Limits of topological protection under local periodic driving

The bulk-edge correspondence guarantees that the interface between two topologically distinct insulators supports at least one topological edge state that is robust against static perturbations. Here, we address the question of how dynamic perturbations of the interface affect the robustness of edge states. We illuminate the limits of topological protection for Floquet systems in the special case of a static bulk. We use two independent dynamic quantum simulators based on coupled plasmonic and dielectric photonic waveguides to implement the topological Su-Schriefer-Heeger model with convenient control of the full space- and time-dependence of the Hamiltonian. Local time-periodic driving of the interface does not change the topological character of the system but nonetheless leads to dramatic changes of the edge state, which becomes rapidly depopulated in a certain frequency window. A theoretical Floquet analysis shows that the coupling of Floquet replicas to the bulk bands is responsible for this effect. Additionally, we determine the depopulation rate of the edge state and compare it to numerical simulations.

Enabling 3D hepatocyte spheroids for microphysiometry

Advances in the areas of tissue engineering and microfabrication techniques have enabled promising in vitro platforms, known as Organs-on-Chips, with the aim of mimicking complex in vivo conditions for more accurate toxicology studies. To analyze the physiological change induced by chemicals or toxic substances continuously, sensors can be used in order to measure the intracellular and extracellular environment of single cells, cell constructs, or tissue, and therefore the integration of monitoring techniques into 3D tissue culture platforms provides an essential step for the next generation Organ-on-Chip platforms. However, current in vitro platforms are not capable of combining the culture of 3D models with monitoring techniques. To address this, a novel spheroid encapsulation is designed for fluidic contact between 3D models in microwells and Intelligent Mobile Lab for In Vitro Diagnostics (IMOLA-IVD) BioChip sensors while preventing spheroid fusion. In this work, spheroid culturing protocols were developed for optimized spheroid growth and an evaluation of spheroid integrity on different porous layers was performed in order to provide a defined spheroid encapsulation on BioChip sensors.

A fully synthetic lung model for wound-ballistic experiments-First results

PURPOSE

Today, synthetic models have all but replaced animal and corpse models in examining damage to soft-tissues and skeletal structures by ballistic trauma. As, however, non-solid organs such as the lungs, have not been able to be replaced by a fully synthetic model we attempted to create such a model.

MATERIAL AND METHODS

20% ordnance gelatine was frothed with a household mixer and cooled to stable foam. Several of these foam blocks were then stuck together with liquid gelatine and placed between 10% gelatine blocks. As controls, we embedded pig lungs in gelatine and compared the wound channels seen in computed tomography created upon shooting with 9mm Luger.

RESULTS

The fully synthetic models displayed radiological and physical densities comparable to real lungs. The wound profile characteristics of the fully synthetic lung models were very similar to the semisynthetic swine-gelatine models regarding the permanent wound cavity. Furthermore, in both semi- and fully synthetic models we detected a ring surrounding the permanent wound channel, most likely representing the remnants of the temporary wound cavity.

CONCLUSION

Our results indicate that this fully synthetic lung model is a viable substitute for ballistic experiments on lungs. We believe that further research on the temporary wound channel in lungs is possible with this model in order to provide more insight into the effect of ballistic trauma to the lungs not seen otherwise.

An automated microphysiological assay for toxicity evaluation

Screening a newly developed drug, food additive or cosmetic ingredient for toxicity is a critical preliminary step before it can move forward in the development pipeline. Due to the sometimes dire consequences when a harmful agent is overlooked, toxicologists work under strict guidelines to effectively catalogue and classify new chemical agents. Conventional assays involve long experimental hours and many manual steps that increase the probability of user error; errors that can potentially manifest as inaccurate toxicology results. Automated assays can overcome many potential mistakes that arise due to human error. In the presented work, we created and validated a novel, automated platform for a microphysiological assay that can examine cellular attributes with sensors measuring changes in cellular metabolic rate, oxygen consumption, and vitality mediated by exposure to a potentially toxic agent. The system was validated with low buffer culture medium with varied conductivities that caused changes in the measured impedance on integrated impedance electrodes.

