The Amplitude Mode in the Quantum Phase Model

We derive the collective low energy excitations of the quantum phase model of interacting lattice bosons within the superfluid state using a dynamical variational approach. We recover the well known sound (or Goldstone) mode and derive a gapped (Higgs type) mode that was overlooked in previous studies of the quantum phase model. This mode is relevant to ultracold atoms in a strong optical lattice potential. We predict the signature of the gapped mode in lattice modulation experiments and show how it evolves with increasing interaction strength.Comment: 4 pages, 3 figure

Dynamics of plasma blobs in a shear flow

The global dynamic of plasma blobs in a shear flow is investigated in a simple magnetized torus using the spatial Fourier harmonics (k-space) framework. Direct experimental evidence of a linear drift in k space of the density fluctuation energy synchronized with blob events is presented. During this drift, an increase of the fluctuation energy and a production of the kinetic energy associated with blobs are observed. The energy source of the blob is analyzed using an advection-dissipation-type equation that includes blob-flow exchange energy, linear drift in k space, nonlinear processes, and viscous dissipations. We show that blobs tap their energy from the dominant E B vertical background flow during the linear drift stage. The exchange of energy is unidirectional as there is no evidence that blobs return energy to the flow

Influence of berry growth and growth regulators on the development of grape peduncles in Vitis vinifera L.

Removal of grape berries (cv. Roter Gutedel) after setting (10 d after anthesis) had just a slight effect on the subsequent health of the peduncle. But if younger berries of flowers were removed before this stage the peduncle formed abscission layers along its length, and/or it died. Treatment of deflowered peduncles with a-naphthalene acetic acid (NAi\) prevented peduncle abscission and death; it is suggested that auxins produced by flowers have a hormonal role in maintaining normal development of the peduncle. Treatment with 2-chloroethyltrimethyl ammonium chloride (CCC), benzyladenine (BA), indole-3-acetic acid (IAA) or 3-indolebutyric acid (IBA) did not give these effects. The lack of effect of the latter two compounds (auxins) is possibly due to their catabolism.Treatment with gibberellic acid (GA) resembled NAA in that it also maintained the health of deflowered peduncles, but GA had the additional effect of causing prolonged development of metaxylem. Gibberellin produced by developing berries may also have a hormonal role in peduncle development. The occurrence of grape peduncle necrosis (stiellaehme), which appears associated with a gibberellin deficiency during setting, supports this idea

Test your surrogate data before you test for nonlinearity

The schemes for the generation of surrogate data in order to test the null hypothesis of linear stochastic process undergoing nonlinear static transform are investigated as to their consistency in representing the null hypothesis. In particular, we pinpoint some important caveats of the prominent algorithm of amplitude adjusted Fourier transform surrogates (AAFT) and compare it to the iterated AAFT (IAAFT), which is more consistent in representing the null hypothesis. It turns out that in many applications with real data the inferences of nonlinearity after marginal rejection of the null hypothesis were premature and have to be re-investigated taken into account the inaccuracies in the AAFT algorithm, mainly concerning the mismatching of the linear correlations. In order to deal with such inaccuracies we propose the use of linear together with nonlinear polynomials as discriminating statistics. The application of this setup to some well-known real data sets cautions against the use of the AAFT algorithm.Comment: 14 pages, 15 figures, submitted to Physical Review

Calcifediol versus vitamin D3 effects on gait speed and trunk sway in young postmenopausal women: a double-blind randomized controlled trial

UNLABELLED In this double-blind RCT, 4-month treatment with calcifediol compared with vitamin D3 improved gait speed by 18 % among young postmenopausal women. Consistently, change in 25(OH)D blood levels over time were significantly correlated with improvement in gait speed in these women. No effect could be demonstrated for trunk sway. INTRODUCTION The aim of this study is to test the effect of calcifediol compared with vitamin D3 on gait speed and trunk sway. METHODS Twenty healthy postmenopausal women with an average 25(OH)D level of 13.2 ng/ml (SD = ±3.9) and a mean age of 61.5 years (SD = ±7.2) were randomized to either 20 μg of calcifediol or 20 μg (800 IU) of vitamin D3 per day in a double-blind manner. At baseline and at 4 months of follow-up, the same physiotherapist blinded to treatment allocation tested 8-m gait speed and a body sway test battery (Sway star pitch and roll angle plus velocity while walking 8 m, and standing on both legs on a hard and soft surface). All analyses adjusted for baseline measurement, age, and body mass index. RESULTS Mean 25(OH)D levels increased to 69.3 ng/ml (SD = ±9.5) in the calcifediol group and to 30.5 ng/ml (SD = ±5.0) in the vitamin D3 group (p < 0.0001). Women receiving calcifediol compared with vitamin D3 had an 18 % greater improvement in gait speed at 4-month follow-up (p = 0.046) adjusting for baseline gait speed, age, and body mass index. Also, change in gait speed was significantly correlated with change in serum 25(OH)D concentrations (r = 0.5; p = 0.04). Across three tests of trunk sway, there were no consistent differences between groups and no significant correlation between change in 25(OH)D serum concentrations and change in trunk sway. CONCLUSIONS Calcifediol improved gait speed in early postmenopausal women compared with vitamin D3 and change in 25(OH)D level was moderately correlated with improvement in gait speed. A benefit on trunk sway could not be demonstrated

