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Excited with p-polarized light, the near-edge He 1s photoemission signal from monolayers of He adsorbed on the close-packed surfaces of silver, copper, ruthenium, and platinum shows periodic splitting with photoelectron momentum. By applying a simple single scattering model, we explain this effect by zero-point motion induced variation of the photo hole's image charge screening and interference of the photoelectron's final state wavefunction. Relativistic one-step photoemission calculations support this interpretation. In the second part of our study, we investigate neutral double excitations of He bilayers adsorbed on platinum by monitoring the emission of He+ ions. We identify strong matrix and zero-point motion effects, namely resonances absent for isolated He, density and light polarization dependence, line broadening and a correlation of excitation and kinetic ion-energy. [ABSTRACT FROM AUTHOR]

This article discusses the development of novel material surfaces for cardiovascular implants using a technique called Direct Laser Interference Patterning (DLIP). The study aimed to design nano-structured surfaces using DLIP and test their suitability for cardiovascular implants using cardiovascular cell lines in vitro. The results showed that the designed surfaces were able to control the behavior and growth of myocardial cells, making them potentially useful for cardiovascular implants. Further testing with other cell lines and blood interaction is planned. [Extracted from the article]

We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive ρ 0 meson muoproduction at COMPASS using 160 GeV/c polarised μ + and μ - beams impinging on a liquid hydrogen target. The measurement covers the kinematic range 5.0 GeV/ c 2 < W < 17.0 GeV/ c 2 , 1.0 (GeV/c) 2 < Q 2 < 10.0 (GeV/c) 2 and 0.01 (GeV/c) 2 < p T 2 < 0.5 (GeV/c) 2 . Here, W denotes the mass of the final hadronic system, Q 2 the virtuality of the exchanged photon, and p T the transverse momentum of the ρ 0 meson with respect to the virtual-photon direction. The measured non-zero SDMEs for the transitions of transversely polarised virtual photons to longitudinally polarised vector mesons ( γ T ∗ → V L ) indicate a violation of s-channel helicity conservation. Additionally, we observe a dominant contribution of natural-parity-exchange transitions and a very small contribution of unnatural-parity-exchange transitions, which is compatible with zero within experimental uncertainties. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow one to evaluate in a model-dependent way the role of parton helicity-flip GPDs in exclusive ρ 0 production. [ABSTRACT FROM AUTHOR]

We have experimentally determined the lateral registry and geometric structure of free-base porphine (2H-P) and copper-metalated porphine (Cu-P) adsorbed on Cu(111), by means of energy-scanned photoelectron diffraction (PhD), and compared the experimental results to density functional theory (DFT) calculations that included van der Waals corrections within the Tkatchenko-Scheffler approach. Both 2H-P and Cu-P adsorb with their center above a surface bridge site. Consistency is obtained between the experimental and DFT-predicted structural models, with a characteristic change in the corrugation of the four N atoms of the molecule's macrocycle following metalation. Interestingly, comparison with previously published data for cobalt porphine adsorbed on the same surface evidences a distinct increase in the average height of the N atoms above the surface through the series 2H-P, Cu-P, and cobalt porphine. Such an increase strikingly anti-correlates the DFT-predicted adsorption strength, with 2H-P having the smallest adsorption height despite the weakest calculated adsorption energy. In addition, our findings suggest that for these macrocyclic compounds, substrate-to-molecule charge transfer and adsorption strength may not be univocally correlated. [ABSTRACT FROM AUTHOR]

Off the central California coast near Pt. Sal, a large-amplitude internal bore was observed for 20 h over 10 km cross shore, or 100–10-m water depth (D), and 30 km along coast by remote sensing, 39 in situ moorings, ship surveys, and drifters. The bore is associated with steep isotherm displacements representing a significant fraction of D. Observations were used to estimate bore arrival time tB, thickness h, and bore and nonbore (ambient) temperature difference ΔT, leading to reduced gravity g′. Bore speeds c, estimated from mapped tB, varied from 0.25 to 0.1 m s−1 from D = 50 to 10 m. The h varied from 5 to 35 m, generally decreased with D, and varied regionally along isobath. The bore ΔT varied from 0.75° to 2.15°C. Bore evolution was interpreted from the perspective of a two-layer gravity current. Gravity current speeds U, estimated from the local bore h and g′, compared well to observed bore speeds throughout its cross-shore propagation. Linear internal wave speeds based on various stratification estimates result in larger errors. On average bore thickness h = D/2, with regional variation, suggesting energy saturation. From 50- to 10-m depths, observed bore speeds compared well to saturated gravity current speeds and energetics that depend only on water depth and shelf-wide mean g′. This suggests that this internal bore is the internal wave analog to a saturated surfzone surface gravity bore. Along-coast variations in prebore stratification explain variations in bore properties. Near Pt. Sal, bore Doppler shifting by barotropic currents is observed. [ABSTRACT FROM AUTHOR]