Direct sampling of electric-field vacuum fluctuations

The ground state of quantum systems is characterized by zero-point motion. This motion, in the form of vacuum fluctuations, is generally considered to be an elusive phenomenon that manifests itself only indirectly. Here, we report direct detection of the vacuum fluctuations of electromagnetic radiation in free space. The ground-state electric-field variance is inversely proportional to the four-dimensional space-time volume, which we sampled electro-optically with tightly focused laser pulses lasting a few femtoseconds. Subcycle temporal readout and nonlinear coupling far from resonance provide signals from purely virtual photons without amplification. Our findings enable an extreme time-domain approach to quantum physics, with nondestructive access to the quantum state of light. Operating at multiterahertz frequencies, such techniques might also allow time-resolved studies of intrinsic fluctuations of elementary excitations in condensed matter.

Wirkung elektromagnetischer Felder des GSM-Mobilfunksystems auf auditives und vestibuläres Labyrinth und Hirnstamm

BACKGROUND

It is the subject of this study to investigate the biological effect of the HF radiation produced by the Global System for Mobile Communications-( GSM)-mobile phone on the inner ear with its sensors of the vestibular and auditive systems.

METHODS/PATIENTS

Thermographic investigations made on various model materials and on the human temporal bone should show whether mobile phone does induce any increases of temperature which would lead to a relevant stimulus for the auditive and vestibular system or not. We carried out video-nystagmographic recordings of 13 subjects, brainstem electric response audiometry of 24 ears, and recordings of distorsion products of otoacoustic emissions of 20 ears. All tests were made with and without a mobile phone in use. The data was then analyzed for variation patterns in the functional parameters of the hearing and balance system that are subject to the (non)existence of electromagnetic radiation from the mobile phone.

RESULTS

The thermographic investigations suggest that the mobile phone does not induce any increases of temperature which would lead to a relevant stimulus for the auditive and vestibular system. Video-nystagmographic recordings under field effect do not furnish any indication of vestibular reactions generated by field effects. Compared with the recording without field, the brainstem electric response audiometry under field effect did not reveal any changes of the parameters investigated, i. e. absolute latency of the peaks I, III, V and the interpeak latency between the peaks I and V. The distorsion products of otoacoustic emissions do not indicate, comparing the three measuring situations, i. e. before field effect, pulsed field and continuous field, any possible impacts of the HF field on the spectrum or levels of emissions for none of the probands.

CONCLUSION

The investigations made show that the electromagnetic fields generated in using the mobile phone do not have an effect on the inner ear and auditive system to the colliculus inferior in the brainstem and on the vestibular receptors in the inner ear and the vestibular system.

Chain breaks and the susceptibility of Sr2Cu1-xPdxO3+delta and other doped quasi-one-dimensional antiferromagnets

We study the magnetic susceptibility of one-dimensional S=1/2 antiferromagnets containing nonmagnetic impurities which cut the chain into finite segments. For the susceptibility of long anisotropic Heisenberg chain segments with open boundaries we derive a parameter-free result at low temperatures using field-theory methods and the Bethe ansatz. The analytical result is verified by comparing with quantum Monte Carlo calculations. We then show that the partitioning of the chain into finite segments can explain the Curie-like contribution observed in recent experiments on Sr2Cu(1-x)PdxO(3+delta). Possible additional paramagnetic impurities seem to play only a minor role.

Real space imaging of one-dimensional standing waves: direct evidence for a Luttinger liquid

Electronic standing waves with two different wavelengths were directly mapped near one end of a single-wall carbon nanotube as a function of the tip position and the sample bias voltage with high-resolution position-resolved scanning tunneling spectroscopy. The observed two standing waves caused by separate spin and charge bosonic excitations are found to constitute direct evidence for a Luttinger liquid. The increased group velocity of the charge excitation, the power-law decay of their amplitudes away from the scattering boundary, and the suppression of the density of states near the Fermi level were also directly observed or calculated from the two different standing waves.

