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Background and aims: Although psychological stress has been implicated as a cause of idiopathic infertility in both men and women, it has received little scientific attention among males as compared to females. The aim of the study was to examine the association between occupational, life stress, family functioning and semen quality. Methods and results: The study population consisted of 327 men who were attending an infertility clinic for diagnostic purposes. Psychological stress was assessed based on two questionnaires: The Subjective Work Characteristics Questionnaire and the Perceived Stress Scale. The level of satisfaction with family functioning and support was evaluated by means of the APGAR Family Scale. The findings suggest that, on the one hand, exposure to occupational stressors can be negatively associated with semen quality (there was a positive association between stress and the percentage of sperm with DNA damage ( p = 0.03) and atypical sperm ( p = 0.05)); on the other hand, there was no correlation between the level of life stress and semen quality indicators. Negative associations were found between satisfaction with family functioning and the percentage of motile sperm cells ( p = 0.02), VAP ( p = 0.05), VSL ( p = 0.05) and VCL ( p = 0.04). Conclusion: The study indicates that occupational stress can affect male semen quality; however, due to limited data on this issue, the obtained results should be confirmed in longitudinal studies. [ABSTRACT FROM AUTHOR]

Technological progress in material synthesis, as well as artificial realization of condensed matter scenarios via ultra-cold atomic gases in optical lattices or epitaxial growth of thin films, is opening the gate to investigate a plethora of unprecedented strongly correlated electron systems. In a large subclass thereof, a metallic state of layered electrons undergoes an ordering transition below some temperature into unconventional states of matter driven by electronic correlations, such as magnetism, superconductivity (SC), or other Fermi surface (FS) instabilities. While these phenomena have been a well-established direction of research in condensed matter for decades, the variety of today's accessible scenarios pose fundamental new challenges to describe them. A core complication is the multi-orbital nature of the low-energy electronic structure of these systems, such as the multi-dorbital nature of electrons in iron-pnictides and transition-metal oxides in general, but also electronic states of matter on lattices with multiple sites per unit cell such as the honeycomb or kagome lattice. In this review, we propagate the functional renormalization group (FRG) as a suited approach to investigate multi-orbital FS instabilities. The primary goal of the review is to describe the FRG in explicit detail and render it accessible to everyone both at a technical and intuitive level. Summarizing recent progress in the field of multi-orbital FS instabilities, we illustrate how the unbiased fashion by which the FRG treats all kinds of ordering tendencies guarantees an adequate description of electronic phase diagrams and often allows to obtain parameter trends of sufficient accuracy to make qualitative predictions for experiments. This review includes detailed and illustrative examples of magnetism and, in particular, SC for the iron-pnictides from the viewpoint of FRG. Furthermore, it discusses candidate scenarios for topological bulk singlet SC and exotic particle–hole condensates on hexagonal lattices such as sodium-doped cobaltates, graphene doped to van-Hove filling, and the kagome Hubbard model. In total, the FRG promises to be one of the most versatile and revealing numerical approaches to address unconventional FS instabilities in future fields of condensed matter research. [ABSTRACT FROM AUTHOR]

In conventional and high transition temperature copper oxide and iron pnictide superconductors, the Cooper pairs all have even parity. As a rare exception, Sr2RuO4 is the first prime candidate for topological chiral p-wave superconductivity, which has time-reversal breaking odd-parity Cooper pairs known to exist before only in the neutral superfluid 3He. However, there are several key unresolved issues hampering the microscopic description of the unconventional superconductivity. Spin fluctuations at both large and small wave vectors are present in experiments, but how they arise and drive superconductivity is not yet clear. Spontaneous edge current is expected but not observed conclusively. Specific experiments point to highly band- and/or momentum-dependent energy gaps for quasiparticle excitations in the superconducting state. Here, by comprehensive functional renormalization group calculations with all relevant bands, we disentangle the various competing possibilities. In particular, we show the small wave vector spin fluctuations, driven by a single two-dimensional band, trigger p-wave superconductivity with quasi-nodal energy gaps. [ABSTRACT FROM AUTHOR]

