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Introduced Pacific salmon (Oncorhynchus spp.) deliver novel, pulsed resource subsidies to Great Lakes streams. We explored interactions between native brook trout (Salvelinus fontinalis) and non-native brown trout (Salmo trutta) in the context of this resource pulse. Diets surveyed before and during salmon spawning showed that, regardless of species, trout consumed 4.5-fold more biomass during than before salmon runs. Brook trout grew more quickly than brown trout under controlled feeding regimes due, in part, to their higher food conversion efficiency of 36% compared with 21%. Bioenergetics model simulations explored the influence of temperature on the exploitation of resource pulses and found 35% lower growth rates and increased gorging at colder temperatures. Overall, we found evidence that brook trout and brown trout foraging and growth are modulated by the salmon resource pulse, especially through gorging on eggs. However, these species exhibit distinct physiological adaptations and environmental preferences that may influence their ultimate capacity to exploit resource pulses. The effects of environmental conditions and salmon subsidies on stream-resident trout have broader consequences for fisheries management and conservation efforts.

Nature photonics 14(6), 391 - 397 (2020). doi:10.1038/s41566-020-0607-z, The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created., Published by Nature Publ. Group, London [u.a.]

The impacts on pipes or beams are of fundamental mechanical interest. These impacts can be studied analytically. This makes it easier to examine the basic effects and to compare these effects with the results of finite element analyzes (FEA). The displacements of a pipe with two-sided stops and harmonic excitation are investigated. For hard impacts many modes must be used in the analytical calculations, which leads to considerable numerical problems and sometimes chaotic behavior. The influence of a small viscose damping is small compared with the effects of the mode numbers. For plastic impacts and elastic impacts with more realistic stiffness of the stops a moderate number of modes can be used. The comparison of the displacements for hard, plastic and elastic (with high stiffness of the stops) shows a remarkable good agreement with the results of the FEA for hard impacts. This confirms the plastic impact approach in the FE software Abaqus. It is noted that for plastic impacts already two modes give an acceptable description of the displacements.

Nowadays, it is important to realize systems that can model the electrical activity of neurons taking into account almost all the properties of the intracellular and extracellular environment in which they are located. It is in this sense that we propose in this paper, the improved model of Hindmarsh–Rose (HR) which takes into account the fluctuation of the membrane potential created by the variation of the ion concentration in the cell. Considering the effect of the electric field that is produced on the dynamic behavior of neurons, the essential properties of the model such as equilibrium point and its stability, bifurcation diagrams, Lyapunov spectrum, frequency spectra, time series of the membrane potential and phase portraits are thoroughly investigated. We thus prove that Hopf bifurcation occurs in this system when the parameters are chosen appropriately. We also observe that by varying specific parameters of the electric field, the model presents a very rich and striking event, namely hysteresis phenomenon, which justifies the coexistence of multiple attractors. Besides, by applying a suitable sinusoidal excitation current, we prove that the neuron under electric field effect can present several important electrical activities including quiescent, spiking, bursting and even chaos. We propose the improved HR model under electric field effect (mHR) to study the finite-time synchronization between two neurons when performing synapse coupling across the membrane potential and the electric field coupling. As a result, we find that the synchronization between the two neurons is weakly influenced by the variation of the intensity of the electric field coupling while it is strongly impacted when the intensity of the synapse coupling is modified. From these results, it is obvious that the electric field can be another effective bridge connection to encourage the exchange and coding of the signal. Using the finite-time synchronization algorithm, we theoretically quantify the synchronization time between these neurons. Finally, Pspice simulations are presented to show the feasibility of the proposed model as well as that of the developed synchronization strategy.

Current production trends and demands for Fibre Reinforced Plastics are exceeding the capabilities of classical, recognised inspection and test methods, especially their capabilities to monitor the mass production of carbon fibre reinforced plastic parts. Novel non-destructive measurement methods to efficiently perform quality assurance within industrial mass production are required. This research is focused on a novel method to assess the properties of textile reinforcements employed in liquid composite moulding processes. This method non-destructively measures the resistance provided by semi-finished textiles to compressive deformation and fluid flow. Rather than calculating permeability using traditional methods, simple measures of injectability of textile reinforcements are determined using an air pulse applied within the stack or preform. On this basis, a simple, mobile prototype device has been developed to support production and quality control to evaluate the injectability and compressibility properties of stacks and preforms and gather information about processes and systems.