Quantum confinement of a two-dimensional electron gas by supramolecular nanoporous networks is investigated using the boundary elements method based on Green's functions for finite geometries and electron plane wave expansion for periodic systems. The "particle in a box" picture was analyzed for cases with selected symmetries that model previously reported architectures constructed from organic and metal-organic scattering centers confining surface state electrons of Ag(111) and Cu(111). First, by analyzing a series of cases with systematically defined parameters (scattering geometry, potentials, and effective broadening), we demonstrate how the scattering processes affect the properties of the confined electrons. For the features of the local density of states reported by scanning tunneling spectroscopy (STS), we disentangle the contributions of lifetime broadening and splitting of quantum well states due to coupling of neighboring quantum dots. For each system, we analyze the local electron density distribution and relate it to the corresponding band structure as calculated within the plane-wave expansion framework. Then, we address two experimental investigations, where in one case only STS data and in the other case mainly angle-resolved photoemission spectroscopy (ARPES) data were reported. In both cases, the experimental findings can be successfully simulated. Furthermore, the missing information can be complemented because our approach allows to correlate the information obtained by STS with that of ARPES. The combined analysis of several observations suggests that the scattering potentials created by the network originate primarily from the adsorbate-induced changes of the local surface dipole barrier. [ABSTRACT FROM AUTHOR]

Quantification of the isotope altitude effect from precipitation allows the identification of recharge altitudes in high-relief areas. However, steep terrains frequently limit the use of this precipitation-based approach. Perennial rivers often provide easy, year-round access for water sampling. However, in high-relief regions rivers may not adequately represent regional precipitation isotope patterns because they integrate isotope signals along their course. This prevents the calculation of an altitudinal isotope gradient from river water samples alone. We present a study that shows how a river-based sampling approach served to determine the altitude effect. Replacing the original sample site altitude with the mean upstream catchment elevation as calculated from a digital elevation model allowed us to establish a plausible altitude isotope effect from stream water. The correction approach was verified independently using precipitation isotope data. This approach can potentially be transferred to other regions where precipitation sampling at various elevations is difficult to determine. [ABSTRACT FROM AUTHOR]

Background: Accurate and rapid testing for SARS-COV-2 antibodies could improve the diagnosis and management of COVID-19. In this study, we aim to evaluate the diagnostic accuracy of a commercially available point-of-care lateral flow kit independently and in comparison to an established platform-based system.Method: Samples from 144 PCR-confirmed COVID-19 cases and 130 pre-pandemic negative controls were tested in parallel by MP Rapid 2019-NCOV IgM/IgG Combo test and Roche Elecsys. Comparison of results based on serum and capillary blood testing was undertaken.Results: Sensitivity at day 15 onwards was 100% for both methods. Between days 1 and 7 post admission, the IgM/IgG Combo test and Roche Elecsys shown sensitivity of 74% (95%CI: 62%-85%) vs. 67% (95% CI: 55%-79%, P = 0.3947). Combo test specificities were 100% for IgG, 98.5% for IgM vs. Roche Elecsys specificity of 100%. Concordance analysis showed 98.5% agreement to the Roche Elecsys method (Cohen's Kappa 0.96 95% CI [0.92-0.99]). Capillary blood results showed complete agreement with serum samples using the Combo test.Conclusion: In comparison to Roche Elecsys, our data show that the MP Rapid 2019-NCOV IgM/IgG Combo test provides a high-confidence assay system for the detection of previous exposure to SARS-COV-2 infection with advantage of affording near-patient testing. [ABSTRACT FROM AUTHOR]

We report on the adsorption and self-metalation of a prototypic tetrapyrrole compound, the free-base porphine (2H-P), on the Cu(111) surface. Our multitechnique study combines scanning tunneling microscopy (STM) results with near-edge X-ray absorption fine-structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) data whose interpretation is supported by density functional theory calculations. In the first layer in contact with the copper substrate the molecules adsorb coplanar with the surface as shown by angle-resolved NEXAFS measurements. The quenching of the first resonance in the magic angle spectra of both carbon and nitrogen regions indicates a substantial electron transfer from the substrate to the LUMO of the molecule. The stepwise annealing of a bilayer of 2H-P molecules sequentially transforms the XP and NEXAFS signatures of the nitrogen regions into those indicative of the coordinated nitrogen species of the metalated copper porphine (Cu-P), i.e., we observe a temperature-induced self-metalation of the system. Pre- and post-metalation species are clearly discriminable by STM, corroborating the spectroscopic results. Similar to the free-base porphine, the Cu-P adsorbs flat in the first layer without distortion of the macrocycle. Additionally, the electron transfer from the copper surface to the molecule is preserved upon metalation. This behavior contrasts the self-metalation of tetraphenylporphyrin (2H-TPP) on Cu(111), where both the molecular conformation and the interaction with the substrate are strongly affected by the metalation process. [ABSTRACT FROM AUTHOR]

By exploiting an established on-surface metallation strategy, we address the ability of the corrolic macrocycle to stabilise transition metal ions in high-valent (III) oxidation states in metal-supported molecular layers. This approach offers a route to engineer adsorbed metal complexes that cannot be easily fabricated by organic synthesis methods and bear a vacant axial coordination site for catalytic conversions. [ABSTRACT FROM AUTHOR]

