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In recent years, researchers in pre-Hispanic Central America have used new approaches that greatly amplify and enhance evidence of plants and their uses. This paper presents a case study from Puerto Escondido, located in the lower Ulúa River valley of Caribbean coastal Honduras. We demonstrate the effectiveness of using multiple methods in concert to interpret ethnobotanical practice in the past. By examining chipped-stone tools, ceramics, sediments from artifact contexts, and macrobotanical remains, we advance complementary inquiries. Here, we address botanical practices “in the home,” such as foodways, medicinal practices, fiber crafting, and ritual activities, and those “close to home,” such as agricultural and horticultural practices, forest management, and other engagements with local and distant ecologies. This presents an opportunity to begin to develop an understanding of ethnoecology at Puerto Escondido, here defined as the dynamic relationship between affordances provided in a botanical landscape and the impacts of human activities on that botanical landscape.
Multiple pregnancies (MP) are almost always the result of multiple ovulations (MO) (Ginther and Bergfelt, 1988). Twinning is the most common non-infectious cause of abortion in the mare (Roberts and Myhre, 1983) and represents a significant economic loss. As a consequence, further investigation into its occurrence and outcome is warranted in order to determine effective management practices.
Ultrasonic scanning was used to monitor and classify ovulation in 1582 Thoroughbred mares. Further ultrasonic scanning at Day 13 was used to identify and classify the resulting pregnancies (single pregnancy (SP), or MP)) in varying samples of mares. All MP mares underwent manual reduction of the smallest embryo at Day 13. 1170 mares, both SP and crushed MP, were monitored for the remainder of pregnancy with regard to pregnancy failure or success. Chi squared was used to test for significance throughout.
Longitude-coordinated high-precision photometry has been obtained a few weeks before the beginning of a strong Be and shell phase (1988) in HR 8762 (o And). The star showed variations of a few millimagnitudes in amplitude; i.e., just over the detection threshold. The classical 1.57-day double-wave period is still detected, showing that it probably never fades out completely, whatever the phase of the star. These variations can be interpreted as normal photospheric activity in a regular rotating B star. Although the variations of HR 8762 during our campaign were quite small, we could detect their amplitudes at a level of a few mmag.
We still have to check whether they are still “in phase” with previous photometric observations: if this is the case, it means that in the “spot” hypothesis, these (superficial?) features would remain in the same position on the photosphere, changing only in surface area and/or brightness with the star's activity.
We present preliminary results of a long-term spectroscopic monitoring of a magnitude-limited (V < 7.5) sample of OB-supergiants (07.5-B9) aimed at establishing the incidence of co-rotating, large-scale wind structures. In the optical, this can be achieved by detecting rotationally modulated variability in Hα. Dramatic line-profile variations operating on a daily (and in some cases on a hourly) timescale are observed. Firm conclusions regarding the origin of the variability must, however, await a detailed period analysis. There is no clear evidence for a causal link between photospheric and wind activities.
Studies of the atomic and molecular components of the interstellar medium in the vicinity of hot, massive stars have the potential of revealing a wealth of information on the way the star affects the distribution and physical state of the surrounding ISM during its various evolutionary phases, as well as potentially providing some information on the star itself and its past evolution.
The B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. As of July 2014, a total of 98 objects were observed over 20 nights with FORS2 and HARPSpol. Our preliminary results indicate that the fraction of magnetic OB stars with an organised, detectable field is low. This conclusion, now independently reached by two different surveys, has profound implications for any theoretical model attempting to explain the field formation in these objects. We discuss in this contribution some important issues addressed by our observations (e.g., the lower bound of the field strength) and the discovery of some remarkable objects.
Paleoethnobotanical analyses of samples excavated at Los Naranjos, Honduras, provide an unprecedented record of the diversity of plants used at an early center with monumental architecture and sculpture dating between 1000 and 500 B.C. and contribute to understandings of early village life in Mesoamerica. Los Naranjos is the major site adjacent to Lake Yojoa, where analysis of an important pollen core suggests very early clearing of the landscape and shifts in the relative prevalence of certain plants over time, including increases in maize. Our results from starch grain, phytolith, and macrobotanical analysis complicate interpretation of previous pollen core dates, suggesting that maize was not as central as expected to the early inhabitants of the settlement. Moreover, with identification of macrobotanical remains recovered from flotation of sediments and extraction of microbotanical remains from adhering sediments and the surfaces of obsidian tools, we can compare the potential of each analysis in interpretations of plant use. No single method would have allowed recovery and identification of all the plants documented across sample types. The presence of botanical residues on the obsidian tools provides direct evidence of processing. Even in the small sample analyzed, we can recognize tools used exclusively for culinary processing, tools used only for non-culinary tasks, and multi-purpose tools.