Highlights: • Larvae upregulate genes associated with fatty acid and glycogen synthesis under moderate ocean acidification (OA) • Larvae under high levels of OA fail to regulate • Dysfunctional metabolism and stress associated with pathologies in internal organs • Lack of differential gene regulation and stress response in juveniles correspond to a higher resilience to OA stress Elevated environmental carbon dioxide (pCO2) levels have been found to cause organ damage in the early life stages of different commercial fish species, including Atlantic cod (Gadus morhua). To illuminate the underlying mechanisms causing pathologies in the intestines, the kidney, the pancreas and the liver in response to elevated pCO2, we examined related gene expression patterns in Atlantic cod reared for two months under three different pCO2 regimes: 380 μatm (control), 1800 μatm (medium) and 4200 μatm (high). We extracted RNA from whole fish sampled during the larval (32 dph) and early juvenile stage (46 dph) for relative expression analysis of 18 different genes related to essential metabolic pathways. At 32 dph, larvae subjected to the medium treatment displayed an up-regulation of genes mainly associated with fatty acid and glycogen synthesis (GYS2, 6PGL, ACoA, CPTA1, FAS and PPAR1b). Larvae exposed to the high pCO2 treatment upregulated fewer but similar genes (6PGL, ACoA and PPAR1b,). These data suggest stress-induced alterations in the lipid and fatty acid metabolism and a disrupted lipid homeostasis in larvae, providing a mechanistic link to the findings of lipid droplet overload in the liver and organ pathologies. At 46 dph, no significant differences in gene expression were detected, confirming a higher resilience of juveniles in comparison to larvae when exposed to elevated pCO2 up to 4200 μatm.

Ecosystem linkages created by migratory organisms such as Pacific salmon (Oncorhynchus spp.) facilitate the transfer of ecologically beneficial resource subsidies and environmentally damaging contaminants to recipient food webs. In the Laurentian Great Lakes, introduced Pacific salmon accumulate large contaminant burdens that they disperse to streams during spawning in the form of carcass and gametic tissue, with uncertain consequences for stream food webs. Here, we describe a coupled bioenergetics-bioaccumulation model parameterized using empirical and literature-sourced data to predict the dual effect of Pacific salmon on stream-resident brook trout (Salvelinus fontinalis) growth and contaminant bioaccumulation. Within the model, we developed four unique scenarios to ascertain how the (1) trophic pathway to contamination, (2) level of salmon egg consumption, (3) intensity and duration of salmon exposure, and (4) age of first exposure to salmon, affected growth and contaminant bioaccumulation in brook trout. Our model demonstrated that salmon egg consumption increased brook trout growth and PCB bioaccumulation while reducing Hg tissue concentrations. Other trophic pathways, including direct carcass consumption and an indirect food web pathway, did not strongly influence growth or contaminant bioaccumulation. Our model also demonstrated that variation in the magnitude and temporal duration of salmon egg consumption mostly strongly influenced the growth and contaminant concentration of younger brook trout. Overall, our model highlighted that Pacific salmon transfer energy and contaminants but this balance is dictated by the food web pathway and plasticity in the diet of stream-resident fish. Our mechanistic, model-based evaluation of salmon contaminant biotransport can be extended to predict the impact of other migratory fishes on recipient food webs.

