Hie-Isolde High Beta Cavity Study and Measurements

The upgrade of the ISOLDE machine at CERN foresees a superconducting linac based on two gap independently phased Nb sputtered Quarter Wave Resonators (QWRs) working at 101.28MHz and producing an accelerating field of 6MV/m on axis. A careful study of the fields in the cavity has been carried out in order to pin down the crucial e-m parameters of the structure such as peak fields, quality factor and e-m power dissipated on the cavity wall. A tuning system with about 200kHz frequency range has been developed in order to cope with fabrication tolerances. In this paper we will report on the cavity simulations. The tuning plate design will be described. Finally the frequency measurements on a cavity prototype at room temperature will be presented.Comment: 5 pages, SRF09 Conference in Berli

Beam Dynamics Studies for the HIE-ISOLDE Linac at CERN

The upgrade of the normal conducting (NC) Radioactive Ion Beam EXperiment (REX)-ISOLDE heavy ion accelerator at CERN, under the High Intensity and Energy (HIE)-ISOLDE framework, proposes the use of superconducting (SC) quarter-wave resonators (QWRs) to increase the energy capability of the facility from 3 MeV/u to beyond 10 MeV/u. A beam dynamics study of a lattice design comprising SC QWRs and SC solenoids has confirmed the design's ability to accelerate ions, with a mass-to-charge ratio in the range 2.5 < A/q < 4.5, to the target energy with a minimal emittance increase. We report on the development of this study to include the implementation of realistic fields within the QWRs and solenoids. A preliminary error study is presented in order to constrain tolerances on the manufacturing and alignment of the linac.Comment: 3 pages, 8 figures, 1 table, submitted to the Particle Accelerator Conference (PAC) 2009 in Vancouver. Page formatting changed to US letter siz

Efficient Coherent Control by Optimized Sequences of Pulses of Finite Duration

Reliable long-time storage of arbitrary quantum states is a key element for quantum information processing. In order to dynamically decouple a spin or quantum bit from a dephasing environment, we introduce an optimized sequence of $N$ control pulses of finite durations \tau\pp and finite amplitudes. The properties of this sequence of length $T$ stem from a mathematically rigorous derivation. Corrections occur only in order $T^{N+1}$ and \tau\pp^3 without mixed terms such as T^N\tau\pp or T^N\tau\pp^2. Based on existing experiments, a concrete setup for the verification of the properties of the advocated realistic sequence is proposed.Comment: 8 pages, 1 figur

Energy-based predictions in Lorenz system by a unified formalism and neural network modelling

In the framework of a unified formalism for Kolmogorov-Lorenz systems, predictions of times of regime transitions in the classical Lorenz model can be successfully achieved by considering orbits characterised by energy or Casimir maxima. However, little uncertainties in the starting energy usually lead to high uncertainties in the return energy, so precluding the chance of accurate multi-step forecasts. In this paper, the problem of obtaining good forecasts of maximum return energy is faced by means of a neural network model. The results of its application show promising results

Compensation of Transverse Field Asymmetry in the High-beta Quarter-wave Resonator of the HIE-ISOLDE Linac at CERN

The superconducting upgrade of the REX-ISOLDE radioactive ion beam (RIB) post-accelerator at CERN will utilise a compact lattice comprising quarter-wave resonators (QWRs) and solenoids, accelerating beams in the mass range 2.5 < A/q < 4.5 to over 10 MeV/u. The short and independently phased quarter-wave structures allow for the acceleration of RIBs over a variable velocity profile and provide an unrivalled longitudinal acceptance when coupled with solenoid focusing. The incorporation of the solenoids into the cryomodule shortens the linac, whilst maximising the acceptance, but the application of solenoid focusing in the presence of asymmetric QWR fields can have consequences for the beam quality. The rotation of an asymmetric beam produces an effective emittance growth in the laboratory reference system. We present modifications of the cavity geometry to optimise the symmetry of the transverse fields in the high-beta QWR. A racetrack shaped beam port is analysed and a modification made to the inner conductor with a geometry that will enable a niobium film to be effectively sputtered onto the cavity surface.Comment: 5 pages, 9 figures, presented at the 14th international conference on RF superconductivit

