Differential cross-section for positronium formation in electron-atomic hydrogen collisions

The L=0 and 1 partial wave amplitudes obtained by a two-state coupled static approximation with correlation with the L greater than or equal to 2 Born amplitudes were combined to obtain the differential cross section for positronium formation in electron-atomic hydrogen collisions. For positron energies of 0.64 and 0.75 ryd, minima at the scattering angles of 57 deg and 51 deg are found. Total cross sections for positronium formation for low and intermediate impact energies are given. Measurement of the differential cross section for the process positron + helium yields positronium + helium ion for the detection of possible minima is suggested

Feshbach resonances in positron-hydrogen scattering

Using a wave function including the 1s-2s-2p eigenstates of hydrogen and the 1s ground state of positronium, we have calculated the position and width of the lowest Feshbach resonance in the e(+)-H system, which lies between the positronium rearrangement threshold and the n=2 hydrogen threshold. The method differs from the usual close-coupling method, resembling in its formulation the projection operator technique, although orthogonality of closed-channel and open-channel functions is not demanded. The resonance lies 9.8281 eV above the ground state of hydrogen and has width of 0.029 eV in this approximation

Large dimension Configuration Interaction calculations of positron binding to the group II atoms

The Configuration Interaction (CI) method is applied to the calculation of the structures of a number of positron binding systems, including e+Be, e+Mg, e+Ca and e+Sr. These calculations were carried out in orbital spaces containing about 200 electron and 200 positron orbitals up to l = 12. Despite the very large dimensions, the binding energy and annihilation rate converge slowly with l, and the final values do contain an appreciable correction obtained by extrapolating the calculation to the l to infinity limit. The binding energies were 0.00317 hartree for e+Be, 0.0170 hartree for e+Mg, 0.0189 hartree for e+Ca, and 0.0131 hartree for e+Sr.Comment: 13 pages, no figs, revtex format, Submitted to PhysRev

New representation of orbital motion with arbitrary angular momenta

A new formulation is presented for a variational calculation of $N$-body systems on a correlated Gaussian basis with arbitrary angular momenta. The rotational motion of the system is described with a single spherical harmonic of the total angular momentum $L$, and thereby needs no explicit coupling of partial waves between particles. A simple generating function for the correlated Gaussian is exploited to derive the matrix elements. The formulation is applied to various Coulomb three-body systems such as $e^-e^-e^+, tt\mu, td\mu$, and $\alpha e^-e^-$ up to $L=4$ in order to show its usefulness and versatility. A stochastic selection of the basis functions gives good results for various angular momentum states.Comment: Revte

Low-energy quenching of positronium by helium

Very low-energy scattering of orthopositronium by helium has been investigated for simultaneous study of elastic cross section and pick-off quenching rate using a model exchange potential. The present calculational scheme, while agrees with the measured cross section of Skalsey et al, reproduces successfully the parameter ^ 1Z_{\makebox{eff}}, the effective number of electrons per atom in a singlet state relative to the positron. Together with the fact that this model potential also leads to an agreement with measured medium energy cross sections of this system, this study seems to resolve the long-standing discrepancy at low energies among different theoretical calculations and experimental measurements.Comment: 4 latex pages, 3 postscript figure

Hyperfine structure of the ground state muonic He-3 atom

On the basis of the perturbation theory in the fine structure constant $\alpha$ and the ratio of the electron to muon masses we calculate one-loop vacuum polarization and electron vertex corrections and the nuclear structure corrections to the hyperfine splitting of the ground state of muonic helium atom $(\mu\ e \ ^3_2He)$. We obtain total result for the ground state hyperfine splitting $\Delta \nu^{hfs}=4166.471$ MHz which improves the previous calculation of Lakdawala and Mohr due to the account of new corrections of orders $\alpha^5$ and $\alpha^6$. The remaining difference between our theoretical result and experimental value of the hyperfine splitting lies in the range of theoretical and experimental errors and requires the subsequent investigation of higher order corrections.Comment: Talk on poster section of XXIV spectroscopy congress, 28 February-5 March 2010, Moscow-Troitsk, Russia, 21 pages, LaTeX, 8 figure

A phase II study of dacetuzumab (SGN-40) in patients with relapsed diffuse large B-cell lymphoma (DLBCL) and correlative analyses of patient-specific factors

BACKGROUND: Patients with DLBCL who are ineligible for or have relapsed after aggressive salvage chemotherapy have a poor prognosis. CD40 is expressed on multiple B-cell neoplasms including DLBCL and is a potential target for immunotherapy. Dacetuzumab (SGN-40), a non-blocking, partial agonist, humanized IgG1, anti-CD40 monoclonal antibody, has previously demonstrated anti-lymphoma activity in a phase I study. METHODS: A phase II study was undertaken to evaluate the rate and duration of objective responses and safety of single-agent dacetuzumab in relapsed DLBCL. Forty-six adult patients with relapsed/refractory DLBCL received up to 12 cycles of intravenous dacetuzumab using intrapatient dose-escalation to a target dose of 8 mg/kg/week in an initial 5-week cycle, followed by 4-week cycles of 8 mg/kg/week. Study endpoints included rate and duration of objective responses, safety, survival, pharmacokinetics, immunogenicity, and exploratory correlative studies. RESULTS: Overall response rate was 9% and disease control rate (complete remission + partial remission + stable disease) was 37%. Common non-hematologic adverse events (AEs) included fatigue, headache, chills, fever, and nausea. The most frequent Grade 3–4 non-hematologic AE was deep venous thrombosis (3 patients). Grade 3–4 lymphopenia (41%), neutropenia (13%), or thrombocytopenia (19%) occurred without associated infection or bleeding. Reversible ocular events, including conjunctivitis and ocular hyperemia, occurred in 8 patients (17%). Patient-specific factors, including Fc-gamma-RIIIa polymorphism, did not appear to correlate with antitumor activity. CONCLUSIONS: Single-agent dacetuzumab has modest activity and manageable toxicity in unselected patients with relapsed DLBCL. Combination regimens and robust methods of patient selection may be necessary for further development. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT00435916

Rare association of thymoma, myasthenia gravis and sarcoidosis : a case report

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Expert Consensus Recommendations for the Suspicion and Diagnosis of Transthyretin Cardiac Amyloidosis

Cardiomyopathy is a manifestation of transthyretin amyloidosis (ATTR), which is an underrecognized systemic disease whereby the transthyretin protein misfolds to form fibrils that deposit in various tissues and organs. ATTR amyloidosis is debilitating and associated with poor life expectancy, especially in those with cardiac dysfunction, but a variety of treatment options have recently become available. Considered a rare disease, ATTR amyloidosis may be more prevalent than thought, particularly in older persons. Diagnosis is often delayed because of a lack of disease awareness and the heterogeneity of symptoms at presentation. Given the recent availability of effective treatments, early recognition and diagnosis are especially critical because treatment is likely more effective earlier in the disease course. The Amyloidosis Research Consortium recently convened a group of experts in ATTR amyloidosis who, through an iterative process, agreed on best practices for suspicion, diagnosis, and characterization of disease. This review describes these consensus recommendations for ATTR associated with cardiomyopathy as a resource to aid cardiologists and others in the recognition and diagnosis of ATTR associated with cardiomyopathy. Included in this review is an overview of red flag signs and symptoms and a recommended diagnostic approach, including testing for monoclonal protein, scintigraphy, or biopsy and, if ATTR associated with cardiomyopathy is identified, TTR genotyping