Improvement of an Atomic Clock using Squeezed Vacuum.

Since the pioneering work of Ramsey, atom interferometers are employed for precision metrology, in particular to measure time and to realize the second. In a classical interferometer, an ensemble of atoms is prepared in one of the two input states, whereas the second one is left empty. In this case, the vacuum noise restricts the precision of the interferometer to the standard quantum limit (SQL). Here, we propose and experimentally demonstrate a novel clock configuration that surpasses the SQL by squeezing the vacuum in the empty input state. We create a squeezed vacuum state containing an average of 0.75 atoms to improve the clock sensitivity of 10000 atoms by 2.05_{-0.37}^{+0.34} dB. The SQL poses a significant limitation for today's microwave fountain clocks, which serve as the main time reference. We evaluate the major technical limitations and challenges for devising a next generation of fountain clocks based on atomic squeezed vacuum.

A novel measurement system for assessing the nose in patients with cleft lip and palate (CLP).

Objective: The presented study shows a new and innovative method to determine nasal asymmetries in a simple way in patients with cleft lip and palate (CLP) in order to plan corrective surgery. Design: 86 non-syndromic patients with cleft lip and palate were divided into 2 groups: a) patients with unilateral cleft lip and palate b) patients with bilateral cleft lip and palate. Patients: follow-up of hospital records of 86 patients aged 2-18 years. Main outcome: Based on standardised photos of the nose from 3 different directions, the nose symmetry was assessed. A new digital measurement system was used, which is integrated into proven clinical programmes. These were compared with a control group. In addition, a mirror fog test and a standardised questionnaire were used. Result: The overall results showed a good symmetry of the nose postoperatively, as well as a high satisfaction of the patients and their parents. Profile and angle measurements showed a better result. Conclusio: The presented measurement system and especially the Cleft Lip Component Symmetry Index (CLCSI) allows an individual and very effective assessment of the symmetry of the nose as well as a control of the growth in patients with CLP. The method is easy to apply in daily practice, even for untrained practitioners.

High-precision tracking of sperm swimming fine structure provides strong test of resistive force theory.

The shape of the flagellar beat determines the path along which a sperm cell swims. If the flagellum bends periodically about a curved mean shape then the sperm will follow a path with non-zero curvature. To test a simple hydrodynamic theory of flagellar propulsion known as resistive force theory, we conducted high-precision measurements of the head and flagellum motions during circular swimming of bull spermatozoa near a surface. We found that the fine structure of sperm swimming represented by the rapid wiggling of the sperm head around an averaged path is, to high accuracy, accounted for by resistive force theory and results from balancing forces and torques generated by the beating flagellum. We determined the anisotropy ratio between the normal and tangential hydrodynamic friction coefficients of the flagellum to be 1.81+/-0.07 (mean+/-s.d.). On time scales longer than the flagellar beat cycle, sperm cells followed circular paths of non-zero curvature. Our data show that path curvature is approximately equal to twice the average curvature of the flagellum, consistent with quantitative predictions of resistive force theory. Hence, this theory accurately predicts the complex trajectories of sperm cells from the detailed shape of their flagellar beat across different time scales.

Decreased oxidative stress in patients with idiopathic dilated cardiomyopathy one year after immunoglobulin adsorption.

OBJECTIVES: In a substudy to a recently reported investigation that demonstrated the benefit of immunoglobulin adsorption (immunoadsorption) for patients with idiopathic dilated cardiomyopathy (IDC), we tested whether this benefit is associated with a reduction of oxidative stress. BACKGROUND: The progression of cardiomyopathy is believed to be related to the increase of oxidative stress. Therefore, reduction of oxidative stress could be one of the effects of immunoadsorption for improvement of cardiac performance and clinical status. METHODS: Plasma markers for oxidative stress-thiobarbituric acid-reactive substances (TBARS), lipid peroxides (LPO), anti-oxidized low-density lipoprotein-autoantibodies (anti-oxLDL-AB), thiol groups and vitamin E-were compared in 31 patients, of whom 16 underwent immunoadsorption and 15 received conventional treatment (controls). All patients received a daily supplement of vitamins, minerals and trace elements. RESULTS: After one year, TBARS (p = 0.026), LPO (p = 0.026) and anti-oxLD

Satisfying the Einstein-Podolsky-Rosen criterion with massive particles.

