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The ability of the aorta to buffer blood flow and provide diastolic perfusion (Windkessel function) is a determinant of cardiovascular health. We have reported cardiac dysfunction indicating downstream vascular abnormalities in young adult baboons who were intrauterine growth restricted (IUGR) at birth as a result of moderate maternal nutrient reduction. Using 3 T MRI, we examined IUGR offspring (eight male, eight female; 5.7 years; human equivalent 25 years) and age-matched controls (eight male, eight female; 5.6 years) to quantify distal descending aortic cross-section (AC) and distensibility (AD). ANOVA showed decreased IUGR AC/body surface area (0.9±0.05 cm2/m2v. 1.2±0.06 cm2/m2, M±s.e.m., P<0.005) and AD (1.7±0.2 v. 4.0±0.5×10−3/mmHg, P<0.005) without sex difference or group-sex interaction, suggesting intrinsic vascular pathology and impaired development persisting in adulthood. Future studies should evaluate potential consequences of these changes on coronary perfusion, afterload and blood pressure.
CRESST II is an experiment for direct WIMP search, using cryogenic detectors. the ratio of the two signals (temperature rise and scintillation light) measured for each interaction is an excellent parameter for discrimination of the radioactive background. the main remaining background is the neutron flux present at the experimental site, since neutrons produce the same signals as WIMPs do. Based on Monte Carlo simulations the present work shows how neutrons from different origins affect CRESST and which measures have to be taken into account to reach the sensitivity goal.
In the last decade the triennial reports from Commission 49 have covered various topics like (nonlinear) plasma processes, magnetohydrodynamic phenomena and flows in the heliosphere, solar wind composition, transient events in, and latitudinal dependencies of, the heliosphere, interstellar gas flow through the interface region, kinetic versus magnetohydrodynamic theory in heliospheric plasmas and charged dust in space plasmas. Continuing the tradition of summarizing specific aspects to give astronomers outside our own specialty a flavour of our field, we now address recent advances in understanding coronal mass ejections in interplanetary space and the inner heliospheric solar wind under quiet and perturbed conditions. We owe a great debt of gratitude to the eminent contributors for their valiant efforts in writing these succinct but clear reports and guiding us through the recent literature.
We recently showed that the mRNA expression of genes encoding for specific nutrient sensing receptors, namely the free fatty acid receptors (FFAR) 1, 2, 3, and the hydroxycarboxylic acid receptor (HCAR) 2, undergo characteristic changes during the transition from late pregnancy to lactation in certain adipose tissues (AT) of dairy cows. We hypothesised that divergent energy intake achieved by feeding diets with either high or low portions of concentrate (60% v. 30% concentrate on a dry matter basis) will alter the mRNA expression of FFAR 1, 2, 3, as well as HCAR2 in subcutaneous (SCAT) and retroperitoneal AT (RPAT) of dairy cows in the first 3 weeks postpartum (p.p.). For this purpose, 20 multiparous German Holstein cows were allocated to either the high concentrate ration (HC, n=10) or the low concentrate ration (LC, n=10) from day 1 to 21 p.p. Serum samples and biopsies of SCAT (tail head) and RPAT (above the peritoneum) were obtained at day −21, 1 and 21 relative to parturition. The mRNA abundances were measured by quantitative PCR. The concentrations of short-chain fatty acid (SCFA) in serum were measured by gas chromatography-flame ionisation detector. The FFAR1 and FFAR2 mRNA abundance in RPAT was higher at day −21 compared to day 1. At day 21 p.p. the FFAR2 mRNA abundance was 2.5-fold higher in RPAT of the LC animals compared to the HC cows. The FFAR3 mRNA abundance tended to lower values in SCAT of the LC group at day 21. The HCAR2 mRNA abundance was neither affected by time nor by feeding in both AT. On day 21 p.p. the HC group had 1.7-fold greater serum concentrations of propionic acid and lower concentrations of acetic acid (trend: 1.2-fold lower) compared with the LC group. Positive correlations between the mRNA abundance of HCAR2 and peroxisome proliferator-activated receptor γ-2 (PPARG2) indicate a link between HCAR2 and PPARG2 in both AT. We observed an inverse regulation of FFAR2 and FFAR3 expression over time and both receptors also showed an inverse mRNA abundance as induced by different portions of concentrate. Thus, indicating divergent nutrient sensing of both receptors in AT during the transition period. We propose that the different manifestation of negative EB in both groups at day 21 after parturition affect at least FFAR2 expression in RPAT.
