Resonance-continuum interference in the di-photon Higgs signal at the LHC

A low mass Standard Model Higgs boson should be visible at the Large Hadron Collider through its production via gluon-gluon fusion and its decay to two photons. We compute the interference of this resonant process, gg -> H -> gamma gamma, with the continuum QCD background, gg -> gamma gamma induced by quark loops. Helicity selection rules suppress the effect, which is dominantly due to the imaginary part of the two-loop gg -> gamma gamma scattering amplitude. The interference is destructive, but only of order 5% in the Standard Model, which is still below the 10-20% present accuracy of the total cross section prediction. We comment on the potential size of such effects in other Higgs models.Comment: 10 pages, 2 figure

Broken symmetries and directed collective energy transport

We study the appearance of directed energy current in homogeneous spatially extended systems coupled to a heat bath in the presence of an external ac field E(t). The systems are described by nonlinear field equations. By making use of a symmetry analysis we predict the right choice of E(t) and obtain directed energy transport for systems with a nonzero topological charge Q. We demonstrate that the symmetry properties of motion of topological solitons (kinks and antikinks) are equivalent to the ones for the energy current. Numerical simulations confirm the predictions of the symmetry analysis and, moreover, show that the directed energy current drastically increases as the dissipation parameter $\alpha$ reduces. Our results generalize recent rigorous theories of currents generated by broken time-space symmetries to the case of interacting many-particle systems.Comment: 4 pages, 2 figure

Diffusion and Current of Brownian Particles in Tilted Piecewise Linear Potentials: Amplification and Coherence

Overdamped motion of Brownian particles in tilted piecewise linear periodic potentials is considered. Explicit algebraic expressions for the diffusion coefficient, current, and coherence level of Brownian transport are derived. Their dependencies on temperature, tilting force, and the shape of the potential are analyzed. The necessary and sufficient conditions for the non-monotonic behavior of the diffusion coefficient as a function of temperature are determined. The diffusion coefficient and coherence level are found to be extremely sensitive to the asymmetry of the potential. It is established that at the values of the external force, for which the enhancement of diffusion is most rapid, the level of coherence has a wide plateau at low temperatures with the value of the Peclet factor 2. An interpretation of the amplification of diffusion in comparison with free thermal diffusion in terms of probability distribution is proposed.Comment: To appear in PR

Primary spinal cord tumors of childhood: effects of clinical presentation, radiographic features, and pathology on survival

To determine the relationship between clinical presentation, radiographic features, pathology, and treatment on overall survival of newly diagnosed pediatric primary spinal cord tumors (PSCT). Retrospective analysis of all previously healthy children with newly diagnosed PSCT at a single institution from 1995 to present was performed. Twenty-five pediatric patients (15 boys, average 7.9 years) were diagnosed with PSCT. Presenting symptoms ranged from 0.25 to 60 months (average 7.8 months). Symptom duration was significantly shorter for high grade tumors (average 1.65 months) than low grade tumors (average 11.2 months) (P = 0.05). MRI revealed tumor (8 cervical, 17 thoracic, 7 lumbar, 7 sacral) volumes of 98–94,080 mm3 (average 19,474 mm3). Homogeneous gadolinium enhancement on MRI correlated with lower grade pathology (P = 0.003). There was no correlation between tumor grade and volume (P = 0.63) or edema (P = 0.36) by MRI analysis. Median survival was 53 months and was dependent on tumor grade (P = 0.05) and gross total resection (P = 0.01) but not on gender (P = 0.49), age of presentation (P = 0.82), duration of presenting symptoms (P = 0.33), or adjuvant therapies (P = 0.17). Stratified Kaplan–Meier analysis confirmed the association between degree of resection and survival after controlling for tumor grade (P = 0.01). MRI homogeneous gadolinium enhancement patterns may be helpful in distinguishing low grade from high grade spinal cord malignancies. While tumor grade and gross total resection rather than duration of symptoms correlated with survival in our series, greater than one-third of patients had reported symptoms greater than 6 months duration prior to diagnosis

