26,498 research outputs found

    Enhanced binding revisited for a spinless particle in non-relativistic QED

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    We consider a spinless particle coupled to a quantized Bose field and show that such a system has a ground state for two classes of short-range potentials which are alone too weak to have a zero-energy resonance

    A metal–organic framework/α-alumina composite with a novel geometry for enhanced adsorptive separation

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    The development of a metal–organic framework/α-alumina composite leads to a novel concept: efficient adsorption occurs within a plurality of radial micro-channels with no loss of the active adsorbents during the process. This composite can effectively remediate arsenic contaminated water producing potable water recovery, whereas the conventional fixed bed requires eight times the amount of active adsorbents to achieve a similar performance

    Theoretical studies of the local structures and EPR parameters for Cu2+^{2+} center in Cd2_{2}(NH4_{4})2_{2}(SO4_{4})3_{3} single crystal

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    The electron paramagnetic resonance (EPR) parameters (gg factors gig_{i} and the hyperfine structure constants Ai{{A}}_{{i}}, i=x,y,z{i} = {x}, {y}, {z}) are interpreted by using the perturbation formulae for a 3d93{d}^{9} ion in rhombically ({D}2h_{2h}) elongated octahedra. In the calculated formulae, the crystal field parameters are set up from the superposition model, and the contribution to the EPR parameters from the admixture of dd-orbitals in the ground state wave function of the Cu2+^{2+} ion was taken into account. Based on the calculation, local structural parameters of the impurity Cu2+^{2+} center in Cd2_{2}(NH4_{4})2_{2}(SO4_{4})3_{3} (CAS) crystal were obtained (i.e., Rx2.05{R}_{{x}}\approx 2.05 {\AA}, Ry1.91{R}_{{y}} \approx 1.91 {\AA}, Rz2.32{R}_{{z}} \approx 2.32 {\AA}). The theoretical EPR parameters based on the above Cu2+^{2+}-O2^{2-} bond lengths in CAS crystal show a good agreement with the observed values. The results are discussed.Comment: 5 page

    Hooge's Constant of Carbon Nanotube Field Effect Transistors

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    The 1/f noise in individual semiconducting carbon nanotubes (s-CNT) in a field effect transistor configuration has been measured in ultra-high vacuum and following exposure to air. The amplitude of the normalized current spectral noise density is independent of source-drain current, indicating the noise is due to mobility rather than number fluctuations. Hooge's constant for s-CNT is found to be 9.3 plus minus 0.4x10^-3. The magnitude of the 1/f noise is substantially degreased by exposing the devices to air

    A Machine-Synesthetic Approach To DDoS Network Attack Detection

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    In the authors' opinion, anomaly detection systems, or ADS, seem to be the most perspective direction in the subject of attack detection, because these systems can detect, among others, the unknown (zero-day) attacks. To detect anomalies, the authors propose to use machine synesthesia. In this case, machine synesthesia is understood as an interface that allows using image classification algorithms in the problem of detecting network anomalies, making it possible to use non-specialized image detection methods that have recently been widely and actively developed. The proposed approach is that the network traffic data is "projected" into the image. It can be seen from the experimental results that the proposed method for detecting anomalies shows high results in the detection of attacks. On a large sample, the value of the complex efficiency indicator reaches 97%.Comment: 12 pages, 2 figures, 5 tables. Accepted to the Intelligent Systems Conference (IntelliSys) 201

    Simultaneous current-, force- and work function measurement with atomic resolution

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    The local work function of a surface determines the spatial decay of the charge density at the Fermi level normal to the surface. Here, we present a method that enables simultaneous measurements of local work function and tip-sample forces. A combined dynamic scanning tunneling microscope and atomic force microscope is used to measure the tunneling current between an oscillating tip and the sample in real time as a function of the cantilever's deflection. Atomically resolved work function measurements on a silicon (111)-(7×77\times 7) surface are presented and related to concurrently recorded tunneling current- and force- measurements.Comment: 8 pages, 4 figures, submitted to Applied Physics Letter

