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Colesevelam HCl is a potent bile acid–binding polymer. This study's aim was to determine effects of colesevelam HCl on sterol and bile acid excretion in patients with type IIa hypercholesterolemia. Twenty-four patients (low-density lipoprotein cholesterol, 130 to 220 mg/dL) enrolled in an open-label, parallel-design study, entered an American Heart Association/National Cholesterol Education Program diet for 6 weeks and were randomized to colesevelam HCl, 2.3 or 3.8 g/day for 4 weeks. In an apparent dose-related manner, respective mean serum concentrations HCl of low-density lipoprotein cholesterol decreased by 10% (P< 0.01) and 13% (P= 0.05), mean total cholesterol levels decreased by 4.9% (P= 0.05) and 6.1% (P= 0.09), and total fecal bile acid excretion showed median changes of +324% (P< 0.05) and +316% (P< 0.05). Colesevelam HCl did not affect fecal neutral sterol or fecal fatty acid excretion; however, 24-hr urinary mevalonic acid levels significantly increased in both treatment groups (P< 0.05). The cholesterol-lowering action of colesevelam HCl appears to be mediated through increased bile acid excretion.

The new Benninger CPB dyeing station can now dye any batch size of knitwear at very low costs. The new development is suited for trough dyeing and nip dyeing. While for trough dyeing, the BICOFLEX squeezing rollers are Ipositioned nearly vertically, which provides optimal ease of service and access to the dyeing trough and to the selvedge uncurling elements, nip dyeing has horizontally configured squeezing rollers. The liquor volume for nip dyeing is reduced to 1.8 l/m of roller width, resulting in a negligible loss of residual liquor, even for short-lot production. It is important that in both processes, the knitwear is guided through the system with a minimum of fabric tension. [ABSTRACT FROM AUTHOR]

Glutathione S-transferase omega-1 (GSTO1) protects from oxidative stress, a risk factor for Alzheimer disease (AD), vascular dementia (VaD), and stroke. Polymorphisms in GSTO1might influence the function of the protein and thus the risk of AD, VaD, and stroke.

Abstract:: We report results of a theoretical and experimental study of the ground state nonlinear Hanle effect under strong laser excitation. It is shown that besides the well-known zero-magnetic field suppression of absorption on F g = F→F e = F - 1 transitions caused by population trapping, an optical pumping induced enhanced absorption occurs on F g = F→F e = F + 1 transitions for small B-fields. The latter effect becomes more pronounced for high F values. The experiment with atomic vapor of Cs (D2 line, F g = 4) confirms an increase of the spectrally unresolved fluorescence yield at zero magnetic field and 600 mW/cm2 laser intensity by 9% or 42%, when excitation occurs with linearly or circularly polarized light, respectively. The results of the experiment agree with numerical simulation studies using equations of motion for a density matrix.

Abstract:: We study the behaviour of an atom-cavity system exposed to a stimulated Raman adiabatic passage (STIRAP) process in a four-level system, with a coupling scheme which generate two degenerate dark states. We find that the non-adiabatic interaction of the two dark states guarantees that the cavity Fock states can always be generated by both intuitively and counterintuitively ordered pulses. Furthermore, we propose a method to entangle two atoms. Depending on the ordering of the pulses two orthogonal entangled states can be prepared. Since these entangled states do not have component of the excited states included, the technique is robust against the detrimental consequences of spontaneous emission.

