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A continuous migration model with stable demography.
A probability model of a population undergoing migration, mutation, and mating in a geographic continuum R is constructed, and an integro-differential equation is derived for the probability of genetic identity. The equation is solved in one case, and asymptotic analysis done in others. Individuals at x, y epsilon R in the model mate with probability V(x, y) dt in any time interval (t, t + dt). In two dimensions, if V(x, y) = V(x - y) where V(x) approximately V(x/beta)/beta2 approaches a delta function, the equilibrium probability of identity vanishes as beta Leads to 0. The asymptotic rate at which this occurs is discussed for mutation rates u = u0 Greater than 0 and for beta approximately cua, alpha Greater than 0, and u Leads to 0.
A nonamidated peptide homologous to porcine peptide YY and neuropeptide YY.
A 37-residue peptide has been purified from the endocrine pancreas of the anglerfish. The first 36 residues were sequenced by gas phase Edman degradation. The sequence at the carboxyl-terminus was determined by sequencing the carboxyl-terminal tryptic dipeptide. The sequence of the peptide, which is consistent with the amino acid composition, was determined to be: Y X P X P X K X P X E X T X P X G X S X N X A X S X P X E X D X W X A X S X Y X Q X A X A X V X R X H X Y X V X N X L X I X T X R X Q X R X Y X G. Fast atom bombardment/mass spectrometry of the peptide identified a molecular ion with an average mass of 4221.3, in good agreement with the theoretical mass based upon the determined amino acid sequence. The peptide has an equal degree of sequence identity to both porcine neuropeptide YY (64%) and gastrointestinal peptide YY (64%), but less sequence identity to porcine pancreatic polypeptide (47%). Unlike the related mammalian peptides, the major form of the anglerfish peptide terminates in tyrosyl-glycine rather than tyrosineamide.
[Esthetic refinements in cheiloplasty or the use of the V, W, X, Y, Z technics].
Classically, V-wedge excision of the lip allows direct closure of defects less than a third of its width. But undue tension may cause dehiscence of the suture lines responsible of narrowing of the mouth and excessive scarring especially on the external mucosa. To avoid these aesthetic complications modified incision should be made: W followed by a V-Y advancement closure, completed by a Z plasty on the vermilion.
Advection diffusion in nonchaotic closed flows: non-Hermitian operators, universality, and localization.
The qualitative spectral properties characterizing the advection-diffusion operator in two-dimensional steady incompressible flows can be obtained from the analysis of simple model flows on the torus, the velocity field of which attains the simple expression v (x) = (0, v(y) (x) ) . For this class of simple flows, the advection-diffusion operator reduces to a one-dimensional Schrödinger operator in the presence of an imaginary potential, which shares some spectral analogies with non-Hermitian quantum operators (e.g., spectral invariance), and is characterized by eigenfunction localization. The latter property (i.e., eigenfunction localization) is strictly related to the occurrence of a universal scaling of the eigenvalue spectrum with the Peclet number, the scaling exponent of which depends exclusively on the local behavior of the potential close to its critical points. The analysis is extended to a class of unbounded non-Hermitian operators, which include the Laplacian and the biharmonic operators coupled to an imaginary potential as special cases.
Characteristic diameter pulse waveform patterns of the inferior vena cava in fetuses with abnormalities of cardiac structure.