In 1935, Einstein, Podolsky and Rosen (EPR) questioned the completeness of quantum mechanics by devising a quantum state of two massive particles with maximally correlated space and momentum coordinates. The EPR criterion qualifies such continuous-variable entangled states, where a measurement of one subsystem seemingly allows for a prediction of the second subsystem beyond the Heisenberg uncertainty relation. Up to now, continuous-variable EPR correlations have only been created with photons, while the demonstration of such strongly correlated states with massive particles is still outstanding. Here we report on the creation of an EPR-correlated two-mode squeezed state in an ultracold atomic ensemble. The state shows an EPR entanglement parameter of 0.18(3), which is 2.4 s.d. below the threshold 1/4 of the EPR criterion. We also present a full tomographic reconstruction of the underlying many-particle quantum state. The state presents a resource for tests of quantum nonlocality and a wide variety of applications in the field of continuous-variable quantum information and metrology.

Increased level of HSP27 but not of HSP72 in human heart allografts in relation to acute rejection.

BACKGROUND: Increased expression of heat shock proteins (HSPs) was assumed during cardiac allograft rejection. To find evidence for this in man, we quantified HSP27 and HSP72 in cardiac allograft biopsies. METHODS: In parallel to histological assessment of rejection, HSP27 was quantified by Western blotting in a total of 43 biopsies sampled from 3 patients. HSP72 was analyzed in parallel in 30 of the 43 cases. For comparison, HSPs were analyzed in myocardium. RESULTS: HSP27 was significantly higher in rejecting cardiac allografts than in non-rejecting allografts and non-failing myocardium (1.52 +/- 0.25 vs. 0.83 +/- 0.11 vs. 0.50 +/- 0.05 microg/mg protein). Similarity for HSP72 (6.27 +/- 1.54 vs. 4.06 +/- 1.03 vs. 6.27 +/- 0.76 microg/mg protein) was not found. CONCLUSION: For the first time in humans with cardiac allograft rejection, increased expression of HSP27, which could be important for cardiac self-protection, was demonstrated. For the lack of increased HSP72 expression, the influence of the cyclosporine A treatment was discussed.

Pacemaker-induced arrhythmias.

The pacemaker ECG with different types of pacemakers used for the treatment of bradyarrhythmias is considered. The arrhythmias induced or interfered with by the pacemakers receive special consideration. The normal function of the most common types of pacing systems is schematically presented.

Consequences of long-term selenium-deficient diet on the prostacyclin and thromboxane release from rat aorta.

It is known that peroxides, which are increased during Se deficiency because of reduced glutathione peroxidase (GSH-Px) activity, can influence the prostacyclin I2/thromboxane A2 (PGI2/TXA2) ratio. In this study we analyzed the PGI2 and TXA2 formation of aortas of long-term Se-deficient rats. Despite low GSH-Px activity in the Se-deficient group, the basal PGI2 and TXA2 formation was not different versus control animals (PGI2: 2295+/-1134 pg/mg vs 2940+/-1134 pg/mg; TXA2: 3.83+/-1.06 pg/mg vs 5.67+/-2.99 pg/mg). However, we checked the capacity of the aortas of Se-deficient rats to compensate for a suddenly increased peroxide concentration. After peroxide stimulation, the PGI2 release was significantly lower in the Se-deficient group compared to the control group (PGI2: 3507+/-1829 pg/mg vs 7986+/-2636 pg/mg). Again, the TXA2 release did not show any differences. The release ratio of PGI2/TXA2 decreased under peroxide stress in Se-deficient animals. Although long-term Se deficiency showed a relatively well-balanced metabolism under resting conditions, sudden stress, accompanied by an excessive radical production, cannot be compensated.

Long-term performance of endocardial leads with steroid-eluting electrodes.

