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A split-and-delay unit for the XUV and soft X-ray spectral range has been installed at beamlines FL23 and FL24 at the FLASH2 Free-Electron Laser at DESY. It enables time-resolved pump-probe experiments covering the whole spectral range of FLASH2 from 30 eV up to 1500 eV. Using wavefront beam splitting and grazing incidence mirrors a sub-fs resolution with a relative pulse delay of -5 ps ≤ uτ ≤ +18 ps is achieved. Two different mirror coatings are required to cover the complete spectral range and thus, a design that is based on a three dimensional beam path was developed. This allows the choice between different sets of mirrors with either coating for the fixed branch. In the variable branch two coatings are available on the same set of mirrors. A Ni coating allows a total transmission above T > 0.50 for photon energies between hν ≈ 30 eV and 650 eV at a grazing angle of a ϑvariable = 1.8° in the beam path with variable delay. With a Pt coating a transmission of T > 13 % is possible for photon energies up to hν = 1500 eV. In the fixed beam path at a grazing angle of ϑfixed = 1.3° a transmission of T > 60 % with a Ni coating and T > 28 % with a Pt coating is possible.

Summary Plant hydraulic characteristics were studied in diploid, tetraploid and hexaploid cytotypes of Atriplex canescens (Chenopodiaceae) to investigate the potential physiological basis underlying the intraspecific habitat differentiation among plants of different ploidy levels. Populations of A. canescens from different habitats of the Chihuahuan Desert (New Mexico, USA) were analyzed using flow cytometry to determine ploidy levels. Traits related to xylem water transport efficiency and safety against drought-induced hydraulic failure were measured in both stems and leaves. At the stem level, cytotypes of higher ploidy showed consistently lower leaf-specific hydraulic conductivity but greater resistance to drought-induced loss of hydraulic conductivity. At the leaf level, comparisons in hydraulics between cytotypes did not show a consistent pattern, but exhibited high plasticity to proximal environmental conditions related to soil water availability. The results suggest that a trade-off between stem hydraulic efficiency and safety across ploidy levels underlies niche differentiation among different cytotypes of A. canescens. Polyploidization may have been facilitated by environmental heterogeneity related to water availability, and variation in water-related physiology found in the present study suggests an important functional basis for the niche differentiation and coexistence of A. canescens cytotypes in desert environments.

This paper describes a new developed dry coating for threaded Oil Country Tubular Goods (OCTG) premium pipe connections. An overview of the development is presented including the setup of the coating system and technical parameters. The basic structure of the coating system is described. The advantages of the coating compared to commonly used thread compounds are illustrated. Finally the operational areas of the coating system are presented. Different coating systems, their galling resistance and thermal stability were characterized employing tribological methods. The results of best-ranked coating systems were verified with make-up and break-out tests (M&B) on horizontal coupling application machines. Several dimensions and grades of OCTG premium connections were investigated regarding M&B capability under different conditions (e.g. deep temperature). Additionally the M&B capability was investigated with a vertical power tong, in order to simulate real life stabbing conditions on rig site. Parallel shortand long-term corrosion test series were performed to investigate the storage behavior. Finally tests according standard ISO 13679 were performed on threaded dry-coated specimens. An asymmetric coating system showed the best performance in surface adhesion and wear protection by several tribological tests. The M&B results of the dry-coated connections – without any additional lubricants – showed a stable behavior regarding torque turn monitoring. Premium connections coated with the new system were successfully made-up 15 times without initial and intermediate treatment. Recorded torque-turn diagrams revealed an unbelievable steady behavior after each make-up. In contrast to the standard procedure with doped threads the dry-coated connections haven’t to be cleaned and lubricated after each break-out. Thus, the use is significantly less time-consuming and a major risk of failure can be avoided. Additional the M&B tests with a vertical power tong and long pipes provide as well this steady behavior. The new coating system performs in a temperature range from -60°C to +60°C. Also the elevated temperatures according to ISO 13679 tests do not influence the behavior of the coating. ISO 13679 tests on a premium connection with applied dry thread coating were successfully performed. Short and long-term corrosion tests showed that dry-coated connections have enhanced corrosion stability than uncoated connections with storage compound. Hence long storage times before first make-up have no impact on the performance of the dry-coated pipe connections. A new ready-to-use product is introduced to the gas and oil industry. With the described new dry thread coating system no other lubricant is needed for the make-up of OCTG premium tubing and casing connections. This reduces risks and costs at the rig site due to easier handling. Additional there is also a positive environmental impact by replacing commonly used thread compounds through the new dry thread coating system.

