Size dependent tunnel diode effects in gold tipped CdSe nanodumbbells.

PubMed

Saraf, Deepashri; Kumar, Ashok; Kanhere, Dilip; Kshirsagar, Anjali

2017-02-07

We report simulation results for scanning tunneling spectroscopy of gold-tipped CdSe nanodumbbells of lengths ∼27 Å and ∼78 Å. Present results are based on Bardeen, Tersoff, and Hamann formalism that takes inputs from ab initio calculations. For the shorter nanodumbbell, the current-voltage curves reveal negative differential conductance, the characteristic of a tunnel diode. This behaviour is attributed to highly localized metal induced gap states that rapidly decay towards the center of the nanodumbbell leading to suppression in tunneling. In the longer nanodumbbell, these gap states are absent in the central region, as a consequence of which zero tunneling current is observed in that region. The overall current-voltage characteristics for this nanodumbbell are observed to be largely linear near the metal-semiconductor interface and become rectifying at the central region, the nature being similar to its parent nanorod. The cross-sectional heights of these nanodumbbells also show bias-dependence where we begin to observe giant Stark effect features in the semiconducting central region of the longer nanodumbbell.

Improved marine reservoir age estimation and palaeoclimate synchronisation of the early Holocene Levantine/NW-Arabian region based on identification of the S1 tephra in Dead Sea and Tayma palaeolake sediments

NASA Astrophysics Data System (ADS)

Neugebauer, Ina; Wulf, Sabine; Schwab, Markus J.; Serb, Johanna; Plessen, Birgit; Appelt, Oona; Brauer, Achim

2017-04-01

Due to a lack of tephras identified in marine and terrestrial palaeoclimate records from the Levantine-Arabian area, this region is still not sufficiently connected to the eastern Mediterranean tephrostratigraphical lattice. Here we report on the first finding of cryptotephra in the Holocene lacustrine sediment records of the Dead Sea and the Tayma palaeolake (NW Arabian Peninsula). The major elemental chemistry of the rhyolitic glass shards proves this tephra identical to the distal 'S1 tephra' identified in the Yammoûneh palaeolake, Lebanon (Develle et al, 2009), in a marine sediment record from the SE Levantine basin (Hamann et al., 2010) and in the Sodmein Cave archaeological site in Egypt (Barton et al., 2015). The 'S1 tephra', most likely corresponding to the early Holocene 'Dikkartın' dome eruption of the Erciyes Daǧ volcano in central Anatolia, Turkey, has been dated in the marine record at 8830 ± 140 cal yr BP. We present new age estimates of the 'S1 tephra' based on radiocarbon dating of terrestrial plant remains (Migowski et al., 2004) and pollen concentrates (Dinies et al., 2015), which reveal modelled ages of 8939 ± 83 cal yr BP in the Dead Sea sediments and 9041 ± 254 cal yr BP in Tayma. This allows the estimation of an early Holocene marine reservoir age of ca. 320 years in the SE Levantine Sea. The timing of the volcanic eruption during the early Holocene humid period, which led to the formation of sapropel S1 in the Mediterranean Sea, and the identification of the 'S1 tephra' more than 1200 km to the south are crucial for the synchronisation of marine and terrestrial palaeoclimate records in the eastern Mediterranean region. References: Barton et al., 2015. The role of cryptotephra in refining the chronology of Late Pleistocene human evolution and cultural change in North Africa. Quaternary Sci. Rev. 118, 151-169. Develle et al., 2009. Early Holocene volcanic ash fallout in the Yammoûneh lacustrine basin (Lebanon): Tephrochronological

Physiology of transgenic mice with brown fat ablation: obesity is due to lowered body temperature.