BACKGROUND: Changes in the vessel lumen diameter pulse waveform closely follow changes in the transmural pressure pulse waveform. AIM: To study diameter pulse waveform recorded noninvasively from the fetal inferior vena cava (IVC) in fetuses with cardiac abnormality. STUDY DESIGN: A paired ultrasonic phase-locked echo tracking system with a high sampling frequency (3000 Hz) was used to follow the movement of diametrically opposite points of the IVC. The lumen was measured as the interval between these points. SUBJECTS: We studied 80 normal fetuses (20 to 40 weeks) and 11 fetuses with cardiac abnormality. RESULTS: The four component waves of the IVC diameter pulse waveform (A, X, V, Y) were identified and measured in the fetal recording. In the normal group, the A and V values increased linearly with advancing gestation. There was an increase in the depth of X and Y descents. Each cardiac abnormality produced characteristic changes in the A, X, V and Y waves of the IVC diameter pulse waveform. The most impressive IVC diameter pulse waveform pattern in fetal cardiac abnormality was the depth of the X descent from the A crest to X trough. In the circumstance of pulmonary stenosis, the A wave was large and prominent (deeper X descent, high pulsatility waveform). In the presence of a dilated right ventricle, or an incompetent tricuspid valve, the X descent was shallow (low pulsatility waveform). CONCLUSION: The fetal IVC diameter pulse waveform can be simply recorded. The high pulsatility waveform may result from increased end-diastolic pressure with a consequent increased resistance to flow into the ventricle from the atrium. The low pulsatility waveform may indicate depressed myocardial function.
Dawson type heteropolyanions. 3. Syntheses and 31P, 51V, and 183W NMR structural investigation of octadeca(molybdo-tungsto-vanado)diphosphates related to the [H2P2W12O48]12- anion.
The synthesis and multinuclear NMR characterization of mixed molybdenum-vanadium-tungsten polyoxometalates [P(2)Mo(x)V(y)W(18-(x+y))O(62)](n-) (x + y < or = 8) related to the Dawson structure are reported. The mixed species are obtained from the hexavacant anion [H(2)P(2)W(12)O(56)](12-) by successive condensation and hydrolysis reactions. The strategy of synthesis is mainly based on the steric control of hydrolysis reactions by the nature and the strength of the base, the relative kinetic lability of molybdenum and tungsten in hydrolysis reactions, and the conservation of the framework when vacant sites are refilled by new metal atoms. Rather good values of (31)P chemical shift variations can be predicted by an additive model taking into account the contribution of substituting groups, depending on their position in the structure. The influence of Mo/W and V/W substitutions on (183)W chemical shifts of the remaining W atoms has been discussed and seems to be preferentially passed on through corner junctions.
In vitro flow mapping of regurgitant jets. Systematic description of free jet with laser Doppler velocimetry.
BACKGROUND: Color Doppler and magnetic resonance imaging give pictures of abnormal jets within which the respective contribution of fluid mechanics and image artifacts are difficult to establish because of current technical limitations of these modalities. We conducted the present study to provide numerical descriptions of the velocity fields within regurgitant free jets. METHODS AND RESULTS: Laser Doppler measurements were collected in rigid models with pulsatile flow conditions, giving several series of two-dimensional flow images. The data were studied with the use of two-dimensional or M-mode flow images as well as regular plots. Numerical descriptions validated in steady flow conditions were tested at the various times of the cycle. In these free jets, the momentum was conserved throughout the cycle. The transverse velocity profiles were approximately similar. A central laminar core was found at peak ejection and during the deceleration. Its length (l = 4.08 d-0.036 mm, r = .99) and its diameter (d) were proportional to the orifice diameter. At peak ejection, the velocity decay was hyperbolic, and the transverse velocity profiles were clearly gaussian. The different relations that were tested could be combined in a single formula describing the velocity field: V(x,y,t peak) = V(O,O,t peak).4.(d/x).10(-45(y/x)2) (r = .92). CONCLUSIONS: These in vitro measurements demonstrated the presence of a central laminar core and similar transverse velocity profiles in free turbulent jets. This allowed us to validate a series of numerical relations that can be combined to describe the velocity fields at peak ejection. On the other hand, further studies are needed to describe the various singularities often encountered in pathology.
Cluster configurations in modulated EuVxMo8+/-yO14 crystals.