Despite considerable progress in the production of alternative diets, small concentrations of antinutrients remain common in aquaculture nutrition, resulting in a perpetual limitation with regard to the inclusion of plant ingredients in aquafeeds. These compounds are known to impair the general performance of fish when fed for a prolonged period of time, potentially affecting the animal's susceptibility to stress, too. Therefore, a 12-week feeding trial was conducted to examine the chronic effects of purified rapeseed protein concentrate (RPC), containing low concentrations of glucosinolates and phytic acid, on the relative expression of multiple target genes in the liver of juvenile turbot (Psetta maxima, L.). Our results revealed divergent patterns of gene expression, suggesting different coping strategies dependent on the grade of RPC substitution. Data implies increased metabolic rate of turbot fed a 33% RPC-substituted diet due to an upregulation of cytochrome c oxidase mRNA, accompanied by minor adjustments in metabolic pathways. While no signs of reduced welfare were found, data adumbrate a beneficial hormetic reaction. In the highest treatment level (66% RPC), diminished fish condition and reduced growth performance coincided with a downregulation of insulin-like growth factor I, further indicating a potential impaired resistance to stress. An additional downregulation of transferrin hints towards an increased liability to bacterial infections.

Self-mated wear and friction of Alloy 600 superalloy was studied in a water-submersed ring-on-rod configuration, loading the side of a 6.35 mm diameter rod across the flat surface of a rotating annular ring of 100 mm outer diameter and 70 mm inner diameter producing two sliding contacts along the ring. Tests were conducted at sliding speeds of 0.178 and 0.330 m/s for sliding distances of 100 m. Normal loads of 51 and 204 N were applied, and initial Ra surface roughnesses of the rings along the sliding direction were either smooth (∼0.2 μm) or rough (∼7.5 μm). Increased initial ring roughness caused a ∼20-fold increase in rod wear at the lighter load, whereas at the heavier load increased initial roughness only caused a ∼4-fold increase in wear. At lower initial ring roughness the 4-fold decrease in normal load caused a large (one order-of-magnitude) decrease in rod wear, whereas for rings of higher initial roughness the 4-fold decrease in normal load caused only minor (2-fold or less) decreases in rod wear. Wear during this 100 m sliding distance only experienced a minor effect from the 1.8-fold change in sliding speed, as did friction. In all cases friction coefficient rapidly settled into the range 0.6–0.7, except in the cases of lower load on rings of lower initial roughness where friction coefficient remained above 1 for most of this sliding duration. At this lower load the initial ∼0.2 μm rod roughnesses increased to nearly 0.8 μm by the 100 m sliding distance, whereas at the higher load this same sliding distance resulted in roughnesses returning near to the initial 0.2 μm. It was hypothesized more highly loaded cases also went through initial roughening prior to smoothening back to 0.2 μm roughness within the 100 m sliding distance, and given additional sliding the more lightly loaded cases would also experience subsequent smoothening. Increasing sliding distance to 400 m, roughnesses indicated a smoothening back to 0.2 μm level during those lightly loaded tests, with friction coefficient correspondingly dropping from 1 into the 0.6–0.7 range observed in all other cases. Extended sliding to 400 m at light loading against rings of lower initial roughness also allowed a rod wear rate which increased with increased sliding distance to be observed, approaching the same rate observed against initially rough rings within the 100 m sliding distance.

The thermal stability and decomposition pathways of six Dion-Jacobson-related double-layered perovskites, ALaNb{sub 2}O{sub 7} (A = H, Li, Na, Ag) and (ACl)LaNb{sub 2}O{sub 7} (A = Fe, Cu), are investigated. These compounds are made by low temperature (

The slip ring apparatus in doubly fed induction generators is used to transfer the rotor current from the rotating to the static part of the generator. During the current transfer micro brush fires occur in the contact area when the minimum contact force F C is not maintained. This depends on the spring force applied to the brush top side, the sliding speed V s of the slip ring, the electrical variables (e.g. amplitude of brush current, contact voltage) and environmental influences (e.g. air humidity, ambient temperature, dust). All these variables are measured in our slip ring apparatus. Consequently, this rises the contact temperature that affects the wear of the contact materials (graphite). Using the envelope analysis method, the electrical variables were examined in the frequency domain, where the first and the even harmonic were considered. Since the system is asymmetrical, the mean of the side bands amplitudes for each position is calculated. To evaluate the influence of v and F C , the quotient with the fundamental amplitude A C is formed and is defined as the sparking intensity. With this method, both parameters the sliding speed and the contact force must be approximately constant and the measurement time must be at least 30 seconds.

