Straight Theta Research Articles

Linkage of Paget Disease of Bone to a Novel Region on Human Chromosome 18q23

Paget disease of bone (PDB) is characterized by increased osteoclast activity and localized abnormal bone remodeling. PDB has a significant genetic component, with evidence of linkage to chromosomes 6p21.3 (PDB1) and 18q21-22 (PDB2) in some pedigrees. There is evidence of genetic heterogeneity, with other pedigrees showing negative linkage to these regions. TNFRSF11A, a gene that is essential for osteoclast formation and that encodes receptor activator of nuclear factor-kappa B (RANK), has been mapped to the PDB2 region. TNFRSF11A mutations that segregate in pedigrees with either familial expansile osteolysis or familial PDB have been identified; however, linkage studies and mutation screening have excluded the involvement of RANK in the majority of patients with PDB. We have excluded linkage, both to PDB1 and to PDB2, in a large multigenerational pedigree with multiple family members affected by PDB. We have conducted a genomewide scan of this pedigree, followed by fine mapping and multipoint analysis in regions of interest. The peak two-point LOD scores from the genomewide scan were 2.75, at D7S507, and 1.76, at D18S70. Multipoint and haplotype analysis of markers flanking D7S507 did not support linkage to this region. Haplotype analysis of markers flanking D18S70 demonstrated a haplotype segregating with PDB in a large subpedigree. This subpedigree had a significantly lower age at diagnosis than the rest of the pedigree (51.2+/-8.5 vs. 64.2+/-9.7 years; P=.0012). Linkage analysis of this subpedigree demonstrated a peak two-point LOD score of 4.23, at marker D18S1390 (straight theta=0), and a peak multipoint LOD score of 4.71, at marker D18S70. Our data are consistent with genetic heterogeneity within the pedigree and indicate that 18q23 harbors a novel susceptibility gene for PDB.

Novel mental retardation-epilepsy syndrome linked to Xp21.1-p11.4.

We evaluated a kindred with X-linked mental retardation and epilepsy. Seven affected males with mild to moderate mental retardation developed seizures (primarily generalized, tonic-clonic, and atonic) that began on average at 6.8 months of age (range, 4 to 14 months). These patients did not have a history of infantile spasms. There were no dysmorphic features. Other than mental retardation, the neurological examination was unremarkable, with exception of 2 affected subjects who had mild generalized rigidity and ataxia. We identified tight linkage to a group of markers on Xp21.1-p11.4. A maximum two-point LOD score of +3.83 at straight theta = 0 was obtained for markers DXS8090, DXS1069, DXS8102, and DXS8085. This locus spans 7.7cM between DXS1049 and DXS8054 and does not overlap the locus for X-linked West syndrome. The tetraspanin gene, implicated in nonspecific mental retardation, is mapped to this region. We sequenced the tetraspanin coding sequence in subjects with X-linked mental retardation and epilepsy and did not identify disease-specific mutations. The syndrome we describe, designated X-linked mental retardation and epilepsy, is clinically and genetically distinct from X-linked West syndrome and other X-linked mental retardation-epilepsy syndromes.

Relativistic analytical wave functions and scattering factors for neutral atoms beyond Kr and for all chemically important ions up to I-.

Relativistic wave functions for elements with Z = 37-54 [Su & Coppens (1998). Acta Cryst. A54, 646-652] have been fitted with a linear combination of Slater-type functions as defined by Bunge, Barrientos & Bunge [At. Data Nucl. Data Tables (1993), 53, 113-162], for use in charge-density analysis and other applications. In addition, numerical relativistic wave functions have been calculated for all chemically relevant ions up to Z = 54, and corresponding analytical expressions have been derived. X-ray scattering factors calculated from the numerical wave functions are parameterized [in the sin(straight theta)/lambda ranges 0.0-2.0, 2.0-4.0 and 4.0-6.0 A(-1)] with six Gaussian functions, using the same method applied previously by Su & Coppens [Acta Cryst. (1997), A53, 749-762].

