793 research outputs found

    Topologically massive gravity as a Pais-Uhlenbeck oscillator

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    We give a detailed account of the free field spectrum and the Newtonian limit of the linearized "massive" (Pauli-Fierz), "topologically massive" (Einstein-Hilbert-Chern-Simons) gravity in 2+1 dimensions about a Minkowski spacetime. For a certain ratio of the parameters, the linearized free theory is Jordan-diagonalizable and reduces to a degenerate "Pais-Uhlenbeck" oscillator which, despite being a higher derivative theory, is ghost-free.Comment: 9 pages, no figures, RevTEX4; version 2: a new paragraph and a reference added to the Introduction, a new appendix added to review Pais-Uhlenbeck oscillators; accepted for publication in Class. Quant. Gra

    Outbreak of Phytophthora cinnamomi causing severe decline of avocado trees in southern Turkey

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    Acknowledgements: This research was supported by Bati Akdeniz Agricultural Research Institute (BATEM), and we appreciate the help of the staff of the Ministry of Agriculture and Forestry. We are also thankful to Dr Emrah Yıldırım for preparation of the map.Peer reviewedPostprin

    Optimum Power Allocation for Average Power Constrained Jammers in the Presense of Non-Gaussian Noise

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    Cataloged from PDF version of article.We study the problem of determining the optimum power allocation policy for an average power constrained jammer operating over an arbitrary additive noise channel, where the aim is to minimize the detection probability of an instantaneously and fully adaptive receiver employing the Neyman-Pearson (NP) criterion. We show that the optimum jamming performance can be achieved via power randomization between at most two different power levels. We also provide sufficient conditions for the improvability and nonimprovability of the jamming performance via power randomization in comparison to a fixed power jamming scheme. Numerical examples are presented to illustrate theoretical results

    Short Communication Effects of short chain fatty acid (SCFA) supplementation on performance and egg characteristics of old breeder hens

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    A study was conducted to determine the effect of supplementing the diet of breeder hens with a short-chain fatty acid (SCFA) premix, containing 509 g fatty acid salts/kg of which 285 g were calcium butyrate, on their eggshell characteristics and the hatching percentage of the eggs. One thousand six hundred 66-week old White Bovans laying breeder hens were used in this experiment. They were housed in eight identical pens, each containing 200 birds, and four pens were used per treatment. The SCFA premix was included at 1000 mg/kg in the treatment diet, and fed for a period of nine weeks. Responses were compared with an unsupplemented treatment. Supplementation started when the hens were 66 weeks old. From day 75 eggs were collected for the next seven weeks and the occurrence of cracked, dirty and misshapen eggs was recorded, and the hatching percentage of the eggs was determined. Eggshell strength was lower in eggs from the control (1.76 ± 0.05) than from the treatment group (2.07 ± 0.03). The percentage of eggs produced by the control group (68.6 ± 0.08) was significantly lower than that by the supplemented group (71.5 ± 0.15). Percentage of dirty, cracked and misshapen eggs, and the hatchability percentage of the control group (1.15 ± 0.03, 3.44 ± 0.05, 6.27 ± 0.03 and 88.93 ± 0.06, respectively) were also significantly lower than in the group receiving SCFA (0.47 ± 0.03, 2.21 ± 0.03, 3.81 ± 0.03 and 93.36 ± 0.05, respectively). It was concluded that dietary supplementation of SCFA to layer breeder hens from 66 weeks of age onwards improved eggshell strength, reduced the percentage of dirty, cracked and misshapen eggs and increased the hatching percentage of the eggs. The positive responses were suggested to be largely due to the butyrate in the SCFA. Keywords: Butyrate; SCFA; eggshell quality; hatching characteristics South African Journal of Animal Science Vol. 37 (3) 2007: pp.158-16

    All unitary cubic curvature gravities in D dimensions

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    We construct all the unitary cubic curvature gravity theories built on the contractions of the Riemann tensor in D -dimensional (anti)-de Sitter spacetimes. Our construction is based on finding the equivalent quadratic action for the general cubic curvature theory and imposing ghost and tachyon freedom, which greatly simplifies the highly complicated problem of finding the propagator of cubic curvature theories in constant curvature backgrounds. To carry out the procedure we have also classified all the unitary quadratic models. We use our general results to study the recently found cubic curvature theories using different techniques and the string generated cubic curvature gravity model. We also study the scattering in critical gravity and give its cubic curvature extensions.Comment: 24 pages, 1 figure, v2: A subsection on cubic curvature extensions of critical gravity is added, v3: The part regarding critical gravity is revised. Version to appear in Class. Quant. Gra

    Real-life experience of patients with sarcomatoid renal cell carcinoma: a multicenter retrospective study