Some oxidized forms of cholesterol (oxysterols) are thought to be atherogenic and cytotoxic. Because plant sterols are structurally related to cholesterol, we examined whether oxidized plant sterols (oxyphytosterols) could be identified in human serum and soy-based lipid emulsions. We first prepared both deuterated and nondeuterated reference compounds. We then analyzed by gas-liquid chromatography-mass spectrometry the oxyphytosterol concentrations in serum from patients with phytosterolemia or cerebrotendinous xanthomatosis, in a pool serum and in two lipid emulsions. 7-Ketositosterol, 7 beta-hydroxysitosterol, 5 alpha, 6 alpha-epoxysitosterol, 3 beta,5 alpha,6 beta-sitostanetriol, and probably also 7 alpha-hydroxysitosterol were present in markedly elevated concentrations in serum from phytosterolemic patients only. Also, campesterol oxidation products such as 7 alpha-hydroxycampesterol and 7 beta-hydroxycampesterol were found. Interestingly, sitosterol was oxidized for approximately 1.4% in phytosterolemic serum, which is rather high compared with the approximate 0.01% oxidatively modified cholesterol normally seen in human serum. The same oxyphytosterols were also found in two lipid emulsions in which the ratio of oxidized sitosterol to sitosterol varied between 0.038 and 0.041.In conclusion, we have shown that oxidized forms of plant sterols are present in serum from phytosterolemic patients and two frequently used soy-based lipid emulsions. Currently, it is unknown whether oxyphytosterols affect health, as has been suggested for oxysterols. However, 7 beta-hydroxycholesterol may be one of the more harmful oxysterols, and both sitosterol and campesterol were oxidized into 7 beta-hydroxysitosterol and 7 beta-hydroxycampesterol. The relevance of these findings therefore deserves further exploration.

Extreme ultraviolet lithography (EUVL) is under discussion to be implemented in the production of chips as early as 2005 to 2007 for reducing structures in semiconductor devices to below 70 nm. The challenging task of developing optical components and radiation sources within this short period of time is pushing technology. As discharge produced and laser produced plasmas are the main candidates for EUV-sources, plasma technology is forced to leap forward significantly. Progress in EUV-sources is expected to open EUV-technology for other applications in science and technology with increased need for spatial resolution, elemental contrast or sensitivity. Various technical concepts for realising high power sources for EUV lithography are under investigation world-wide. Laser produced and discharge produced plasmas are the most promising schemes. Discharge produced pinch plasmas in general are of special interest, because their prospected costs (esp. cost of ownership) for the demanded throughput is expected to be much lower than with laser produced plasmas. However, the discharge plasmas are of high risk, because many crucial tasks have to be solved before reaching the required power levels. Beside the optimisation of the EUV-generation - which is the key to build the most reliable device with demanded EUV power - the success will depend on the individual technical aspects of each source concept. Currently investigated pinch plasma concepts are evaluated based on their potential to be upgraded to fulfil the challenging demands of EUV-lithography.

In the present study, we examined the long-term effect of oxidative stress induced neurodegeneration on sterol concentrations in striatum and serum of Wistar and Lewis rats. Three weeks after treatment with 3-nitropropionic acid, no differences in 24S-hydroxycholesterol concentrations were observed in striatal homogenates and serum. Ratios of striatal campesterol to cholesterol were higher after 3-nitropropionic acid treatment as compared to controls of both rat strains suggesting an increased passage of this exogenous plant sterol across the blood-brain-barrier. Ratios of lathosterol to cholesterol in serum and striatum were lower in treated rats as compared with controls of both rat strains. Absolute concentrations of serum and striatal cholesterol precursors and plant sterols differed between the controls of both rat strains. It was concluded that the changes observed in sterol concentrations in the striatum and serum indicate that cholesterol homeostasis may be affected during neurodegenerative processes associated with blood-brain-barrier damage.