Brillouin scattering study of elastic properties in ferroelectric copolymer single-crystalline films

The in-plane elastic properties of as-grown random copolymer poly (vinylidene fluoride-trifluoroethylene) single-crystalline films with 75/25 molecular ratio have been studied by Brillouin light scattering up to approximately 140 degrees C from room temperature, covering the D6h-C2v ferroelectric phase transition at approximately 126 degrees C. The in-plane longitudinal acoustic (LA) phonons propagating parallel and perpendicular to the polymer chains were examined. In spite of the strongly first-order nature of the phase transition, both LA velocities exhibit only a broad down step in the temperature range between approximately 100 degrees C and approximately 130 degrees C, depending on the propagation direction, with increasing temperature. The LA phonon width perpendicular to the polymer chains increases with increasing temperature, and exhibits a broad maximum centered at approximately 120 degrees C. On the other hand, the LA phonon width along the polymer-chain axis is much wider than the width perpendicular to the polymer chains, and continues to increase even in the paraelectric phase. Treating the E(u) symmetry electric polarizations (Px,P(y)) of the D6h point group as the macroscopic order parameter, a Laudau free energy was developed to discuss the elastic properties. Using the free energy, we found that the elastic anomalies expected through the electrostrictive couplings between the order parameter and the elastic strains are strongly suppressed by the intrinsic electrical nature of the ferroelectric polymer. For both LA phonons, the temperature development of the phonon frequency and width can be reasonably reproduced by the Cole-Davidson relaxation model for the velocity dispersion with an exponent of betaCD=0.4. The relaxation time was found to obey the Arrhenius law tau=tau(0) exp(DeltaE/k(B)T) with DeltaE=0.55+/-0.01 eV and tau(0)=(4.0+/-0.6)x10(-18) s. At 24.0 degrees C in the ferroelectric phase, the in-plane phonon width anisotropy can be reasonably described by gammaB(straight theta)/2pi=0.18+0.72 sin4 straight theta for the LA phonon and gammaB(straight theta)/2pi=0.02+0.095 sin2 2straight theta for the transverse acoustic phonon, where the phonon propagation angle straight theta is measured from the perpendicular direction with respect to the polymer-chain axis. The straight theta dependence is strongly related to the one-dimensional freedom constrained in each copolymer chain.

Exact multilocal renormalization group and applications to disordered problems.

We develop a method, the exact multilocal renormalization group (EMRG) which applies to a broad set of theories. It is based on the systematic multilocal expansion of the Polchinski-Wilson exact renormalization group (ERG) equation together with a scheme to compute correlation functions. Integrating out explicitly the nonlocal interactions, we reduce the ERG equation obeyed by the full interaction functional to a flow equation for a function, its local part. This is done perturbatively around fixed points, but exactly to any given order in the local part. It is thus controlled, at variance with projection methods, e.g., derivative expansions or local potential approximations. Our EMRG method is well-suited to problems such as the pinning of disordered elastic systems, previously described via functional renormalization group (FRG) approach based on a hard cutoff scheme. Since it involves arbitrary cutoff functions, we explicitly verify universality to O(epsilon=4-D), both of the T=0 FRG equation and of correlations. Extension to finite temperature T yields the finite size (L) susceptibility fluctuations characterizing mesoscopic behavior (Deltachi)2 approximately L(straight theta)/T, where straight theta is the energy exponent. Finally, we obtain the universal scaling function to O(epsilon(1/3)) which describes the ground state of a domain wall in a random field confined by a field gradient, compare with exact results and variational method. Explicit two loop exact RG equations are derived and the application to the FRG problem is sketched.

Extra Dimensions and the strong CP problem.

In higher dimensional theories, such as brane world models with quasilocalized non-Abelian gauge fields, the vacuum structure turns out to be trivial. Since the gauge theory behaves at large distances as a 4 + delta dimensional, thus the topology of the infinity is that of S(3+delta) rather than S(3). This topology does not support finite action instantonic configurations and thus the CP violating theta term vanishes on the brane world volume. As well there are no contributions to the straight theta term from the higher dimensional solitonic configurations. In this way, the strong CP problem is absent in the models with quasilocalized gluons.