Local magnetic susceptibility of the positive muon in the quasi-one-dimensional S=1/2 antiferromagnet dichlorobis (pyridine) copper (II)

We report muon spin rotation measurements of the local magnetic susceptibility around a positive muon in the paramagnetic state of the quasi-one-dimensional spin 1/2 antiferromagnet dichlorobis (pyridine) copper (II). Signals from three distinct sites are resolved and have a temperature dependent frequency shift which is significantly different than the magnetic susceptibility. This difference is attributed to a muon induced perturbation of the spin 1/2 chain. The obtained frequency shifts are compared with transfer matrix density-matrix renormalization-group numerical simulations.

Active medical implants and occupational safety--measurement and numerical calculation of interference voltage

Low frequency electric and magnetic fields may interfere with implanted cardiac pacemakers causing a life-threatening malfunction of the device. In order to assess the safety of workers in the vicinity of industrial electrical devices the interference voltage at the input port of a pacemaker is an important measure. In order to investigate the coupling of fields emanating from electrical devices a numerical method for the calculation of interference voltages is presented and applied to the investigation of homogeneous electric and magnetic fields in the frequency range from 50 Hz to 1 MHz. Implantation of the pacemaker in the right pectoral, left pectoral and abdominal area using a realistic model of the human body as well as different grounding conditions are considered. The numerical method is successfully validated by measurements and shows good agreement with results in the literature.

Phase diagram of an impurity in the spin-1/2 chain: two-channel Kondo effect versus Curie law

We consider a magnetic S = 1/2 impurity in the antiferromagnetic spin chain as a function of two coupling parameters: the symmetric coupling of the impurity to two sites in the chain J1 and the coupling between the two sites J2. By using field theory arguments and numerical calculations we can identify all possible fixed points and classify the renormalization flow between them, which leads to a nontrivial phase diagram. Depending on the detailed choice of the two (frustrating) coupling strengths, the stable phases correspond either to a decoupled spin with Curie law behavior or to a non-Fermi-liquid fixed point with a logarithmically diverging impurity susceptibility as in the two-channel Kondo effect. Our results resolve a controversy about the renormalization flow.

Effects of microwaves emitted by cellular phones on human slow brain potentials

The influence of electromagnetic fields (EMF) emitted by cellular phones on preparatory slow brain potentials (SP) was studied in two different experimental tasks: In the first, healthy male human subjects had to perform simple self-paced finger movements to elicit a Bereitschaftspotential; in the second, they performed a complex and cognitive demanding visual monitoring task (VMT). Both tasks were performed with and without EMF exposure in counterbalanced order. Whereas subjects' performance did not differ between the EMF exposure conditions, SP parameters were influenced by EMF in the VMT: EMF exposure effected a significant decrease of SPs at central and temporo-parieto-occipital brain regions, but not at the frontal one. In the simple finger movement task, EMF did not affect the Bereitschaftspotential.

Scanning tunneling microscopy of a luttinger liquid

Explicit predictions for scanning tunneling microscopy (STM) on interacting one-dimensional electron systems are made using the Luttinger liquid formalism. The STM current changes with the distance from an impurity or boundary in a characteristic way, which reveals the spin-charge separation and the interaction strength in the system. The current exhibits Friedel-like oscillations, but also carries additional modulated behavior as a function of voltage and distance, which shows the spin-charge separation in real space. Moreover, very close to the boundary the current is strongly reduced, which is an indication of the interaction strength in the system.

Microwaves emitted by cellular telephones affect human slow brain potentials

The influence of electromagnetic fields (EMF) emitted by cellular telephones on preparatory slow brain potentials (SP) was studied in two experiments, about 6 months apart. In the first experiment, a significant decrease of SP was found during exposure to EMF in a complex visual monitoring task (VMT). This effect was replicated in the second experiment. In addition to the VMT, EMF effects on SP were analysed in two further, less demanding tasks: in a simple finger movement task to elicit a Bereitschaftspotential (BP) and in a two-stimulus task to elicit a contingent negative variation (CNV). In comparison to the VMT, no significant main EMF effects were found in BP and CNV tasks. The results accounted for a selective EMF effect on particular aspects of human information processing, but did not indicate any influence on human performance, well-being and health.

