A robust empirical seasonal prediction of winter NAO and surface climate

A key determinant of winter weather and climate in Europe and North America is the North Atlantic Oscillation (NAO), the dominant mode of atmospheric variability in the Atlantic domain. Skilful seasonal forecasting of the surface climate in both Europe and North America is reflected largely in how accurately models can predict the NAO. Most dynamical models, however, have limited skill in seasonal forecasts of the winter NAO. A new empirical model is proposed for the seasonal forecast of the winter NAO that exhibits higher skill than current dynamical models. The empirical model provides robust and skilful prediction of the December-January-February (DJF) mean NAO index using a multiple linear regression (MLR) technique with autumn conditions of sea-ice concentration, stratospheric circulation, and sea-surface temperature. The predictability is, for the most part, derived from the relatively long persistence of sea ice in the autumn. The lower stratospheric circulation and sea-surface temperature appear to play more indirect roles through a series of feedbacks among systems driving NAO evolution. This MLR model also provides skilful seasonal outlooks of winter surface temperature and precipitation over many regions of Eurasia and eastern North America

Time-Symmetric Quantum Theory of Smoothing

Smoothing is an estimation technique that takes into account both past and future observations, and can be more accurate than filtering alone. In this Letter, a quantum theory of smoothing is constructed using a time-symmetric formalism, thereby generalizing prior work on classical and quantum filtering, retrodiction, and smoothing. The proposed theory solves the important problem of optimally estimating classical Markov processes coupled to a quantum system under continuous measurements, and is thus expected to find major applications in future quantum sensing systems, such as gravitational wave detectors and atomic magnetometers.Comment: 4 pages, 1 figure, v2: accepted by PR

Vertical Variability and Lateral Distribution of Late Wisconsinan Sediments Parallel to theAxis of the Buried Valley of Mud Brook North of Akron, Summit County, Ohio

Author Institution: Department of Geology & Environmental Science, University of AkronThe buried valley of Mud Brook in northern Summit County, OH, contains sediments associated with the late Wisconsinan glaciation. The vertical variability and lateral distribution of these sediments can be ascertained from information derived from logs from highway borings and water wells along a 15-km north-south transect parallel to the axis of the buried valley. Textural, carbonate, clay mineral, and lithologic analyses of samples from roadcuts, geological borings, and some highway department borings provide additional information to assign lithofacies units to specific glaciations. Cross sections show that nearly similar depositional environments existed before each late Wisconsinan glacial advance. The proglacial sediments consist of outwash and lacustrine deposits overridden by ice that deposited an overlying till. Sediments associated with the Lavery and Hiram advances overlie a Kent-aged kame plateau within the Summit County Morainic Complex at the southern end of the study area. Farther north meltwater accumulated and drowned ground moraine to form post-glacial lakes that were eventually drained as the drainage network of Mud Brook became better integrated

Bellman equations for optimal feedback control of qubit states

Using results from quantum filtering theory and methods from classical control theory, we derive an optimal control strategy for an open two-level system (a qubit in interaction with the electromagnetic field) controlled by a laser. The aim is to optimally choose the laser's amplitude and phase in order to drive the system into a desired state. The Bellman equations are obtained for the case of diffusive and counting measurements for vacuum field states. A full exact solution of the optimal control problem is given for a system with simpler, linear, dynamics. These linear dynamics can be obtained physically by considering a two-level atom in a strongly driven, heavily damped, optical cavity.Comment: 10 pages, no figures, replaced the simpler model in section

Changes in biomechanical properties of chemotherapy bone cement after a year in saline storage

Introduction: Acrylic based bone cements are a versatile treatment modality in Orthopaedic surgery due to their wide variety of uses and tolerance to high degree of customization. Bone cement can be used to repair and stabilize pathologic fractures and may potentially prevent recurrence post tumor resection. Chemotherapeutic bone cements are favorable because they can potentially minimize systemic side effects and the need for radiation. Cements can be combined with soluble fillers such as polyethylene glycol (PEG) to optimize drug elution. Even though studies have measured the mechanical properties of bone cement in dry state, the exact change in the mechanical properties of bone cement after drug/soluble filler elution is largely unknown. This study investigates the change in mechanical properties of commercially available bone cements modified with PEG fillers after one year of storage in drug elution medium. Methods: Confidence Ultra, Vertebroplastic, and Palacos cement were used and mixed with varying amounts (0–50%) of PEG and chemotherapy agents (methotrexate or doxorubicin). Bone cement specimens were stored in a saline solution for one year after which they were tested in compression at 1 mm/min until failure. Results: The modulus and compression strength of bone cements decreased with increase in soluble filler composition. Although soluble fillers were shown to weaken the mechanical properties of the bone cement, Palacos and Vertebroplastic cements retained their mechanical properties better than Confidence. Discussion: When using chemotherapeutic bone cements, combining soluble fillers enhances drug elution at the expense of mechanical properties. However, the results showed that mechanical properties of different commercially available bone cements behave differently with similar percentages of soluble filler and drug added making it difficult to predict changes in mechanical properties of bone cement intraoperatively. This elucidates the need for well characterized bone cement optimized for chemotherapy drug delivery

