Tomographic inversion using ℓ1\ell_1-norm regularization of wavelet coefficients

We propose the use of $\ell_1$ regularization in a wavelet basis for the solution of linearized seismic tomography problems $Am=d$, allowing for the possibility of sharp discontinuities superimposed on a smoothly varying background. An iterative method is used to find a sparse solution $m$ that contains no more fine-scale structure than is necessary to fit the data $d$ to within its assigned errors.Comment: 19 pages, 14 figures. Submitted to GJI July 2006. This preprint does not use GJI style files (which gives wrong received/accepted dates). Corrected typ

Risks of hospitalization and drug consumption in children and young adults with diagnosed celiac disease and the role of maternal education: A population-based matched birth cohort study

Background: Celiac disease (CD) may affect healthcare use in children and young adults. Socio-economic factors may act as a confounder or effect modifier. We assessed such hypotheses in a population-based birth cohort of young celiac subjects and references matched by maternal education. Methods: The cohort included all newborns recorded in the Medical Birth Register of Friuli-Venezia Giulia Region (Italy) between 1989 and 2011. CD incident cases were identified through pathology reports, hospital discharges and copayment exemptions and matched with up to five references by sex, year of birth and maternal education. Cox regression models were used to estimate Hazard Ratios (HRs) for major causes of inpatient diagnosis and drug prescription occurring after diagnosis in CD patients compared to references, stratifying by time of first event and maternal education. Results: We identified 1294 CD cases and 5681 references. CD cases had a higher risk of hospital admission for any cause (HR: 2.34; 95 % CI 2.08-2.63) and for all major ICD9-CM categories except obstetric complications, skin and musculoskeletal diseases, and injuries and poisoning. Prescription of all major ATC drug categories, except dermatologicals and genito-urinary medications, was significantly increased in CD subjects. For most outcomes, HRs were highest in the first year after CD diagnosis but remained significant after five or more years. HRs were similar across different categories of maternal education. Conclusions: Diagnosed CD subjects had a higher risk of hospitalization and medication use compared to the general population, even five or more years after diagnosis, with no effect modification of maternal education

Some results on the eigenfunctions of the quantum trigonometric Calogero-Sutherland model related to the Lie algebra E6

The quantum trigonometric Calogero-Sutherland models related to Lie algebras admit a parametrization in which the dynamical variables are the characters of the fundamental representations of the algebra. We develop here this approach for the case of the exceptional Lie algebra E6.Comment: 17 pages, no figure

CH 3 GHz Observations of the Galactic Center

A 3 $\times$ 3 map of the Galactic Center was made at 9\arcmin resolution and 10\arcmin spacing in the CH $^2\Pi_{1/2}$, J=1/2, F=1-1 transition at 3335 MHz. The CH emission shows a velocity extent that is nearly that of the CO(1-0) line, but the CH line profiles differ markedly from the CO. The 3335 MHz CH transition primarily traces low-density molecular gas and our observations indicate that the mass of this component within $\sim$ 30 pc of the Galactic Center is $\sim$ 9 $\times$ 10$^6$ M$_\odot$. The CO-H$_2$ conversion factor obtained for the low-density gas in the mapped region is greater than that thought to apply to the dense molecular gas at the Galactic Center. In addition to tracing the low-density molecular gas at the Galactic Center, the CH spectra show evidence of emission from molecular clouds along the line of sight both in the foreground and background. The scale height of these clouds ranges from 27 - 109 pc, consistent with previous work based on observations of molecular clouds in the inner Galaxy.Comment: 29 pages, 12 figure

Additional symmetries of constrained CKP and BKP hierarchies

The additional symmetries of the constrained CKP (cCKP) and BKP (cBKP) hierarchies are given by their actions on the Lax operators, and their actions on the eigenfunction and adjoint eigenfunction $\{\Phi_i,\Psi_i \}$ are presented explicitly. Furthermore, we show that acting on the space of the wave operator, $\partial_k^*$ forms new centerless $W^{cC}_{1+\infty}$ and $W^{cB}_{1+\infty}$-subalgebra of centerless $W_{1+\infty}$ respectively. In order to define above symmetry flows $\partial_k^*$ of the cCKP and cBKP hierarchies, two vital operators $Y_k$ are introduced to revise the additional symmetry flows of the CKP and BKP hierarchies.Comment: 14 pages, accepted by SCIENCE CHINA Mathematics(2010

The Escherichia coli RnlA–RnlB toxin–antitoxin complex: production, characterization and crystallization

The Escherichia coli rnlAB operon encodes a toxin–antitoxin module that is involved in protection against infection by bacteriophage T4. The full-length RnlA–RnlB toxin–antitoxin complex as well as the toxin RnlA were purified to homogeneity and crystallized. When the affinity tag is placed on RnlA, RnlB is largely lost during purification and the resulting crystals exclusively comprise RnlA. A homogeneous preparation of RnlA–RnlB containing stoichiometric amounts of both proteins could only be obtained using a His tag placed C-terminal to RnlB. Native mass spectrometry and SAXS indicate a 1:1 stoichiometry for this RnlA–RnlB complex. Crystals of the RnlA–RnlB complex belonged to space group C2, with unit-cell parameters a = 243.32, b = 133.58, c = 55.64 Å, β = 95.11°, and diffracted to 2.6 Å resolution. The presence of both proteins in the crystals was confirmed and the asymmetric unit is likely to contain a heterotetramer with RnlA2:RnlB2 stoichiometry

Polynomials Associated with Equilibria of Affine Toda-Sutherland Systems

An affine Toda-Sutherland system is a quasi-exactly solvable multi-particle dynamics based on an affine simple root system. It is a `cross' between two well-known integrable multi-particle dynamics, an affine Toda molecule and a Sutherland system. Polynomials describing the equilibrium positions of affine Toda-Sutherland systems are determined for all affine simple root systems.Comment: 9 page

Thermodynamic Stability of the Transcription Regulator PaaR2 from Escherichia coli O157:H7

PaaR2 is a putative transcription regulator encoded by a three-component parDE-like toxin-antitoxin module from Escherichia coli O157:H7. Although this module’s toxin, antitoxin, and toxin-antitoxin complex have been more thoroughly investigated, little remains known about its transcription regulator PaaR2. Using a wide range of biophysical techniques (circular dichroism spectroscopy, size-exclusion chromatography-multiangle laser light scattering, dynamic light scattering, small-angle x-ray scattering, and native mass spectrometry), we demonstrate that PaaR2 mainly consists of α-helices and displays a concentration-dependent octameric build-up in solution and that this octamer contains a global shape that is significantly nonspherical. Thermal unfolding of PaaR2 is reversible and displays several transitions, suggesting a complex unfolding mechanism. The unfolding data obtained from spectroscopic and calorimetric methods were combined into a unifying thermodynamic model, which suggests a five-state unfolding trajectory. Furthermore, the model allows the calculation of a stability phase diagram, which shows that, under physiological conditions, PaaR2 mainly exists as a dimer that can swiftly oligomerize into an octamer depending on local protein concentrations. These findings, based on a thorough biophysical and thermodynamic analysis of PaaR2, may provide important insights into biological function such as DNA binding and transcriptional regulation