PubMed

Klaus, S; Münzberg, H; Trüloff, C; Heldmaier, G

1998-02-01

We investigated the physiological basis for development of obesity in uncoupling protein-diphtheria toxin A chain (UCP-DTA) transgenic mice. In these mice the promoter of the brown adipose tissue (BAT)-specific UCP was used to drive expression of DTA, resulting in decreased BAT function and development of obesity and insulin resistance (Lowell, B. B., S. V. Susulic, A. Hamann, J. A. Lawitts, J. Himms-Hagen, B. B. Boyer, L. Kozak, and J. S. Flier. Nature 366: 740-742, 1994). In adult UCP-DTA mice, we measured food intake and food assimilation, locomotor activity, metabolic rate, and body temperature in comparison to control animals. No differences could be observed in food intake or assimilation and locomotor activity. Weight-specific metabolic rates at temperatures between 20 and 37 degrees C, however, were consistently lower in transgenic mice. Continuous telemetric recording of core body temperature showed that transgenic mice displayed a downshift in body temperature levels of approximately 0.9 degree C. In summary, we provide evidence that attenuated body temperature levels alone can be responsible for development of obesity and that BAT thermogenesis is a major determinant of body temperature levels in rodents.

Quantum Monte Carlo Simulations of the Quartz to Stishovite Transition in SiO2

NASA Astrophysics Data System (ADS)

Cohen, R. E.; Towler, Mike; Lopez Rios, Pablo; Drummond, Neil; Needs, Richard

2007-03-01

The quartz-stishovite transition has been a long standing problem for density functional theory (DFT). Although conventional DFT computations within the local density approximation (LDA) give reasonably good properties of silica phases individually, they do not give the energy difference between quartz and stishovite accurately. The LDA gives stishovite as a lower energy structure than quartz at zero pressure, which is incorrect. The generalized gradient approximation (GGA) has been shown to give the correct energy difference between quartz and stishovite (about 0.5 eV/formula unit) (Hamann, PRL 76, 660, 1996; Zupan et al., PRB 58, 11266, 1998), and it was generally thought that the GGA was simply a better approximation than the LDA. However, closer inspection shows that other properties are not better for the GGA than the LDA, so there is room for improvement. A new density functional that is an improvement for most materials unfortunately does not improve the quartz-stishovite transition (Wu and Cohen, PRB 73, 235116, 2006). We are performing QMC computations using the CASINO code to obtain the accurate energy difference between quartz and stishovite to obtain more accurate high pressure properties, and to better understand the errors on DFT and how DFT can be improved.

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

DOE PAGES

Li, Liang; Zhang, Rui; Vinson, John; ...

2018-03-05

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Comparison of the FaroArm Laser Scanner With the MicroScribe Digitizer Using Basicranial Measurements.

PubMed

Vu, Alexander F; Chundury, Rao V; Perry, Julian D

2017-07-01

To compare the results of a mechanical 3-dimensional laser scanner for craniofacial measurements of the basicranium to a validated coordinate device. Access was granted by the Cleveland Natural History Museum to evaluate the Hamann-Todd Human Osteological Collection for this study. The MicroScribe and the FaroArm were used to gather coordinate data of various bony landmarks measurements including the prosthion, staphylion, hormion, and basion. Seventy-three human skulls were measured and scanned. Distances calculated from the coordinates were tested for agreement using the Bland-Altman test. There were no significant differences in the bias or slope measures between the MicroScribe and the FaroArm. In addition to the univariate test for slope significance, multivariable analysis using age, gender, and race as additional predictors showed no significant difference in any variable (P < 0.05). This is the first study demonstrating agreement of the FaroArm in any human skull measurement with the validated MicroScribe digitizer. Compared with the MicroScribe digitizer, the FaroArm allows for 3-dimensional imaging and the ability to store, handle, and view data digitally. Future use of real-time facial measurements using the FaroArm offers potential for improved surgical planning and outcomes.

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Liang; Zhang, Rui; Vinson, John

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Scaling theory of tunneling diffusion of a heavy particle interacting with phonons

NASA Astrophysics Data System (ADS)

Itai, K.

1988-05-01

The author discusses motion of a heavy particle in a d-dimensional lattice interacting with phonons by different couplings. The models discussed are characterized by the dimension (d) and the set of two indices (λ,ν) which specify the momentum dependence of the dispersion of phonon energy (ω~kν) and of the particle-phonon coupling (~kλ). Scaling equations are derived by eliminating the short-time behavior in a renormalization-group scheme using Feynman's path-integral method, and the technique developed by Anderson, Yuval, and Hamann for the Kondo problem. The scaling equations show that the particle is localized in the strict sense when (2λ+d+2)/ν<2 and is not localized when (2λ+d+2)/ν>2. In the marginal case, i.e., (2λ+d+2)/ν=2, localization occurs for couplings larger than a critical value. This marginal case shows Ohmic dissipation and is a close analogy to the Caldeira-Leggett model for macroscopic quantum tunneling and the hopping models of Schmid's type. For large-enough (2λ+d+2)/ν, the particle is considered practically localized, but the origin of the localization is quite different from that for (2λ+d+2)/ν<=2. .AE

Adult females and pubic bone growth.