Prevalence of latent and manifest suprascapular neuropathy in high-performance volleyball players

The aim of the present study was to evaluate the prevalence of latent and manifest suprascapular neuropathy in high-level male volleyball players. Thirty subjects were examined clinically and electrophysiologically. Suprascapular neuropathy, most probably at the level of the suprascapular notch, was demonstrated in 12 subjects, being latent in eight. Taking into account our clinical findings in a further 36 international-level players, a remarkably high overall prevalence of suprascapular nerve lesion of 33% (22 of 66 subjects) was found. All cases involved the side of the body with the player's smashing arm. These findings suggest that careful monitoring of suprascapular nerve function may be useful in high-performance volleyball players, as early diagnosis is essential to prevent more severe damage.

[Compression neuropathy of the suprascapular nerve in high performance volleyball players]

Individual observations during the course of the medical care of the German men's national volleyball team in international tournaments gave cause to investigate more thoroughly the increasing occurrence of an atrophy of the infraspinatus m. in volleyball players at international level. An examination of three men's national teams specially slanted to throw light on this problem revealed that 28% (10 out of 36 players) had an atrophy of the infraspinatus m. On the basis of these findings, a prospective study was carried out, with the object of clarifying to what extent a developing or manifest compression neuropathy of the suprascapularis n. was present in a defined population of high-level volleyball players (1st National League, men). 32 players were examined as to the extent to which a functional impairment of the suprascapularis n. occurred in the pursuit of the competitive sport of volleyball. The study revealed a functional impairment of the suprascapular n. in 45% of the both clinically and neurophysiologically examined sportsmen. It follows in consequence that a control examination is advisable in the case of a latent disorder, so as to detect any continuation or possible deterioration. In the event of a developing or manifest atrophy of the infraspinatus m. the operative relief of the suprascapular n. in the region of the scapular incisure may be considered in addition to conservative therapy.

[Differential diagnosis of shoulder pain: chronic neuropathy of the suprascapular nerve]

Suprascapular neuropathy may present with chronic shoulder pain and weakness of abduction and external rotation of the arm. Therefore, it should always be included in the differential diagnosis of shoulder pain. Usually, the nerve is compressed at the suprascapular notch or the spinoglenoid notch. Here, the nerve is relatively fixed. In the etiology, repeated and forceful movements around the shoulder joint, especially in athletes such as volleyball players, are considered to be frequent causes of suprascapular nerve damage, whereas ligament hypertrophy and ganglia are uncommon. If conservative therapy fails, surgical decompression of the nerve is required for relief of pain and resolution of weakness.

Influence of clinical findings, positional manoeuvres, and systolic ankle arterial pressure on transcutaneous oxygen tension in peripheral arterial occlusive disease

The mutual effects of systolic ankle arterial pressures, positional manoeuvres, and calf artery occlusions on transcutaneous oxygen partial pressures (tcpO2) were studied in 388 legs of 258 patients with peripheral arterial occlusive disease (PAOD). The tcpO2-vs-perfusion pressure relationship could be satisfactorily fitted by a non-linear regression model deduced from the tcpO2 theory. Flow-insensitive ranges of tcpO2-vs-flow hyperbolas were reduced by both leg lowering and moving the electrode towards proximal measuring sites. Lower tcpO2 values were found in case of occluded compared to patent calf arteries at ankle arterial pressure indices below 0.4. The tcpO2 positional variability increased with worsening hemodynamic compensation and was most pronounced in critical limb ischaemia (ischaemic rest pain, non-healing ulcerations). According to a retrospective analysis, a critical ischaemia could be assumed if supine and sitting tcpO2-values exceed neither 10 nor 45 mmHg, respectively.

[The pathogen spectrum and its resistance behavior in children with urinary tract infections in Angola]

In 225 children (135 boys, 90 girls) suffering from clinical relevant urinary tract infection the bacterial spectrum and resistance behaviour to routinely used antibiotics were evaluated. In 65.4% of the patients a significant bacteriuria was found: E. coli (34.6%), proteus (22.3%), klebsiella (14.6%), citrobacter (9.2%), enterobacter (5.4%) and pseudomonas (5.4%). In testing a high resistance of bacterias to trimethoprim/sulfamethoxazol, ampicillin, and gentamycin was found, whereas good susceptibility was found to nitrofurantoin and nalidixin acid.