Beside their haptic function, vibrissae of harbour seals (Phocidae) and California sea lions (Otariidae) both represent highly sensitive hydrodynamic receptor systems, although their vibrissal hair shafts differ considerably in structure. To quantify the sensory performance of both hair types, isolated single whiskers were used to measure vortex shedding frequencies produced in the wake of a cylinder immersed in a rotational flow tank. These measurements revealed that both whisker types were able to detect the vortex shedding frequency but differed considerably with respect to the signal-to-noise ratio (SNR). While the signal detected by sea lion whiskers was substantially corrupted by noise, harbour seal whiskers showed a higher SNR with largely reduced noise. However, further analysis revealed that in sea lion whiskers, each noise signal contained a dominant frequency suggested to function as a characteristic carrier signal. While in harbour seal whiskers the unique surface structure explains its high sensitivity, this more or less steady fundamental frequency might represent the mechanism underlying hydrodynamic reception in the fast swimming sea lion by being modulated in response to hydrodynamic stimuli impinging on the hair. [ABSTRACT FROM AUTHOR]

There is increasing evidence that proteins in tubular fluid are "nephrotoxic." In vivo it is difficult to study protein loading of tubular epithelial cells in isolation, i.e., without concomitant glomerular damage or changes of renal hemodynamics, etc. Recently, a unique amphibian model has been described which takes advantage of the special anatomy of the amphibian kidney in which a subset of nephrons drains the peritoneal cavity (open nephrons) so that intraperitoneal injection of protein selectively causes protein storage in and peritubular fibrosis around open but not around closed tubules. There is an ongoing debate as to what degree albumin per se is nephrotoxic and whether modification of albumin alters its nephrotoxicity. We tested the hypothesis that carbamylation and glycation render albumin more nephrotoxic compared with native albumin and alternative albumin modifications, e.g., lipid oxidation and lipid depletion. Preparations of native and modified albumin were injected into the axolotl peritoneum. The kidneys were retrieved after 10 days and studied by light microscopy as well as by immunohistochemistry [transforming growth factor (TGF)-β, PDGF, NF-κB, collagen I and IV, RAGE], nonradioactive in situ hybridization, and Western blotting. Two investigators unaware of the animal groups evaluated and scored renal histology. Compared with unmodified albumin, glycated and carbamylated albumin caused more pronounced protein storage. After no more than 10 days, selective peritubular fibrosis was seen around nephrons draining the peritoneal cavity (open nephrons), but not around closed nephrons. Additionally, more intense expression of RAGE, NF-κB, as well as PDGF, TGF-β, EGF, ET-1, and others was noted by histochemistry and confirmed by RT-PCR for fibronectin and TGF-β as well as nonradioactive in situ hybridization for TGF-β and fibronectin. The data indicate that carbamylation and glycation increase the capacity of albumin to cause tubular cell damage and peritubular fibrosis. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the study was to characterize the PAH exposure level based on 1-hydroxypyrene (1-HP) in urine of Polish pregnant women and to assess the relationship between PAH and factors such as smoking, environmental tobacco smoke exposure, place of residence, heating and cooking method. Materials and Methods: The study population included in this analysis consisted of 449 pregnant women who had been the subjects of the prospective Polish Mother and Child Cohort study performed in 8 regions of Poland. The women were interviewed three times during pregnancy (once in each trimester). 1-HP concentration in urine was chosen as the biomarker of exposure to PAH. The urine sample was analysed using high performance liquid chromatography (HPLC). The active and passive smoking exposure was verified by saliva cotinine, analysed by high performance liquid chromatography coupled with tandem mass spectrometry (LC-MSMS) and isotope dilution method. Results: 1-HP concentration in urine ranged from 0.02 to 10.2 μg/g creatinine with the geometric mean (GM) 0.4 μg/g creatinine. The significantly higher concentration of urinary 1-HP in pregnant women was observed for summer collection (GM ratio: 1.1; p = 0.01), among smokers (GM ratio: 1.7; p < 0.001) and for the women living in big cities (GM ratio: 1.3; p = 0.001). Conclusions: The significantly higher concentration of urinary 1-HP in pregnant women was observed for summer collection, among smokers and those living in big cities. [ABSTRACT FROM AUTHOR]