Multiple brain developmental venous anomalies as a marker for constitutional mismatch repair deficiency syndrome

The occurrence of multiple developmental venous anomalies in this study of 10 patients with constitutional mismatch repair deficiency syndrome (CMMRD) suggests that developmental venous anomalies may be a characteristic of this syndrome that has not been previously described. A retrospective descriptive analysis of brain MR imaging studies from 3 families with CMMRD was performed. Analysis included the number of developmental venous anomalies, location, draining vessels, and associated vascular anomalies (for instance, cavernomas) with clinical correlation of symptoms and tumors. CMMRD is a cancer-predisposition syndrome with very high penetrance and most reported individuals are affected during childhoodInternational Biallelic Mismatch Repair Deficiency ConsortiumMeagan’s Walk, the CIHR Joint Canada- Israel Health Research Program, and an American Association for Cancer Research Stand Up 2 Cancer Catalyst TM Research Gran

Organometallic iridium(III) anticancer complexes with new mechanisms of action: NCI-60 screening, mitochondrial targeting, and apoptosis

Platinum complexes related to cisplatin, cis-[PtCl2(NH3)2], are successful anticancer drugs; however, other transition metal complexes offer potential for combating cisplatin resistance, decreasing side effects, and widening the spectrum of activity. Organometallic half-sandwich iridium (IrIII) complexes [Ir(Cpx)(XY)Cl]+/0 (Cpx = biphenyltetramethylcyclopentadienyl and XY = phenanthroline (1), bipyridine (2), or phenylpyridine (3)) all hydrolyze rapidly, forming monofunctional G adducts on DNA with additional intercalation of the phenyl substituents on the Cpx ring. In comparison, highly potent complex 4 (Cpx = phenyltetramethylcyclopentadienyl and XY = N,N-dimethylphenylazopyridine) does not hydrolyze. All show higher potency toward A2780 human ovarian cancer cells compared to cisplatin, with 1, 3, and 4 also demonstrating higher potency in the National Cancer Institute (NCI) NCI-60 cell-line screen. Use of the NCI COMPARE algorithm (which predicts mechanisms of action (MoAs) for emerging anticancer compounds by correlating NCI-60 patterns of sensitivity) shows that the MoA of these IrIII complexes has no correlation to cisplatin (or oxaliplatin), with 3 and 4 emerging as particularly novel compounds. Those findings by COMPARE were experimentally probed by transmission electron microscopy (TEM) of A2780 cells exposed to 1, showing mitochondrial swelling and activation of apoptosis after 24 h. Significant changes in mitochondrial membrane polarization were detected by flow cytometry, and the potency of the complexes was enhanced ca. 5× by co-administration with a low concentration (5 μM) of the γ-glutamyl cysteine synthetase inhibitor L-buthionine sulfoximine (L-BSO). These studies reveal potential polypharmacology of organometallic IrIII complexes, with MoA and cell selectivity governed by structural changes in the chelating ligands

Driven diffusion in a periodically compartmentalized tube: homogeneity versus intermittency of particle motion

We study the effect of a driving force F on drift and diffusion of a point Brownian particle in a tube formed by identical ylindrical compartments, which create periodic entropy barriers for the particle motion along the tube axis. The particle transport exhibits striking features: the effective mobility monotonically decreases with increasing F, and the effective diffusivity diverges as F → ∞, which indicates that the entropic effects in diffusive transport are enhanced by the driving force. Our consideration is based on two different scenarios of the particle motion at small and large F, homogeneous and intermittent, respectively. The scenarios are deduced from the careful analysis of statistics of the particle transition times between neighboring openings. From this qualitative picture, the limiting small-F and large-F behaviors of the effective mobility and diffusivity are derived analytically. Brownian dynamics simulations are used to find these quantities at intermediate values of the driving force for various compartment lengths and opening radii. This work shows that the driving force may lead to qualitatively different anomalous transport features, depending on the geometry design