A phylogenetic investigation of American members of the tribe Atripliceae (Chenopodiaceae) was conducted to examine evolutionary patterns and ecophysiological change in the North American lineages. Molecular phylogenetic analyses including representatives of all American genera of Atripliceae and data from 18S–26S nuclear ribosomal (ITS, ETS) and cpDNA (3′trnK intron) sequences suggest that neither Atriplex, as traditionally recognized, nor the North American members of Atriplex constitute a monophyletic group. Congruence between well-supported nuclear and cpDNA clades and results of expanded leaf anatomical and isotopic analyses indicate that American taxa belong to two distantly related lineages with different photosynthetic pathways; only one shift from C3 to C4 photosynthesis is required to explain photosynthetic pathway evolution in sampled lineages of Atripliceae. Conservatism in photosynthetic pathway evolution in the tribe is exemplified by the endemic, C3 North American Atriplex taxa, wh...

 Premise of the study : Atripliceae (Chenopodiaceae), including Atriplex (300 spp.) as the largest genus of the family, are an ecologically important group of steppes and semideserts worldwide. Relationships in Atripliceae are poorly understood due to obscure and potentially convergent morphological characters.  Methods : Using sequence variation of two chloroplast markers ( rbcL gene, atpB-rbcL spacer) and one nrDNA marker (ITS) analyzed with BEAST, we investigated the systematics and biogeography of Atripliceae. We surveyed fl ower morphology and fruit anatomy to study the evolution of fland fruits in the tribe.  Key results : Female fl owers with persistent foliar cover (the diagnostic character of traditional Atripliceae) evolved three times in Chenopodioideae, in Atripliceae s.s., Axyrideae, and Spinacia . Atripliceae s.s. started to diversify during the Early Miocene in Eurasia, separating into the Archiatriplex and the Atriplex clades. The former consists of eight species-poor, disjunct, and morphologically heterogeneous genera and is likely a relictual lineage. The Atriplex clade comprises the majority of species and evolved one C 4 lineage 14.1 – 10.5 Ma, which diversifi ed rapidly worldwide. The C 4 Atriplex entered North America during the Middle/Late Miocene and spread to South America subsequently. Australia was colonized by two C 4 lineages both arriving during the Late Miocene. One of them diversifi ed rapidly, giving rise to most Australian Atriplex species.  Conclusions : Atripliceae s.s. comprise Archiatriplex , Atriplex , Exomis, Extriplex , Grayia , Halimione , Holmbergia , Manochlamys , Proatriplex , and Stutzia . Microgynoecium is included based on morphology but only weak molecular support. Axyris , Krascheninnikovia , and Ceratocarpus (here described as Axyrideae) and Spinacia are excluded from Atripliceae.

Measurements of the rotational alignment of D2 (J″ = 8) desorbing from Pd(100) show a significant dependence on the sulfur coverage. Molecules desorbing from clean palladium show a low rotational alignment of A0(2) = + 0.07, those from c(2 × 2) S/Pd(100) an alignment of A0(2) = + 0.60. At all coverages a helicopter type of motion prevails. We have developed different models to describe the dependence of the rotational alignment on the sulfur coverage. Using Monte Carlo simulations the relative abundances of different reaction sites are calculated. These abundances and the mJ population distributions for clean and sulfur influenced sites are used to model the behaviour for the rotational alignment at different S coverage. It is shown that at low coverages the reactions occur dominantly at bridge sites while at high S coverage hollow sites become important.

To provide two jitter‐free soft x‐ray pulses for femtosecond x‐ray pump and probe experiments a split and delay unit (autocorrelator) has been constructed for the VUV—FEL in Hamburg (FLASH). Here we report experiments applying this autocorrelator to examine the average temporal properties of FEL pulses delivered from FLASH at 24 nm (51.8 eV). In a linear autocorrelation experiment the spatio‐temporal coherence properties are measured for both the first and the third harmonic of the FEL pulses. Furthermore, we report on the first evaluation of the pulse length from the time‐resolved observation of doubly charged helium ions produced by direct two‐photon double ionization at 24 nm. In summary the determination of the longitudinal pulse parameter of FLASH at 24 nm to 6 fs and 29±5 fs for the coherence time and the pulse length (FWHM) respectively proofs the autocorrelator as a valuable tool for time resolved two pulse X‐ray experiments.