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    Sarcomatoid renal cell carcinoma (sRCC) is a rare variant of renal cell carcinoma (RCC) and is associated with a poor prognosis. We reviewed the outcomes of patients from oncology centers in Turkey. Our aim is to share our real-life experience and to contribute to the literature. The demographic and clinical features, treatment, and survival outcomes of 148 patients with sRCC were analyzed. The median age at the time of diagnosis was 58 years (range: 19-83 years). Most patients (62.8%) had clear-cell histology. Most patients were in the intermediate Memorial Sloan-Kettering Cancer Center (MSKCC) risk group (67.6%) and were stage 4 at the time of diagnosis (63.5%). The most common sites of metastasis were the lung (60.1%), lymph nodes (47.3%), and bone (35.8%). The patients received a median of two lines (range: 0-6) of treatment. The most common side effects were fatigue, hematological side effects, hypertension, and hypothyroidism. The median follow-up was 20.9 months (range: 1-162 months). The median overall survival (OS) was 30.8 months (95% confidence interval: 24.9-36.7 months). In multivariate analysis, high MSKCC scores, sarcomatoid differentiation rates >50%, having stage 4 disease, and having lung metastasis at the time of diagnosis were independent factors for poor prognosis affecting OS. No difference was observed between patients who received tyrosine kinase inhibitor (TKI) as the first or second-line treatments. Similarly, no difference between TKI and immunotherapy as the second-line treatment. In conclusion, sRCC is a rare variant of RCC with a poor prognosis and response to treatment. Larger-scale prospective studies are needed to define an optimal treatment approach for longer survival in this aggressive variant

    Photonuclear reactions with Zinc: A case for clinical linacs

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    The use of bremsstrahlung photons produced by a linac to induce photonuclear reactions is wide spread. However, using a clinical linac to produce the photons is a new concept. We aimed to induce photonuclear reactions on zinc isotopes and measure the subsequent transition energies and half-lives. For this purpose, a bremsstrahlung photon beam of 18 MeV endpoint energy produced by the Philips SLI-25 linac has been used. The subsequent decay has been measured with a well-shielded single HPGe detector. The results obtained for transition energies are in good agreement with the literature data and in many cases surpass these in accuracy. For the half-lives, we are in agreement with the literature data, but do not achieve their precision. The obtained accuracy for the transition energies show what is achievable in an experiment such as ours. We demonstrate the usefulness and benefits of employing clinical linacs for nuclear physics experiments

    Revisiting Synthesis Model of Sparse Audio Declipper

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    The state of the art in audio declipping has currently been achieved by SPADE (SParse Audio DEclipper) algorithm by Kiti\'c et al. Until now, the synthesis/sparse variant, S-SPADE, has been considered significantly slower than its analysis/cosparse counterpart, A-SPADE. It turns out that the opposite is true: by exploiting a recent projection lemma, individual iterations of both algorithms can be made equally computationally expensive, while S-SPADE tends to require considerably fewer iterations to converge. In this paper, the two algorithms are compared across a range of parameters such as the window length, window overlap and redundancy of the transform. The experiments show that although S-SPADE typically converges faster, the average performance in terms of restoration quality is not superior to A-SPADE

    Pistacia terebinthus as a dietary supplement for laying hens

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    The aim of this study was to explore the potential of Pistacia terebinthus (terebinth) seed meal as a dietary supplement for laying hens. One hundred and ninety-two Babcock 30-week-old laying hens were assigned to one of six treatments (n = 32) with four replicates (n = 8). The hens were fed diets containing 0%, 1%, 2%, 3%, 4%, and 5% terebinth seed meal for eight weeks. Weekly egg production, feed consumption, egg weight, and egg mass were recorded. Egg quality was assessed at the beginning, middle and end of the study. Blood sampling was carried out on 12 birds from each treatment. Total antioxidant capacity, total oxidant status and oxidative stress index were determined. Egg production was greater from hens fed 3% and 4% terebinth than those in the other treatments. Egg weight was increased by supplementation with 2% or more terebinth. Feed consumption, feed conversion ratio, eggshell breaking strength, yolk colour, Haugh units, concentrations of glucose, total cholesterol, high density lipoprotein, low density lipoprotein, alanine aminotransferase, aspartate aminotransferase, total protein, phosphorus and calcium in serum, and total antioxidant capacity, total oxidant status, and the oxidative stress index did not differ across treatments. It is concluded that dietary terebinth seed supplementation generated positive effects on egg production and egg weight without adverse effects on egg quality or the metabolism of the hen.Keywords: antioxidant, egg production, egg quality, feed consumption, serum biochemistr

    Quantum beat spectroscopy: stimulated emission probe of hyperfine quantum beats in the atomic Cs 8p 2P3/2^{2}P_{3/2} level

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    Measurements of hyperfine polarization quantum beats are used determine the magnetic dipole (A) and electric quadrupole (B) coupling constants in the excited atomic Cs 8p level. The experimental approach is a novel combination of pulsed optical pumping and time-delayed stimulated emission probing of the excited level. From the measured evolution of the atomic linear polarization degree as a function of probe delay time, we determine the hyperfine coupling constants A = 7.42(6) MHz and B = 0.14(29) MHz
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