Dominant Intermediate Charcot-Marie-Tooth Neuropathy Maps to Chromosome 19p12-p13.2

The hereditary disorders of peripheral nerve form one of the most common groups of human genetic diseases, collectively called Charcot-Marie-Tooth (CMT) neuropathy. Using linkage analysis we have identified a new locus for a form of CMT that we have called "dominant intermediate CMT" (DI-CMT). A genomewide screen using 383 microsatellite markers showed strong linkage to the short arm of chromosome 19 (maximum LOD score 4.3, with a recombination fraction (straight theta) of 0, at D19S221 and maximum LOD score 5.28, straight theta=0, at D19S226). Haplotype analysis performed with 14 additional markers placed the DI-CMT locus within a 16.8-cM region flanked by the markers D19S586 and D19S546. Multipoint linkage analysis suggested the most likely location at D19S226 (maximum multipoint LOD score 6.77), within a 10-cM confidence interval. This study establishes the presence of a locus for DI-CMT on chromosome 19p12-p13.2.

Fluctuation-dominated phase ordering driven by stochastically evolving surfaces: depth models and sliding particles.

We study an unconventional phase ordering phenomenon in coarse-grained depth models of the hill-valley profile of fluctuating surfaces with zero overall tilt, and for hard-core particles sliding on such surfaces under gravity. We find that several such systems approach an ordered state with large scale fluctuations which make them qualitatively different from conventional phase ordered states. We consider surfaces in the Edwards-Wilkinson (EW), Kardar-Parisi-Zhang (KPZ) and noisy surface-diffusion (NSD) universality classes. For EW and KPZ surfaces, coarse-grained depth models of the surface profile exhibit coarsening to an ordered steady state in which the order parameter has a broad distribution even in the thermodynamic limit, the distribution of particle cluster sizes decays as a power-law (with an exponent straight theta), and the scaled two-point spatial correlation function has a cusp (with an exponent alpha=1/2) at small values of the argument. The latter feature indicates a deviation from the Porod law which holds customarily, in coarsening with scalar order parameters. We present several numerical and exact analytical results for the coarsening process and the steady state. For linear surface models with a dynamical exponent z, we show that alpha=(z-1)/2 for z<3 and alpha=1 for z>3, and there are logarithmic corrections for z=3, implying alpha=1/2 for the EW surface and 1 for the NSD surface. Within the independent interval approximation we show that alpha+straight theta=2. We also study the dynamics of hard-core particles sliding locally downward on these fluctuating one-dimensional surfaces, and find that the surface fluctuations lead to large-scale clustering of the particles. We find a surface-fluctuation driven coarsening of initially randomly arranged particles; the coarsening length scale grows as approximately t(1/z). The scaled density-density correlation function of the sliding particles shows a cusp with exponents alpha approximately 0.5 and 0.25 for the EW and KPZ surfaces. The particles on the NSD surface show conventional coarsening (Porod) behavior with alpha approximately 1.

Persistence in the one-dimensional A+B--> Ø reaction-diffusion model.

The persistence properties of a set of random walkers obeying the A+B--> Ø reaction, with equal initial density of particles and homogeneous initial conditions, is studied using two definitions of persistence. The probability P(t) that an annihilation process has not occurred at a given site has the asymptotic form P(t) approximately const+t(-straight theta), where straight theta is the persistence exponent (type I persistence). We argue that, for a density of particles rho>>1, this nontrivial exponent is identical to that governing the persistence properties of the one-dimensional diffusion equation, partial differential(t)straight phi= partial differential(xx)straight phi, where straight theta approximately 0.1207 [S. N. Majumdar, C. Sire, A. J. Bray, and S. J. Cornell, Phys. Rev. Lett. 77, 2867 (1996)]. In the case of an initial low density, rho(0)<<1, we find straight theta approximately 1/4 asymptotically. The probability that a site remains unvisited by any random walker (type II persistence) is also investigated and found to decay with a stretched exponential form, P(t) approximately exp(-constxrho(1/2)(0)t(1/4)), provided rho(0)<<1. A heuristic argument for this behavior, based on an exactly solvable toy model, is presented.

Dynamic charge-density correlation function in weakly charged polyampholyte globules.