By applying two separate experimental methods the parity of the two components of the Λ-doublet of the X 2 1 2 ground state of NO is determined. In the first method the assignment is made by simultaneously measuring one-and-two photon laser induced fluorescence spectra of the A 2 Σ + state and applying the appropriate selection rules. In the second setup hexapole focusing and resonance-enchanced multiphoton ionisation (REMPI) are combined. The upper component of the Λ-doublet is focused by the hexapole and the total parity of this state is assigned by detection with REMPI, again using the A 2 Σ + ← X 2 Π 1 2 transiti methods show that the upper component of the Λ-doublet of the X 2 Π 1 2 (ν=0, J =0.5) state of NO has negative total parity. This assignment supports theoretical results obtained from a perturbation analysis by de Vivie and Peyerimhoff who have calculated that G 2 Σ − acts as the major contributor to the Λ-doublet splitting.

Physical phenomena associated with energy deposition into adsorbed molecules will be discussed. This energy may be provided to the adsorbate either thermally, by a catalytic surface reaction or by laser radiation. When enough energy is supplied adsorbed molecules eventually desorb from the substrate. Observation of the desorption flux with internal state selection provides detailed information about the molecular dynamics in this process, because the internal excitations are associated with the dynamics on the potential energy hypersurface. The rotational cooling effect previously observed in molecular beam scattering has also been found for desorption. In several systems strong vibrational excitation has been observed. Recent developments permit in addition the velocity distributions of molecules to be determined with internal quantum state resolution. The complete energetics of desorbing molecules can thus be determined. Finally, making use of the polarized nature of the laser radiation, alignment effects in the desorption can be observed, permitting to analyze the vector properties of the rotational angular momentum.

Rotational alignment in a polyatomic molecule is produced by stimulated S‐branch Raman pumping. This technique, applied to pump the (ν2‘=1) vibration of acetylene, generates a nearly perfect quadrupole aligned MJ distribution (A0(2)=−1) for Jf=2. First results concerning the collisional alignment decay rate constant are reported.

The word chromosome has survived for over 100 years, because it succinctly defines what early cytologists were able to see with the most modern instrument of their time, a light microscope. It was introduced in a review that became widely known and was published almost simultaneously in German, English and French (Waldeyer 1888, 1889, 1890a, 1890b). In the late 19th century, these three languages were in strong competition for international status as the idiom of science. At the same time, Greek was also considered as a candidate for a nationalistically neutral language of science, and it seems more than coincidence that the word [Greek letters: see text] matches well the coherent Greek terminology used to describe the cell cycle in mitosis as well as meiosis. Emil Heitz (1935) maintained--in the face of reactionary German efforts to replace the term--that in using "the ineradicable word chromosome we think last of all that it indicates a body, that stains intensely,". Significantly, the key word is no longer restricted to eukaryotes, but has been readily adopted by microbial geneticists (Heidelberg el al. 2000) and acknowledged as defining the elementary unit of genomic partition.

Local environments of Si suboxides at the interface between a thermally grown SiO2 film and Si(111) were studied by angle-scanned photoelectron diffraction. Si 2p core-level spectra containing chemically shifted components were recorded. The components were deconvoluted by least squares fitting and assigned to different Si oxidation states. The obtained diffraction patterns of the various suboxides exhibit different features. Comparison of these patterns with multiple scattering calculations including a multipole R-factor analysis shows that a simple chemical abrupt interface model describes well the environment of the suboxides and indicates ordered SiO2 close to the interface.

Surveillance of infectious episodes in institutionalized elderly men permanently resident on two wards of a veterans' hospital was undertaken for a 12-month period. One-hundred eleven episodes were identified in 50 residents (74 per cent). The most frequent infections included lower respiratory tract infections (incidence 59/100 patient-years), febrile episodes with no source (43.4), skin and soft tissue infections (36.5), and gastroenteritis (33). Only pneumonia was associated with significant mortality. A specific etiologic agent was seldom identified other than for skin and soft tissue infections. Antimicrobial therapy was prescribed for 87 per cent of all infections. Ward staff absenteeism was associated with peak occurrences of infections in residents. Resident characteristics that correlated with infection were incontinence of bladder and of bowel. Mental status or degree of mobility did not correlate. While infections occur frequently in this population, mortality is common only with pneumonia. Infections occur more frequently in residents who have greater functional impairment.

The relative genome sizes and the proportions of X- and Y-chromosomal DNA in Drosophila hydei, D. neohydei and D. eohydei were measured by microspectrophotometry. Some implications of the results with respect to genome evolution in these species are discussed.

A method is presented according to which tolerances for active ingredient release from pharmaceutical dosage forms are calculated. The procedure is based on a statistical model. In accordance with this, the mean value is specified as a measure of the amount of active ingredient released, and the standard deviation as a measure of the uniformity of the active ingredient release. The determination of drug release tolerances is standardized. Based on clinically tested samples, changes arising from the manufacture and the storage are taken into account, thus establishing a manufacturing standard. Depending on the information available, a dynamic adaption of drug release tolerances (e.g., during the development phase) is recommended.