Aim: The generation of accurate, comparable results from traceable measurement procedures is a primary goal in harmonization efforts. In this study, the analytical performance of routine methods for calcium and albumin measurement is assessed to define the impact of the analytical bias of calcium and albumin on adjusted calcium equation performance and on reference intervals.Method: In collaboration with the Wales External Quality Assurance Scheme, six months' worth of anonymized data that cover a concentration range of clinical interest were collected. The data were grouped by analytical platforms/methods.Results: Albumin BCG methods are positively biased (8%) to BCP methods. The overall bias for BCP methods ranges from 5.1 to -4.3% and the overall bias for BCG methods is from 2 to -6.7%. Bias for both methods is higher than the allowable minimal bias for albumin. Calcium concentrations for Roche Cobas CPC and NM-BAPTA, Beckman Arsenazo III, Abbott Architect Arsenazo III were within bias of 1.5 to -1%. However, Siemens calcium methods CPC and Arsenazo III appear to suffer from concentration-dependent bias ranging from +3 to -6%, which exceeds even the minimal allowable limits for calcium (1.3%). Adjusted calcium shows significant bias of 11%. Even with the exclusion of Siemens Advia, the scatter of adjusted calcium results exceeds that for total calcium.Conclusion: This study shows wider than acceptable analytical variation for albumin and calcium. This variation may contribute to overall adjusted calcium equations variation and invalidate the application of a harmonized reference interval for calcium and albumin. [ABSTRACT FROM AUTHOR]

Background: Harmonization of reference intervals for analytes that have a sound calibration and metrological traceability is a widely recommended practice. The UK Pathology Harmony has recently harmonized reference intervals for calcium and albumin. In this study, we have determined the reference intervals for calcium and albumin on the UK's most commonly used analytical platforms.Method: A prospective reference population of healthy individuals was recruited according to the IFCC CRIDL criteria. A second indirect population was collected from 14 primary care setting and measured in laboratories using various analytical platforms and methods (Roche, Abbott, Beckman and Siemens analytical platforms).Results: In total, 299 subjects were recruited; the central 95th centile values for calcium for three out of four analytical platforms were in a close agreement with UK Pathology Harmony reference intervals of 2.2-2.6 mmol/L. Reference intervals of BCG methods from both cohorts and irrespective of analytical platforms were higher for both lower and upper reference limits than those for BCP. In comparison, the indirect study showed an age-related variation. The younger population reference intervals varied by up to 5.7% at the lower reference limit and up to 12% at the upper reference limit compared with Pathology Harmony reference intervals, and the older population showed a variation of up to 14% at both limits.Conclusion: While calcium reference intervals can be a subject for harmonization, albumin reference intervals studied showed large variation which is unsupportive of embracing a common reference interval for albumin. [ABSTRACT FROM AUTHOR]

Background: A recent attempt to improve the diagnostic value of adjusted calcium addressed a primary care-specific adjusted calcium equation, but validated the new equation for Roche Cobas, BCG and NM-BAPTA methods only. In this study, we aim to validate a population-specific equation for other methods and platforms.Method: We collected retrospective patient data-sets from 15 hospital laboratories using a range of commercially available analytical platforms and methods for calcium and albumin measurements. Raw data-sets were collected and filtered according to Payne's criteria, and separate adjusted calcium equations were derived for hospitalized and primary care patients.Results: Mean albumin and calcium results were significantly higher in primary care populations (P < 0.0001). The prevalence of hypocalcaemia using adjusted calcium ranged between 6% and 44% for inpatient data-sets and was higher in users of BCG methods. The application of community-specific adjustment equation to primary care data-sets reduced the prevalence of hypocalcaemia (mean 1.7%, range 0.8-3.7%).Conclusion: We demonstrated that the use of a community-specific calcium adjustment equation to a primary care population reduces both the percentage and the variation of hypocalcaemia between different laboratories. [ABSTRACT FROM AUTHOR]

Background: Calcium circulates bound to albumin and changes in albumin concentration will therefore affect total calcium measurements. In order to mitigate this, correction factors are frequently used. The most widely used correction equation was described by Payne and colleagues in 1973. This equation was derived from well-defined hospitalized patients' data. Current clinical practice is consistent with the general application of the adjusted calcium equation irrespective of clinical setting. This study aims to assess the validity of this approach by the derivation of a community care-specific adjusted calcium equation ('community equation') and the comparison of its performance to a hospitalized patient equation and ionized calcium.Method: Retrospective data were collected according to Payne's criteria from an inpatient and community care setting. Data were used to derive the two equations: the in-patient equation and community equation. The outcome of these equations was compared with ionized calcium obtained from 123 healthy participants.Results: The community equation correctly identified the calcium status of 92% of the 123 healthy participants, while the inpatient equation identified 46% only. Regression analysis against ionized calcium showed a higher R2 for the community equation than for the inpatient equation. Furthermore, we have shown that mean albumin and calcium concentrations are significantly different between these two populations.Conclusion: In this study, we found that the diagnostic accuracy of the adjusted calcium equation in ambulant patients was improved by the derivation of a population-specific equation for the community care setting. [ABSTRACT FROM AUTHOR]