Recombinant DNA engineering was combined with mutant selection and fermentation improvement to develop a strain of Bacillus subtilis that produces commercially attractive levels of riboflavin. The B. subtilis riboflavin production strain contains multiple copies of a modified B. subtilis riboflavin biosynthetic operon (rib operon) integrated at two different sites in the B. subtilis chromosome. The modified rib operons are expressed constitutively from strong phage promoters located at the 5′ end and in an internal region of the operon. The engineered strain also contains purine analog-resistant mutations designed to deregulate the purine pathway (GTP is the precursor for riboflavin), and a riboflavin analog-resistant mutation in ribC that deregulates the riboflavin biosynthetic pathway.

Orton (1936) observed that dyslexic readers display not only obvious linguistic processing errors, but also diminished lateralized specialization of other cerebral hemispheric functions. To explore his “intergrading” hypothesis, six developmental dyslexics (DDs) and a group of good readers (GRs) were tested on measures of interhemispheric coordination. All subjects (ages 16 to 47) demonstrated normal oculomotor control and visual acuity prior to testing. Subjects were instructed to track three different point-light source patterns, (single stimulus in one hemifield, dual stimuli in one hemifield and a pair of simultaneous, symmetric, bihemifield stimuli [SSBS]), presented in random sequence and arrayed horizontally at ±5, ±10, and ±15 degrees eccentricity. Tested with unihemifield stimuli, all subjects showed normal saccadic latencies and trajectories. In response to SSBS, all GRs showed pronounced directional preference, choosing largely to track one side over the other. DDs showed reduced laterality bias (p

In this paper, a new hybrid process to manufacture holes in laminated carbon fiber reinforced plastics is presented. It combines the advantages of conventional drilling (fast and easy to control) and laser drilling (high entry and exit quality of the holes). It is shown, that considerable improvements of the quality of drilled holes can be achieved via laser-preprocessing.

Large percentages of wind power plants are using double-fed induction generators (DFIG). The slip ring apparatus in DFIGs is used to transfer the rotor current from the rotating to the static part of the generator. During transfer of current, micro brush fires occur in contact area, caused by the separation of brush and slip ring. As a result of the discharge of electric arc energy, temperature rises in area of contact. This phenomenon is largely influenced by the electromagnetic forces, the radial eccentricity, the electro-hydrodynamic and the mechanical forces. In addition, the increased temperature in the contact area influences the wear of graphite brushes. To investigate these influences in our slip ring apparatus on the exciting of the micro brush fires, a Field Programmable Gate Array (FPGA)-based measuring system and software is designed. This system helps us to gauge the relevant measured variables and to characterize the micro brush fires. The measurement system communicates with the computer via the programs (C++ and Labview). The C++-program is used to transfer the data via the Universal Serial Port (USB). The program Labview communicates with the C++-part via TCP-IP to configure the FPGA and to visualize these data.

The mechanical components consist of the slip ring system. This system is used in double-fed asynchronous generators in wind turbines and consists of graphite brushes and slip rings. The obtained rotor current flows between the graphite-brushes and the slip rings, passing through a frequency converter into the electrical grid. While transmitting power-micro brush fires hazard in the area of contact is often present. This is caused by the separation of contact components. This phenomenon is largely influenced by the electromagnetic forces, the radial eccentricity and the electro-hydrodynamic and mechanical forces. In this paper, the nonlinear characteristics of transient behaviors between the graphite-brushes and the slip rings will be analyzed. Using ANSYS software combined with Workbench, a finite element model (FEM) of the contact problem is established and simulated.

The problem of interpolating a free form curve network with irregular topology is investigated in order to create a curvature continuous surface. The spanning curve segments are parametric quintic polynomials, the interpolating surface elements are biquintic Gregory patches. A necessary compatibility condition is formulated and proved which need to be satisfied at each node of the curve network. Constraints are derived for assuring G 2 continuity between biquintic Gregory patches, which share a common side or a common corner point. The above conditions still leave certain geometric freedom for defining the entire G 2 surface, so following some analysis a particular construction is presented, by which after computing the principle curvatures at each node the free parameters are locally set for each interpolating Gregory patch.