PubMed

Fuller, K

1998-07-01

Previous research (Tague [1994] Am. J. Phys. Anthropol. 95:27-40) has shown an age effect in pubic bone length among adult women. Tague found that in three prehistoric Native American skeletal samples, women aged 18-24 had a significantly shorter linea terminalis than did women aged 25 and older. The purpose of this research is to determine whether such a difference can be discerned in other female skeletal samples. Three female skeletal samples were used in this analysis: 75 African-American and 42 European-American females aged 18-39 from the Hamann-Todd Collection (collected between 1893 and 1938; Iscan, 1990) and 99 African-American females aged 18-39 from the Terry Collection (collected between 1914 and 1965; Cobb, 1933; Iscan, 1990). Several chord measurements of pubic bone length along the linea terminalis were analyzed by one-tailed t-tests of the separate samples subdivided into two age groups: 18-24 and 25-39 years. Of 15 comparisons between age groups, none differed significantly by age group within each sample. It is concluded that the observed significant difference in pubic bone length in the Native American female skeletal samples cannot be replicated in other samples and that there is no age effect on pubic bone length in the samples tested in this analysis. Tague's findings reflect either the occurrence of late menarche in prehistoric populations or differential survivorship.

A test of the preauricular sulcus as an indicator of sex.

PubMed

Karsten, Jordan K

2018-03-01

Although the presence of a preauricular sulcus is often cited as an indicator of female sex, very little research has been conducted to substantiate this claim. This article examines both the relationship between the incidence and morphology of the preauricular sulcus and sex. A total of 500 left ossa coxae from the Hamann-Todd Human Osteological Collection belonging to 261 males and 239 females were examined to investigate the relationship between the preauricular sulcus and sex. The sample includes both American Blacks and Whites. Each individual was scored based on groove presence and morphology. Differences between the sexes in terms of overall prevalence and morphology were investigated using chi-squared tests. Additionally, possible relationships between ancestry and the manifestation of the preauricular sulcus were investigated using multiple regression analysis. Overall, the presence or absence of the preauricular sulcus resulted in correct sex assessment in 75.8% of ossa coxae. However, the accuracy differed between the sexes, with 62.84% of males and 89.96% of females being assessed correctly. Males were significantly more likely to display a short, narrow sulcus (score 4) than females, whereas females were observed to be significantly more likely to have a wide, long sulcus. Ancestry was not related to sulcus manifestation. The results presented here suggest that the presence of a preauricular sulcus should not be considered positive proof of female sex. However, the complete lack of a sulcus could be considered suggestive of male sex. © 2017 Wiley Periodicals, Inc.

Gender differences in the anatomy of the distal femur.

PubMed

Gillespie, R J; Levine, A; Fitzgerald, S J; Kolaczko, J; DeMaio, M; Marcus, R E; Cooperman, D R

2011-03-01

Recently, gender-specific designs of total knee replacement have been developed to accommodate anatomical differences between males and females. We examined a group of male and female distal femora matched for age and height, to determine if there was a difference in the aspect ratio (mediolateral distance versus anteroposterior distance) and the height of the anterior flange between the genders. The Hamann-Todd Collection provided 1207 skeletally mature cadaver femora. The femoral length, the anteroposterior height, height of the lateral and medial flanges and the mediolateral width were measured in all the specimens. The mechanical axis of the femur, the cut articular width and the aspect ratio were assessed. Statistical analysis of the effect of gender upon the aspect ratio and the lateral and medial flanges was undertaken, controlling for age, height and race. The mean aspect ratio of male femora was 1.21 (SD 0.07) and of female femora it was 1.16 (SD 0.06) (p < 0.001). There was no significant difference between male and female specimens in the mean size of the lateral flange (6.57 mm (SD 2.57) and 7.02 mm (SD 2.36), respectively; p = 0.099) or of the medial flange (3.03 mm (SD 2.47) and 3.56 mm (SD 2.32), respectively; p = 0.67). Future work in the design of knee prostheses should take into account the overall variability of the anatomy of the distal femur.