We study solutions of statistically neutral polyampholyte chains containing a large fraction of neutral monomers. It is known that such solutions phase separate at very low concentrations, even if the quality of the solvent with respect to the neutral monomers is good. The precipitate is semidilute if the chains are weakly charged. This paper considers straight theta solvents and good solvents, and we calculate the dynamic charge density correlation function g(k,t) in the precipitate, using the quadratic approximation to the Martin-Siggia-Rose generating functional. It is convenient to express the results in terms of dimensionless space and time variables. Let xi be the blob size, and let tau be the characteristic time scale at the blob level. Define the dimensionless wave vector q=xik, and the dimensionless time s=t/tau. In the regime q<1, corresponding to length scales larger than the blob size, and 1<s<q(-4), corresponding to time scales in between the blob relaxation time and the relaxation time at scale q(-1), we find that the charge density fluctuations relax according to the power law g(q,s) approximately q(2)s(-1/2). This relaxation is qualitatively different from that of a neutral semidilute polymer solution. We expect our results to be valid for wave vectors q>0.1, where entanglements are unimportant.

Ripple and kink dynamics.

We propose a relevant modification of the Nishimori-Ouchi model [Phys. Rev. Lett. 71, 197 (1993)] for granular landscape erosion. We explicitly introduce an additional parameter: the angle of repose straight theta(r), and an additional process: avalanches. We show that the straight theta(r) parameter leads to an asymmetry of the ripples, as observed in natural patterns. The temporal evolution of the maximum ripple height h(max) is limited and not linear according to recent observations. The ripple symmetry and the kink dynamics are studied and discussed.

Paget Disease of Bone: Mapping of Two Loci at 5q35-qter and 5q31

Paget disease of bone is characterized by focal increases of the bone-remodeling process. It is the second most common metabolic bone disease after osteoporosis. Genetic factors play a major role in the etiology of Paget disease of bone, and two loci have been mapped for the disorder: PDB1 and PDB2. The gene(s) causing the typical form of the disorder remains to be characterized. To decipher the molecular basis of Paget disease of bone, we performed genetic linkage analysis in 24 large French Canadian families (479 individuals) in which the disorder was segregating as an autosomal dominant trait. After exclusion of PDB2, a genomewide scan was performed on the three most informative family nuclei. LOD scores >1.0 were observed at seven locations. The 24 families were then used to detect strong evidence for linkage to chromosome 5q35-qter. Under heterogeneity, a maximum LOD score of 8.58 was obtained at D5S2073, at straight theta= .1. The same characteristic haplotype was carried by all patients in eight families, suggesting a founder effect. A recombination event in a key family confined the disease region within a 6-cM interval between D5S469 and the telomere. The 16 other families, with very low conditional probability of linkage to 5q35-qter, were further used, to map a second locus at 5q31. Under heterogeneity, a maximum LOD score of 3.70 was detected at D5S500 with straight theta=.00. Recombination events refined the 5q31 region within 12.2 cM, between D5S642 and D5S1972. These observations demonstrate the mapping of two novel loci for Paget disease of bone and provide further evidence for genetic heterogeneity of this highly prevalent disorder. It is proposed that the 5q35-qter and 5q31 loci be named "PDB3" and "PDB4," respectively.

Mapping of Autosomal Dominant Osteopetrosis Type II (Albers-Schönberg Disease) to Chromosome 16p13.3

The osteopetroses are a heterogeneous group of conditions characterized by a bone-density increase due to impaired bone resorption. As well as the two or more autosomal recessive types, two autosomal dominant forms of osteopetrosis, differentiated by clinical and radiological signs, are described. Autosomal dominant osteopetrosis (ADO) type II, also known as "Albers-Schönberg disease," is characterized by sclerosis, predominantly involving the spine (vertebral end-plate thickening, or Rugger-Jersey spine), the pelvis ("bone-within-bone" structures), and the skull base. An increased fracture rate can be observed in these patients. By linkage analysis, the presence, on chromosome 1p21, of a gene causing ADO type II was previously suggested. However, analysis of further families with ADO type II indicated genetic heterogeneity within ADO type II, with the chromosome 1p21 locus being only a minor locus. We now perform a genomewide linkage scan of a French extended family with ADO type II, which allows us to localize an ADO type II gene on chromosome 16p13.3. Analysis of microsatellite markers in five further families with ADO type II could not exclude this chromosomal region. A summed maximum LOD score of 12.70 was generated with marker D16S3027, at a recombination fraction (straight theta) of 0. On the basis of the key recombinants in the families, a candidate region of 8.4 cM could be delineated, flanked by marker D16S521, on distal side, and marker D16S423, on the proximal side. Surprisingly, one of the families analyzed is the Danish family previously suggested to have linkage to chromosome 1p21. Linkage to chromosome 16p13.3 clearly cannot be excluded in this family, since a maximum LOD score of 4.21 at theta=0 is generated with marker D16S3027. Because at present no other family with ADO type II has proved to have linkage to chromosome 1p21, we consider the most likely localization of the disease-causing gene in this family to be to chromosome 16p13.3. This thus reopens the possibility that ADO type II is genetically homogeneous because of a single gene on chromosome 16p13.3.

