Cross-Correlating Cosmic Microwave Background Radiation Fluctuations with Redshift Surveys: Detecting the Signature of Gravitational Lensing

Density inhomogeneities along the line-of-sight distort fluctuations in the cosmic microwave background. Usually, this effect is thought of as a small second-order effect that mildly alters the statistics of the microwave background fluctuations. We show that there is a first-order effect that is potentially observable if we combine microwave background maps with large redshift surveys. We introduce a new quantity that measures this lensing effect, $$, where T is the microwave background temperature and $\delta \theta$ is the lensing due to matter in the region probed by the redshift survey. We show that the expected signal is first order in the gravitational lensing bending angle, $< (\delta \theta)^2 >^{1/2}$, and find that it should be easily detectable, (S/N) $\sim$ 15-35, if we combine the Microwave Anisotropy Probe satellite and Sloan Digital Sky Survey data. Measurements of this cross-correlation will directly probe the ``bias'' factor, the relationship between fluctuations in mass and fluctuations in galaxy counts.Comment: 13 pages, 4 postscript figures included; Uses aaspp4.sty (AASTeX v4.0); Accepted for publication in Astrophysical Journal, Part

Testing LCDM with the Growth Function \delta(a): Current Constraints

We have compiled a dataset consisting of 22 datapoints at a redshift range (0.15,3.8) which can be used to constrain the linear perturbation growth rate f=\frac{d\ln\delta}{d\ln a}. Five of these data-points constrain directly the growth rate f through either redshift distortions or change of the power spectrum with redshift. The rest of the datapoints constrain f indirectly through the rms mass fluctuation \sigma_8(z) inferred from Ly-\alpha at various redshifts. Our analysis tests the consistency of the LCDM model and leads to a constraint of the Wang-Steinhardt growth index \gamma (defined from f=\Omega_m^\gamma) as \gamma=0.67^{+0.20}_{-0.17}. This result is clearly consistent at $1\sigma$ with the value \gamma={6/11}=0.55 predicted by LCDM. A first order expansion of the index \gamma in redshift space leads to similar results.We also apply our analysis on a new null test of LCDM which is similar to the one recently proposed by Chiba and Nakamura (arXiv:0708.3877) but does not involve derivatives of the expansion rate $H(z)$. This also leads to the fact that LCDM provides an excellent fit to the current linear growth data.Comment: 7 pages, 4 figures. Added comments on the data of Table I (after eq. (2.16)). Corrected a typo on eq. (2.15). The mathematica files with the numerical analysis of this study may be found at http://nesseris.physics.uoi.gr/growth/growth.ht

Cosmic Growth History and Expansion History

The cosmic expansion history tests the dynamics of the global evolution of the universe and its energy density contents, while the cosmic growth history tests the evolution of the inhomogeneous part of the energy density. Precision comparison of the two histories can distinguish the nature of the physics responsible for the accelerating cosmic expansion: an additional smooth component - dark energy - or a modification of the gravitational field equations. With the aid of a new fitting formula for linear perturbation growth accurate to 0.05-0.2%, we separate out the growth dependence on the expansion history and introduce a new growth index parameter \gamma that quantifies the gravitational modification.Comment: 8 pages, 3 figures; minor changes to match version accepted to PR

Induced Gravity and the Attractor Dynamics of Dark Energy/Dark Matter

Attractor solutions that give dynamical reasons for dark energy to act like the cosmological constant, or behavior close to it, are interesting possibilities to explain cosmic acceleration. Coupling the scalar field to matter or to gravity enlarges the dynamical behavior; we consider both couplings together, which can ameliorate some problems for each individually. Such theories have also been proposed in a Higgs-like fashion to induce gravity and unify dark energy and dark matter origins. We explore restrictions on such theories due to their dynamical behavior compared to observations of the cosmic expansion. Quartic potentials in particular have viable stability properties and asymptotically approach general relativity.Comment: 11 pages, 10 figures, accepted in JCAP, results unchanged, an explanation added on perfect fluids for general spinor Lagrangian