Abstract:: We report the observation of pronounced coherent population trapping and dark resonances in Rydberg states of xenon. A weak two-photon coupling with radiation of = 250 nm is induced between the 5p61 S 0 ground state of xenon and state 5p 56p[1/2]0, leading to (2+1) resonantly enhanced three-photon ionization. The state 5p 56p[1/2]0 is strongly coupled by radiation with ≃ 600 nm to 5p 5 ns[J C]1 or 5p 5 nd[J C]1 Rydberg states with principal quantum numbers n in the range 18 ?n? 23 and with the rotational quantum number of the ionic core J C = 1/2 or J C = 3/2. The ionization is monitored through observation of the photoelectrons with an energy resolution ΔE = 150 meV which is sufficient to distinguish the ionization processes into the two ionization continua. Pronounced and robust dark resonances are observed in the ionization rate whenever is tuned to resonance with one of the ns- or nd-Rydberg states. The dark resonances are due to efficient population trapping in the atomic ground state 5p61 S 0 through the suppression of excitation of the intermediate state 5p 56p[1/2]0. The resolution is sufficient to resolve the hyperfine structure of the ns-Rydberg levels for odd xenon isotopes. The hyperfine splitting does not vary significantly with n in the given range. Results from model calculations taking the natural isotope abundance into account are in good agreement with the observed spectral structures. Pronounced dark resonances are also observed when the dressing radiation field with is generated from a laser with poor coherence properties. The maximum reduction of the ionization signal clearly exceeds 50%, a value which is expected to be the maximum, when the dip is caused by saturation of the transition rate between the intermediate and the Rydberg state due to incoherent radiation. This work demonstrates the potential of dark resonance spectroscopy of high lying electronic states of rare gas atoms.

Phospholipids and sterols are known to have multiple functions in reproductive tissue of mammals. High concentrations of the cholesterol precursor desmosterol have been described in testis, epididymis, and spermatozoa of various species. These findings and the recent discovery of some cholesterol precursors as meiosis-activating sterols suggest important functions of cholesterol precursors in fertility. Many sterol intermediates appear from the 19-step conversion of lanosterol, the first sterol synthesized in the cascade of cholesterol synthesis, to cholesterol. The biochemical basis of the genetically inherited Smith-Lemli-Opitz syndrome has been described as a defective conversion of 7-dehydrocholesterol to cholesterol. Since this discovery, interest has focused on this special cholesterol precursor. Here, we report high concentrations of 7- and 8-dehydrocholesterol in caput epididymidis and spermatozoa derived from caput epididymidis of Sprague-Dawley and Wistar rats, which comprised up to 30% of total sterols. In contrast to caput epididymidis, 7- and 8-dehydrocholesterol were barely detected in cauda epididymidis or testis. Desmosterol increased several times from caput to cauda epididymidis.This is the first report of the natural appearance of high concentrations of dehydrocholesterols in mammalian tissue, and it underlines the putative importance of cholesterol precursors in reproductive tissue.

The major oxysterols in human circulation are 7 alpha-, 27-, and (24S)-hydroxycholesterol. Two unique experiments were performed to elucidate their origin and kinetics. A volunteer was exposed to (18)O(2)-enriched air. A rapid incorporation of (18)O in both 7 alpha- and 27-hydroxycholesterol and disappearance of label after exposure were observed. The half-life was estimated to be less than 1 h. Incorporation of (18)O in (24S)-hydroxycholesterol was not significant. In the second experiment a volunteer was infused with liposomes containing 10 g of [(2)H(6)]cholesterol. This resulted in an enrichment of plasma cholesterol with (2)H of up to 13%, and less than 0.5% in cerebrospinal fluid cholesterol. The content of (2)H in circulating 7 alpha-hydroxycholesterol remained approximately equal to that of plasma cholesterol and decreased with a half-life of about 13 days. The (2)H content of circulating 27-hydroxycholesterol was initially lower than that of cholesterol but in the last phase of the experiment it exceeded that of cholesterol. No significant incorporation of (2)H in (24S)-hydroxycholesterol was observed.It is evident that 7 alpha-hydroxycholesterol must originate from a rapidly miscible pool, about 80% of 27-hydroxycholesterol from a more slowly exchangeable pool, and more than 90% of (24S)-hydroxycholesterol from a nonexchangeable pool, presumably the brain. The results are discussed in relation to the role of oxysterols in cholesterol homeostasis and their use as markers for pathological conditions. - Meaney, S., M. Hassan, A. Sakinis, D. Lütjohann, K. von Bergmann, A. Wennmalm, U. Diczfalusy, and I. Björkhem. Evidence that the major oxysterols in human circulation originate from distinct pools of cholesterol: a stable isotope study. J. Lipid Res. 2001. 42: 70;-78.