[The status of hemoglobin concentration and hematocrit in Angola children]

Hemoglobin-concentration (Hb) and hematocrit (Ht) were determined in 622 Angolean children between ages of 3 months and 13 years. The children were divided into two groups: group I (n = 530) of low social and economic state, group II (n = 92) children enjoyed good living conditions. 38.9% of all children had a Hb below 6.8mmol/l. 218 of which were part of group I, only 18 were out of group II. An extensive anemia (less than Hb 4.3mmol/l) existed in only 3% of all children. 51.7% of children were below 3 years. Between age groups of 3 months to over 10 years there was a continual rise in Hb of 17.6 +/- 6.6% (boys) and 9.5 +/- 3% (girls). Using the Ht values the percentage of anemic children was only 16.4%. It existed a relationship, especially, clearly observed in group I, between physical development and aemia frequency. Children of group I were more anemic than children of group II.

[The perceptibility of a microwave field under experimental conditions]

The development of effects caused physical environmental factors on subjective images and on behaviour of exposed persons generally presupposes the perceptibility of the factors concerned via receptors. Though there are no indications regarding the existence of specific receptors for electromagnetic fields as yet, one or the other person is certain of being able to notice the presence of electromagnetic fields. The perceptibility of microwave fields and related effects on short-term subjective effects have been tested in an experimental series. We found a) significant differences in the studied effects between experimental and control situations, b) stability of effects in retests, c) increasing correct indications concerning the presence of fields after several training sessions. Subjects could be discriminated regarding the individual level of effects. Moreover female versus male subjects showed different levels of correct indications of fields. The most important symptoms related to field detection are listed.

[Chronic neuropathy of the suprascapular nerve in high performance athletes]

The clinical and electrophysiological examination of 36 top-level volleyball players showed a suprascapular neuropathy in 28% of the subjects. The most commonly observed clinical symptom was a focal severe atrophy of the m. infraspinatus, combined with loss of strength of the arm in abduction and external rotation. In contrast to previous reports on suprascapular neuropathies in volleyball players, the present investigation demonstrates an additional milder affection also of the nerve fibres supplying the m. supraspinatus.

[Glomerulonephritis (GN) in childhood. II. Epidemiology and clinical aspects of various histological forms of glomerulonephritis]

From 101 children with histological verified glomerulonephritis the following data were analyzed according to the morphological alterations: age distribution, symptoms and onset of the disease, previous diseases, and observation time. Differences of these parameters were found firstly between minimal glomerular changes and proliferative lesions. Within the various proliferative forms the differences were minimal. In children with a diffuse mesangio-proliferative glomerulonephritis and MPGN the characteristics of blood pressure, proteinuria and hematuria were observed during a follow-up time of 5 years. In conclusion, a distinction between single types of glomerulonephritis could be made exceptionally without examination of kidney function and morphology.

[The incidence of kidney diseases in a pediatric kidney dispensary]

400 children (141 boys and 259 girls) in a renal disease care system were analyzed regarding their most frequent diagnoses of renal diseases and their age and sex distribution. Furthermore, the familiary situation, the time of observation, the number of consultations and the frequency of morphological changes of the kidney and the urinary tract were examined. 72% of the children suffered from urinary tract infection and in 10% a glomerulopathy and in 5.5% an urolithiasis were found. The symptoms of enuresis occurred in 22.2% of the patients. Infants were the most frequent age group (18%), 70% of which were boys. We found no differences in the incidence of renal diseases in comparison with other reports.

[Oral galactose loading in characterizing the elimination and metabolizing performance of the liver in chronic renal failure]

For characterising the elimination and metabolisation performance of the liver in chronic renal insufficiency the galactose load test was carried out. 9 children with healthy liver and kidneys, 35 children with chronic renal insufficiency (15 were conservatively treated = group 1, 20 were in the chronic haemodialysis programme = group 2) as well as 5 children after kidney transplantation were examined. In group 1 a normal blood galactose concentration was present. Patients of the 2nd group showed increased concentrations of galactose in the blood which might refer to a decreased redox potential in the liver caused by the uraemic intoxication. In the group of patients who underwent a kidney transplantation in the patients with azathioprine therapy a disturbed use of galactose was present. Children with cyclosporin-A had a normal galactose concentration.