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Utilising normal incidence X-ray standing waves we rigourously scrutinise the "inverted model" as the adsorption structure of free-base tetraphenyl porphyrin on Cu(111). We demonstrate that the iminic N atoms are anchored at near-bridge adsorption sites on the surface displaced laterally by 1.1 ± 0.2 Å in excellent agreement with previously published calculations. [ABSTRACT FROM AUTHOR]

The bonding and the temperature-driven metalation of 2H-tetraphenylporphyrin (2H-TPP) on the Cu(111) surface under ultrahigh vacuum conditions were investigated by a combination of x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy with density functional theory calculations. Thin films were prepared by organic molecular beam epitaxy and subsequent annealing. Our systematic study provides an understanding of the changes of the spectroscopic signature during adsorption and metalation. Specifically, we achieved a detailed peak assignment of the 2H-TPP multilayer data of the C1s and the N1s region. After annealing to 420 K both XPS and NEXAFS show the signatures of a metalloporphyrin, which indicates self-metalation at the porphyrin-substrate interface, resulting in Cu-TPP. Furthermore, for 2H-TPP monolayer samples we show how the strong influence of the copper surface is reflected in the spectroscopic signatures. Adsorption results in a strongly deformed macrocycle and a quenching of the first NEXAFS resonance in the nitrogen edge suggesting electron transfer into the LUMO. For Cu-TPP the spectroscopic data indicate a reduced interaction of first-layer molecules with the substrate as demonstrated by the relaxed macrocycle geometry. [ABSTRACT FROM AUTHOR]

We present a combined scanning tunneling microscopy (STM), near-edge x-ray-absorption fine-structure, and x-ray photoemission spectroscopy (XPS) study on the bonding and ordering of tetrapyridyl-porphyrin molecules on the Cu(111) surface in the 300–500 K temperature range. Following deposition at 300 K the molecules are adsorbed with a pronounced conformational adaptation of the anchored species featuring a saddle-shaped macrocycle and terminal groups pointing toward the substrate. Upon moderate annealing supramolecular chains evolve that are stabilized by metal-ligand interactions between the mesopyridyl substituents and copper adatoms resulting in twofold copper coordination. Annealing to temperatures exceeding 450 K strongly alters the molecular appearance in high-resolution STM data. This modification was also induced by controlled voltage pulses and related to a deprotonation of the molecule by XPS. Under appropriate conditions a novel binding motif leads to honeycomb structures coexisting with the chain segments. The conformation withstands annealing without large modification. [ABSTRACT FROM AUTHOR]

The adsorption of terephthalic acid [C6H4(COOH)2, TPA] on a Pd(111) surface has been investigated by means of scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure spectroscopy under ultrahigh vacuum conditions at room temperature. We find the coexistence of one- (1D) and two-dimensional (2D) molecular ordering. Our analysis indicates that the 1D phase consists of intact TPA chains stabilized by a dimerization of the self-complementary carboxyl groups, whereas in the 2D phase, consisting of deprotonated entities, the molecules form lateral ionic hydrogen bonds. The supramolecular growth dynamics and the resulting structures are explained by a self-limiting deprotonation process mediated by the catalytic activity of the Pd surface. Our models for the molecular ordering are supported by molecular mechanics calculations and a simulation of high resolution STM images. [ABSTRACT FROM AUTHOR]

We present a low-temperature scanning tunneling microscopy (STM) study on the supramolecular ordering of tetrapyridyl-porphyrin (TPyP) molecules on Ag(111). Vapor deposition in a wide substrate temperature range reveals that TPyP molecules easily diffuse and self-assemble into large, highly ordered chiral domains. We identify two mirror-symmetric unit cells, each containing two differently oriented molecules. From an analysis of the respective arrangement it is concluded that lateral intermolecular interactions control the packing of the layer, while its orientation is induced by the coupling to the substrate. This finding is corroborated by molecular mechanics calculations. High-resolution STM images recorded at 15 K allow a direct identification of intramolecular features. This makes it possible to determine the molecular conformation of TPyP on Ag(111). The pyridyl groups are alternately rotated out of the porphyrin plane by an angle of 60°. [ABSTRACT FROM AUTHOR]

The potential application of carbon nanotubes as electron sources in electron microscopes is analyzed. The resolution and probe current that can be obtained from a carbon nanotube emitter in a low-voltage scanning electron microscope are calculated and compared to the state of the art using Schottky electron sources. Many analytical equations for probe-size versus probe-current relations in different parameter regimes are obtained. It is shown that for most carbon nanotube emitters, the gun lens aberrations are larger than the emitters’ virtual source size and thus restrict the microscope’s performance. The result is that the advantages of the higher brightness of nanotube emitters are limited unless the angular emission current is increased over present day values or the gun lens aberrations are decreased. For some nanotubes with a closed cap, it is known that the emitted electron beam is coherent over the full emission cone. We argue that for such emitters the parameter “brightness” becomes meaningless. The influence of phase variations in the electron wave front emitted from such a nanotube emitter on the focusing of the electron beam is analyzed. [ABSTRACT FROM AUTHOR]