Morphine withdrawal increases expression of GABAA receptor ε subunit mRNA in locus coeruleus neurons

An increase in the activity of brain stem locus coeruleus noradrenergic neurons has been hypothesised to be a major factor accounting for opiate withdrawal symptoms. These neurons are under GABAergic inhibition. Their GABA(A) receptors have unique pharmacological properties, most likely due to the enriched expression of GABA(A) receptor subtypes containing novel epsilon and straight theta subunits. Using in situ hybridisation of cryostat sections, we now report a significant increase in the epsilon subunit mRNA expression after precipitation of opioid withdrawal by naloxone. Similar changes were detected in tyrosine hydroxylase mRNA expression. The results suggest increased formation of unique GABA(A) receptor subtype(s) in the locus coeruleus neurons during increased neuronal activity.

Measurement of the high energy two-body deuteron photodisintegration differential cross section.

The first measurements of the d(gamma,p)n differential cross section at forward angles and photon energies above 4 GeV were performed at the Thomas Jefferson National Accelerator Facility (JLab). The results indicate evidence of an angular dependent scaling threshold. Results at straight theta(cm) = 37 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 4 GeV, while those at 70 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 1.5 GeV.

H3N(CH2)2NH3]0.5[BePO4], a beryllophosphate analogue of aluminosilicate zeolite gismondine.

Hydrothermally prepared ethylenediammonium beryllophosphate, (C(2)H(10)N(2))(0.5)[BePO(4)], is an analogue of aluminosilicate zeolite gismondine. A three-dimensional network of vertex-sharing BeO(4) and PO(4) tetrahedra [d(av)(Be-O) = 1.618 (3) A, d(av)(P-O) = 1.5246 (14) A and straight theta(av)(Be-O-P) = 139.8 degrees] encapsulates the disordered ethylenediammonium cations in an eight-ring channel system.

Localization of the gene for familial laryngeal abductor paralysis to chromosome 6q16.

Vocal fold paralysis is a common cause of neonatal stridor. Although it is usually classified as idiopathic or iatrogenic in origin, a small subset of patients have a family history of this disorder, indicating a possible genetic cause. To identify the genetic locus of the gene that causes familial laryngeal abductor paralysis. A standard nonorganic protocol was used to extract DNA from whole-blood samples. The DNA samples were quantified by DNA fluorometry, and the concentration of all samples was standardized at 40 ng/microL. A pooled DNA strategy was used to facilitate rapid polymerase chain reaction screening of markers in the Weber v8.0 genome screening set. Polymerase chain reaction screening of individual DNA samples was performed using possible linked markers initially identified as having an allele that appeared with a higher incidence in the affected DNA pools. Statistical analysis of possible linkage was performed using the LINKAGE 5.1 set of linkage analysis computer programs. A family in which a form of familial laryngeal abductor paralysis segregates was ascertained. Whole blood samples were drawn from 40 participating individuals within this family after the subjects' fully informed consent was obtained. Initial screening of the pooled DNA specimens revealed a band pattern for D6S1021 on chromosome 6q16, indicating an allele with a higher incidence in the affected vs the nonaffected pool. Two-point analysis of individual allele patterns confirmed linkage to D6S1021 with an lod score of 3.86 (straight theta = 0.0) at a penetrance value of 0.8. Haplotype analysis with flanking markers defined a 5-centiray critical region between D6S283 and AFMA047YG1. An autosomal dominant form of familial laryngeal abductor paralysis is linked to a 5-centiray region on chromosome 6q16 surrounding D6S1021.