The mystacial vibrissae of harbour seals (Phoca vitulina) constitute a highly sensitive hydrodynamic receptor system enabling the seals to detect and follow hydrodynamic trails. In the wild, hydrodynamic trails, as generated by swimming fish, consist of cyclic burst-and-glide phases, associated with various differences in the physical parameters of the trail. Here, we investigated the impact of glide phases on the trackability of differently aged hydrodynamic trails in a harbour seal. As fish are not easily trained to swim certain paths with predetermined burst-and-glide phases, the respective hydrodynamic trails were generated using a remote-controlled miniature submarine. Gliding phases in hydrodynamic trails had a negative impact on the trackability when trails were 15s old. The seal lost the generated trails more often within the transition zones, when the submarine switched from a burst to a glide moving pattern. Hydrodynamic parameter analysis (particle image velocimetry) revealed that the smaller dimensions and faster decay of hydrodynamic trails generated by the gliding submarine are responsible for the impaired success of the seal tracking the gliding phase. Furthermore, the change of gross water flow generated by the submarine from a rearwards- directed stream in the burst phase to a water flow passively dragged behind the submarine during gliding might influence the ability of the seal to follow the trail as this might cause a weaker deflection of the vibrissae. The possible ecological implications of intermittent swimming behaviour in fish for piscivorous predators are discussed. [ABSTRACT FROM AUTHOR]

In the spin Hall effect, a current passed through a spin–orbit coupled electron gas induces a spin accumulation of inverse sign on either side of the sample. A number of possible mechanisms have been described, extrinsic as well as intrinsic ones, and they may occur in the ballistic as well as the diffusive transport regime. A central problem for experimentalists in studying the effect is the very small signals that result from the spin accumulation. Electrical measurements on metals have yielded reliable signatures of the spin Hall effect, but in semiconductors the spin accumulation could only be detected by optical techniques. Here we report experimental evidence for electrical manipulation and detection of the ballistic intrinsic spin Hall effect (ISHE) in semiconductors. We perform a non-local electrical measurement in nanoscale H-shaped structures built on high-mobility HgTe/(Hg, Cd)Te quantum wells. When the samples are tuned into the p-regime, we observe a large non-local resistance signal due to the ISHE, several orders of magnitude larger than in metals. In the n-regime, where the spin–orbit splitting is reduced, the signal is at least one order of magnitude smaller and vanishes for narrower quantum wells. We verify our experimental observations by quantum transport calculations. [ABSTRACT FROM AUTHOR]

Theories based on the coupling between spin fluctuations and fermionic quasiparticles are among the leading contenders to explain the origin of high-temperature superconductivity, but estimates of the strength of this interaction differ widely. Here, we analyse the charge- and spin-excitation spectra determined by angle-resolved photoemission and inelastic neutron scattering, respectively, on the same crystals of the high-temperature superconductor YBa2Cu3O6.6. We show that a self-consistent description of both spectra can be obtained by adjusting a single parameter, the spin–fermion coupling constant. In particular, we find a quantitative link between two spectral features that have been established as universal for the cuprates, namely high-energy spin excitations and ‘kinks’ in the fermionic band dispersions along the nodal direction. The superconducting transition temperature computed with this coupling constant exceeds 150 K, demonstrating that spin fluctuations have sufficient strength to mediate high-temperature superconductivity. [ABSTRACT FROM AUTHOR]