We report scanning tunneling microscopy observations on the restructuring of a Ag(110) surface induced by the molecule 4-[trans-2-(pyrid-4-yl-vinyl)]benzoic acid (PVBA). Our data reveal that the surface undergoes a mesoscopic step faceting following exposure to submonolayer coverages and thermal activation. A sawtooth arrangement evolves implying long-range mass transport of substrate atoms and forming a regular arrangement of kink sites. Its formation is associated with the molecules’ functional headgroups forming carboxylates with {100} Ag microfacets at step edges, and eventually operating to reshape the surface morphology. Interestingly, the resulting microfacets act as chiral templates for the growth of supramolecular PVBA structures. Theoretical modeling based on ab initio results indicates that chiral recognition processes discriminating between the two enantiomers of adsorbed PVBA molecules occur in this process. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present a comprehensive study on the binding and ordering of C[sub 60] on a Pd(110) surface employing scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS) and x-ray photoelectron diffraction (XPD). Three well-ordered structures evolving at elevated temperatures were identified, with (&sup7; [sub -/+] &sup-1; [sub ±5), (4 × 5), (4 × 8) unit cells and a coverage of 1, 0.82 and 0.77 physical monolayers, respectively. The rearrangement of Pd substrate atoms turns out to play a crucial role in the evolution of thin C[sub 60] films. In STM images alternating bright and dark molecular rows are found for the regular structures. This height difference is attributed to a restructuring of the Pd substrate. Whereas the C[sub 60] molecules of the bright molecular rows are embedded in one layer deep microscopic pits, C[sub 60] accommodated in two layer deep pits account for the dark molecular rows. XPD results complete the understanding of the film structure. They reveal that the orientation of the C[sub 60] cages is unique in the regular structures; the molecules are facing with a 5–6 bond towards the substrate. [ABSTRACT FROM AUTHOR]

Gliders are low‐power autonomous underwater vehicles used to obtain oceanic measurements in vertical sections. Assimilation of glider temperature and salinity into coastal ocean circulation models holds the potential to improve the ocean subsurface structure estimate. In this study, the impact of assimilation of glider observations is studied using a four‐dimensional variational (4DVAR) data assimilation and forecast system set offshore of Oregon and Washington on the U.S. West Coast. Four test cases are compared: (1) no assimilation, (2) assimilation of glider temperature and salinity data alone, (3) assimilation of the glider data in combination with the surface observations including satellite sea surface temperature, sea surface height, and high‐frequency radar surface velocities, and (4) assimilation of the surface data alone. It is found that the assimilation of glider observations alone creates unphysical eddies in the vicinity of the glider transect. As a consequence, the forecast errors in the surface velocity and temperature increase compared to the case without data assimilation. Assimilation of surface and subsurface observations in combination prevents these features from forming and reduces the errors in the forecasts for the subsurface fields compared to the other three experiments. These improvements persisted in 21‐day forecasts run after the last data assimilation cycle. Plain Language Summary: Ocean forecast systems, like our system for the ocean offshore Oregon‐Washington, USA, use numerical models to predict future temperature, currents, sea surface height, and salt concentration. Eventually, these predictions are corrected using observations in a process called data assimilation (DA) in order to better approximate the true state of the ocean. Assimilation of subsurface observations made by autonomous underwater vehicles called gliders can potentially improve the predictions of the ocean state below the surface. In this study, we have assimilated glider observations together with, and in absence of, surface observations. We found that assimilation of glider observations alone creates predictions that are less accurate than those obtained from a model without DA as the DA creates unphysical features. Assimilating the glider observations in tandem with surface observations prevents these features from forming and realizes local improvements to the subsurface ocean predictions that last for 21 days after the last DA correction. These results show that one has to be careful with using glider observations in DA and should always assimilate glider observations in combination with observations that cover large swaths of the ocean surface. Key Points: Glider observations are assimilated with and without surface observations in the challenging Columbia River plume region using 4DVARAssimilation of glider observations alone can create erroneous eddy variability that will deteriorate forecast performanceAssimilating glider in combination with surface observations suppresses these features and improves impact of glider assimilation [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. [ABSTRACT FROM AUTHOR]

Mobile autonomous platforms are revolutionizing our understanding of ocean systems by providing a solution for the four‐dimensional observation problem faced in the ocean. The sensors commonly used in autonomous platforms, however, leave a large gap in our observations of the food chain between primary producers and large predators. Echosounders have the potential to fill this gap. Here, we present details of a new, commercially available quantitative scientific echosounder specifically designed to meet the challenges of deployment in autonomous platforms, including those of relatively low power and small size, while providing data comparable to systems deployed from ships. We detail the integration into a Slocum glider of this echosounder and both upward‐ and downward‐looking transducers to provide guidance for those considering similar efforts. We also identify key features of the system and the challenges that must be overcome to ensure collection of high‐quality data. The most important feature of the integrated glider is that it carries instruments capable of providing depth profiles of bio‐optical and environmental variables that are synoptic with the echosounder data. On a dive‐by‐dive basis, we can use these co‐located data to quantify relationships between the acoustic, bio‐optical, and environmental data. A field deployment of the echosounder‐equipped glider elucidated the processes driving diel migration in zooplankton and nekton in Monterey Bay, emphasizing the novel science questions that can be addressed using contemporary means of accessing the sea and new, integrated tools for describing the habitat and its inhabitants. [ABSTRACT FROM AUTHOR]