Abstract:: Improved molecular constants for the and states of the NaH molecule are presented. NaH molecules are produced by reactive scattering of H and Na2 in a crossed beam experiment. High vibrational levels (6 9) of the NaH molecules are predominantly populated. Their excitation spectrum in the range has been measured using a new variant of Doppler spectroscopy. The transition frequencies involving the vibrational levels 2 8 in the and 6 9 in the state have been determined with an accuracy of better than . Using also previously published data a new set of molecular constants for the and state is derived. In particular, the vibrational dependence of the rotational constants B, D and H as well as some of v”-v' band origins for and is determined. The transition frequencies measured here or published previously are reproduced by these new coefficients with an accuracy of 0.1 cm-1 [rms value] with a maximum deviation of 0.4 cm-1. New RKR potential energy curves have been calculated up to the turning points of the levels v” = 9 in the state and v' = 25 in the state.

Alzheimer's disease (AD) is characterized by the presence of senile plaques, neurofibrillary tangles, and neuronal cell loss associated with membrane cholesterol release. 24S-hydroxycholesterol (24S-OH-Chol) is an enzymatically oxidized product of cholesterol mainly synthesized in the brain. We tested the hypothesis that plasma levels of this oxysterol could be used as a putative biochemical marker for an altered cholesterol homeostasis in the brain of AD patients. Thirty patients with clinical criteria for AD, 30 healthy volunteers, 18 depressed patients, and 12 patients with vascular dementia (non-Alzheimer demented) were studied. Plasma concentrations of 24S-OH-Chol were assayed by isotope dilution;-mass spectrometry, cholesterol was measured enzymatically, and apolipoprotein E (apoE) was genotyped by polymerase chain reaction and restricted fragment length polymorphism. The concentration of 24S-OH-Chol in AD and non-Alzheimer demented patients was modestly but significantly higher than in healthy controls and in depressed patients. There was no significant difference in the concentrations of 24S-OH-Chol between depressed patients and healthy controls nor between AD and non-Alzheimer demented patients. The apoE straightepsilon4 allele influences plasma 24S-OH-Chol. However, this influence could be completely accounted for by the elevated plasma cholesterol in apoE4 hetero- or homozygotes. Plasma 24S-OH-Chol levels correlated negatively with the severity of dementia. AD and vascular demented patients appear to have higher circulating levels of 24S-OH-Chol than depressed patients and healthy controls. We speculate that 24S-OH-Chol plasma levels may potentially be used as an early biochemical marker for an altered cholesterol homeostasis in the central nervous system. 24S-hydroxycholesterol (cerebrosterol) is increased in Alzheimer and vascular demented patients.

Abstract: In traditional schemes of multilevel multilaser excitation, each laser pulse interacts with only one pair of states, and the rotating wave approximation (RWA) is applicable. Here we study the population transfer process in a three-state system when each of the two lasers interacts with each of the pair of states and when the Rabi frequencies characterizing the interaction strengths of the system are comparable to or larger than the difference of the transition frequencies. We show that complete and robust population transfer is possible under conditions more general than those hitherto considered necessary for stimulated Raman adiabatic passage (STIRAP) or for successive π pulses. Using adiabatic Floquet theory we show that successful population transfer can be interpreted as adiabatic passage by means of a transfer state which connects the initial and final states. The Floquet picture offers a convenient interpretation of the population transfer as accompanied by multiple absorption of photons from or emission into the laser fields.

Pulsed plasmas, e.g., laser produced plasma (LPP) and gas discharge based pinch plasmas are known as intense sources of soft x-ray and extreme ultraviolet (EUV) radiation in the wavelength interval of about 1 nm to beyond 50nm. They can be generated in compact, laboratory scale devices. Both schemes exhibit similar source characteristics concerning, e.g., wavelength region, bandwidth, source size, emitted radiation per pulse or average emitted power when operated at similar parameters. By exploiting their technological degrees of freedom their source characteristics can be matched to the special demands of a given application like EUV-lithography or metrology, x-ray microscopy, XPS or other x-ray analytics. In this work laser produced and gas discharge based plasmas are compared with respect to their source characteristics. The comparison concerns to a laser produced plasma using a commercial 1 J Nd:YAG laser with different target concepts (liquid, cryogenic or solid target) and a gas discharge based EUV sources with electrical pulse energies of about 1 J. The same absolute calibrated diagnostics used for both plasmas allows for a direct comparison.