In the context of astrobiological exposure and simulation experiments in the BIOMEX project, the lichen Circinaria gyrosa was investigated by Raman microspectroscopy. Owing to the symbiotic nature of lichens and their remarkable extremotolerance, C. gyrosa represents a valid model organism in recent and current astrobiological research. Biogenic compounds of C. gyrosa were studied that may serve as biomarkers in Raman assisted remote sensing missions, e.g. ExoMars. The surface as well as different internal layers of C. gyrosa have been characterized and data on the detectability and distribution of β-carotene, chitin and calcium oxalate monohydrate (whewellite) are presented in this study. Raman microspectroscopy was applied on natural samples and thin sections. Although calcium oxalates can also be formed by rare geological processes it may serve as a suitable biomarker for astrobiological investigations. In the model organism C. gyrosa, it forms extracellular crystalline deposits embedded in the intra-medullary space and its function is assumed to balance water uptake and gas exchange during the rare, moist to wet environmental periods that are physiologically favourable. This is a factor that was repeatedly demonstrated to be essential for extremotolerant lichens and other organisms. Depending on the decomposition processes of whewellite under extraterrestrial environmental conditions, it may not only serve as a biomarker of recent life, but also of past and fossilized organisms.
Aimed at assessing the circulation of Mycobacterium tuberculosis in a highly endemic prison, this 13-month prospective study was performed on strains isolated from tuberculosis (TB) cases detected passively and actively. We used X-ray screening of newly admitted inmates and mass screening at the beginning of the study and again 1 year later. Of the 94 strains genotyped by restriction fragment-length polymorphism, 79 (84·0%) belonged to one of the 12 identified clusters (2–21 strains each), including two main clusters (18 and 21 cases, respectively). A history of TB treatment was reported in 22/79 (27·8%) clustered cases. Time–space distribution of clustered cases was predominantly consistent with transmission, in micro-epidemics. Given the dominant pattern of exogenous infection and the extensive strain circulation, effective TB control should emphasize reduction of overcrowding and improvement of environmental measures as a complement to detection and treatment of cases.
The observation of transit light curves has become a key technique in the study of exoplanets, since modeling the resulting transit photometry yields a wealth of information on the planetary systems. Considering that the limited accuracy of ground-based photometry does directly translate into uncertainties in the derived model parameters, simplified spherical planet models were appropriate in the past. With the advent of space-based instrumentation capable of providing photometry of unprecedented accuracy, however, a need for more realistic models has arisen.
This paper focuses on the preparation and characterization of crystalline thin films of rare-earth-doped sesquioxides (Y2O3 and Lu2O3) grown by pulsed laser deposition on single-crystal (0001) sapphire substrates. The crystal structure of the films (thicknesses between 1 nm and 500 nm) was determined by X-ray diffraction and surface X-ray diffraction analysis. These measurements show that the films were highly textured along the <111> direction. Using Rutherford backscattering analysis the correct stoichiometric composition of the films could be proved. The surface morphology of the thin films has been studied using atomic force microscopy. Crystalline films show a triangular surface morphology, which is attributed to the <111> growth direction. The emission and excitation spectra of the Eu-doped films down to a thickness of 100 nm look similar to those of the corresponding crystalline bulk material, whereas films with a thickness ≤ 20 nm show a completely different emission behaviour.
High quality GaAs and InP have been grown on silicon substrates, using low pressure metalorganic chemical vapor deposition technique. The growth temperature is 550ºC andthe growth rate 100 A/min.
Photoluminescence, X-ray diffraction and electrochemical profiling verified the high quality of these layers. The use of superlattices as buffer layers, (GaAs/GaInP) in the case of GaAs/Si and (GalnAsP/InP) in the case of InP/Si, decreased the amount of misfit dislocations in the epitaxial layer. Carrier concentrations as low as 5.1015 cm-3 have been measured by electrochemical profiling.
In addition to photoluminescence and electroluminescence porous silicon is capable of emitting an ultraviolet line spectrum. This emission can be observed already at ambient conditions. We could identify this line emission as the spectrum of nitrogen. At a pressure of about 10 mbar the UV-intensity exceeds the intensity at ambient pressure about two orders of magnitude. Angular dependent spectroscopy and the light emission behaviour at lowered pressure led us to the conclusion that the silicon structures in the samples behave as sub-micrometer-sized electron guns. Dye covered glass substrates can be excited by the intense UV-light at about 5-20 mbar so that the red and green light of the dyes can easily be recognized under usual laboratory illumination. A luminous density of 240 Cd/m2 and 40 Cd/m2 could be achieved for the green luminescing ZnS:Cu,Al and the red luminescing YVO4:Eu respectively. Continuous UV-light emission could be observed for more than 1.5 hours at 2 mbar.
