Heisenberg Dimer Single Molecule Magnets in a Strong Magnetic Field

We calculate the static and dynamic properties of single crystal, single molecule magnets consisting of equal spin $S=1/2$ or 5/2 dimers. The spins in each dimer interact with each other via the Heisenberg exchange interaction and with the magnetic induction ${\bf B}$ via the Zeeman interaction, and interdimer interactions are negligible. For antiferromagnetic couplings, the static magnetization and specific heat exhibit interesting low temperature $T$ and strong ${\bf B}$ quantum effects. We calculate the frequency spectrum of the Fourier transform of the real part of the time autocorrelation function ${\cal C}_{11}(t)$ for arbitrary $T, {\bf B}$, and compare our results with those obtained for classical spins. We also calculate the inelastic neutron magnetic dynamical structure factor $S({\bf q},\omega)$ at arbitrary $T, {\bf B}$.Comment: 11 pages, 14 figures, submitted to Phys. Rev.

Robust Imitation Strategies and their Impact on Industry Dynamics

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Extended resection for potentially operable patients with stage III non-small cell lung cancer after induction treatment.

Surgical treatment of locally advanced non-small cell lung cancer including single or multilevel N2 remains a matter of debate. Several trials demonstrate that selected patients benefit from surgery if R0 resection is achieved. We aimed to assess resectability and outcome of patients with locally advanced clinical T3/T4 (American Joint Committee on Cancer 8 <sup>th</sup> edition) tumors after induction treatment followed by surgery in a pooled analysis of 3 prospective multicenter trials. A total of 197 patients with T3/T4 non-small cell lung cancer of 368 patients with stage III non-small cell lung cancer enrolled in the Swiss Group for Clinical Cancer Research 16/96, 16/00, 16/01 trials were treated with induction chemotherapy or chemoradiation therapy followed by surgery, including extended resections. Univariable and multivariable analyses were applied for analysis of outcome parameters. Patients' median age was 60 years, and 67% were male. A total of 38 of 197 patients were not resected for technical (81%) or medical (19%) reasons. A total of 159 resections including 36 extended resections were performed with an 80% R0 and 13.2% pathological complete response rate. The 30- and 90-day mortality were 3% and 7%, respectively, without a difference for extended resections. Morbidity was 32% with the majority (70%) of minor grading complications. The 3-, 5-, and 10-year overall survivals for extended resections were 61% (95% confidence interval, 43-75), 44% (95% confidence interval, 27-59), and 29.5% (95% confidence interval, 13-48), respectively. R0 resection was associated with improved overall survival (hazard ratio, 0.41; P < .001), but pretreatment N2 extension (177/197) showed no impact on overall survival. Surgery after induction treatment for advanced T3/T4 stage including single and multiple pretreatment N2 disease resulted in 80% R0 resection rate and 7% 90-day mortality. Favorable overall survival for extended and not extended resection was demonstrated to be independent of pretreatment N status

Spatial model fitting for large datasets with applications to climate and microarray problems

Many problems in the environmental and biological sciences involve the analysis of large quantities of data. Further, the data in these problems are often subject to various types of structure and, in particular, spatial dependence. Traditional model fitting often fails due to the size of the datasets since it is difficult to not only specify but also to compute with the full covariance matrix describing the spatial dependence. We propose a very general type of mixed model that has a random spatial component. Recognizing that spatial covariance matrices often exhibit a large number of zero or near-zero entries, covariance tapering is used to force near-zero entries to zero. Then, taking advantage of the sparse nature of such tapered covariance matrices, backfitting is used to estimate the fixed and random model parameters. The novelty of the paper is the combination of the two techniques, tapering and backfitting, to model and analyze spatial datasets several orders of magnitude larger than those datasets typically analyzed with conventional approaches. Results will be demonstrated with two datasets. The first consists of regional climate model output that is based on an experiment with two regional and two driver models arranged in a two-by-two layout. The second is microarray data used to build a profile of differentially expressed genes relating to cerebral vascular malformations, an important cause of hemorrhagic stroke and seizures

s-Wave Symmetry Along the c-Axis and s+d In-plane Superconductivity in Bulk YBa2Cu4O8

To clarify the order parameter symmetry of cuprates, the magnetic penetration depth λ was measured along the crystallographic directions a, b, and c in single crystals of YBa2Cu4O8 via muon spin rotation. This method is direct, bulk sensitive, and unambiguous. The temperature dependences of λ a −2 and λ b −2 exhibit an inflection point at low temperatures as is typical for two-gap superconductivity (TGS) with s+d-wave character in the planes. Perpendicular to the planes a pure s-wave gap is observed thereby highlighting the important role of c-axis effects. We conclude that these are generic and universal features in the bulk of cuprates