During a three-year period, 48 steroid-eluting leads (Medtronic 4003 and 4503) have been implanted in 39 patients. 23 were implanted in the atrium and 25 in the ventricle. 36 patients with 45 leads have been observed for more than 12 months. Stimulation thresholds have been followed using pulse generators with variable output (vario): 12 atrial and 11 ventricular leads, 4 atrial leads and 11 ventricular leads have been followed using pulse generators with variable pulse-width (auto-threshold), P-waves have been followed using telemetry or sensitivity programming (23 atrial leads). R-waves have been followed using telemetry in 11 ventricular leads. Mean stimulation thresholds after 2 years are 0.7 V +/- 0.2 in the atrium and 0.8 V +/- 0.3 in the ventricle. P-waves after 2 years are of magnitudes allowing a sensitivity setting of 2.5 mV in 12 cases and of 1.5 mV in 2 cases; R-waves have in all cases been high enough to permit lowest programmable sensitivity setting. During the observation time, two patients have died from nonpacing-related causes. The results obtained from this investigation document low stimulation thresholds and good sensing levels in both ventricle and atrium using the steroid-eluting electrode with no significant changes after 6 weeks postimplant.

Comparison of physical work capacity and systolic time intervals with ventricular inhibited and atrial synchronous ventricular inhibited pacing.

Sixteen patients with a non-invasively programmable pacemaker (Medtronic 2409) were examined with the unit in ventricular inhibited (VVI) and atrial synchronous ventricular inhibited (VDT/I) mode, respectively. Maximal exercise capacity was determined by means of bicycle ergometry. Work load was increased in steps of 10 watts each minute. Atrial and ventricular rates, brachial artery pressure, and respiratory rate were studied at rest and during exercise while systolic time intervals were determined at rest. There was an important increase in maximal exercise capacity when changing from VVI to VDT/I pacing. The extent of improvement was the same for patients above and below the age of 65 years. At comparable work loads VDT/I pacing resulted in significantly lower atrial rates than VVI pacing. Systolic time intervals did not differ between VVI and VDT/I pacing apart from an increase in left ventricular ejection time index with VDT/I pacing. Systolic time intervals and maximal exercise capacity with VVI pacing did not correlate with the increase in exercise capacity induced by VDT/I pacing. Physical performance can be significantly improved by VDT/I pacing in both young and old patients. Exercise capacity on VVI pacing cannot predict the possible benefit of change to VDT/I pacing.

Clinical evaluation of atrial synchronous ventricular inhibited pacemakers.

The technical specifications and the operation of two atrial synchronous ventricular inhibited (ASVIP) pacemaker designs are described along with the results of clinical evaluation of these pacemakers in 30 patients. Clinical advantages of such pacemakers are contrasted with the performance of A-V sequential (DVI) and atrial synchronous (VAT) systems.

Atrial inhibited pacing in the sick sinus node syndrome: clinical value and the demand for rate responsiveness.

A consecutive series of 66 patients (males = 32; mean age +/- SD = 71 +/- 9 years) given atrial inhibited pacemakers for sick sinus nodes were followed to study the incidence of lead failures, chronic atrial tachyarrhythmias, and atrioventricular conduction disturbances. The need for rate responsive pacing was also assessed. Pre and postoperative investigation could include carotid sinus massage, Holter monitoring, exercise testing, and invasive electrophysiology. The mean follow-up time +/- SD was 32 +/- 29 months (median = 26 months). Three patients (5%) had their pacemakers replaced due to lead failures (loss of sensing = 2; exit block = 1). Two pacemakers (3%) were replaced after 5 and 22 months due to atrial fibrillation. Four patients (6%) received new pacemakers because of development of second-degree or complete atrioventricular block after 1, 6, 12, and 31 months, respectively. During exercise, most patients (76%) responded with an increase in sinus rate at least as marked as that achievable with the currently available rate responsive pacemakers. Assuming careful patient selection, atrial inhibited pacing is well suited for many patients with sinus node dysfunction and preserved atrioventricular conduction. There is a limited need for rate responsive pacemakers in these patients.

Acute and long-term atrial and ventricular stimulation thresholds with a steroid-eluting electrode.

Thirty leads with a steroid-eluting electrode (Medtronic 4003 and 4503) have been implanted in 24 patients, 11 in the atrium and 19 in the ventricle. Six patients received the steroid lead in both atrium and ventricle. The stimulation thresholds were followed using Elema pulse generators with Vario function in 15 patients (11 atrial leads and 10 ventricular leads) during 11 +/- 3 months (mean +/- SD). At 0.5 ms pulse duration the mean atrial and ventricular thresholds were 0.55 Volt +/- 0.22 and 0.39 Volt +/- 0.22 respectively at implant, 0.94 Volt +/- 0.13 and 0.82 Volt +/- 0.16 after 12 months. During the entire follow-up period both atrial and ventricular mean thresholds never exceeded 1 V.