Spin-triplet Supercurrent through Inhomogeneous Ferromagnetic Trilayers

Motivated by a recent experiment [J. W. A. Robinson, J. D. S. Witt and M. G. Blamire, Science, \textbf{329}, 5987 (2010)], we here study the possibility of establishing a long-range spin-triplet supercurrent through an inhomogeneous ferromagnetic region consisting of a Ho$\mid$Co$\mid$Ho trilayer sandwiched between two conventional s-wave superconductors. We utilize a full numerical solution in the diffusive regime of transport and study the behavior of the supercurrent for various experimentally relevant configurations of the ferromagnetic trilayer. We obtain qualitatively very good agreement with experimental data regarding the behavior of the supercurrent as a function of the width of the Co-layer, $L_\text{Co}$. Moreover, we find a synthesis of 0-$\pi$ oscillations with superimposed rapid oscillations when varying the width of the Ho-layer which pertain specifically to the spiral magnetization texture in Ho. We are not able to reproduce the anomalous peaks in the supercurrent observed experimentally in this regime, but note that the results obtained are quite sensitive to the exact magnetization profile in the Ho-layers, which could be the reason for the discrepancy between our model and the experimental reported data for this particular aspect. We also investigate the supercurrent in a system where the intrinsically inhomogeneous Ho ferromagnets are replaced with domain-wall ferromagnets, and find similar behavior as in the Ho$\mid$Co$\mid$Ho case. Furthermore, we propose a novel type of magnetic Josephson junction including only a domain-wall ferromagnet and a homogeneous ferromagnetic layer, which in addition to simplicity regarding the magnetization profile also offers a tunable long-range spin-triplet supercurrent. Finally, we discuss some experimental aspects of our findings.Comment: 7 pages, 7 figures. Submitted to Physical Revie

Saccadic eye movement during spaceflight

Saccadic eye movements were studied in six subjects during two Space Shuttle missions. Reaction time, peak velocity and accuracy of horizontal, visually-guided saccades were examined preflight, inflight and postflight. Conventional electro-oculography was used to record eye position, with the subjects responding to pseudo-randomly illuminated targets at 0 deg and + or - 10 deg and 20 deg visual angles. In all subjects, preflight measurements were within normal limits. Reaction time was significantly increased inflight, while peak velocity was significantly decreased. A tendency toward a greater proportion of hypometric saccades inflight was also noted. Possible explanations for these changes and possible correlations with space motion sickness are discussed

Stellenwert der minimal-invasiven Chirurgie beim primären und sekundären Hyperparathyroidismus

BACKGROUND: The standard surgical approach to treat primary (pHPT) and secondary hyperparathyroidism (sHPT) used to be a cervicotomy with exploration of all four parathyroid glands. This access has been challenged recently by the introduction of minimally invasive techniques in order to achieve superior cosmesic results and to reduce theatre time. We analyzed the advantages and morbidities of these surgical aproaches. PATIENTS AND METHODS: Between 1997 and 2006 a total of 123 patients (109 with pHPT and 14 with sHPT) underwent parathyroidectomy at the ENT Department in Luzern. Ultrasonographic scanning was performed on 74 patients (68%), szintigraphy in 8 patients (7%) and both scanning methods in 27 patients (25%). 103 patients were available for follow-up. The indications for each technique were reviewed and outcome measures included serum Calcium and parathyroid hormone levels. RESULTS: Sensitivity for preoperative ultrasonographic and scintigraphic scanning was 67% and 65% for identification of the correct quadrant and 74% and 71% for identification of the correct side. A bilateral exploration was performed until June 2001 for all patients. Thereafter, a minimally invasive approach was chosen for patients with pHPT, whereas patients with sHPT still require bilateral exploration. Adequate preoperative localization was a prerequisite for a minimally invasive technique. Mean postoperative serum Kalzium levels were within the normal range, independently of the surgical technique and disease. Two patients developed hypercalcemia after an initially successful operation. CONCLUSIONS: Review of the literature confirms the shift from bilateral exploration towards minimally invasive techniques. The incidence of persistent or recurrent disease as well as the rate of complications seems comparable. Operation time for minimally invasive techniques is reduced in the hands of an experienced surgeon. However, proper preoperative localization of the diseased parathyroid gland is not always possible and the expenses of intraoperative parathyroid hormone measures do not lower the overall costs. Considerable experience and a multidisiplinary approach (endocrinologist, surgeon, pathologist) is required to adopt efficient minimally invasive techniques. As for sHPT, bilateral exploration remains the treatment of choice