Whole cells of Corynebacterium glutamicum were loaded with high cytoplasmic l-isoleucine concentrations, and isoleucine excretion from these cells was studied in terms of mechanism and regulation. The transmembrane isoleucine flux could be differentiated into carrier-mediated uptake, carrier-mediated excretion, and diffusion. After discrimination from the other transmembrane solute movements, the outward-directed flux, which was due to the activity of the isoleucine excretion carrier, was characterized with respect to its energy dependence and its regulation at the level of expression. Isoleucine excretion was shown to function as a secondary transport process, driven by the membrane potential and coupled to the movement of protons, presumably with a stoichiometry of 2:1 (H(sup+)/isoleucine). Of a variety of putative transport substrates, only leucine was able to compete for isoleucine at the cis (cytosolic) side of the export carrier. Cytoplasmic isoleucine concentrations higher than 20 mM induce the activity of the isoleucine excretion system. This effect is specific for isoleucine and is inhibited by the presence of chloramphenicol. Apart from leucine, other amino acids and related amino acid analogs are not able to induce isoleucine excretion. The complex pattern of regulation of the isoleucine excretion system at the level of activity and expression is shown to be related to the pattern of regulation of the isoleucine uptake system in C. glutamicum in terms of physiological significance.

Neutron diffraction measurements on a high quality single crystal of CeAu2Ge2 reveal two new magnetic structures that coexist with commensurate long range antiferromagnetic order below the Neel temperature T_N ~ 14 K. The new magnetic structures, which exhibit distinct temperature and field dependencies, are described by both commensurate and incommensurate magnetic structures and introduces new region in the H-T phase diagram. These new experimental observations provide essential information for developing a universal understanding of the magnetic properties of this class of Ce-based CeX2M2 (X = Cu, Ag, Au; M = Ge, Si) compounds, which are prototypes for exploring quantum phase transitions and their interplay with unconventional superconductivity.

The slip ring system is used in double-fed asynchronous generators in wind turbines. The rotor current flows through the resulting contact surfaces between the graphite-brushes and slip rings, passing over a frequency converter into the electrical grid. While transmitting power, sometimes micro brush fires in the area of contact occur, which are caused by the separation of the contact components. Influences to that phenomenon are the electromagnetic forces, radial eccentricity and electro hydrodynamic forces. In this paper, the nonlinear characteristics of steady-state contact problems between graphite-brushes and slip rings and the influence of the electromagnetic forces in the contact areas are analyzed. By using ANSYS software, a finite element model (FEM) of the contact problem is established and simulated. For validation, the main parameters of the contact area are also calculated by using the Hertz contact theory. The electromagnetic forces are mathematically determined from the contact areas and current amplitude in the components. The results obtained by simulation and theoretical analysis are both compared and it is shown that the simulation of the contact between graphite-brushes and slip rings and the electromagnetic forces is feasible.

The purpose of this study was to investigate the response of patients with ischemic heart disease and varied left ventricular function following 6 weeks of exercise training. We studied the oxygen consumption (VO2), and central hemodynamic and metabolic responses of 14 patients with coronary artery disease (CAD) stratified by left ventricular ejection fraction (EF). There were two groups of patients: normal EF (NEF), EF = 64 +/- 9.9 (mean +/- S.E.M.); n = 7, and diminished EF (DEF), EF = 36 +/- 11.6; n = 7. The patients ranged in age from 42 to 72 years (54.9 +/- 2.2), and were evaluated prior to and then following training. Measures of VO2, cardiac output (Qt) stroke volume (SV), heart rate (HR), exercise duration (XTIME) and intensity (XI), as well as plasma lactate (LA), and the catecholamines epinephrine (E) and norepinephrine (NE) were obtained in response to maximal cycle ergometry. Subjects trained three times per week, 30 min per session, at an intensity equal to 70% of their peak oxygen consumption. Repeated measures analysis of variance (ANOVA) revealed no interaction between groups suggesting a similar training response. Significant post-training changes (P0.05) were observed in peak VO2 (VO2peak) NEF, 11.8% increase, (16.0 +/- 1.3 to 17.9 +/- 1.1 ml/kg/min) and DEF, 9.3% increase (15.1 +/- 1.6 to 16.5 +/- 1.2 ml/kg/min); submaximal HR, 4% decrease in the NEF (95.57 +/- 4.58 to 92 +/- 4.43 beats/min) and a 6% decrease in the DEF (107.29 +/- 7.44 to 101.43 +/- 6.77 beats/min); XTIME NEF, 11.2% increase (7.8 +/- 0.57 to 8.67 +/- 0.61 min) and DEF, 16.6% increase (7.3 +/- 0.91 to 8.51 +/- 0.69 min); and XI NEF, 19.2% increase (104.3 +/- 11.3 to 124.3 +/- 12.9 W) DEF, 21.2% increase (94.3 +/- 18.5 to 114.3 +/- 16.9 W), and a 15% decrease in resting NE (350 +/- 26 to 296.9 +/- 19 pg/ml). There were no changes in Qt, SV, LA, E, peak NE or peak HR for either group. These findings suggest short-term endurance training at 70% VO2peak provide the necessary stimulus for individuals with CAD and NEF or DEF to display an improvement in XI, XTIME, and VO2peak. The lack of a significant enhancement in Qt with short-term training may indicate that the mechanism by which both study groups were able to attain significantly higher levels of VO2peak may have been attributable to peripheral mechanisms rather than any alterations in Qt, a central mechanism.