Photoemission spectroscopy is central to understanding the inner workings of condensed matter, from simple metals and semiconductors to complex materials such as Mott insulators and superconductors1. Most state-of-the-art knowledge about such solids stems from spectroscopic investigations, and use of subfemtosecond light pulses can provide a time-domain perspective. For example, attosecond (10−18 seconds) metrology allows electron wave packet creation, transport and scattering to be followed on atomic length scales and on attosecond timescales2-7. However, previous studies could not disclose the duration of these processes, because the arrival time of the photons was not known with attosecond precision. Here we show that this main source of ambiguity can be overcome by introducing the atomic chronoscope method, which references all measured timings to the moment of light-pulse arrival and therefore provides absolute timing of the processes under scrutiny. Our proof-of-principle experiment reveals that photoemission from the tungsten conduction band can proceed faster than previously anticipated. By contrast, the duration of electron emanation from core states is correctly described by semiclassical modelling. These findings highlight the necessity of treating the origin, initial excitation and transport of electrons in advanced modelling of the attosecond response of solids, and our absolute data provide a benchmark. Starting from a robustly characterized surface, we then extend attosecond spectroscopy towards isolating the emission properties of atomic adsorbates on surfaces and demonstrate that these act as photoemitters with instantaneous response. We also find that the tungsten core-electron timing remains unchanged by the adsorption of less than one monolayer of dielectric atoms, providing a starting point for the exploration of excitation and charge migration in technologically and biologically relevant adsorbate systems. The absolute timing of the photoelectric effect has proved difficult to measure, but the delay between photon arrival at a tungsten surface and ejection of photoelectrons has now been determined. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate here that theory‐assisted near‐edge X‐ray absorption fine‐structure (NEXAFS) spectroscopy enables the site‐sensitive monitoring of on‐surface chemical reactions, thus, providing information not accessible by other techniques. As a prototype example, we have used free‐base 5,10,15‐tris(pentafluorophenyl)corroles (3H‐TpFPC) adsorbed on Ag(111) and present a detailed investigation of the angle‐dependent NEXAFS of this molecular species as well as of their thermally induced derivatives. For this, we have recorded experimental C and N K‐edge NEXAFS spectra and interpret them based on XAS cross‐section calculations by using a continuous fraction approach and core‐hole including multiprojector PAW pseudopotentials within DFT. We have characterized the as‐deposited low temperature (200 K) phase and unraveled the subsequent changes induced by dehydrogenation (at 330 K) and ring‐closure reactions (at 430 K). By exemplarily obtaining profound insight into the on‐surface chemistry of free‐base corrolic species adsorbed on a noble metal this work highlights how angle‐dependent XAS combined with accurate theoretical modeling can serve for the investigation of on‐surface reactions, whereby even highly similar molecular structures, such as tautomers and isomers, can be distinguished. [ABSTRACT FROM AUTHOR]

This longitudinal study was designed to assess patients' desire for early retirement and investigate which cancer-related and psychosocial characteristics are associated with early retirement. We assessed 750 cancer patients at the beginning ( t0) and end ( t1) of, and 12 months after ( t2) inpatient cancer rehabilitation. At t0, 22% had a desire to retire early. These patients reported significantly longer sick leave periods, less favourable workplace environments, lower work ability, higher psychological distress and lower quality of life than other patients. At t2, 12.5% of patients received temporary or permanent early retirement pensions. Of all patients with a desire for early retirement at t0, 43% had returned to work at t2. This subgroup had a significantly lower physical quality of life than other patients returning to work. The most influential predictors of early retirement were being on sick leave ( OR = 6.50, 95% CI = 1.97-21.47) and a desire for early retirement ( OR = 5.61, 95% CI = 2.73-11.52). Inverse predictors of early retirement were cancer remission ( OR = 0.23, 95% CI = 0.10-0.53), perceived productivity ( OR = 0.38, 95% CI = 0.18-0.83), work satisfaction ( OR = 0.36, 95% CI = 0.17-0.77) and mental quality of life ( OR = 0.94, 95% CI = 0.91-0.98). This underlines the need for cancer-specific multi-professional rehabilitation and occupational therapy programmes. [ABSTRACT FROM AUTHOR]

This paper reports on in situ measurements of the linear energy transfer spectra of galactic cosmic rays and their progeny and of trapped Van Allen belt protons as recorded by a pulse height analyzer (PHA) radiation spectrometer which flew on the STS-95 DISCOVERY mission on the Hubble Orbital Systems Test cradle. The shuttle was launched on October 29, 1998 and had a mission duration of 8.5 days during the minimum phase of the solar activity cycle. The orbit of the STS-95 was about 550 km altitude and 28.5° inclination. Close agreement was seen between radiation environment model predictions and the measurements of the PHA. Agreement is obtained by considering the directionality of the radiation interacting with the shuttle structure. [ABSTRACT FROM PUBLISHER]