Three orthorhombic crystals of chemical formula Eu(x)V(y)Mo(8+/-z)O(14) were investigated by X-ray diffraction (Mo Kalpha radiation, lambda = 0.71073 Å). They have nearly the same lattice parameters (a approximately 11.3, b approximately 10.0, c approximately 9.2 Å), display one-dimensional incommensurate modulations of wavevector q* = gammac* and are characterized by the same superspace group Cmca(00gamma)s00. The crystals differ both in their compositions (namely Eu(0.976(6))V(1.13(5))Mo(7.10(5))O(14), Eu(0.986(4))V(1.10(3))Mo(7.30(1))O(14) and EuMo(7.96(1))O(14)) and in their gamma components [0.195 (2), 0.245 (2) and 0.286 (3), respectively]. The average structures of these crystals appear closely related to the structures of LaMo(7.7)O(14) (not modulated) and LaMo(8)O(14) (modulated); however, two main differences are outlined: first, the modulation direction is c in the Eu-containing crystals but b in the modulated La-containing crystal [q* = (1/3)b*], second, the Eu-containing crystals have centrosymmetric structures while the La-containing crystals have polar structures (space group C2ca). The Mo (or Mo and V) atoms are stacked to form (001) layers of metallic clusters. The density modulation of these structures implies the existence of the new types of clusters Mo(9), Mo(10), Mo(6)V(4), Mo(7)V(3) and Mo(8)V(2) besides the clusters M(8) (Mo(8), Mo(6)V(2) and Mo(7)V) and M(7) (Mo(7) and Mo(6)V) which are already known. Mo(8) units with cis and trans configurations and Mo(6)V(2) units with a trans configuration appear as the main cluster types in these crystals. The nature of the metallic clusters changes along c, but inside one (001) layer it is likely that only one cluster type with a given configuration is present. The main structural result is the formation, in some unit cells, of strong intercluster Mo-Mo, Mo-V or V-V bonds with distances close to 2.6 Å within a layer as well as between two neighbouring layers.
The fetal central venous pressure waveform in normal pregnancy and in umbilical placental insufficiency.
OBJECTIVE: Our purpose was to study the fetal central venous pressure waveform recorded noninvasively from the inferior vena cava in normal and complicated pregnancies by means of newly developed equipment to follow the vessel lumen diameter. STUDY DESIGN: A paired ultrasonic phase-locked loop echo tracking system with a high sampling frequency (3000 Hz) was used to follow the movement (point displacement) of diametrically opposite points of the vessel wall. The lumen was measured as the interval between these points. We studied 70 normal fetuses (20 to 40 weeks) and 54 complicated pregnancies with increased umbilical placental resistance. RESULTS: The four component waves of the central venous pressure waveform (A, X, V, Y) were identified and measured in the fetal recording. The crests of the A and V waves were of approximately equal height. An increase in the descent of the Y trough was observed with advancing gestation. By means of data from the normal group, the complicated group was divided into three subgroups. In 10 fetuses the waveform was normal. In 31 there was a high pulsatile pattern with deep descent from the A crest to X trough so that the pulsatility of the waveform appeared increased. In 13 this was shallow and the pulsatility appeared reduced. Clinical outcome (nonreactive fetal heart rate, percentile birth weight, days in neonatal intensive care unit) was significantly worse in both these latter two subgroups in comparison with normal and in the low compared with the high-pulsatile group. CONCLUSIONS: Human fetal central venous pressure waveforms can be simply recorded and represented by the transluminal diameter waveform. In fetal compromise the high pulsatility waveform may result from a reduced ventricular ejection and increased end-diastolic pressure in response to the increase in ventricular afterload caused by the placental vessel obliteration. In the most profoundly compromised fetuses the low pulsatility waveform may indicate depressed myocardial function and output.
Relaxation of classical particles in two-dimensional anharmonic single-well potentials.
The canonical ensemble relaxation function of a particle in a symmetric anharmonic potential well in D=1 is known to exhibit slow algebraic behavior [S. Sen, R. S. Sinkovits and S. Chakravarti, Phys. Rev. Lett. 77, 4855 (1996); R. S. Sinkovits, S. Sen, J. C. Phillips, and S. Chakravarti, Phys. Rev. E 59, 6497 (1999)]. In the present work, we report a study of relaxation of a particle in symmetric and asymmetric quartic anharmonic potential wells of the form V(x,y)=1 / 2 (x(2)+Cy2)+1 / 4 (x(2)+Cy2)(2) in D=2. The relaxation in the above system is identical to that in D=1 wells when C=0 (since it is then a D=1 system) and C=1. However, for 0 >1, the frequencies associated with well dynamics are strongly affected and hence the power spectra are altered as a function of C. Our calculations suggest that the exponents of the long-time tails associated with the relaxation processes are insensitive to D. In closing, we comment on the consequences of our analysis for the study of slow dynamics in interacting many-particle systems that are connected by harmonic springs with the individual particles in anharmonic potential wells.