Oscillating chemical bulk reactions of the Belousov–Zhabotinsky (BZ) type usually show a well-defined periodical color change representing the underlying chemical reactions. Models including up to more than 50 coupled reactions have been developed to describe the BZ-reaction in detail, however, typically a much simpler set of equations is used (i.e. the Brüsselator, the FKN, or the FitzHugh–Nagumo model). There are various types of oscillating reactions with color changes, for example, from transparent to yellow (Ce catalyzed), or from blue to red (Ferroin catalyzed). In equilibrium systems and in models each color-change is usually a simple curve with one maximum, and the oscillation is stable in time. We have investigated the detailed structure of the intrinsic optical signal (IOS) of a BZ-reaction in-depth andfound, in a nonstationary ferroin catalyzed BZ-reaction, a much more complex optical behavior. Amazingly, this IOS with its detailed time dependence very much resembles electrical and optical signals from important neuronal processes. These are especially the sodium current during action potentials (AP) and the retinal spreading depression (SD). The time-scale of all these processes can be different by decades. This principal similarity, however, points to a deeper common theoretical basis of all these processes as assumed up to now, and makes the presented type of BZ-reaction an ideal model for a variety of neurophysiological signals, although the mechanisms are strictly different. [ABSTRACT FROM AUTHOR]

For seals hunting in dark and murky waters one source of sensory information for locating prey consists of fish- generated water movements, which they can detect using their highly sensitive mystacial vibrissae. As water movements in the wake of fishes can persist for several minutes, hydrodynamic trails of considerable length are generated. It has been demonstrated that seals can use their vibrissae to detect and track hydrodynamic trails generated artificially by miniature submarines. In the present study, we trained a harbour seal to swim predefined courses, thus generating biogenic hydrodynamic trails. The structure of these trails was measured using Particle Image Velocimetry. A second seal was trained to search for and track the trail after the trail-generating seal had left the water. Our trail-following seal was able to detect and accurately track the hydrodynamic trail, showing search patterns either mostly congruent with the trail or crossing the trail repeatedly in an undulatory way. The undulatory trail-following search pattern might allow a seal to relocate a lost trail or successfully track a fleeing, zigzagging prey fish. [ABSTRACT FROM AUTHOR]

We present a numerical study of the doping dependence of the spectral function of the n-type cuprates. Using a variational cluster-perturbation theory approach based upon the self-energy-functional theory, the spectral function of the electron-doped two-dimensional Hubbard model is calculated. The model includes the next-nearest-neighbor electronic hopping amplitude t′ and a fixed on-site interaction U=8t at half-filling and doping levels ranging from x=0.077 to x=0.20. Our results support the fact that a comprehensive description of the single-particle spectrum of electron-doped cuprates requires a proper treatment of strong electronic correlations. In contrast to previous weak-coupling approaches, we obtain a consistent description of the ARPES experiments without the need to (artificially) introduce a doping-dependent on-site interaction U. [ABSTRACT FROM AUTHOR]

In Poland small, nonspecialized farms, growing different crops and raising usually a few animals of various species constitute the majority.The aim of the case–control study was to evaluate the risk factors of work-related respiratory symptoms and occupational asthma and/or rhinitis in Polish farmers and investigate whether the farming characteristics may have influence on the prevalence of atopy and allergic diseases.The study groups comprised 100 cases who were farmers reporting work-related asthmatic and/or rhinitis symptoms from randomly selected family doctors practices (80 of 353) and 102 healthy controls. All subjects were examined by means of a questionnaire, skin prick tests (SPT) to common and occupational allergens, total serum immunoglobulin (Ig)E level and the presence of specific IgE and allergen-specific inhalation challenge tests were performed. The provocation tests were monitored with the spirometry, histamine challenge test and evaluation of nasal symptoms score and nasal washings.Respiratory allergic disease was recognized in 68 symptomatic patients, including 41 cases because of occupational allergens (asthman = 38, rhinitisn = 41). Step-wise logistic regression analysis confirmed the protective role of small farms against the development of work-related symptoms (OR 0.23; 95% CI 0.11, 0.47) as well as the significance of positive SPT to cereals (OR 5.55; 95% CI 1.6, 19.21) and storage mites (OR 3.73; 95% CI 1.27, 10.96) as a risk factor of these symptoms. Cereal farming (OR 13.75; 95% CI 2.39, 78.83) and positive SPT to cereals (OR 26.92; 95% CI 5.33, 135.9) and storage mites (OR 44.07; 95% CI 8.40, 231.1) were found to be significant risk factors of occupational asthma and/or rhinitis.Cereal farming and hypersensitivity to cereals plays the significant role in the development of occupational asthma among Polish farmers. It also seems that working on small farms may protect farmers against work-related respiratory symptoms that are mostly because of allergy. [ABSTRACT FROM AUTHOR]