A new high repetitive, compact and low cost gas discharge based EUV ''lamp'' has been studied as an alternative to laser-produced plasmas as EUV sources. First results using oxygen in a fast discharge of electrically stored energy around 1 J lead to a conversion efficiency of about 0.1 % for the emission at 13.0 nm which is suited for the use with Mo/Si-multilayer mirrors. Using Xenon a broadband emission in the investigated wavelength range from 10 nm to 18 nm is observed. With a first version a source with 40 W electrical input power could be demonstrated that emits about 50 mW/(4@psr) around 13 nm at a repetition rate of 150 Hz. No debris and no electrode erosion was observed after more than 10^7 pulses done up to now. Making use of the remaining optimisation potential this concept seems to be promising to fulfil the requirements of extreme-ultraviolet lithography

We have studied the formation of $\rm Na^+_3$ ions in collisions of Na(3d,5s,4d) atoms with vibrationally excited Na₂(v") molecules in their electronic ground state in a supersonic beam. The cross-section of the Na$(4d_{5/2}) + {\rm Na}_2$ associative ionization is found to be about six times larger than that of the corresponding atomic reaction Na$(4d_{5/2}) + {\rm Na}(3s)\to {\rm Na^+_2}$. Associative ionization in collisions of Na(3d) with Na₂(v") is observed only with vibrationally excited Na₂ molecules. The cross-section $\sigma(v")$ of this reaction increases only slightly with v" for low vibrational excitation, while a strong increase with v" is observed for $v"\ge 26$. The latter observation suggests the opening of the channel leading to the formation of $\rm Na^+_3$ ions in the first electronically excited state for $v"\ge 26$.

Abstract:: The central Inpatient Register of the former German Democratic Republic was used to study the population-based epidemiology of hip fractures among 16.5 million East Germans. Incidence rates for hospital discharges for proximal femoral fractures for the age group 60 years and over were calculated for the years 1971 to 1989, the year before unification. Incidence rates for 1989 are similar to figures reported from the UK and The Netherlands, but lower than Scandinavian rates. A decrease in the admission rate was noted from 1971 to 1974 of 4.5% each year on average, and an increase from 1974 onwards of 4.4% on average. This change was observed to a different extent in all age groups. The female:male ratio of the standardized discharge incidence was stable at 2.3:1 and the female:male ratio of manifest cases increases from 4.1:1 in 1971 to 5.1:1 in 1989. An exponential increase in the incidence rates was observed with age. This apparent rate overestimates both the rate for true incident cases (by about 25–30%, if adjustments are made for readmissions and transfers) and their trend. Adjusted estimates for incident fractures show an increase of 2% annually. Cohort effects due to changed selective forces appear to be one reasonable causal explanation.

Abstract:: The process of dissociative attachment (DA) of low-energy electrons ) to vibrationally excited sodium dimer molecules is studied with high electron energy resolution () in a supersonic molecular beam. A novel photoelectron source, based on two-step photoionization of the sodium atoms in the beam, may deliver a current of up to 1 nA and has been used with a current of typically 0.2 nA in this experiment. The energy dependence of the rate of sodium anion formation is determined by ion detection based on a time-of-flight analysis. The molecules are selectively excited to levels using the technique of coherent population transfer by delayed pulses (STIRAP). The comparison of the experimental data with recent resonance model calculations based on improved potential curves reveals generally good agreement for levels v ”>12. For some distinct differences between theoretical and experimental results persist.