Left atrial function: bridge to central and hormonal determinants of exercise capacity in patients with chronic heart failure.
UNLABELLED: The stroke volume response to exercise is a critical determinant in meeting peripheral metabolic demands in patients with chronic hear failure. The Left atrium, by its position, is important in coupling right and left ventricles, to left preload reserve and to modulate sympathetic activity. We performed this study to investigate the relationship between exercise capacity and diastolic and systolic left atrium function in patients with chronic heart failure. METHODS: We considered 128 consecutive patients with severe chronic heart failure (EF < 35%) due to ischemic or idiopathic dilated cardiomyopathy. Cardiac output, right atrial pressure, pulmonary artery pressures and mean pulmonary wedge pressure (A, X, V, Y wedge pressures) were determined during right cardiac catheterization. By Echocardiography evaluation, we measured atrial pressures and volume during early and late left atrial systolic filling and we calculated left atrial chamber stiffness by this equation P = A*eKV1. (P = left atrial pressure; A = elastic constant (mmHg*ml); e = the base of the natural logarithm; V1 = left atrial volume (ml); K = left atrial chamber stiffness constant (ml-1) = ln (V/X)/(maximal--minimal left atrial volumes)). All patients performed cardiopulmonary exercise test with modified Noughton protocol. Plasma norepinephrine and Atrial natriuretic factor levels were determined. RESULTS: Maximal and minimal left atrial volumes were inversely related to oxygen consumption (r = -.44, p < .001; r = -.61, p < .001). At rest, no differences were found in plasma norepinephrine concentrations (309 +/- 152 pg/ml vs 309 +/- 394 pg/ml; p = ns) and systemic vascular resistance (1706 +/- 435 vs 1771 +/- 524 dynes/cm sec-5; p = ns) in patients with large or normal left atrial volumes. During exercise the chronotropic response increased less in patients with large atrial volumes (56 +/- 13 vs 45 +/- 14; p = .001). The left atrial chamber stiffness constant was inversely related to peak oxygen consumption and exercise time. Patients with different chamber stiffness showed statistical difference in peak VO2 (16 +/- 4 vs 11 +/- 3 ml/kg/min; p = .0001). Left atrial ejection fraction was directly related to peak oxygen consumption (r = 0.55), but the most strongly correlation was with atrial filling fraction (r = .67). CONCLUSIONS: This study demonstrates a strong relationship between left atrial function and exercise capacity in patients with chronic heart failure.
Haplospecific polymorphism between HLA B and tumor necrosis factor.
Polymorphisms were sought between HLA B and tumor necrosis factor (TNF) using three genomic probes. Extensive polymorphism was detected within a panel of 50 cell lines including 37 homozygotes representing 21 different ancestral haplotypes (AH). Following Taq I digestion of genomic DNA, we observed three allelic patterns with probe X (R17A) and four with probe V (R9A). Seven different allelic patterns were found with probe Y (M20A) after Taq I + Rsa I digestion. Family studies showed that the Y, X, and V alleles were inherited and segregated with HLA haplotypes. A striking feature of the allelic patterns detected by these probes was that cells with the same AH had identical Y, X, and V alleles (i.e., the alleles were haplotypic). Of 15 different Y-X-V haplotypes observed, 11 were found to be specific for a particular AH (i.e., were haplospecific). Four were shared by more than one AH, but in these instances there were extensive similarities in other regions within the major histocompatibility complex (MHC), for example, the Japanese 46.2 (HLA Bw46-DRw8) and the Chinese 46.1 (Bw46-DR9) share all alleles between HLA C and C4 and differ only in class II, suggesting their relatively recent divergence by recombination between C4 and DR. Surprisingly, two insulin-dependent diabetes mellitus (IDDM)-resistant but race-specific AHs 52.1 (Bw52-DRB1*1502, Japanese) and 7.1 (B7-DRB1*1501, Caucasoid) carry the same Y-X-V haplotype, suggesting the possibility of localizing gene(s) relevant to IDDM. The present study confirms that MHC AHs have been conserved en bloc, including the region between HLA B and TNF.