Heteroepitaxial films of (111)BaF2/CaF2 on (111)silicon, and (111)BaF2 on (100)silicon are used as substrates for the growth of IV-VI semiconductors. X-ray diffraction measurements show that p-type PbSxSe1-x(0.4 < × < 0.5) films grown on BaF2/CaF2/Si(111) substrates have bi-crystalline (111) and (100) characteristics. This, combined with thermal stress may cause the heteroepitaxy to peel off from the silicon. Films grown on BaF2(111)/Si(100) substrates display only the (111) peaks, and are robust with respect to thermal strain.
A novel epitaxial growth method for fabricating mesa patterns on a micrometer scale has been investigated. Electrical devices have been prepared employing this technique and their characteristics are in good agreement with those of mesa etched devices.
High quality GaAs and InP have been grown on silicon substrates, using low pressure metalorganic chemical vapor deposition technique. The growth temperature is 550°C and the growth rate 100 A/min.
Photoluminescence, X-ray diffraction and electrochemical profiling verified the high quality of these layers. The use of superlattices as buffer layers, (GaAs/GaInP) in the case of GaAs/Si and (GaInAsP/InP) in the case of InP/Si, decreased the amount of misfit dislocations in the epitaxial layer. Carrier concentrations as low as 5.1015 cm−3 have been measured by electrochemical profiling.
Different techniques are presented for the characterization of the two-layered system consisting of a precipitate-free zone and a precipitated zone, generated in CZ-grown silicon wafers by thermal processing. The diffusion length profile can be determined by surface photovoltage characteristics; measurements of the collection efficiency for excess carriers generated by alpha particles gives relevant information about the soft error performance. Finally, oxygen depth profiling by SIMS is discussed. Results are shown and compared with damage patterns obtained from cleavage face etching.
Continued improvements in the manufacturing of Cd1−xZnxTe (CZT) material have resulted in a practical thermoelectrically cooled X-ray and gamma-ray detector of very high energy resolution. A high resolution spectroscopy system was used to measure the Fano factor in CZT at temperatures down to -40°C. The best resolution of the 5.9 keV 55Fe peak was measured to be 188 eV FWHM, while the best resolution of the 59.5 keV 241Am peak was measured to be 482 eV FWHM. The minimum measured Fano factor was 0.082, with several measurements yielding a value of 0.089±0.005. With a resolution of 4.2 keV FWHM for the 662 keV peak of 137Cs, these detectors demonstrate excellent performance in detecting X-rays and gamma rays.
A detailed study of nanoindentation in Continuous Stiffness Mode (CSM) on a family of aromatic thermosetting polymers is carried out to identify the causes for the large variability in the extracted values of the elastic modulus of organic polymer films.
It is shown that the variation of parameters determining the dynamics of the force application such as the CSM frequency, the actual strain or load rate, and the duration of the waiting time segments can lead up to 20% difference in the estimated elastic modulus. The reason for this is related to creep, more specifically to viscoelastic behaviour, typical of organic films. On the other hand, pile-up is shown to have a negligible effect on the extraction of the elastic modulus from indentation depths below 50% of the film thickness, even for films with hardness as low as 0.13GPa. It is also concluded that neither pile-up nor creep phenomena can account for the overestimation of the elastic modulus with nanoindentation as compared to the values extracted with the surface acoustic waves technique.
A hexagonal lattice photonic crystal was fabricated inside the metallic microcavity. And a thin film of Alq3 was incorporated inside the textured cavity as an active medium. The microcavity is designed such that the modified photonic modes due to the textured structure can couple to the excited electronic states of Alq3. This leads to changes in the emission characteristics of Alq3. From the angle-resolved transmission (ARTR) results, the photonic bandgap was observed at all angles from normal incident to 60°. The presence of surface plasmon (SP) was observed in both TM and TE modes of the transmission. Compare to the bulk Alq3 photoluminescence spectrum, significant modification of the photoluminescence (PL) spectrum was observed in the angle-resolved photoluminescence (ARPL). The photoluminescence spectra showed clear suppression in luminescence intensity for the range inside the photonic bandgap. We use decouple approximation for the standing wave modes and derive the photonic waveguide characteristics for two-dimensional textured metallic microcavities. The theoretical result is in good agreement to the experimental result.