Summary Measurements of biliary lipid secretion rates were performed in 14 non-obese patients with radiolucent gallstones (9 females, 5 males; mean age 48 years; mean body weight 65 kg) and in 14 healthy male volunteers (mean age 26 years, mean body weight 74 kg). The results in the gallstone patients differ in several respect from those obtained in the volunteers. Molar percentage of cholesterol was higher (5.8 versus 5.0 mol%;P<0.05) and molar percentage of bile acids lower (73.8 versus 76.9 mol%;P<0.05) in the gallstone patients. However, these changes were not followed by notable differences in cholesterol saturation of bile (94% vs 88%). Generally, hepatic secretion rates of cholesterol were significantly elevated in the gallstone patients (55 vs 46 mg/h;P<0.05) whereas outputs of bile acids and phospholipids did not differ between the two groups. Although patients with cholesterol gallstones tended to have a lower percentage of chenodeoxycholic acid (38 versus 42 mol%) and increased deoxycholic acid (23 versus 16 mol%) in their bile, these differences were not significant. Nevertheless, in patients with cholesterol gallstones a significant positive correlation between deoxycholic acid secretion and cholesterol output was observed. For the whole group of patients and volunteers a positive correlation between age and cholesterol secretion could be demonstrated. The higher hepatic cholesterol secretion in gallstone patients seems not be due to differences in body weight, but rather to the older age of the patients. These results suggest that age itself or age-related changes in deoxycholic acid metabolism contributes to biliary cholesterol output in non-obese patients with cholesterol gallstones.

Extended ultraviolet (EUV) emission characteristics of a laser-produced lithium plasma are determined with regard to the requirements of x-ray photoelectron spectroscopy. The main features of interest are spectral distribution, photon flux, bandwidth, source size, and emission duration. Laser-produced lithium plasmas are characterized as emitters of intense narrow-band EUV radiation. It can be estimated that the lithium Lyman-α line emission in combination with an ellipsoidal silicon/molybdenum multilayer mirror is a suitable EUV source for an x-ray photoelectron spectroscopy microscope with a 50-meV energy resolution and a 10-μm lateral resolution.

SYPNOPSIS177 people aged 65 or over, chosen at random from larger representative samples of elderly people living at home in Newcastle upon Tyne, were given the Weschler Adult Intelligence Scale (WAIS) or a shortened form of it, and followed up for 7 years or till death. Discriminant function analysis showed that the power of the test score to predict death occurring within 2 years was not explained away by its correlations with age, sex, social class or physical disability. Exclusion of clinically diagnosed chronic brain syndromes reduced but did not abolish the relationship found to exist between test score and outcome. The ascertainment of impaired cognitive functioning has important applications in the assessment of prognosis and in the planning of care of elderly people.

Acrodermatitis enteropathica (AE) was diagnosed in 2 siblings, boy and girl, at the age of 10 and 6 weeks. The family history is unremarkable except for consanguinity 5 generations previously. The clinical symptoms of the 2 patients conformed to the known features of AE, the gastrointestinal involvement loosing its significance with increasing age. In one patient in a stage of exacerbation the serum level of oleic acid (18:1) was lowered and of linoleic (18:2) acid slightly increased while that of arachidonic acid was decreased (Fig. 4).

Biliary lipid composition, standard liver function tests, serum lipids and faecal fat excretion were studied in 15 children with chronic intrahepatic cholestasis (severe intrahepatic cholestasis, n=6; paucity of intralobular bile ducts, n=4; benign recurrent cholestasis, n=5) and compared to 15 children without gastrointestinal diseases. Severe and benign intrahepatic cholestasis were associated with normal or moderately elevated serum lipids. Biliary lipid concentrations were extremely reduced, bile acid concentrations were below the critical micellar concentration. This may account for the high incidence of gallstone formation in these patients. Remission periods in patients with benign recurrent cholestasis were not followed by complete normalisation of biliary lipid concentrations, indicating a primary defect in hepatic excretory function. Children with paucity of intralobular bile ducts showed markedly increased serum lipids, but only a two-fold reduction in biliary lipid concentrations. Cholic acid was the predominant bile acid in bile of all cholestatic children even during remission. Neither increased levels of monohydroxy bile acids nor unusual bile acids could be identified in notable amounts.