    The increase of Binding Energy and Enhanced Binding in Non-Relativistic QED

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    We consider a Pauli-Fierz Hamiltonian for a particle coupled to a photon field. We discuss the effects of the increase of the binding energy and enhanced binding through coupling to a photon field, and prove that both effects are the results of the existence of the ground state of the self-energy operator with total momentum P=0P = 0.Comment: 14 pages, Latex. Final version, accepted for publication in J. Math. Phy

    Quantification of the uncertainties within the radiotherapy dosimetry chain and their impact on tumour control

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    BACKGROUND AND PURPOSE: Dose delivered during radiotherapy has uncertainty arising from a number of sources including machine calibration, treatment planning and delivery and can impact outcomes. Any systematic uncertainties will impact all patients and can continue for extended periods. The impact on tumour control probability (TCP) of the uncertainties within the radiotherapy calibration process has been assessed. MATERIAL AND METHODS: The linear-quadratic model was used to simulate the TCP from two prostate cancer and a head and neck (H&N) clinical trial. The uncertainty was separated into four components; 1) initial calibration, 2) systematic shift due to output drift, 3) drift during treatment and 4) daily fluctuations. Simulations were performed for each clinical case to model the variation in TCP present at the end of treatment arising from the different components. RESULTS: Overall uncertainty in delivered dose was +/−2.1% (95% confidence interval (CI)), consisting of uncertainty standard deviations of 0.7% in initial calibration, 0.8% due to subsequent calibration shift due to output drift, 0.1% due to drift during treatment, and 0.2% from daily variations. The overall uncertainty of TCP (95% CI) for a population of patients treated on different machines was +/−3%, +/−5%, and +/−3% for simulations based on the two prostate trials and H&N trial respectively. CONCLUSIONS: The greatest variation in delivered target volume dose arose from calibration shift due to output drift. Careful monitoring of beam output following initial calibration remains vital and may have a significant impact on clinical outcomes

    Effect of starvation on growth, histology and ultrastructure of digestive system of juvenile red swamp crayfish (Procambarus clarkii Girard)

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    The present study was conducted to evaluate the effect of 20 d starvation on growth, survival, histomorphology and ultrastructure changes in the digestive system of juvenile red swamp crayfish (Procambarus clarkii). Juveniles were divided into two groups: a food-deprived group and a control group at 9 day after hatch (DAH). Individuals were sampled at 14, 20, 29 DAH. During the 20 d fasting period, the mean body weight and total body length of crayfish fluctuated around 10.17 mg and 8.12 mm respectively, and the mortality was zero. Histomorphological changes of digestive system were observed in the food-deprived group after 20 days of starvation: the esophagus and stomach walls were thinning, the epithelium atrophied to cuboidal, nuclei were darker and smaller, and nucleolus was difficult to observe; the midgut and hindgut showed wider volume, thinning wall, atrophied epithelial and muscularis and shorter ridges; and hepatopancreas tubule lumens were wider, the lipid droplets in R-cells were smaller and less, and the quantity of typical B-cells decreased. Changes in the ultrastructure of starved crayfish were also observed: the mitochondria of midgut epithelium and R-cells were swollen and vacuolated, and the ridges of which were fractured and reduced. In addition, the electron density of cytoplasmic matrix of R-cells decreased, and the quantity of glycogen granules and lipids also decreased. Changes in the ultrastructure of B-cells were similar to those of R-cells. Though degeneration in histological structure and function of digestive organs were obvious during starvation, juvenile P. clarkii was able to endure a relative long-term starvation

    Integrability of the critical point of the Kagom\'e three-state Potts mode

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    The vicinity of the critical point of the three-state Potts model on a Kagom\'e lattice is studied by mean of Random Matrix Theory. Strong evidence that the critical point is integrable is given.Comment: 1 LaTex file + 3 eps files 7 page
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