the mice with modified HEL induced strong antibody and T‐cell immune responses against the native antigen. The enhanced T‐cell immune response was due to a more specific elevation of the T‐cell responses to the HEL 46–61 epitope region than to other epitope regions, although recognition of the other epitope peptides of HEL was generally increased. Mass spectrometric analyses of the epitope peptides generated by splenic antigen‐presenting cells indicated that production of the epitope peptides encompassing HEL 46–61 was efficient using the modified antigen. These results suggest that modification of the critical amino acid residue(s) involved in hampering induction of an efficient immune response is an effective method to improve the immunogenicity of an inefficient antigen.
Humoral Proinflammatory Cytokine and SAA Generation Profiles and Spatio‐Temporal Relationship Between SAA and Lysosomal Cathepsin B and D in Murine Splenic Monocytoid Cells During AA Amyloidosis
Authors: Phipps‐Yonas H. , Pinard G. , Ali‐Khan Z. 
Published: February 2004

AbstractEvidence shows that tissue macrophages (MΦs), in mice undergoing AA amyloidosis, endocytose acute‐phase humoral serum amyloid A (SAA) and traffic it to lysosomes where it is degraded. Incomplete degradation of SAA leads to intracellular nascent AA fibril formation. In vitro, cathepsin (Cat) B is known to generate amyloidogenic SAA derivatives, whereas Cat D generates non‐amyloidogenic SAA derivatives, and interferon (IFN‐γ)‐treated MΦs show selective increase in Cat B concentration, a factor conducive to AA amyloidogenesis. To understand the cumulative effect of these factors in AA amyloidosis, humoral levels of SAA, IFN‐γ, tumour necrosis factor (TNF‐α) and granulocyte–macrophage colony‐stimulating factor were determined in azocasein (AZC)‐treated CD‐1 mice. We correlated these responses with the spatio‐temporal distribution of SAA, Cat B‐ and Cat D‐immunoreactive splenic reticuloendothelial (RE) cells. AZC‐treated CD‐1 mice similar to that of A/J mice showed partial amyloid resistance; their peak humoral IFN‐γ and SAA responses overlapped during the pre‐amyloid phase. Unexpectedly, Cat D immunoreactivity (IR), instead of Cat B IR, was predominant in the splenic RE cells, indicating an apparent lack of causal relationship between IFN‐γ‐mediated increase in Cat B expression. Partial amyloid resistance in CD‐1 mice, probably a genetic trait, may be linked to high levels of Cat D expression, causing a delay in nascent AA fibril formation.