Thyroid hormone receptors (TRs) form heterodimers with retinoid X receptors (RXRs). Heterodimerization is required for efficient TR DNA binding to most response elements and transcriptional activation by thyroid hormone. RXRs also function as auxiliary proteins for several other receptors. In addition, RXR alpha can be induced by specific ligands to form homodimers. Here we report that RXR-specific retinoids that induce RXR homodimers are effective repressors of the T3 response. We provide evidence that this repression by RXR-specific ligands occurs by sequestering of RXR from TR-RXR heterodimers into RXR homodimers. This ligand-induced squelching may represent an important mechanism by which RXR-specific retinoids and 9-cis retinoic acid mediate hormonal cross talk among a subfamily of nuclear receptors activated by structurally unrelated ligands.

The IR (3500–50 cm −1 ) and Raman (3500–20 cm −1 ) spectra of gaseous and solid cyclopropylmethylsilane, c -C 3 H 5 -CH 2 SiH 3 , have been recorded. Additionally, we have obtained the Raman spectrum of the liquid and the IR spectrum of the sample trapped in an argon matrix. From these data a complete assignment of the normal vibrational modes is provided. The spectra of the gaseous and liquid phases have been interpreted on the basis of the predominance of a conformation having a gauche structure and this form exists exclusively in the solid. Ab initio Hartree-Fock structural optimizations with the 3–21G* and 6–31G* basis sets are consistent with the gauche rotamer lying ~800 cm −1 lower in energy than the cis conformation which has the SiH3 group eis to the cyclopropyl ring. The force fields obtained with the 3–21G* basis set have been used to perforin a normal coordinate analysis. The cyclopropyl torsion has been observed as an IR band of hybrid contour centered at 80 cm −1 in the far-IR spectrum of the gas. Combination band spectra in the 2300–2000 cm −1 region of the mid-IR spectrum of the gas can be attributed to sum and difference bands of the SiH3 and cyclopropyl torsional modes with an SiH3 stretching mode. Analysis of these data leads to a barrier governing internal rotation of the silyl group of 687±50 cm −1 . These results are compared with corresponding quantities in some similar molecules.

This paper presents results of geophysical survey at Zincirli Hoyuk, a 40-hectare site in southern Turkey dating to the early first millennium bc. The site’s lower town offers ideal circumstances for magnetic gradiometry, and survey results from this area, combined with the results of excavations from the 1890s on the central high citadel, now reveal a nearly complete plan of the ancient city. The results therefore present a unique opportunity to explore the relationship between the production of urban space and the social and historical forces that drove it. Our evidence from Zincirli strongly suggests a pattern of distributed authority in creating the built environment of the city, whereby the king and his administrators planned and constructed the circular walls, streets, and citadel, but according to which individual elite households were probably left to plan and build their own residential compounds. The spatial relationships of these features raise important questions regarding social organization at Iron Age Zincirli. The results also offer a model for understanding the unique spatiality of new cities that were founded throughout Syria and Anatolia during the early first millennium and highlight the relationship of Zincirli to these and other planned cities of the ancient Near East.

