Direct measurement of shear-induced cross-correlations of Brownian motion

Shear-induced cross-correlations of particle fluctuations perpendicular and along stream-lines are investigated experimentally and theoretically. Direct measurements of the Brownian motion of micron-sized beads, held by optical tweezers in a shear-flow cell, show a strong time-asymmetry in the cross-correlation, which is caused by the non-normal amplification of fluctuations. Complementary measurements on the single particle probability distribution substantiate this behavior and both results are consistent with a Langevin model. In addition, a shear-induced anti-correlation between orthogonal random-displacements of two trapped and hydrodynamically interacting particles is detected, having one or two extrema in time, depending on the positions of the particles.Comment: 4 pages, 4 figure

Simultaneous neoadjuvant radiochemotherapy with capecitabine and oxaliplatin for locally advanced rectal cancer: Treatment outcome outside clinical trials

Background: Phase II trials of neoadjuvant treatment in UICC-TNM stageII and III rectal cancer with capecitabine and oxaliplatin demonstrated favourable rates on tumour regression with acceptable toxicity. Patients and methods: Retrospective evaluation of 34 patients treated from 2005-2008 outside clinical trials (CTR) with neoadjuvant irradiation (45-50.4Gy) and simultaneous capecitabine 825mg/m2 b.i.d. on days 1-14 and 22-35 and oxaliplatin 50mg/m2 on days 1, 8, 22 and 29 (CAPOX). Twenty-six (77%) patients received one or two courses of capecitabine 1,000mg/m2 b.i.d. on days 1-14 and oxaliplatin 130mg/m2 on day 1 (XELOX) prior to simultaneous chemoradiotherapy. Results: UICC-TNM stage regression was observed in 60% (n = 20). Dworak's regression grades 3 and 4 were achieved in 18.2% (n = 6) and 15.1% (n = 5) of the patients. Sphincter-preserving surgery was performed in 53% (n = 8) of patients with a tumour of the lower rectum. Within the mean observation of 24 months, none of the patients relapsed locally, 1patient had progressive disease and 5patients (15%) relapsed distantly. Toxicity of grade 3 and 4 was mainly diarrhoea 18% (n = 6) and perianal pain 9% (n = 3). Nevertheless, severe cardiac events (n = 2), severe electrolyte disturbances (n = 2), and syncopes (n = 2) were observed as well. Conclusion: Treatment efficacy and common toxicity are similar to the reports of phaseI/II trials. However, several severe adverse events were observed in our cohort study. The predisposing factors for these events have yet to be studied and may have implications for the selection of patients outside CT

Distribution of Trichinella spiralis Larvae in Tissues of Swine

Studies on the distribution of Trichinella spiralis in selected muscles of experimentally infected swine have indicated that the diaphragm generally contained the highest concentration of T. spiralis, followed by tongue, masseter, gluteal and intercostol muscles. Numerous tissues and organs devoid of striated muscle were also invaded by trichina larvae. Infected tissues were obtained from the circulatory, digestive, reproductive, nervous, endocrine, and excretory systems

Characterizing flows with an instrumented particle measuring Lagrangian accelerations

We present in this article a novel Lagrangian measurement technique: an instrumented particle which continuously transmits the force/acceleration acting on it as it is advected in a flow. We develop signal processing methods to extract information on the flow from the acceleration signal transmitted by the particle. Notably, we are able to characterize the force acting on the particle and to identify the presence of a permanent large-scale vortex structure. Our technique provides a fast, robust and efficient tool to characterize flows, and it is particularly suited to obtain Lagrangian statistics along long trajectories or in cases where optical measurement techniques are not or hardly applicable.Comment: submitted to New Journal of Physic

Carrier-wave Rabi flopping signatures in high-order harmonic generation for alkali atoms

We present the first theoretical investigation of carrier-wave Rabi flopping in real atoms by employing numerical simulations of high-order harmonic generation (HHG) in alkali species. Given the short HHG cutoff, related to the low saturation intensity, we concentrate on the features of the third harmonic of sodium (Na) and potassium (K) atoms. For pulse areas of 2$\pi$ and Na atoms, a characteristic unique peak appears, which, after analyzing the ground state population, we correlate with the conventional Rabi flopping. On the other hand, for larger pulse areas, carrier-wave Rabi flopping occurs, and is associated with a more complex structure in the third harmonic. These new characteristics observed in K atoms indicate the breakdown of the area theorem, as was already demonstrated under similar circumstances in narrow band gap semiconductors

Coherent Control for a Two-level System Coupled to Phonons

The interband polarizations induced by two phase-locked pulses in a semiconductor show strong interference effects depending on the time tau_1 separating the pulses. The four-wave mixing signal diffracted from a third pulse delayed by tau is coherently controlled by tuning tau_1. The four-wave mixing response is evaluated exactly for a two-level system coupled to a single LO phonon. In the weak coupling regime it shows oscillations with the phonon frequency which turn into sharp peaks at multiples of the phonon period for a larger coupling strength. Destructive interferences between the two phase-locked pulses produce a splitting of the phonon peaks into a doublet. For fixed tau but varying tau_1 the signal shows rapid oscillations at the interband-transition frequency, whose amplitude exhibits bursts at multiples of the phonon period.Comment: 4 pages, 4 figures, RevTex, content change

Searching for periodic sources with LIGO

We investigate the computational requirements for all-sky, all-frequency searches for gravitational waves from spinning neutron stars, using archived data from interferometric gravitational wave detectors such as LIGO. These sources are expected to be weak, so the optimal strategy involves coherent accumulaton of signal-to-noise using Fourier transforms of long stretches of data (months to years). Earth-motion-induced Doppler shifts, and intrinsic pulsar spindown, will reduce the narrow-band signal-to-noise by spreading power across many frequency bins; therefore, it is necessary to correct for these effects before performing the Fourier transform. The corrections can be implemented by a parametrized model, in which one does a search over a discrete set of parameter values. We define a metric on this parameter space, which can be used to determine the optimal spacing between points in a search; the metric is used to compute the number of independent parameter-space points Np that must be searched, as a function of observation time T. The number Np(T) depends on the maximum gravitational wave frequency and the minimum spindown age tau=f/(df/dt) that the search can detect. The signal-to-noise ratio required, in order to have 99% confidence of a detection, also depends on Np(T). We find that for an all-sky, all-frequency search lasting T=10^7 s, this detection threshhold is at a level of 4 to 5 times h(3/yr), where h(3/yr) is the corresponding 99% confidence threshhold if one knows in advance the pulsar position and spin period.Comment: 18 pages, LaTeX, 12 PostScript figures included using psfig. Submitted to Phys. Rev.