A review of host major-gene resistance to potato viruses X, Y, A and V in potato: genes, genetics and mapped locations.
In view of modern developments in the technologies available for breeding potatoes for resistance to virus diseases, it is timely to review the host major genes that confer resistance, in Solanum species, to potato viruses X, Y, A and V (the viruses for which the resistance genes have been most extensively studied). Over the course of 60 years, many such genes in Solanum species have been characterized: a comprehensive list is presented. Inheritance studies are reviewed, including linkage studies and molecular mapping, and the positions of resistance genes mapped so far are listed. It is apparent from recent research that disease resistance genes are often clustered in particular regions of the chromosomes; the significance of these resistance gene clusters is discussed. The information presented will be useful for potato breeding, and for genetic and mapping studies and gene cloning.
Donor insemination (transsexual): parentage -- X, Y and Z v. United Kingdom.
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Solubility of human enamel mineral.
The solubility of human enamel was investigated in dilute phosphoric acid solutions (0.07 mMols/L to 1.54 mMols/L) under controlled partial pressures of CO2 (0.005% to 3.33% in mixtures with N2) at 25 degrees C. The enamel mineral was considered as carbonatoapatite containing acid phosphate having the stoichiometry [Ca]5-x-y[HPO4]v[PO4]3-x[CO3]w[OH]l-x-y. During equilibration, a second apatitic phase precipitated, as observed under the electronmicroscope. Solubility models are advanced consistent with the adapted stoichiometry and the precipitation of the second phase. The latter appears to have a carbonate content similar to that of the enamel mineral even when precipitated under the lowest partial pressure of CO2, suggesting that a molar content of about 0.3 of carbonate stabilizes the apatitic lattice. Based on the adopted stoichiometry of enamel mineral, Ca4.34 (HPO4).08 (CO3).29 (PO4)2.63 (OH).05, its solubility product constant was calculated as Ksp = 1.74 (+/- 0.081)x10(-6), expressed as the mean activity product.
A novel esterase from Burkholderia gladioli which shows high deacetylation activity on cephalosporins is related to beta-lactamases and DD-peptidases.
The gene (estB) encoding for a novel esterase (EstB) from Burkholderia gladioli (formerly Pseudomonas marginata) NCPPB 1891 was cloned in Escherichia coli. Sequence analysis showed an open reading frame encoding a polypeptide of 392 amino acid residues, with a molecular mass of about 42 kDa. Comparison of the amino acid sequence with those of other homologous enzymes indicated homologies to beta-lactamases, penicillin binding proteins and DD-peptidases. The serine residue (Ser(75)) which is located within a present class A beta-lactamase motif ([F,Y]-X-[L,I,V,M,F,Y]-X-S-[T,V]-X-K-X-X-X-X-[A,G,L]-X-X-[L,C]) was identified by site-directed mutagenesis to represent the active nucleophile. A second serine residue (Ser(149)) which is located within a G-x-S-x-G motif which is typically found in esterases and lipases was demonstrated not to play a significant role in enzyme function. The estB gene was overexpressed in E. coli using a tac promoter-based expression system. Investigation of EstB protein with respect to the ability to hydrolyse beta-lactam substrates clearly demonstrated that this protein has no beta-lactamase activity. The recombinant enzyme is active on triglycerides and on nitrophenyl esters with acyl chain lengths up to C6. The preference for short chain length substrates indicated that EstB is a typical carboxylesterase. As a special feature EstB esterase was found to have high deacetylation activity on cephalosporin derivatives.
[Reptide alkaloids. V. Structures of adouetines X,Y,Y1, and Z, the alkaloids of Waltheria americana L. (Sterculiaceae)].
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