We present a cantilever-based near-field probe with integrated Mie scattering dielectric SiO2 microsphere (MSDM) for near-field optical imaging as well as femtosecond spectroscopy applications. In contrast to the state-of-the-art transmissive near-field probes, the MSDM reveals a transmission of almost unity known from far-field microscopy configuration. For proper handling, the microsphere is integrated at the apex of a conventional pyramidal aperture tip carried by an atomic force microscopy cantilever. It proved to be mechanically robust during the scanning process even if operating it in the contact mode. The spherical symmetry provides on the one hand a well-defined mechanical contact point with the sample irrespective of its inclination angle to the sample surface. On the other hand, the symmetry of the device preserves the polarization of light proving to be useful for the investigation of the polarization dependent behavior of plasmonic nanostructures. The high transmission combined with low dispersion renders spectroscopic investigations on the femtosecond timescale with a moderate lateral resolution. Second order autocorrelation experiments on a BBO crystal reveals a time resolution well below 100 fs at 191 nm spatial resolution.

Optimal open-loop control, i.e. the application of an analytically derived control rule, is demonstrated for nanooptical excitations using polarization-shaped laser pulses. Optimal spatial nearfield localization in gold nanoprisms and excitation switching is realized by applying a π shift to the relative phase of the two polarization components. The achieved near-field switching confirms theoretical predictions, proves the applicability of predefined control rules in nanooptical light-matter interaction, and reveals local mode interference as an important control mechanism.

We show experimentally as well as in simulation that the phase-sensitive superposition of different plasmonic modes leads to a spatially controllable enhancement of the near-field inside and in the vicinity of a metallic nanostructure. Multiphoton photoemission electron microscopy maps the local near-field distribution. By controlling the relative phase Theta between two orthogonally polarized light pulses the spatial distribution of the near-field is manipulated on the basis of the interference of the near-field modes. This demonstration of optical near-field control is corroborated by finite integral time domain calculations.

The magnetic interlayer coupling of Fe19Ni81/Cu/Co trilayered microstructures has been studied by means of x-ray magnetic circular dichroism in combination with photoelectron emission microscopy (XMCD-PEEM). We find that a parallel coupling between magnetic domains coexists with a non-parallel coupling between magnetic domain walls (DWs) of each ferromagnetic layer. We attribute the non-parallel coupling of the two magnetic layers to local magnetic stray fields arising at DWs in the magnetically harder Co layer. In the magnetically softer FeNi layer, non-ordinary DWs, such as 270 degrees and 90 degrees DWs with overshoot of the magnetization either inwards or outwards relative to the turning direction of the Co magnetization, are identified. Micromagnetic simulations reveal that in the absence of magnetic anisotropy, both types of overshooting DWs are energetically equivalent. However, if a uniaxial in-plane anisotropy is present, the relative orientation of the DWs with respect to the anisotropy axis determines which of these DWs is energetically favorable.

Einleitung: Die transiente Elastographie der Leber (Fibroscan®) ist auf eine bestimmte Eindringtiefe und Standard-Messkammer festgelegt. Acoustic Radiation Force Impulse Imaging (ARFI) ist eine neue Technologie, die mittels einer Standard-Ultraschallsonde mit flexibler Messkammer auch zur Leberelastographie unter Sicht genutzt werden kann.

Einleitung: Acoustic Radiation Force Impulse Imaging (ARFI) ist eine neue Ultraschalltechnologie, welche die Elastographie verschiedener Gewebe erlaubt, da mittels einer Standard-Ultraschallsonde eine flexible Messkammer von 1cm Durchmesser unter Sicht platziert werden kann. Ziel der Untersuchung war die Gewinnung erster Daten zur Elastographie der Milz insbesondere mit Frage der Erkennung von portaler Hypertension.

A process scheme for the fabrication of scanning near-field optical and force microscopy cantilever sensors with coaxial tips is presented. A hollow fourfold pyramidal tip is used, coated from both sides by 100nm aluminium. Focused Ion Beam milling is performed to structure the tips. First measurements on a model system demonstrate the performance of these sensors.

