Alumina+Silica+/-Germanium Alteration in Smectite-Bearing Marathon Valley, Endeavour Crater Rim, Mars

Mars Exploration Rover Opportunity has been exploring Mars for 12+ years, and is presently investigating the geology of a western rim segment of 22 kilometers diameter, Noachian- aged Endeavour crater. The Alpha Particle X-ray Spectrometer has determined the compositions of a pre-impact lithology, the Matijevic fm., and polymict impact breccias ejected from the crater, the Shoemaker fm. Opportunity is now investigating a region named Marathon Valley that cuts southwest-northeast through the central portion of the rim segment and provides a window into the lower stratigraphic record. (Geographic names used here are informal.) At the head of Marathon Valley, referred to here as Upper Marathon Valley, is a shallow, ovoid depression approximately 2535 millimeters in size, named Spirit of Saint Louis. Layering inside Spirit of Saint Louis appears continuous with the Upper Marathon Valley rocks outside, indicating they are coeval. Spirit of Saint Louis is partly bounded by approximately 10-20 centimeters wide zone containing reddish altered rocks (red zone). Red zones also form prominent curvilinear features in Marathon Valley. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectra provide evidence for a really extensive Fe-Mg smectite in the Marathon Valley region, indicating distinct styles of aqueous alteration. The CRISM detections of smectites are based on metal-OH absorptions at approximately 2.3 and 2.4 micron that are at least two times the background noise level

Raman spectra of epitaxial graphene on SiC and of epitaxial graphene transferred to SiO2

Raman spectra were measured for mono-, bi- and trilayer graphene grown on SiC by solid state graphitization, whereby the number of layers was pre-assigned by angle-resolved ultraviolet photoemission spectroscopy. It was found that the only unambiguous fingerprint in Raman spectroscopy to identify the number of layers for graphene on SiC(0001) is the linewidth of the 2D (or D*) peak. The Raman spectra of epitaxial graphene show significant differences as compared to micromechanically cleaved graphene obtained from highly oriented pyrolytic graphite crystals. The G peak is found to be blue-shifted. The 2D peak does not exhibit any obvious shoulder structures but it is much broader and almost resembles a single-peak even for multilayers. Flakes of epitaxial graphene were transferred from SiC onto SiO2 for further Raman studies. A comparison of the Raman data obtained for graphene on SiC with data for epitaxial graphene transferred to SiO2 reveals that the G peak blue-shift is clearly due to the SiC substrate. The broadened 2D peak however stems from the graphene structure itself and not from the substrate.Comment: 27 pages, 8 figure

Tensor Analyzing Powers for Quasi-Elastic Electron Scattering from Deuterium

We report on a first measurement of tensor analyzing powers in quasi-elastic electron-deuteron scattering at an average three-momentum transfer of 1.7 fm$^{-1}$. Data sensitive to the spin-dependent nucleon density in the deuteron were obtained for missing momenta up to 150 MeV/$c$ with a tensor polarized $^2$H target internal to an electron storage ring. The data are well described by a calculation that includes the effects of final-state interaction, meson-exchange and isobar currents, and leading-order relativistic contributions.Comment: 4 pages, 3 figure

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STUDY QUESTION: What is the cost-effectiveness of in vitro fertilization(IVF) with conventional ovarian stimulation, single embryotransfer (SET) and subsequent cryocycles or IVF in a modified natural cycle (MNC) compared with intrauterine insemination with controlled ovarian hyperstimulation (IUI-COH) as a first-line treatment in couples with unexplained subfertility and an unfavourable prognosis on natural conception?. SUMMARY ANSWER: Both IVF strategies are significantly more expensive when compared with IUI-COH, without being significantly more effective. In the comparison between IVF-MNC and IUI-COH, the latter is the dominant strategy. Whether IVF-SET is cost-effective depends on society's willingness to pay for an additional healthy child. WHAT IS KNOWN ALREADY: IUI-COH and IVF, either after conventional ovarian stimulation or in a MNC, are used as first-line treatments for couples with unexplained or mild male subfertility. As IUI-COH is less invasive, this treatment is usually offered before proceeding to IVF. Yet, as conventional IVF with SET may lead to higher pregnancy rates in fewer cycles for a lower multiple pregnancy rate, some have argued to start with IVF instead of IUI-COH. In addition, IVF in the MNC is considered to be a more patient friendly and less costly form of IVF. STUDY DESIGN, SIZE, DURATION: We performed a cost-effectiveness analysis alongside a randomized noninferiority trial. Between January 2009 and February 2012, 602 couples with unexplained infertility and a poor prognosis on natural conception were allocated to three cycles of IVF-SET including frozen embryo transfers, six cycles of IVF-MNC or six cycles of IUI-COH. These couples were followed until 12 months after randomization. PARTICIPANTS/MATERIALS, SETTING, METHODS: We collected data on resource use related to treatment, medication and pregnancy from the case report forms. We calculated unit costs from various sources. For each of the three strategies, we calculated the mean costs and effectiveness. Incremental cost-effectiveness ratios (ICER) were calculated for IVF-SET compared with IUI-COH and for IVF-MNC compared with IUI-COH. Nonparametric bootstrap resampling was used to investigate the effect of uncertainty in our estimates. MAIN RESULTS AND THE ROLE OF CHANCE: There were 104 healthy children (52%) born in the IVF-SET group, 83 (43%) the IVF-MNC group and 97 (47%) in the IUI-COH group. The mean costs per couple were (sic)7187 for IVF-SET, (sic)8206 for IVF-MNC and (sic)5070 for IUI-COH. Compared with IUI-COH, the costs for IVF-SET and IVF-MNC were significantly higher (mean differences (sic)2117; 95% CI: (sic)1544-(sic)2657 and (sic)3136, 95% CI: (sic)2519-(sic)3754, respectively). The ICER for IVF-SET compared with IUI-COH was (sic)43 375 for the birth of an additional healthy child. In the comparison of IVF-MNC to IUI-COH, the latter was the dominant strategy, i.e. more effective at lower costs. LIMITATIONS, REASONS FOR CAUTION: We only report on direct health care costs. The present analysis is limited to 12 months. WIDER IMPLICATIONS OF THE FINDINGS: Since we found no evidence in support of offering IVF as a first-line strategy in couples with unexplained and mild subfertility, IUI-COH should remain the treatment of first choice

Grain Boundaries in Graphene on SiC(0001ˉ\bar{1}) Substrate

Grain boundaries in epitaxial graphene on the SiC(000$\bar{1}$) substrate are studied using scanning tunneling microscopy and spectroscopy. All investigated small-angle grain boundaries show pronounced out-of-plane buckling induced by the strain fields of constituent dislocations. The ensemble of observations allows to determine the critical misorientation angle of buckling transition $\theta_c = 19 \pm~2^\circ$. Periodic structures are found among the flat large-angle grain boundaries. In particular, the observed $\theta = 33\pm2^\circ$ highly ordered grain boundary is assigned to the previously proposed lowest formation energy structural motif composed of a continuous chain of edge-sharing alternating pentagons and heptagons. This periodic grain boundary defect is predicted to exhibit strong valley filtering of charge carriers thus promising the practical realization of all-electric valleytronic devices