Understanding the molecular regulation of immunoglobulin A (IgA) expression is important as it plays an essential role in the first-line defence through mucosal secretions. Using inbred mouse strains, we identified two independent and dominant acting genetic loci that synergistically cause a 40-fold upregulation in serum IgA levels when introduced into the murine strain C57Bl/6J (B6). The first locus on chromosome 12 appears to be mainly responsible for the natural four-fold higher IgA levels in C3HeB/FeJ (C3H) compared to B6 mice. A second independent, chemically induced mutation on chromosome 5 caused a two-fold elevation when transferred from C3H into B6 mice. Both loci in concert effect a 40-fold elevation against the B6 genetic background. We determined the chromosomal localization of the two loci simultaneously by a one-step mapping process. The chemically induced mutation was identified within the immunoglobulin joining chain (IgJ) gene on chromosome 5. The major serum IgA modifier between the C3H and B6 was located on chromosome 12. This modifier region was mapped to a 350?kb region containing several immunoglobulin heavy-chain genes and the Iga germline switch gene. We speculate that by interfering with both IgA expression and distribution, synergistic regulation of IgA is achieved.Genes and Immunity (2004) 5, 375-380. doi:10.1038/sj.gene.6364105 Published online 3 June 2004 [ABSTRACT FROM AUTHOR]

This prospective study describes the incidence, risk factors and natural history of occupational respiratory allergy in apprentice bakers. Two hundred and eighty-seven apprentice bakers were examined using a questionnaire, skin prick tests (SPTs) to common and occupational allergens, evaluation of total serum IgE level and specific anti-flour and α-amylase IgE, before, 1 year and 2 years after the onset of vocational training. To diagnose occupational respiratory disease, spirometry, histamine and allergen-specific inhalation challenge tests were performed. The incidence of work-related chest symptoms was 4.2% in the first year and 8.6% in the second year of exposure. Hypersensitivity to occupational allergens developed in 4.6 and 8.2% of subjects, respectively. The incidence of occupational allergic rhinitis was 8.4% after 1 year and 12.5% after 2 years, and that of occupational asthma/cough-variant asthma 6.1 and 8.7%, respectively. The latency period of work-related rhinitis symptoms was 11.6 ± 7.1 months and chest symptoms 12.9 ± 5.5 months. Only in 20% of occupational asthmatics could allergic rhinitis be diagnosed a stage earlier. In 21 out of 25 subjects with occupational asthma, chronic cough was the sole clinical manifestation of the disease. Stepwise logistic regression analysis revealed that positive SPT to common allergens was a significant risk factor of hypersensitivity to occupational allergens (OR = 10.6, 95% CI 5.27; 21.45), occupational rhinitis (OR = 3.9, 95% CI 1.71; 9.14) and occupational asthma (OR = 7.4, 95% CI 3.01; 18.04). Moreover, positive SPT to occupational allergens on entry to the training was a significant risk factor of asthma (OR = 6.9, 95% CI 0.93; 51.38). The incidence of occupational asthma and rhinitis in apprentice bakers is high and increases z with the duration of exposure. Skin reactivity to common and occupational allergens is the main risk factor of bakers’ asthma. Most cases of work-related respiratory symptoms among apprentice bakers are related to a specific sensitization. In most subjects who developed occupational asthma, rhinitis occurred at the same time as the chest symptoms did. [ABSTRACT FROM AUTHOR]