The effects of phenobarbital (5.4–7.5 mg/kg body weight) for 14 days were studied in four children with severe intrahepatic cholestasis (group I) and in four with a syndromatic type of paucity of intralobular bile ducts (group II). Phenobarbital administration resulted in a moderate improvement of pruritus in all patients. There was a significant decrease of bilirubin in serum (group I: from 4.8 to 2.7 mg/dl; group II: from 6.1 to 2.1 mg/dl); total bile acids (group I: from 416 to 337 µmol/l; group II: from 156 to 123 µmol/l) and cholesterol (group I: from 248 to 207 mg/dl; group II: from 351 to 292 mg/dl). Alkaline phosphatase activity increased from 929 to 1126 U/l in group I and from 1751 to 2360 U/l in group II. SGOT and SGPT activities remained unchanged in both groups. In group I total biliary lipid concentration and bile acid output increased from 0.09 to 0.17 g/dl and from 3.9 to 7.2 µmol/kg per 30 min, respectively. Molar percentages of cholesterol, phospholipids and bile acids in bile remained unchanged. In group II total lipid concentrations and bile acid output increased from 1.62 to 2.0 g/dl and from 27.8 to 39.1 µmol/kg per 30 min, respectively. The molar percentage of cholesterol decreased from 5.6 to 3.5 mol%.

Zusammenfassung Als Grundlage von Polymeruntersuchungen wird ein Meßverfahren vorgestellt, das die Beobachtung der Protonen-Spin-Spin-Relaxation von Ein- und Zweiphasensy steinen in einem Zeitbereich von 10-6 bis 10-1 s unter Verwendung einer logarithmischen Zeitachse gestattet. Hierdurch wird eine einwandfreie Kennzeichnung der Einphasensysteme hinsichtlich der Kettenbeweglichkeit vom Festbis in den Schmelzzustand und der Zweiphasensysteme für jede Phase separat ermöglicht. Durch die Kombination einer Reihe von in der Literatur beschriebener Meßverfahren werden Störeffekte, die die Relaxationskurve verzerren, ausgeschaltet. Die gemessenen Relaxationskurven werden durch Vergleich mit geeigneten Kurvenprofilen mathematisch analysiert. Einige Anwendungsbeispiele werden diskutiert.

Summary For a quantitative description of rubber crosslinking it is desirable to determine the crosslink density of the network. Styrene-butadiene-styrene block copolymers can be regarded as model networks for a rubber with uniform chain lengths between the crosslinks. For these model networks the relation between the proton spin-spin relaxation time and the crosslink density is determined. Below a critical value for the molecular weight of the rubber segment (Mc = 40 000) which corresponds to the formation of entanglements, the relaxation time is proportional to the crosslink spacing. Above the critical value the relaxation time is almost independent of the molecular weight of the rubber.

Summary Studies to detect disorders of pulmonary function were performed on 42 workers at a poultry farm. All the subjects were exposed to organic dusts and sensitised to poultry antigens. Typical signs of bird fancier's lung were recorded in two of them.

Wind energy is one of the leading renewable energy technologies for the generation of electricity. Electrical energy may be generated over a wide range of operating conditions, particularly if far more than one windturbine is connected to the network. Low electrical energy production in one part of the windfarm may occur with high production in another part together with highly variable reactive power consumption from the system. A GTO-based Static Var Compensator also called Static Var Generator (SVG) or STATCOM is used in the Rejsby Hede Windfarm in Denmark for dynamic reactive power compensation and voltage limitation when islanding occurs. This paper describes the design aspects and studies, the converter technology and the control and protection schemes of this first application of SVG technology for windfarm operation. The installation will go into operation in 1997.

60Co-gamma-rays can be used efficiently for sterilizing products, such highly refined ones as drugs, vaccines, biochemicals. Examples of advanced stage application are: sterilization of enzymes used for food production and of supplements for drug manufacture. As economical aspects are of growing importance also for production of vaccines and antigens for diagnostic purposes, methods should take into account quantitative factors and qualitative biological properties. Therefore cautious inactivation of microorganisms incl. viruses is demonstrated. Special problems of irradiation are discussed.

