997 research outputs found

    Primary Fallopian Tube Cancer : A Rare Gynecological Malignancy

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    Primary fallopian tube carcinoma is a rare gynecological cancer. Loco regionally advanced disease is clinically difficult to differentiate from similar stage ovarian and primary peritoneal carcinomas. Early stage fallopian tube tumors, despite having unique clinical presentation are provisionally diagnosed as an ovarian carcinoma due to rarity and symptom overlap with these more common gynecological cancers. We present a case of early fallopian tube cancer provisionally diagnosed as an ovarian carcinoma and review the current literature regarding etiology and treatment

    Quantitative analysis of pedestrian counterflow in a cellular automaton model

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    Pedestrian dynamics exhibits various collective phenomena. Here we study bidirectional pedestrian flow in a floor field cellular automaton model. Under certain conditions, lane formation is observed. Although it has often been studied qualitatively, e.g., as a test for the realism of a model, there are almost no quantitative results, neither empirically nor theoretically. As basis for a quantitative analysis we introduce an order parameter which is adopted from the analysis of colloidal suspensions. This allows to determine a phase diagram for the system where four different states (free flow, disorder, lanes, gridlock) can be distinguished. Although the number of lanes formed is fluctuating, lanes are characterized by a typical density. It is found that the basic floor field model overestimates the tendency towards a gridlock compared to experimental bounds. Therefore an anticipation mechanism is introduced which reduces the jamming probability.Comment: 11 pages, 12 figures, accepted for publication in Phys. Rev.

    Evaporation of alpha particles from 31^31P nucleus

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    The energy spectra of alpha particles have been measured in coincidence with the evaporation residues for the decay of the compound nucleus 31^31P produced in the reaction 19^19F (96 MeV) + 12^12C. The data have been compared with the predictions of the statistical model code CASCADE. It has been observed that significant deformation effect in the compound nucleus need to be considered in order to explain the shape of the evaporated alpha particle energy spectra.Comment: 4 pages, 3 figures, revtex, epsf styl

    Pelvic lymphadenectomy as a component of interval cytoreduction for ovarian cancer: is there a benefit? A pilot study

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    Background: Management strategy in ovarian cancer includes a combination of cytoreductive surgery and chemotherapy. Interval cytoreductive surgery has been shown to be oncologically non-inferior to primary cytoreduction with the additional benefit of reduced morbidity. Lymphadenectomy as a component of cytoreductive surgery has been controversial with an unproven therapeutic benefit.Methods: Records of patients with a histological diagnosis of ovarian cancer and treated with interval cytoreduction were evaluated. Disease related, pathological and treatment data collected for analysis.Results: The study included 32 patients with a mean age of 56 years (41-76). Serous papillary tumors (42%) were the predominate histology and the majority were in stage III disease (84%). Optimal cytoreduction was achieved in 93%. The mean nodal harvest was 9.8 nodes with left pelvic dissection yielding slightly more nodes than the right (4.5 vs 5.2). Nodal positivity was observed in just one patient (3%). A total of 314 were nodes examined with only 2 (0.6%) yielding persistent disease. The nodal positivity yield tested as a categorical variable by the binomial test returned P=0.0001.Conclusions: It is possible to omit pelvic nodal dissection during interval cytoreduction in otherwise optimally cytoreduced patients particularly when imaging and intraoperative assessment are not suggestive of pelvic nodal metastasis

    Sub-Riemannian Geometry and Time Optimal Control of Three Spin Systems: Quantum Gates and Coherence Transfer

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    Many coherence transfer experiments in Nuclear Magnetic Resonance Spectroscopy, involving network of coupled spins, use temporary spin-decoupling to produce desired effective Hamiltonians. In this paper, we show that significant time can be saved in producing an effective Hamiltonian, if spin-decoupling is avoided. We provide time optimal pulse sequences for producing an important class of effective Hamiltonians in three spin networks. These effective Hamiltonians are useful for coherence transfer experiments and implementation of quantum logic gates in NMR quantum computing. It is demonstrated that computing these time optimal pulse sequences can be reduced to geometric problems that involve computing sub-Riemannian geodesics on Homogeneous spaces

    Performance of Tomato with Organic Manures in Plastic Tunnel

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    Tomato is one of the most demanded vegetable with increasing trend of commercial cultivation in Nepal. As it is the heavy feeder crop thus soil nutrient management has been always challenging. Since, in modern world organic production has been favored by consumers for many reasons thus we aimed to compare the efficacy of various compost, mineral fertilizers and their combinations in tomato production and soil productivity. For the purpose a field experiment in plastic tunnel was carried out in Horticulture Research Division, Khumaltar in two consecutive years (2014 and 2015). Srijana, a popular tomato hybrid among commercial producers, was purposively selected. Eight treatments (control, recommended doses of chemical fertilizers, compost 15 t ha-1 + cattle urine, compost 10 t ha-1 + cattle urine, compost 12.5 t ha-1 + cattle urine, compost 15 t ha-1 + 1/4 recommended dose of chemical fertilizers, compost 10 t ha-1 + ¾ recommended dose of chemical fertilizer and compost 12.5 t ha-1 + 1/2 recommended dose of chemical fertilizer) were laid out in randomized complete block design and replicated thrice. The result showed significant (p < 0.05) positive correlation between the plant height and yield of tomato. The treatment with compost dose of 12.5 t ha-1 with half dose of recommended dose of chemical fertilizers produced the highest incremental yield (85% increment) over other treatments followed by compost 15 t ha-1 with cattle urine. Addition of soil organic carbon, soil nitrogen, soil potassium by the increasing level of compost though not significant, but increment in carbon content, nitrogen content and potassium content of soil observed in successive years. For commercial producer at plastic tunnel, compost at the rate 12.5 t ha-1 with half dose of recommended level of chemical fertilizer (100:90:40 kg N:P:K ha-1) is recommended to apply in field, while for organic producer, application of 15 tha-1 compost with fermented cattle urine is recommended