Terrestrial carbon export via inland aquatic systems is a key process in the global carbon cycle. It includes loss of carbon to the atmosphere via outgassing from rivers, lakes, or reservoirs and carbon fixation in the water column as well as in sediments. This review focuses on headwater streams that are important because their stream biogeochemistry directly reflects carbon input from soils and groundwaters. Major drivers of carbon dioxide partial pressures ( pCO2) in streams and mechanisms of terrestrial dissolved inorganic, organic and particulate organic carbon (DIC, DOC, and POC) influxes are summarized in this work. Our analysis indicates that the global river average pCO2 of 3100 ppmV is more often exceeded by contributions from small streams when compared to rivers with larger catchments (> 500 km2). Because of their large proportion in global river networks (> 96% of the total number of streams), headwaters contribute large-but still poorly quantified-amounts of CO2 to the atmosphere. Conservative estimates imply that globally 36% (i.e., 0.93 Pg C yr−1) of total CO2 outgassing from rivers and streams originate from headwaters. We also discuss challenges in determination of CO2 sources, concentrations, and fluxes. To overcome uncertainties of CO2 sources and its outgassing from headwater streams on the global scale, new investigations are needed that should include groundwater data. Such studies would also benefit from applications of integral CO2 outgassing isotope approaches and multiscale geophysical imaging techniques. [ABSTRACT FROM AUTHOR]

Single-molecule magnets based on lanthanide double-deckers are attracting significant attention due to their unrivaled single-ion anisotropy. To exploit their fascinating electronic and magnetic properties in devices for information storage or spin transport, studies on the preservation or variation of electronic and magnetic functionalities upon adsorption on surfaces are necessary. Herein, we introduced a comprehensive scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) surface science study, complemented by density functional theory (DFT) simulations, of a recently synthesized single-molecule magnet based on porphyrazine deckers, conveniently equipped with ethyl moieties to make them soluble and sublimable. We demonstrated that the double-decker species were intactly adsorbed on Au(111), Ag(111), and Cu(111) in a flat-on fashion and self-assembled in hexagonal close-packed layers. Systematic multi- and monolayer XPS was performed on the surface-confined species, confirming the preservation of the electronic properties of the ligands and the lanthanide center upon adsorption. [ABSTRACT FROM AUTHOR]

Study Question: Does 'metformin' reduce the incidence of ovarian hyperstimulation syndrome (OHSS) for women with polycystic ovary syndrome (PCOS) undergoing a GnRH antagonist assisted conception treatment cycle?Summary Answer: A short course of metformin does not reduce the incidence of OHSS for women with PCOS undergoing a GnRH antagonist treatment cycle.What Is Known Already: Metformin does reduce the incidence of OHSS in a GnRH-agonist treatment cycle.Study Design, Size, Duration: A randomised placebo-controlled trial (RCT) using metformin or placebo. Randomisation was blinded to both patient and investigator, using a random permuted blocks method with a 50:50 allocation ratio. The study was completed over 5 years (2009-2014) with 153 randomised patients. A sample size calculation based on the incidence of OHSS was completed prospectively suggesting a minimum of 146 recruits was required for the trial with a power of 80% and a type 1 error of 0.05.Participants/materials, Setting, Methods: All patients met the Rotterdam criteria for PCOS and were treated with a standard GnRH antagonist IVF/ICSI treatment cycle in a tertiary infertility clinic. The study medication was started prior to stimulation and continued to oocyte retrieval. Of the 153 patients, 77 received metformin and 76 placebo.Main Results and the Role Of Chance: There was no reduction in the incidence of moderate-severe OHSS (Placebo (PLA) 12.2%, metformin (MET) = 16%, 95% CI -0.08-0.16, P = 0.66). There was no difference in total gonadotrophin dose (PLA = 1200, MET = 1200, 95% CI -118.67-118.67, P = 0.75), oocytes retrieved (PLA = 15, MET = 14, 95% CI -2.37-4.37, P = 0.66) or fertilisation rate (PLA = 60.7%, MET = 53.3%, 95% CI -0.96-14.94, P = 0.07). However, using metformin resulted in a reduced clinical pregnancy rate (CPR) per cycle started (PLA = 48.7%, MET = 28.6%, 95% CI 0.04-0.35, P = 0.02) and live birth rate (PLA = 51.6%, MET = 27.6%, 95% CI 0.05-0.40, P = 0.02). Furthermore, when ethnicity was taken into account there was a significant reduction in pregnancy outcome for the South Asian population irrespective of metformin or placebo use (CPR per cycle started, White Caucasian = 44.4%, South Asian = 19.4%; 95% CI 0.06-0.39, P = 0.01).Limitations, Reasons For Caution: This study was only undertaken on an infertility population with PCOS with a limited duration of study medication use.Wider Implications Of the Findings: This is the first adequately powered RCT to assess the impact of metformin on OHSS in a high-risk group (women with PCOS) undergoing a GnRH antagonist cycle. It does not support the empirical prescribing of metformin as an adjunct to a GnRH antagonist treatment cycle.Study Funding/competing Interests: None.Trial Registration Number: EudraCT number 2009-010952-81.Trial Registration Date: 21 September 2009.Date Of First Patient's Enrolment: 30 October 2009. [ABSTRACT FROM AUTHOR]