Nonvolatile unipolar resistive switching has been observed in Sm doped BFO thin films in Pt/Sm: BFO/SRO stack geometry. The initial forming voltage was found to be ∼ 11 V. After the forming process repeatable switching of the resistance of Sm:BFO film was obtained between low and high resistance states with nearly constant resistance ratio ∼ 105 and non overlapping switching voltages in the range of 0.7-1 V and 4-6 V respectively. The temperature dependent measurements of the resistance of the device indicated metallic and semiconducting conduction behavior in low and high resistance states respectively. The current conduction mechanism of the Pt/Sm:BFO/SRO device in low resistance states was found to be dominated by the Ohmic behavior while in case of high resistance state and at high voltages it deviated significantly from normal Ohmic behavior and was found to correspond the Pool-Frankel (PF) emission. The Pt/Sm:BFO/SRO structure also showed efficient photo-response in high and low resistance states with increase in photocurrent which was significantly higher in low resistance state when illuminated with white light.
The electron field emission properties of sulfur-assisted nanocrystalline carbon (n-C: S) thin films grown on molybdenum substrates by hot-filament CVD technique using methane-hydrogen (CH4/H2) and hydrogen sulfide-hydrogen (H2S/H2) gas mixtures were investigated. The field emission properties of the S-assisted films are reported as a function of sulfur concentration. The incorporation of S caused structural and microstructural changes that were characterized with SEM, AFM and Raman spectroscopy (RS). The S-assisted films show smoother surfaces and smaller grains than those grown without. The lowest turn-on field measured was around 4.5 – 5.0 V/μm films grown with 500 ppm of hydrogen sulfide and at 900 °C. The electron field emission properties of S-assisted films were also compared to those grown without sulfur (i.e., intrinsic). An inverse correlation between the threshold field (Ec) and sulfur concentration was found. These finding are attributed to defect induced states within the electronic band structure.
Polycrystalline diamond thin films deposited by the electron cyclotron resonance-assisted chemical vapor deposition (ECR-CVD) were investigated using spectroscopic ellipsometry (SE) from the near IR to UV range (830 nm-270 nm). Employing the conventional Bruggeman effective medium approximation (EMA) and linear regression analysis (LRA) to the raw ellipsometry data (ψλi), δ(λi)) provided the details about the film microstructure: (i) the multilayer structure and the ovearall thickness of the films; (ii) the volume fraction of the constituents (sp3 - and sp2- bonded carbon) and of voids in the bulk layer; (iii) the inhomogeneity of the structure along the growth axis and its variation with the seeding density; and (iv) the surface roughness layer. A simplified three-layer structural model consisting of an interfacial layer, an intermediate (or bulk) layer and the top surface roughness layer has been proposed to simulate the ellipsometry data. The results obtained through ellipsometry modeling such as surface roughness layer and overall film thickness were compared with rms surface roughness from atomic force microscopy (AFM) and profilometry respectively, in order to validate the model employed. The results such as fv and fsp2C for the bulk layer and its behavior with respect to process parameters are discussed.
Results are reported on the electron field emission properties of intrinsic and S- incorporated nanocrystalline carbon (n-C:S) thin films grown on molybdenum substrates by hotfilament CVD technique from methane-hydrogen (CH4/H2) and hydrogen sulphide-hydrogen (H2S/H2) gas pre mixtures respectively. The field emission properties for the S-incorporated films were investigated as a function of substrate temperature (TS). Lowest turn-on field was observed at 4.5 V/μm for one of the sample, which was grown at 900 °C, demonstrating the effect of sulfur addition. The S-incorporation also causes microstructural and structural changes, as characterized with ex situ techniques such as SEM, AFM and Raman spectroscopy (RS). Sassisted films show smoother surfaces and finer-grained than those grown without it. The electron field emission properties of S-assisted films is also compared to the film grown without it (intrinsic) at a particular deposition temperature and the turn-on field was found to be almost half for the S-assisted film than for the non S-assisted film. The influence of growth temperature was also conducted and an inverse correlation was found with the turn-on field (Ec). These studies were performed in order attempt to “tailor-the-material” as a viable cold cathode material by introducing the defecTS and altering the electronic structure.
Sulfur incorporated nanocrystalline carbon (n-C:S) thin films grown on molybdenum substrates by hot-filament chemical vapor deposition (HFCVD) using gas mixtures of methane, hydrogen and a range of hydrogen sulfide (H2S) concentrations are optically examined using Raman spectroscopy (RS) and ex situ spectroscopic phase modulated ellipsometry (SPME) from near IR to near UV (1.5-5.0 eV) obtaining their vibrational frequencies and pseudodielectric function, respectively. The ellipsometry data (<εr(E)>, <εi(E)>) were modeled using Bruggeman effective-medium theory (BEMT) and five parameters Forouhi and Bloomer (FB) dispersion Model. A simplified two-layer model consisting of a top layer comprising an aggregate mixture of sp3C+sp2C+void and a bulk layer (L2), defined as a dense amorphized FB-modeled material was found to simulate the data reasonably well. Through these simulations, it was possible to estimate the dielectric function of our n-C: S material, along with the optical bandgap (Eg), film thickness (d), and roughness layer (σ) as a function of [H2S]. The physical interpretation(s) of the modeling parameters obtained were discussed. The Raman and ellipsometry results indicate that the average size of nanocrystallites in the sulfur-incorporated carbon thin films becomes smaller with increasing H2S concentration, consistent with AFM measurements. The bandgap was found to decrease systematically with increasing H2S concentration, indicating the enhancement of midgap states and sp2 C network, in agreement with RS results. These results are compared to those obtained for the films grown without sulfur (n-C), in order to study the influence of sulfur addition to the CVD process. This analysis led to a correlation between the film microstructure and its electronic properties.