    Optimal Control of Quantum Dissipative Dynamics: Analytic solution for cooling the three level Λ\Lambda system

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    We study the problem of optimal control of dissipative quantum dynamics. Although under most circumstances dissipation leads to an increase in entropy (or a decrease in purity) of the system, there is an important class of problems for which dissipation with external control can decrease the entropy (or increase the purity) of the system. An important example is laser cooling. In such systems, there is an interplay of the Hamiltonian part of the dynamics, which is controllable and the dissipative part of the dynamics, which is uncontrollable. The strategy is to control the Hamiltonian portion of the evolution in such a way that the dissipation causes the purity of the system to increase rather than decrease. The goal of this paper is to find the strategy that leads to maximal purity at the final time. Under the assumption that Hamiltonian control is complete and arbitrarily fast, we provide a general framework by which to calculate optimal cooling strategies. These assumptions lead to a great simplification, in which the control problem can be reformulated in terms of the spectrum of eigenvalues of ρ\rho, rather than ρ\rho itself. By combining this formulation with the Hamilton-Jacobi-Bellman theorem we are able to obtain an equation for the globaly optimal cooling strategy in terms of the spectrum of the density matrix. For the three-level Λ\Lambda system, we provide a complete analytic solution for the optimal cooling strategy. For this system it is found that the optimal strategy does not exploit system coherences and is a 'greedy' strategy, in which the purity is increased maximally at each instant.Comment: 9 pages, 3 fig

    Time-optimal synthesis of unitary transformations in coupled fast and slow qubit system

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    In this paper, we study time-optimal control problems related to system of two coupled qubits where the time scales involved in performing unitary transformations on each qubit are significantly different. In particular, we address the case where unitary transformations produced by evolutions of the coupling take much longer time as compared to the time required to produce unitary transformations on the first qubit but much shorter time as compared to the time to produce unitary transformations on the second qubit. We present a canonical decomposition of SU(4) in terms of the subgroup SU(2)xSU(2)xU(1), which is natural in understanding the time-optimal control problem of such a coupled qubit system with significantly different time scales. A typical setting involves dynamics of a coupled electron-nuclear spin system in pulsed electron paramagnetic resonance experiments at high fields. Using the proposed canonical decomposition, we give time-optimal control algorithms to synthesize various unitary transformations of interest in coherent spectroscopy and quantum information processing.Comment: 8 pages, 3 figure

    Astrophysical S_{17}(0) factor from a measurement of d(7Be,8B)n reaction at E_{c.m.} = 4.5 MeV

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    Angular distribution measurements of 2^2H(7^7Be,7^7Be)2^2H and 2^2H(7^7Be,8^8B)nn reactions at Ec.m.E_{c.m.}\sim~4.5 MeV were performed to extract the astrophysical S17(0)S_{17}(0) factor using the asymptotic normalization coefficient (ANC) method. For this purpose a pure, low emittance 7^7Be beam was separated from the primary 7^7Li beam by a recoil mass spectrometer operated in a novel mode. A beam stopper at 0^{\circ} allowed the use of a higher 7^7Be beam intensity. Measurement of the elastic scattering in the entrance channel using kinematic coincidence, facilitated the determination of the optical model parameters needed for the analysis of the transfer data. The present measurement significantly reduces errors in the extracted 7^7Be(p,γ\gamma) cross section using the ANC method. We get S17S_{17}~(0)~=~20.7~±\pm~2.4 eV~b.Comment: 15 pages including 3 eps figures, one figure removed and discussions updated. Version to appear in Physical Review

    Multiple-spin coherence transfer in linear Ising spin chains and beyond: numerically-optimized pulses and experiments

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    We study multiple-spin coherence transfers in linear Ising spin chains with nearest neighbor couplings. These constitute a model for efficient information transfers in future quantum computing devices and for many multi-dimensional experiments for the assignment of complex spectra in nuclear magnetic resonance spectroscopy. We complement prior analytic techniques for multiple-spin coherence transfers with a systematic numerical study where we obtain strong evidence that a certain analytically-motivated family of restricted controls is sufficient for time-optimality. In the case of a linear three-spin system, additional evidence suggests that prior analytic pulse sequences using this family of restricted controls are time-optimal even for arbitrary local controls. In addition, we compare the pulse sequences for linear Ising spin chains to pulse sequences for more realistic spin systems with additional long-range couplings between non-adjacent spins. We experimentally implement the derived pulse sequences in three and four spin systems and demonstrate that they are applicable in realistic settings under relaxation and experimental imperfections-in particular-by deriving broadband pulse sequences which are robust with respect to frequency offsets.Comment: 11 page
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