The concept of self-assembling container molecules as yocto-litre reaction flasks is gaining prominence. However, the idea of using such containers as a means of protection is not well developed. Here, we illustrate this idea in the context of kinetic resolutions. Specifically, we report on the use of a water-soluble, deep-cavity cavitand to bring about kinetic resolutions within pairs of esters that otherwise cannot be resolved because they react at very similar rates. Resolution occurs because the presence of the cavitand leads to a competitive binding equilibrium in which the stronger binder primarily resides inside the host and the weaker binding ester primarily resides in the bulk hydrolytic medium. For the two families of ester examined, the observed kinetic resolutions were highest within the optimally fitting smaller esters.

The electron ionization mass spectrum of 2-(2-carboxy-4,5-dimethoxyphenyl)-6,7-dimethoxyisoquinolinium inner salt 1 is discussed and general fragmentation routes of its molecular ion are proposed. Comparison of the data obtained for 1 with the EI-MS data of metameric protopine alkaloids (allocryptopine, argemexicaine A, argemexicaine B) and the pseudobenzyloisoquinoline alkaloid taxilamine allows a differentiation between these metamers. The data will be useful for the identification of metabolites of alkaloids of these types in biological matrices.

Metazathioprine (MAZA), a methylated derivative of azathioprine (AZA), demonstrated the greatest values of apparent and specific partition coefficients in n-octanol/phosphate buffer at pH 5.7 and pH 7.4 among purine derivatives such as 6-mercaptopurine (6-MP), 6-thioguanine (6-TG) and AZA. Introduction of a methyl group into the imidazole ring of AZA increases lipophilic properties of MAZA compared to AZA. Mass balance of purine derivatives in n-octanol and in phosphate buffer indicated their chemical stability in those media.

The vitamin hormone retinoic acid (RA) regulates many complex biological programs. The hormonal signals are mediated at the level of transcription by multiple nuclear receptors. These receptors belong to the steroid/thyroid hormone receptor superfamily that also includes a large number of orphan receptors whose biological roles have not yet been determined. Although much has been learned in recent years about RA receptor (RAR) functions, little is known about how specific RA response programs are restricted to certain tissues and cell types during development and in the adult. It has been recently shown that RAR activities are regulated by retinoid X receptors (RXR) through heterodimer formation. In an effort to isolate and further characterize nuclear receptors that modulate RAR and/or RXR activities, we have screened cDNA libraries by using a RXR alpha cDNA probe. Two clones, COUP alpha and COUP beta, identical and closely related to the orphan receptor COUP-TF, were obtained. We show that COUP proteins dramatically inhibit retinoid receptor activities on certain response elements that are activated by RAR/RXR heterodimers or RXR homodimers. COUP alpha and -beta bind strongly to these response elements, including a palindromic thyroid hormone response element and a direct repeat RA response element as well as an RXR-specific response element. In addition, we found that the previously identified COUP-TF binding site in the ovalbumin gene functions in vitro as an RA response element that is repressed in the presence of COUP. Our data suggest that the COUP receptors are a novel class of RAR and RXR regulators that can restrict RA signaling to certain elements. The COUP orphan receptors may thus play an important role in cell- or tissue-specific repression of subsets of RA-sensitive programs during development and in the adult.

Retinoid response pathways are mediated by two classes of receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). A central question is whether distinct response pathways are regulated by these two classes of receptors. The observation that the stereoisomer 9-cis-retinoic acid binds with high affinity to RXRs suggested that this retinoid has a distinct role in controlling RXR activity, but it was almost simultaneously discovered that RXRs function as auxiliary receptors for RARs and related receptors, and are essential for DNA binding and function of those receptors. Hence, although RARs seem to operate effectively only as heterodimeric RAR/RXR complexes, RXRs themselves apparently function predominantly, if not exclusively, as auxiliary receptors. Here we report that 9-cis-retinoic acid induces RXR homodimer formation. Our results demonstrate a new mechanism for retinoid action by which a ligand-induced homodimer mediates a distinct retinoid response pathway.