Previously, the pressure, temperature and strain rate sensitivities of transformation plasticity have been investigated for monotonic loading of Mg- PSZ. Research in this area has been extended to fully reversed cyclic loading of the type used in plastic strain control fatigue. Cyclic deformation experiments were performed to permit investigation of constitutive behavior under stable deformation conditions at microstrain levels. It was found that cyclic microstrains over a range of temperatures and strain rates were associated with reversible transformation plasticity in the strongly thermally-activated regime. These results are compared to the constitutive relations of transformation plasticity which have been previously developed to explain macrostrain observations.
The constitutive behavior of transformation plasticity in single phase fine grain Ce-TZP and polyphase coarse grain Mg-PSZ was studied. A material independent pressure sensitivity and a microstructure dependent strain rate sensitivity and temperature sensitivity were found to be associated with the transformation yield stress. Autocatalysis of various extent operates in all cases, forming broad macroscopic shear bands in TZP and fine crystallographic slip bands which terminate at grain boundaries in PSZ. Transformation plasticity is apparently athermal near the Mb temperature in TZP, but not in PSZ except in brittle fracture. A strong crystallographic texture of the transformed phase develops during deformation. These results are analyzed in terms of a shear-dilatant yield criterion and a rate equation which account for stress assistance in martensitic transformation. An elastic-plastic fracture mechanical model is developed to estimate both the shear and dilatation contributions to the transformation plastic work in the crack tip plastic zone. On the basis of approximately equal shear and dilatation contributions to transformation plasticity, the model predicts a transformation zone height which is four times that of the previous model, and a toughness increment which is two times that of the previous model. These predictions are found in good agreement with the reported toughness-zone size relationship. The effect of temperature and chemical stability on toughness is also rationalized.
During the five years of the mission, the Gaia spectrograph, the Radial Velocity
Spectrometer (RVS) will repeatedly survey the celestial sphere down to magnitude
V ~ 17–18. This talk presents: (i) the system which is currently developed within
the Gaia Data Processing and Analysis Consortium (DPAC) to reduce and calibrate the
spectra and to derive the radial and rotational velocities, (ii) the RVS expected
performances and (iii) scientific returns.
Hydrogenated amorphous silicon (a-Si:H) films prepared by the glow discharge (GD) technique show superior optoelectronic properties over those prepared by rf sputtering (RFS). To find out whether this is associated to structural differences in the amorphous network, we have carried out a comprehensive comparison of the Raman spectra of the two types of films grown at different substrate temperatures. The use of two properly chosen excitation radiations allowed the observation of the Raman spectra from the near surface versus that from the bulk of the films. The results show that the short-range order in the bulk of GD films is close to that of the ideal tetrahedral network, having an rms bond angle deviation (Δθ) of ≈9°. In contrast, the smallest value of Δθfound in the RFS films was ≈15°. There is also a short-range order inhomogeneity in both sets of materials that can be reduced significantly by selecting the appropriate substrate temperature. The intermediate-range disorder is relatively small and uniform in GD films, while large differences exist in this parameter between the surface and bulk of RFS films. In general, the results indicate that the short-range order and the inhomogeneity in intermediate-range order present in the RFS films cannot be improved to equal those of GD materials by annealing at temperatures low enough that no substantial hydrogen effusion occurs. These structural differences are argued to be the reasons for the superior phototransport properties of GD over RFS materials and are interpreted in terms of the differences between the two deposition processes.
The compositional and microstructural transformations induced by heavy ions (GeV/amu Fe and Si ions) on nanocomposite carbon (n-C) films were investigated by Raman Spectroscopy (RS), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectrscopy (XPS). Two identical sets of n-C films were prepared in a sulfur-assisted hot filament chemical vapor deposition (HFCVD) system using methane, hydrogen and hydrogen sulfide. Films with various sp3 C and sp2 C bonding distributions were present within each set, which were obtained by varying the substrate temperature (400-600 °C). One set of films was submitted to a 20 krad dose of energetic Si and Fe ions at the NASA space radiation simulation facility hosted in Brookhaven National Laboratory's Alternating Gradient Synchrotron (AGS). All the films showed the characteristic diamond (tetragonal sp3 C) band at around 1332 cm-1 and the graphitic (trigonal sp2 C) D and G bands at around 1350 and 1590 cm-1, respectively, evidencing their composite nature. The results indicate that sp2 C ←sp3 C interconversions take place in the nanocomposite carbon material during heavy ion irradiation. A mechanism is proposed to explain this behavior. The overall results imply that there could be a range of sp3/sp2 C ratios for which carbon bonding interconversion takes place under ion radiation without significant changes to the average composition of the material. Nanocomposite carbon materials with this characteristic would be radiation insensitive. A technique could be developed based on this carbon bonding interconversion property by using focused energetic beams onto carbon films to produce a robust information storage technology that would survive catastrophic events.