Abstract:: The well-known process of stimulated Raman adiabatic passage (STIRAP) provides a robust technique for achieving complete population transfer between the first and last state of a three-state chain, with little population, even transiently, in the intermediate state. The extension of STIRAP to general N-state chainwise-linked systems continues to generate interest. Recently Malinovsky and Tannor (Phys. Rev. A 56, 4929 (1997)) have shown with numerical simulation that a resonant pulse sequence, which they term “straddle STIRAP”, can produce (under appropriate conditions, including specific pulse areas) complete population transfer with very little population in intermediate states. Their proposal supplements a pair of counterintuitively ordered delayed laser pulses, driving the first and last transition of the chain and corresponding to the pump and Stokes pulses in STIRAP, with one or more additional strong pulses of longer duration which couple the intermediate transition(s) and overlap both the pump and the Stokes pulses. In this paper, we modify the “straddling” Malinovsky-Tannor pulse sequence so that the intermediate couplings are constant (and strong), at least during the times when the pump and Stokes pulses are present, and the intermediate states therefore act as a strongly coupled subsystem with constant eigenvalues. Under this condition, we show that the original N-state chain is mathematically equivalent to a system comprising N-2 parallel -transitions, in which the initial state is coupled simultaneously to N-2 dressed intermediate states, which in turn are coupled to the final state. The population transfer is optimized by suitably tuning the pump and Stokes frequencies to resonance with one of these dressed intermediate states, which effectively acts as the single intermediate state in a three-state STIRAP-like process. We show that tuning to a dressed intermediate state turns the system (for both odd N and even N) into a three-state system - with all of the properties of conventional STIRAP (complete population transfer, little transient population in the intermediate states, insensitivity to variations in the laser parameters, such as pulse area). The success of the tuning-to-dressed-state idea is explained by using simple analytic approaches and illustrated with numerical simulations for four-, five-, six- and seven-state systems.

We discuss stimulated Raman adiabatic passage (STIRAP) for pulses whose amplitude is modulated with constant frequency. We discuss in detail the case of a Lambda (Raman) system driven by two amplitude-modulated pulses. We present a variety of numerical solutions to the relevant Schrödinger equation, which we interpret using the Floquet theorem for the solution of systems of linear equations with periodic coefficients, the concept of quasienergies, and the assumption of adiabatic evolution. We find thresholds for successful population transfer and show that some peculiarities of the depicted efficiency of population transfer can be interpreted as pairs of Landau-Zener transitions in the areas of avoided crossings of quasienergies. We provide an analytic expression for the transfer efficiency in these cases. We show that the efficiency of population transfer is much more sensitive to the population decay from the upper level than in the case of smooth (non modulated) laser pulses. We note the applicability of the results to cases beyond the rotating wave approximation.

A comprehensive data set from experiments and model calculations for investigating the behavior of optically pumped supersonic beam lasers is presented. The results for Na_2 demonstrate the roles of stimulated Raman scattering and one-photon population inversion on the gain for collinear optical pumping of supersonic beam gain media for both circular and slit nozzles. For the wavelengths investigated, Raman gain dominates, and an effective photon conversion of greater than 24% is realized. Lasing both with and without frequency-selective elements is studied. Laser transitions terminating on a large range of vibrational levels of the X state are observed. The density-matrix calculations for the gain coefficient include the dynamics of the expansion and the influence of condensation. These results show good qualitative agreement with the experimental data.

Dipyridamol has in addition to a coronardilatating effect an antithrombotic one too. Moreover it facilitates the release of O2 from haemoglobin by increase of the concentration of 2,3-diphosphoglycerate in the erythrocytes. Allopurinol causes a potential resynthesis of ATP in the cells by inhibition of the metabolism of uric acid. Both substances therefore seemed to be suitable for a medicamental therapy of the noise-induced cochlear damage. The expected favourable effect of Dipyridamol and Allopurinol on the organ of Corti after sound exposure (RMP-measurement before and after exposure to pure tone 120 dB SPL) however had not been confirmed by experiment on animals (guinea Pig).