Iris is an ESA (European Space Agency) programme to develop a satellite based communications system contributing to modernise the Air Traffic Services (ATS) in Europe. This paper describes a new Pan-European approach to certifying such satellite systems for use in air traffic control (ATC) and practical implementation steps that can be taken. (12 pages)

Many essential biological pathways, including cell growth, development, and metabolism, are regulated by thyroid hormones (THs). TH action is mediated by intracellular receptors that belong to a large family of ligand-dependent transcription factors, including the steroid hormone and retinoic acid receptors. So far it has been assumed that TH receptors (TRs) regulate gene transcription only through the classical protein-DNA interaction mechanism. Here we provide evidence for a regulatory pathway that allows cross-talk between TRs and the signal transduction pathway used by many growth factors, oncogenes, and tumor promoters. In transient transfection studies, we observed that the oncogenes c-jun and c-fos inhibit TR activities, while TRs inhibit induction of the c-fos promoter and repress AP-1 site-dependent gene activation. A truncated TR that lacks only 17 amino acids from the carboxy terminus can no longer antagonize AP-1 activity. The cross-regulation between TRs and the signal transduction pathway appears to be based on the ability of TRs to inhibit DNA binding of the transcription factor AP-1 in the presence of THs. The constituents of AP-1, c-Jun, and c-Fos, vice versa, can inhibit TR-induced gene activation in vivo, and c-Jun inhibits TR DNA binding in vitro. This novel regulatory pathway is likely to play a major role in growth control and differentiation by THs.

Gene regulation by thyroid hormones is mediated through multiple nuclear receptors. Only some of these thyroid hormone receptor (TR) isoforms become transcriptional enhancers in the presence of the thyroid hormone T3. Here we analyze the regulatory function of the human TR alpha 2 isoform. This protein does not bind T3 and is not a transcriptional activator of thyroid hormone-responsive elements (TRE). Transfected TR alpha 2 functions as a constitutive repressor of the transcriptional activators TR alpha 1 and TR beta 1 but also represses heterologous receptors, including the retinoic acid receptor and the estrogen receptor, which can activate TRE-controlled genes. TR alpha 2 protein showed strongly reduced DNA binding to a palindromic TRE when compared with the active TRs. Hybrid receptor analysis revealed that the special properties of the TR alpha 2 protein, including its repressor function and DNA binding characteristics, are intrinsic properties of its carboxyterminus and can be transferred to other receptors. Although it has been shown that the active TRs can act as repressors and silencers due to their strong DNA binding in the absence of hormone, our data show that TR alpha 2 is unlikely to inhibit TRs and other receptors through a competitive DNA binding mechanism. Antibody gel shift experiments suggest that repression by TR alpha 2 might result from interaction with active receptors. Thus, the receptor-like TR alpha 2 isoform differs from typical nuclear receptors in its DNA-binding and ligand-binding properties and appears to regulate the activity of other receptors via protein-protein interaction.

This paper examines the information transfer of the units in the general purpose Hungarian soil classification in relation to land productivity evaluations. Statistical analyses of a national soil and plant production database have been applied. Results show that in some cases soil groupings, both in the general purpose taxonomy and productivity classifications, may be incorrect. Taxonomic misclassification can occur at higher levels of soil classification. Without a more specified classification of soil characteristics in the lower taxonomic units important information can be lost., A genetikai talajosztályozás egységeinek információ tartalma számos gyakorlati alkalmazáshoz nyújt alapot, köztük a talajbonitációhoz is. Vizsgálatainkkal arra kerestünk választ, vajon az osztályozási egységek elkülönítésére szolgáló kategória-határok valóban megfelelő felosztást eredményeznek-e, ha gyakorlati szempontból vizsgáljuk azokat. A statisztikai vizsgálatokkal nyert eredményeink azt mutatják, hogy a rendszertani kategóriák gyakran félrevezetők lehetnek a valós talajtulajdonságokat illetően, így a kategóriák interpretációs alkalmazásával nagymértékű információvesztés történhet.