K-ATP channel gene expression is induced by urocortin and mediates its cardioprotective effect

Background-Urocortin is a novel cardioprotective agent that can protect cardiac myocytes from the damaging effects of ischemia/reperfusion both in culture and in the intact heart and is effective when given at reperfusion.Methods and Results-We have analyzed global changes in gone expression in cardiac myocytes after urocortin treatment using gene chip technology. We report that urocortin specifically induces enhanced expression of the Kir 6.1 cardiac potassium channel subunit. On the basis of this finding, we showed that the cardioprotective effect of urocortin both in isolated cardiac cells and in the intact heart is specifically blocked by both generalized and mitochondrial-specific K-ATP channel blockers, whereas the cardioprotective effect of cardiotrophin-1 is unaffected. Conversely, inhibiting the Kir 6.1 channel subunit greatly enhances cardiac cell death after ischemia.Conclusions-This is, to our knowledge, the first report of the altered expression of a K-ATP. channel subunit induced by a cardioprotective agent and demonstrates that K-ATP, channel opening is essential for the effect of this novel cardioprotective agent

Optimized Dynamical Decoupling for Time Dependent Hamiltonians

The validity of optimized dynamical decoupling (DD) is extended to analytically time dependent Hamiltonians. As long as an expansion in time is possible the time dependence of the initial Hamiltonian does not affect the efficiency of optimized dynamical decoupling (UDD, Uhrig DD). This extension provides the analytic basis for (i) applying UDD to effective Hamiltonians in time dependent reference frames, for instance in the interaction picture of fast modes and for (ii) its application in hierarchical DD schemes with $\pi$ pulses about two perpendicular axes in spin space. to suppress general decoherence, i.e., longitudinal relaxation and dephasing.Comment: 5 pages, no figure

Evaluation of cephalometric, hormonal and enzymatic parameters in young obese subjects

Aim The aim of the present investigation was to analyse cephalometric skeletal structures and hormonal and enzymatic parameters in young obese subjects in comparison with those of normal weight subjects. Materials and methods The whole sample consisted of 50 Caucasian patients (28 males and 22 females) whose lateral radiographs, laboratory hormonal and enzymatic analyses were already available. The test group included 25 obese patients (11 females and 14 males, average age: 9.8 ± 2.11 years old), while the control group included 25 normal weight subjects matched for age and sex (11 females and 14 males, 9.9 ± 2.5 years old). Data were statistically analysed: Student’s t-test for independent samples was adopted and the level of significance was set at: p< 0.05. Results As regards cephalometric records, the anterior cranial base length was significantly greater in the test group (S-N: 69.9 ± 4 mm) compared to the controls (S-N: 68.1 ± 2.7 mm). Moreover, the maxillary lenght was higher in the test group (Pm-A: 48.5 ± 2.5 mm ) in comparison to the control group (Pm-A: 46.1 ± 1.9 mm). As regards skeletal class and vertical dimension, no significant differences were found between the two groups, with the exception of the intermaxillary plane angle, which was significantly lower in the obese subjects in comparison to the controls. Laboratory analysis showed significant (p <0.05) higher levels of leptin and insulin in the test group in comparison with control subjects. Furthermore, LH, FSH, IGF-1 values were significantly (p <0.05) lower in the test group in comparison with the control group. Conclusion Obese subjects exhibited an increase of some craniofacial parameters and alteration of some laboratory parameters that may be involved in the process of skeletal maturation, in comparison to normal weight subjects. These findings may be of interest in orthodontics, as young obese subjects may need a different orthodontic treatment plan in comparison to Evaluation normal weight subjects of the same age