Two kinds of experiments with tunable VUV laser light have been carried out with H atoms: (1) High resolution resonant two‐photon ionization, H(1 2S1/2)+hνα→H(2 2P1/2,3/2)+ hνuv→H++e with tunable Lyman‐α light and (2) resonant tow photon excitation of high Rydberg states. H(1 2S1/2)+hνα→H(2 2P)+hνuv →H(n 2S, n 2D)→H++e followed by ionization through collisions. In both cases an atomic beam configuration has been employed and H+ ions were detected with a mass filter. The smallest bandwidth of tunable Lyman‐α radiation achieved was ∼1.0 Ghz, enough for partial resolution of the hyperfine structure doublet of the 1 2S1/2 ground state. The application to produce polarized protons by high resolution two photon ionization is discussed. Rydberg states have been excited up to n∼48 and detected by collisional ionization under the given experimental conditons.

The investigation of the internal energy distribution of molecules after the interaction with a surface by tunable laser spectroscopy has attracted much interest recently. While several research groups have studied the scattering of molecules from surfaces [1, 2], only a few experiments have been carried out on the desorption of molecules. A major difficulty arises from the fact that the measurement time during molecular desorption from a previously cold surface is relatively short, lasting only minutes. A complete rotational population distribution can thus only be obtained from several successive adsorption - desorption cycles. In this way Cavanagh and King investigated the desorption of NO from Ru(001) [3]. This experimental constraint has been removed recently by studying the desorption of hydrogen which can permeate through metal, allowing thus a continuous desorption experiment at controlled surface temperature [4, 5]. In addition to these experimental advantages detailed information is available about the recombinative desorption of hydrogen from metal surfaces. Angular distributions sharply peaked in the forward direction, proportional to cosnθ with 3 ≤ n ≤ 10 have been observed [6, 7]. Also fast velocity distributions with mein kinetic energy up to four times the surface thermal energy have been measured [7, 8]. These deviations from Knudsens cosine law and from the Maxwellian kinetic energy distribution suggest dynamical constraints to this process, which should also be reflected in the population distribution of the molecular quantum states. In this contribution we report results on the recombinative desorption of H2[5] and D2 molecules from a polycrystalline palladium surface.

The role of internal energy in the scattering of molecular beams from surfaces has recently attracted much attention.1-3 Most of these experiments however are confined to the scattering of molecules distributed over the lowest few rotational levels of the ground vibrational state. In the experiments presented here, laser spectroscopic techniques are utilized to perform state-to-state molecular beam scattering experiments. Two laser beams intersect the molecular beam: tunable infrared laser radiation excites the incident molecular beam to a single vibrational-rotational state then tunable ultraviolet laser radiation state-selectively probes the molecular beam through two photon resonance enhanced ionization. The beam of vibrationally excited molecules is well defined in time allowing the direct determination of velocity distributions for a laser-selected state by taking time-of-flight spectra at various probe laser positions. We report here the angular and velocity distribution of vibrationally excited molecules that we have observed surviving the collision with a freshly cleaved LiF(100) surface.

Minimizing obscuration in Cassegrain optical systems places limits on the secondary mirror diameter and width of the supporting spider vanes. Accompanying those limits is the requirement that the focus, tilt, and decentration drives fit within the obscuration limits. This paper presents a design solution to the problem of minimizing obscuration while providing adjustment capability for focus, tilt, and decentration using stepper motors with integral harmonic drives coupled to eccentrics and flexures to ultimately achieve resolutions of half-micron in focus, 5 micron translation and 70 microradians in the tilt mode. The resulting design eliminates friction, hysteresis and injurious thermal effects by means of flexural connecting members of super invar.

By frequency mixing in rare gases it is now possible to generate tunable coherent radiation in the entire wavelength region from 105 nm to 200 nm1. This techniques will thus open the way for many applications of tunable VUV radiation to physical and photochemical problems. In this contribution we want to report on results of the excitation of atomic hydrogen in an atomic beam. The tunable VUV radiation excited the 1 2S1/2-- 2 2P Lyman - α transition, and a second tunable UV laser served to excite the (2 2P) - H atoms further to high Rydberg states or the ionization continuum. Preliminary results together with a detailed description of the apparatus has been published2,3.

Laser spectroscopic techniques are finding increasing applications in surface science experiments. In our laboratory, the state-specificity and time resolution capabilities of laser techniques are applied to molecular beam-surface scattering experiments in order to perform state-to-state studies in which the angular, velocity and internal energy distributions are determined for the scattering of a laser excited incident molecular beam in a well-defined vibrationally excited single quantum state.