Structures of copper(II) and manganese(II) di(hydrogen malonate) dihydrate; effects of intensity profile truncation and background modelling on structure models.

The crystal structures of the title compounds were determined with net intensities I derived via the background-peak-background procedure. Least-squares optimizations reveal differences between the low-order (0 < s < 0.7 A(-1)) and high-order (0.7 < s < 1.0 A(-1)) structure models. The scale factors indicate discrepancies of up to 10% between the low-order and high-order reflection intensities. This observation is compound independent. It reflects the scan-angle-induced truncation error, because the applied scan angle (0.8 + 2.0 tan theta) degrees underestimates the wavelength dispersion in the monochromated X-ray beam. The observed crystal structures show pseudo-I-centred sublattices for three of its non-H atoms in the asymmetric unit. Our selection of observed intensities (I > 3 sigma) stresses that pseudo-symmetry. Model refinements on individual data sets with (h + k + l) = 2n and (h + k + l) = 2n + 1 illustrate the lack of model robustness caused by that pseudo-symmetry. To obtain a better balanced data set and thus a more robust structure we decided to exploit background modelling. We described the background intensities B(H-->) with an 11th degree polynomial in straight theta. This function predicts the local background b at each position H--> and defines the counting statistical distribution P(B), in which b serves as average and variance. The observation R defines P(R). This leads to P(I) = P(R)/P(B) and thus I = R - b and sigma(2)(I) = I so that the error sigma(I) is background independent. Within this framework we reanalysed the structure of the copper(II) derivative. Background modelling resulted in a structure model with an improved internal consistency. At the same time the unweighted R value based on all observations decreased from 10.6 to 8.4%. A redetermination of the structure at 120 K concluded the analysis.

Bubble propagation in a pipe filled with sand.

Granular flow with strong hydrodynamic interactions has been studied experimentally. Experiments have been carried out to study the movement of a single bubble in an inclined tube filled with glass beads and air. A maximum bubble velocity was found at an inclined angle straight theta(m). The density variations in the sand were measured by capacitance measurements, and a decompactification zone was observed just above the bubble when the inclination angle straight theta was larger than straight theta(m). The length of the decompactification front increased with increasing inclination angle and disappeared for angles smaller than straight theta(m). Both pressure and visualization experiments were carried out and compared with the density measurements.

Transport properties in a two-temperature plasma: theory and application.

An alternate derivation of transport properties in a two-temperature plasma has been performed. Indeed, recent works have shown that the simplified theory of transport properties out of thermal equilibrium introduced by Devoto and then Bonnefoi, very often used in two-temperature modeling, is questionable and particularly does not work when calculating the combined diffusion coefficients of Murphy. Thus, in this paper, transport properties are derived without Bonnefoi's assumptions in a nonreactive two-temperature plasma, assuming chemical equilibrium is achieved. The electron kinetic temperature T(e) is supposed to be different from that of heavy species T(h). Only elastic processes are considered in a collision-dominated plasma. The resolution of Boltzmann's equation, thanks to the Chapman-Enskog method, is used to calculate transport coefficients from sets of linear equations. The solution of these systems allows transport coefficients to be written as linear combinations of collision integrals, which take into account the interaction potential for a collision between two particles. These linear combinations are derived by extending the definition and the calculation of bracket integrals introduced by Chapman et al. to the thermal nonequilibrium case. The obtained results are rigorously the same as those of Hirschfelder et al. at thermal equilibrium. The derivation of diffusion velocity and heat flux shows the contribution of a new gradient, that of the temperature ratio straight theta=T(e)/T(h). An application is presented for a two-temperature argon plasma. First, it is shown that the two-temperature linear combinations of collision integrals are drastically modified with respect to equilibrium. Secondly, the two-temperature simplified theory of transport coefficients of Devoto and Bonnefoi underestimates the electron thermal conductivity with respect to the accurate value at T(e)=20 000 K. Lastly, contrary to the simplified theory of transport coefficients, the diffusion coefficients satisfy the symmetry conditions. An example is given at T(e)=6000 K for different values of straight theta for the diffusion coefficient between electrons and heavy species D(e-Ar) as well as for that between argon atoms and argon ions D(Ar-Ar+).