Surface Morphology of Unused and Used HydromerR-Coated Intravenous Catheters

HydromerR-coated polyurethane (Erythroflex)R catheters, unused, or intravenously inserted for 2-20 days, were studied by scanning electron microscopy (SEM). Both unfixed and fixed (2% glutar-aldehyde in phosphate buffer), and air-or critical-point dried (CPD) specimens were investigated. The catheter segments were sputter-coated with approx. 20 nm gold and studied at an accelerating voltage of 20 kV. The specimens were examined for surface depositions, thickness and structure of the HydromerR layers, and occurrence of adhering and embedded bacteria. The outer HydromerR layer showed, in the un-used specimens, scratches and fissures, as well as adhering foreign bodies. In used specimens, the layer was swollen, with cracks (like dried earth ), and, occasionally , amorphous substances and coccoid bacteria were seen adhering. Damage to the layer, or even its total disappearance was also noted in some specimens. The inner (luminal) HydromerR layer was, in unused specimens, clean and slightly wavy. In used catheters, it was thicker, possibly swollen, with small, isolated or agglomerated protrusions, like a lunar landscape . Adhering platelets and amorphous substances were also occasionally seen. The results suggest that the HydromerR is a fragile material in both its dry and wet forms. Thus, the HydromerR-coated catheters should neither be stored in flexible packs, nor inserted by the Seldinger technique. The findings do not support the belief that the HydromerR-coating can prevent either thrombus formation, or intraluminal occlusion of the in-situ catheters

Josephson effect in thin-film superconductor/insulator/superconductor junctions with misaligned in-plane magnetic fields

We study a tunnel junction consisting of two thin-film s-wave superconductors separated by a thin, insulating barrier in the presence of misaligned in-plane exchange fields. We find an interesting interplay between the superconducting phase difference and the relative orientation of the exchange fields, manifested in the Josephson current across the junction. Specifically, this may be written $I_\text{J}^\text{C} = (I_0+I_m ~ \cos\phi) \sin\Delta\theta$, where I_0 and I_m are constants, and $\phi$ is the relative orientation of the exchange fields while $\Delta\theta$ is the superconducting phase difference. Similar results have recently been obtained in other S/I/S junctions coexisting with helimagnetic or ferromagnetic order. We calculate the superconducting order parameter self-consistently, and investigate quantitatively the effect which the misaligned exchange fields constitute on the Josephson current, to see if I_m may have an appreciable effect on the Josephson current. It is found that I_0 and I_m become comparable in magnitude at sufficiently low temperatures and fields close to the critical value, in agreement with previous work. From our analytical results, it then follows that the Josephson current in the present system may be controlled in a well-defined manner by a rotation of the exchange fields on both sides of the junction. We discuss a possible experimental realization of this proposition.Comment: 8 pages, 8 figures. Accepted for publication in Phys. Rev.

Cosmology with X-ray Cluster Baryons

X-ray cluster measurements interpreted with a universal baryon/gas mass fraction can theoretically serve as a cosmological distance probe. We examine issues of cosmological sensitivity for current (e.g. Chandra X-ray Observatory, XMM-Newton) and next generation (e.g. Con-X, XEUS) observations, along with systematic uncertainties and biases. To give competitive next generation constraints on dark energy, we find that systematics will need to be controlled to better than 1% and any evolution in f_gas (and other cluster gas properties) must be calibrated so the residual uncertainty is weaker than (1+z)^{0.03}.Comment: 6 pages, 5 figures; v2: 13 pages, substantial elaboration and reordering, matches JCAP versio