Self-Averaging Scaling Limits of Two-Frequency Wigner Distribution for Random Paraxial Waves

Two-frequency Wigner distribution is introduced to capture the asymptotic behavior of the space-frequency correlation of paraxial waves in the radiative transfer limits. The scaling limits give rises to deterministic transport-like equations. Depending on the ratio of the wavelength to the correlation length the limiting equation is either a Boltzmann-like integral equation or a Fokker-Planck-like differential equation in the phase space. The solutions to these equations have a probabilistic representation which can be simulated by Monte Carlo method. When the medium fluctuates more rapidly in the longitudinal direction, the corresponding Fokker-Planck-like equation can be solved exactly.Comment: typos correcte

Characterization of gsp-Mediated Growth Hormone Excess in the Context of McCune-Albright Syndrome

McCune-Albright syndrome (MAS) is a disorder characterized by the triad of café-au-lait skin pigmentation, polyostotic fibrous dysplasia of bone, and hyperfunctioning endocrinopathies, including GH excess. The molecular etiology of the disease is postzygotic activating mutations of the GNAS1 gene product, Gsα. The term gsp oncogene has been assigned to these mutations due to their association with certain neoplasms. The aim of this study was to estimate the prevalence of GH excess in MAS, characterize the clinical and endocrine manifestations, and describe the response to treatment. Fifty-eight patients with MAS were screened, and 22 with stigmata of acromegaly and/or elevated GH or IGF-I underwent oral glucose tolerance testing. Twelve patients (21%) had GH excess, based on failure to suppress serum GH on oral glucose tolerance test, and underwent a TRH test, serial GH sampling from 2000-0800 h, and magnetic resonance imaging of the sella. We found that vision and hearing deficits were more common in patients with GH excess (4 of 12, 33%) than those without (2 of 56, 4%). Of interest, patients with a history of precocious puberty and GH excess who had reached skeletal maturity achieved normal adult height despite a history of early epiphyseal fusion. All 9 patients tested had an increase in serum GH after TRH, 11 of 12 (92%) had hyperprolactinemia, and all 8 tested had detectable or elevated nighttime GH levels. Pituitary adenoma was detected in 4 of 12 (33%) patients. All patients with elevated IGF-I levels were treated with cabergoline (7 patients), long-acting octreotide (LAO; 8 patients), or a combination of cabergoline and LAO (4 patients). In six of the seven patients (86%) treated with cabergoline, serum IGF-I decreased, but not to the normal range. In the eight patients treated with LAO alone, IGF-I decreased, and, in four, returned to the normal range. The remaining 4 patients were treated with a combination of cabergoline and LAO. For them, symptoms of GH excess diminished, and IGF-I decreased further, but did not enter the normal range. GH excess is common in MAS and results in a distinct clinical phenotype characterized by inappropriately normal stature, TRH responsiveness, prolactin cosecretion, small or absent pituitary tumors, a consistent but inadequate response to treatment with cabergoline, and an intermediate response to LAO

A fully-discrete scheme for systems of nonlinear Fokker-Planck-Kolmogorov equations

We consider a system of Fokker-Planck-Kolmogorov (FPK) equations, where the dependence of the coefficients is nonlinear and nonlocal in time with respect to the unknowns. We extend the numerical scheme proposed and studied recently by the authors for a single FPK equation of this type. We analyse the convergence of the scheme and we study its applicability in two examples. The first one concerns a population model involving two interacting species and the second one concerns two populations Mean Field Games

Comparison of Ventricular Refractory Periods Determined by Incremental and Decremental Scanning of an Extrastimulus

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73345/1/j.1540-8159.1989.tb02699.x.pd