The adsorption of thymine, a pyrimidine based nucleobase, was studied on the (110) termination of rutile titanium dioxide in order to understand the thermal stability and gross structural parameters of the interaction between a strongly polar adsorbate and a highly corrugated transition metal oxide surface. Near-edge X-ray absorption fine structure (NEXAFS), X-ray photoelectron spectroscopy (XPS), temperature programmed XPS and temperature programmed desorption indicated the growth of a room temperature stable bilayer, which could only be removed by annealing to 450 K. The remaining first layer was remarkably robust, surviving annealing up to 550 K before undergoing N–H bond scission. The comparison to XPS of a sub-monolayer exposure of 1-methyluracil shows that the origin of the room temperature stable bilayer is not intermolecular interactions. This discovery, alongside the deprotonation of one of the first layer's pyrimidinic nitrogen atoms at room temperature, suggests that the thymine molecules in the first layer bind to the undercoordinated surface Ti atoms, and the second layer thymine molecules coordinate with the bridging oxygen atoms which protrude above the Ti surface plane on the (110) surface. The NEXAFS results indicate an almost upright orientation of the molecules in both layers, with a 30 ± 10° tilt away from the surface normal. [ABSTRACT FROM AUTHOR]

We demonstrate that chemically well-defined aromatic self-assembled monolayers (SAMs) bonded via a carboxylate head group to surfaces of ferromagnetic (FM = Co, Ni, Fe) transition metals can be prepared at ambient temperature in ultra-high vacuum and are thermally stable up to 350–400 K (depending on the metal). The much superior stability over thiolate-bonded SAMs, which readily decompose above 200 K, and the excellent electronic communication guaranteed by the carboxylate bonding render benzoate/FM-metal interfaces promising candidates for application in spintronics. [ABSTRACT FROM AUTHOR]

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MAS-NMR was used to study the structure and dynamics at ambient temperatures of the membrane-anchor domain of YadA (YadA-M) in a pellet of the outer membrane of E. coli in which it was expressed. YadA is an adhesin from the pathogen Yersinia enterocolitica that is involved in interactions with the host cell, and it is a model protein for studying the autotransport process. Existing assignments were sucessfully transferred to a large part of the YadA-M protein in the E. coli lipid environment by using 13C-13C DARR and PDSD spectra at different mixing times. The chemical shifts in most regions of YadA-M are unchanged relative to those in microcrystalline YadA-M preparations from which a structure has previously been solved, including the ASSA region that is proposed to be involved in transition-state hairpin formation for transport of the soluble domain. Comparisons of the dynamics between the microcrystalline and membrane-embedded samples indicate greater flexibility of the ASSA region in the outer-membrane preparation at physiological temperatures. This study will pave the way towards MAS-NMR structure determination of membrane proteins, and a better understanding of functionally important dynamic residues in native membrane environments. [ABSTRACT FROM AUTHOR]

The array of 3 × 3 modules of the electromagnetic calorimeter ECAL0 of the COMPASS experiment at CERN has been tested with an electron beam of the ELSA (Germany) facility. The dependence of the response and the energy resolution of the calorimeter from the angle of incidence of the electron beam has been studied. A good agreement between the experimental data and the results of Monte Carlo simulation has been obtained. It will significantly expand the use of simulation to optimize event reconstruction algorithms. [ABSTRACT FROM AUTHOR]

The propagation and transport of electrons in crystals is a fundamental process pertaining to the functioning of most electronic devices. Microscopic theories describe this phenomenon as being based on the motion of Bloch wave packets. These wave packets are superpositions of individual Bloch states with the group velocity determined by the dispersion of the electronic band structure near the central wavevector in momentum space. This concept has been verified experimentally in artificial superlattices by the observation of Bloch oscillations-periodic oscillations of electrons in real and momentum space. Here we present a direct observation of electron wave packet motion in a real-space and real-time experiment, on length and time scales shorter than the Bloch oscillation amplitude and period. We show that attosecond metrology (1 as = 10−18 seconds) now enables quantitative insight into weakly disturbed electron wave packet propagation on the atomic length scale without being hampered by scattering effects, which inevitably occur over macroscopic propagation length scales. We use sub-femtosecond (less than 10−15 seconds) extreme-ultraviolet light pulses to launch photoelectron wave packets inside a tungsten crystal that is covered by magnesium films of varied, well-defined thicknesses of a few ångströms. Probing the moment of arrival of the wave packets at the surface with attosecond precision reveals free-electron-like, ballistic propagation behaviour inside the magnesium adlayer-constituting the semi-classical limit of Bloch wave packet motion. Real-time access to electron transport through atomic layers and interfaces promises unprecedented insight into phenomena that may enable the scaling of electronic and photonic circuits to atomic dimensions. In addition, this experiment allows us to determine the penetration depth of electrical fields at optical frequencies at solid interfaces on the atomic scale. [ABSTRACT FROM AUTHOR]