Using a combination of exact enumeration and the dynamical mean-field theory (DMFT) we study the drastic change of the spectral properties, obtained in the half-filled two-dimensional Hubbard model at a transition from an antiferromagnetic to a paramagnetic Mott insulator, and compare it with the results obtained using the quantum Monte Carlo method. The coherent hole (electron) quasiparticle spin-polaron subbands are gradually smeared out when the AF order disappears, either for increasing Coulomb repulsion U at fixed temperature T, or for increasing T at fixed U. Within the DMFT we present numerical evidence (a continuous disappearance of the order parameter) suggesting that the above magnetic transition is second order both in two and in three dimensions. [ABSTRACT FROM AUTHOR]

The lateral line of fish is composed of neuromasts used to detect water motions. Neuromasts occur as superficial neuromasts on the skin and as canal neuromasts in subepidermal canals. Fibres of the lateral line nerves innervate both. There have been extensive studies on the responses of lateral line nerve fibres to dipole stimuli applied in still water. However, despite the fact that many fish live in rivers and/or swim constantly, responses of lateral line nerve fibres to dipole stimuli presented in running water have never been recorded. We investigated how the peripheral lateral line of still water fish (Carassius auratus) and riverine fish (Oncorhynchus mykiss) responds to minute sinusoidal water motions while exposed to unidirectional water flow. Both goldfish and trout have two types of posterior lateral line nerve fibres: Type I fibres, which most likely innervate superficial neuromasts, were stimulated by running water (10 cm s–1). The responses of type I fibres to water motions generated by a vibrating sphere were masked if the fish was exposed to running water. Type II fibres, which most likely innervate canal neuromasts, were not stimulated by running water. Consequently, responses of type II fibres to a vibrating sphere were not masked under flow conditions. [ABSTRACT FROM AUTHOR]

Angular-resolved photoemission data on half-filled doped cuprate materials are compared with an exact-diagonalization analysis of the three-band Hubbard model, which is extended to the infinite lattice by means of a perturbation in the intercluster hopping (cluster perturbation theory). A study of the band dispersion and spectral weight of the insulating cuprate Sr 2CuO 2Cl 2 allows us to fix a consistent parameter set, which turns out to be appropriate at finite dopings as well. In the overdoped regime, our results for the spectral weight and for the Fermi surface give a good description of the experimental data on Bi 2Sr 2CaCu 2O 8+δ. In particular, the Fermi surface is hole-like and centered around k=(π, π) . Finally, we introduce a hopping between two layers and address the issue of bilayer splitting. [ABSTRACT FROM AUTHOR]

Presents a study that tackled the employment status of pregnant women in central Poland. Risk of preterm delivery and small-for-gestational-age infants. Methodology used in the study; Discussion on the results of the study; Conclusion.

The behavior of wave propagation, as well that of isolated waves as that of self-sustained activity, in excitable media is characterized by the dispersion relation of the system. For the Belousov-Zhabotinsky (BZ)-reaction as by far the best described system, a number of theoretical considerations and experimental investigations do exist. From the theoretical point of view the dispersion relation of the BZ-reaction has two branches, an upper "fast" or stable branch typified by singular solutions and a lower "slow" branch whose solutions are regular, with a connection between the two branches, defining the smallest possible period and the absolute refractory period of the system. Experimental data are usually located on the upper branch giving higher propagation velocity at increasing period. Only one set of results was published in the early 1970s with velocity being an increasing function of frequency. This set of data was stated to be "dijficult to believe" in later papers. We now present here a more detailed study of a BZ-system with a dispersion relation with an increasing velocity at decreasing period, verifying the existence of an "inverse" dispersion relation at least in the nonstationary gels we have used. [ABSTRACT FROM AUTHOR]