Einleitung: Die transiente Elastografie der Leber (Fibroscan®) ist auf eine bestimmte Eindringtiefe und eine Standard-Messkammer festgelegt. Acoustic Radiation Force Impulse Imaging (ARFI) ist eine neue Technologie, die mittels einer Standard-Ultraschallsonde mit flexibler Messkammer auch zur Leberelastografie unter Sicht genutzt werden kann.

Poster Session -Thursday, April 23 are >7 kPa for significant fibrosis and >14 for cirrhosis.However, there is growing evidence that fibrosis is not the only determinant of liver stiffness: inflammation, cholestasis and variation in the parenchymal blood content can also interfere.In case of heart failure the increased pressure in the right cardiac chambers is followed by dilation of the hepatic veins and distension of the capsule with an enlarged and firm liver.We studied a series of patients with acutely decompensated heart failure (ADHF), in order to describe the variations of liver stiffness and assess their relation with clinical course and laboratory data.Methods: 23 consecutive patients (9 males, 14 females, aged 79.7±12.2years) with clinical diagnosis of ADHF requiring intravenous diuretics were included.Exclusion criteria were: BMI > 30 kg/m 2 and suspected diagnosis of liver disease on the basis of history, ultrasonographic or biochemical parameters.At admission and discharge all patients underwent TE and simultaneous blood sample for NT pro b natriuretic peptide (NTprobBNP), which is released in response to volume overload (values >900 pg/ml are diagnostic for ADHF).Results: At admission, NTprobBNP was >900 pg/ml in 22 patients.LSM failed in 3 (13%), and was >7 in 12/20 patients (60%) and >14 in 5/20 (25%) Between admission and discharge, we observed a significant reduction of both LSM (median 8.85; IQr 6.30, 12.63 vs. 7.80; 5.85, 11.75; p < 0.001), and NTprobBNP values (median 7226; IQr 3254, 13625 vs. 4441; 1216-6116; p < 0.001).The delta of variation between admission and discharge of liver stiffness and NTprobBNP were significantly related (R = 0.536, P < 0.05).Conclusions: Our data indicate that 60% percent of patients with ADHF have increased liver stiffness as assessed by TE.The return to clinical compensation is accompanied by LSM reduction as compared to baseline values, and the extent of LSM variation parallels that of NTprobBNP values.Thus, LSM likely reflects reversible hepatic congestion.

We report on a picosecond time-resolved x-ray magnetic circular dichroic-photoelectron emission microscopy study of the evolution of the magnetization components of a microstructured permalloy platelet comprising three cross-tie domain walls. A laser-excited photoswitch has been used to apply a triangular 80 Oe, 160 ps magnetic pulse. Micromagnetic calculations agree well with the experimental results, both in time and frequency, illustrating the large angle precession in the magnetic domains with magnetization perpendicular to the applied pulse, and showing how the magnetic vortices revert their core magnetization while the antivortices remain unaffected.

The stratification of reticulorumen (RR) contents has been described in domestic ruminants, but suspected to be absent in certain wild ruminant species. To investigate how such stratification could be quantified, we tested variables indicating stratification in three oxen with rumen cannulae, fed once daily for 3 h, one of three different forages (fresh grass FG, grass hay GH, lucerne hay LH). Ingesta samples from dorsal rumen (DR), ventral rumen (VR) and reticulum (RET) were taken at 0, 3, 6, 12 and 24 h after the last meal and analyzed for dry matter (DM) concentration, mean particle size and proportion of floating/sedimenting particles. Viscosity was measured in centrifuged RR fluid. There was no relevant variation in rumen fluid viscosity over time or with feeding regime. Dry matter content in DR was always higher than in VR or RET and increased after feeding. When LH and FG were fed, DR always contained larger particles than VR, except at 6 and 12 h of feeding GH. The proportion of floating particles was higher in DR than VR except at GH 6 h and GR between 6 and 12 h. The floating particle fraction mostly contained larger particles, except for GH 3 h in both DR and VR and for FG 3-12 h in DR. Changes in the distribution of particle size and proportion of floating particles over time comply with the theoretical course of fermentative digestion for different forages, but make these variables unreliable indicators of stratification in less controlled settings, such as investigations in wild ruminants. In contrast, viscosity of rumen fluids appears constant over time and feeding regime and might be used as a species-specific variable. The difference in DM content in DR and VR is a reliable indicator for RR contents stratification characterized by an oversaturation of the contents with fluid, leading to lower VR DM contents.