Erfahrungen bei der Messung der Ergebnisqualität in der interventionellen Schmerztherapie

BACKGROUND There is a growing interest in patient-related outcome measurement. In this field questionnaires on touch screens are becoming more common. This study was designed to identify problems in usability and feasibility of a web-based questionnaire. STUDY PARTICIPANTS AND METHODS Patients who underwent a lumbar infiltration were recruited in 5 centers and 50 patients participated of which half were older than 62 years. One third of the patients had basically no former experience with computers or touch screens. The outcome was assessed before treatment and during follow-up on a simple web-based patient questionnaire, the Activity Index. Results were presented graphically and discussed during consultation. Patients, nurses and doctors were asked for standardized feedback. RESULTS Of the patients 84% completed the questionnaire in up to 6 min. An adapted form of the system usability scale (SUS) achieved an acceptance score of 71.8%. Problems in handling occurred mostly in older patients (>65 years). The system was scored with 72.9% and 78.5% in efficiency and handling, respectively, by the nurses. The attending physicians rated the usefulness and comprehensibility of the graphical representation of the results on average as 83.3% and both were scored neutral to positive; however, an average of 11.6% rated some aspects of the report to be suboptimal. CONCLUSION This web-based questionnaire is the first of its kind to be evaluated in everyday practice of interventional pain therapy for lumbar back pain. The vast majority of the patients were able to efficiently complete the questionnaire. The questionnaire was highly acceptable to patients, nurses and doctors. We found some usability problems but mainly in the older age group

i-gel™ supraglottic airway in clinical practice: a prospective observational multicentre study

Background The i-gel™ supraglottic airway device has been studied in randomized controlled studies, but it has not been evaluated in a large prospective patient cohort. Therefore, we performed this prospective multicentre observational study to evaluate success rates, airway leak pressure, risk factors for i-gel failure, and adverse events. Methods With Ethics Committee approval and waiver of patients' consent, data about anaesthesia providers, patient characteristics, and the performance of the i-gel were recorded in five independent hospitals in Switzerland over a period of 24 months. We analysed success rates, leak pressures, adverse events, and risk factors for failure. Results Data from 2049 i-gel uses were analysed. Patients' mean age was 47 (range 6-91) yr. The primary i-gel success rate without changing size was 93%; the overall success rate was 96%. Insertion was deemed very easy or easy in 92%. The mean airway leak pressure was 26 (8) cm H2O. The mean anaesthesia time was 67 (42) min. Risk factors associated with i-gel failure were males (P<0.001), impaired mandibular subluxation (P=0.01), poor dentition (P=0.02), and older age (P<0.01). Adverse events recorded were laryngeal spasms (n=25, 1.2%), blood stained airway devices (n=79, 3.9%), transient nerve damage (n=2, 0.1%), one case of transient vasovagal asystole, and one glottic haematoma. Conclusions The i-gel is a reliable supraglottic airway device failing in <5% and providing high airway leak pressures. Males, impaired mandibular subluxation, poor dentition, and older age are risk factors associated with primary device failure. Serious adverse events are rar

Analysis of Dynamic Brain Imaging Data

Modern imaging techniques for probing brain function, including functional Magnetic Resonance Imaging, intrinsic and extrinsic contrast optical imaging, and magnetoencephalography, generate large data sets with complex content. In this paper we develop appropriate techniques of analysis and visualization of such imaging data, in order to separate the signal from the noise, as well as to characterize the signal. The techniques developed fall into the general category of multivariate time series analysis, and in particular we extensively use the multitaper framework of spectral analysis. We develop specific protocols for the analysis of fMRI, optical imaging and MEG data, and illustrate the techniques by applications to real data sets generated by these imaging modalities. In general, the analysis protocols involve two distinct stages: `noise' characterization and suppression, and `signal' characterization and visualization. An important general conclusion of our study is the utility of a frequency-based representation, with short, moving analysis windows to account for non-stationarity in the data. Of particular note are (a) the development of a decomposition technique (`space-frequency singular value decomposition') that is shown to be a useful means of characterizing the image data, and (b) the development of an algorithm, based on multitaper methods, for the removal of approximately periodic physiological artifacts arising from cardiac and respiratory sources.Comment: 40 pages; 26 figures with subparts including 3 figures as .gif files. Originally submitted to the neuro-sys archive which was never publicly announced (was 9804003

Scaling of avalanche queues in directed dissipative sandpiles

We simulate queues of activity in a directed sandpile automaton in 1+1 dimensions by adding grains at the top row with driving rate $0 < r \leq 1$. The duration of elementary avalanches is exactly described by the distribution $P_1(t) \sim t^{-3/2}\exp{(-1/L_c)}$, limited either by the system size or by dissipation at defects $L_c= \min (L,\xi)$. Recognizing the probability $P_1$ as a distribution of service time of jobs arriving at a server with frequency $r$, the model represents a new example of the $$ server queue in the queue theory. We study numerically and analytically the tail behavior of the distributions of busy periods and energy dissipated in the queue and the probability of an infinite queue as a function of driving rate.Comment: 11 pages, 9 figures; To appear in Phys. Rev.