1 The present investigation was undertaken to evaluate the effect of environmental tobacco smoke (ETS) on the risk of preterm delivery (PD) and small-for-gestational age (SGA) infants in a female non-smoking population of central Poland. 2 The study group were 1751 women classified as non-smokers in the comprehensive project on ‘Socio-economic and environmental risk factors of preterm delivery and small-for-gestational-age babies in central Poland’ conducted on a randomly selected population of 2080 women who gave birth to a child between June 1, 1996 and May 31, 1997. The PD group comprised 95 non-smoking women who delivered before 37 weeks of pregnancy and the SGA group included 111 non-smoking mothers of babies with birthweight below the 10th percentile of the standard curves for central Poland. Passive exposure to tobacco smoke was determined based on a structured interview. 3 In the stepwise multiple logistic regression model maternal passive smoke exposure lasting 7 h or more was found to be a significant risk factor for preterm delivery. No significant effect of passive smoking on the risk of SGA was observed. 4 The information about the adverse effects of ETS exposure on pregnancy duration and outcome should be incorporated in the health promotion programmes for women. [ABSTRACT FROM AUTHOR]

We investigate, within the fluctuation-exchange approximation, a correlated-electron model for represented by two inequivalent Hubbard layers coupled by an interlayer hopping . An energy offset is introduced in order to produce a different charge carrier concentration in the two layers. We compare several single-particle and magnetic excitations, namely, the single particle scattering rate, the spectral function and the spin lattice as well as spin-spin relaxation times in the two layers as a function of . We show that the induced interlayer magnetic coupling produces a tendency to “equalization” of the magnetic properties in the two layers whereby antiferromagnetic fluctuations are suppressed in the less doped layer and enhanced in the heavily doped one.The strong antiferromagnetic bilayer coupling causes the charge carriers in the plane with larger doping concentration to behave similar to those of the underdoped layer, they are coupled to. This effect grows for decreasing temperature. For high temperatures or if both layers are optimally or overdoped, i.e. when the antiferromagnetic correlation length becomes of the order or smaller than one lattice site the charge carrier and magnetic dynamics of the two layers is disconnected and the equalization effect disappears. These results are in good agreement with NMR experiments on by Stern et al. [Phys. Rev B 51, 15478 (1995)]. We also compare the results with calculations on bilayer systems with equivalent layers as models for the constituent compounds and . [ABSTRACT FROM AUTHOR]

We discuss properties of a recently proposed SO(5) symmetric ladder model. Key features of the single particle spectral function that are emerging from the symmetry are numerically identified in the ladder model and in the photoemission spectrum of the two-dimensional t-J model. [ABSTRACT FROM AUTHOR]

The voltage-dependency of alamethicin pore formation is explained by a flip-flop gating mechanism of single alamethicin molecules. The energetically preferred aggregate structure is changed from antiparallel to parallel molecule orientation by membrane voltage application. The electrical field is sensed by the permanent dipole of the α-helical molecule part which spans the hydrophobic membrane core. Ion conducting pore and pore states result from electrostatic repulsion of a varying number of parallel dipoles which arrange circularly. This model is consistent with published data and with two additional experimental facts, that pore state distributions are ionic strength dependent and pore state conductances depend on ionic current direction. [ABSTRACT FROM AUTHOR]

A new method of membrane reconstitution was developed by fusion of channel protein containing vesicles with planar bilayer membranes. The fusion process only occurred below and near the phase transition temperature of the lipid used. We obtained the following results: 1. Our system is solvent-free and vesicles do not come into contact with the air/water interface. This obviates a possible denaturation of hydrophobic proteins. 2. Channel forming proteins and protein complexes, respectively, are active in a frozen lipid matrix. 3. We detected an unknown channel in cilia fragments. 4. Purified acetylcholine receptors form fluctuating channels in a membrane consisting of a pure synthetic lecithin (two component system). [ABSTRACT FROM AUTHOR]