The dynamics of laser-excited electronic excitations (localized surface plasmons) in spherical Ag nanoparticles is studied by phase and time resolved two photon photoemission (TR-2PPE) and photoelectron emission microscopy (TR-PEEM). A two-dimensional array of nearly identical, parallelly oriented particles is deposited lithographically on a transparent ITO covered glass substrate. We are able to show that the parallel acquisition mode of the PEEM enables us to resolve local variations in the ultrafast electron dynamics in the nanoparticles with an accuracy of 1fs and a lateral resolution in the nanometer regime. A qualitative interpretation of the mapped inhomogeneities in the local electron dynamics is provided.

The time-resolved two-photon photoemission technique (TR-2PPE) has been applied to study static and dynamic properties of localized surface plasmons (LSP) in silver nanoparticles. Laterally, integrated measurements show the difference between LSP excitation and nonresonant single electron-hole pair creation. Studies below the optical diffraction limit were performed with the detection method of time-resolved photoemission electron microscopy (TR-PEEM). This microscopy technique with a resolution down to 40nm enables a systematic study of retardation effects across single nanoparticles. In addition, as will be shown in this paper, it is a highly sensitive sensor for coupling effects between nanoparticles.

In combining time-resolved two-photon photoemission (TR-2PPE) and photoemission electron microscopy (PEEM) the ultra-fast dynamics of collective electron excitations in silver nanoparticles (localized surface plasmons – LSPs) is probed at fs and nm resolution. Here we demonstrate that the sampling of the LSP dynamics by means of time-resolved PEEM enables detailed insight into the propagation processes associated with these excitations. In phase-integrated as well as phase-resolved measurements we observe spatio-temporal modulations in the photoemission yield from a single nanoparticle. These modulations are assigned to local variations in the electric near field as a result of the phase propagation of a plasmonic excitation through the particle. Furthermore, the control of the phase between the fs pump and probe laser pulses used for these experiments can be utilized for an external manipulation of the nanoscale electric near-field distribution at these particles.

We show experimentally that optimally polarization-shaped femtosecond laser pulses provide spatial control over electron photoemission from nanostructures. Emission patterns are manipulated with subdiffraction resolution, illustrating the potential of electric near-field control in nanophotonics.

Well-prepared periodic arrays of silver nanoparticles are investigated by means of linear and non-linear photoemission electron microscopy. The structures show homogeneous photoemission for UV excitation in the linear photoemission regime whereas striking inhomogeneities are mapped in the case of the nonlinear (2 photon) excitation using ultrashort 400nm laser pulses. A detailed analysis enables to assign these inhomogeneities to defect induced electron momentum transfer processes only effective for the 2 photon excitation process. We propose this mechanism to be of relevance for the appearance of so-called hot spots in nonlinear photoemission as identified in other 2PPE studies in the past. Furthermore, the complementarity between all-optical studies and nonlinear photoemission studies of localized surface plasmons in nanoparticles is discussed.

This report summarizes data obtained via a mailed questionnaire from 129 Department of Veterans Affairs (VA) hospitals regarding current practices in the care of central venous catheters (CVCs) used for total parenteral nutrition (TPN). The size of VA hospitals' acute medical-surgical beds ranged from 14 to 1320 (median 168) beds. Over 6000 patients annually received CVCs for TPN. Hospitals reported using triple-lumen catheters most frequently as their CVC for TPN (80.3%). A povidone-iodine scrub was used to prepare the skin for CVC insertion by 72.6% of reporting hospitals. Sixty percent of hospitals used transparent polyurethane dressings. Care of CVCs varied among hospitals. Catheter-related infection and sepsis rates were within the national average, although < 50% of responding hospitals provided data on these outcomes. The results of this survey point to the need for a national standardized database relative to patients receiving TPN via a CVC.