Correlation of Periodontal Disease With Inflammatory Arthritis in the Time Before Modern Medical Intervention.

PubMed

Rothschild, Bruce

2017-03-01

Controversy exists regarding possible correlation of periodontal disease with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Confounding factors may relate to stringency of inflammatory disease diagnosis and the effect of therapeutic intervention for RA on periodontal disease. These factors are investigated in this study. Forty-five individuals with documented RA (n = 15), spondyloarthropathy (n = 15), and calcium pyrophosphate deposition disease (CPPD) (n = 15), from the Hamann-Todd collection of human skeletons compiled from 1912 to 1938, and 15 individuals contemporarily incorporated in the collection were examined for tooth loss, cavity occurrence, average and maximum lingual and buccal depth of space between tooth and bone, periosteal reaction, serpentine bone resorption, abscess formation, and root penetration of the bone surface and analyzed by analysis of variance. Tooth loss was common, but actual number of teeth lost, cavity occurrence, average and maximum lingual and buccal depth of space between tooth and bone, periosteal reaction, serpentine grooving surrounding teeth (considered a sign of inflammation), abscess formation, and root exposure (penetration of bone surface) were indistinguishable among controls and individuals with RA, spondyloarthropathy, and CPPD. Although many factors can affect periodontal disease, presence of inflammatory arthritis does not appear to be one of them. The implication is that dental disease was common in the general population and not necessarily associated with arthritis, at least before the advent of modern rheumatologic medications. As specific diagnosis did not affect prevalence, perhaps current prevalence controversy may relate to current intervention, a subject for further study.

A cadaveric investigation into the demographic and bony alignment properties associated with osteoarthritis of the patellofemoral joint.

PubMed

Weinberg, Douglas S; Tucker, Braden J; Drain, Joseph P; Wang, David M; Gilmore, Allison; Liu, Raymond W

2016-06-01

Patellofemoral joint osteoarthritis is common, although circumstances dictating its evolution and pathogenesis remain unclear. Advances in surgical technique have improved the ability to modify long-bone alignment in the coronal, sagittal, and axial planes. However, to our knowledge, there is no significant long-term data available in regard to the relationship between anatomic alignment parameters most amenable to surgical modification and patellofemoral joint osteoarthritis. Five-hundred and seventy-one cadaveric skeletons were obtained from the Hamann-Todd osteological collection. Mechanical lateral distal femoral angle, medial proximal tibial angle, tibial slope, femoral version, tibial torsion, the position of the tibial tubercle relative to the width of the tibial plateau, trochlear depth, and patellar size were measured using validated techniques. A previously published grading system for patellofemoral joint arthritis was used to quantify macroscopic signs of degenerative joint disease. Increasing age (standardized beta 0.532, p<0.001), female gender (standardized beta 0.201, p=0.002), and decreasing mechanical lateral distal femoral angle (standardized beta -0.128, p=0.025) were independent correlates of increased patellofemoral joint osteoarthritis. A relatively more laterally positioned tibial tubercle trended towards predicting patellofemoral joint osteoarthritis (standardized beta 0.080, p=0.089). These findings confirm that patellofemoral joint osteoarthritis is strongly associated with increasing age and female gender. Valgus alignment of the distal femur, a relatively more lateral location of the tibial tubercle, and a shallower trochlear grove appear to have modest effects on the development of patellofemoral joint osteoarthritis. Copyright © 2016 Elsevier B.V. All rights reserved.

WIND STRUCTURE AND LUMINOSITY VARIATIONS IN THE WOLF-RAYET/LUMINOUS BLUE VARIABLE HD 5980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Georgiev, Leonid; Koenigsberger, Gloria; Hillier, D. John

Over the past 40 years, the massive luminous blue variable/Wolf-Rayet system HD 5980 in the Small Magellanic Cloud (SMC) has undergone a long-term S Doradus-type variability cycle and two brief and violent eruptions in 1993 and 1994. In this paper we analyze a collection of UV and optical spectra obtained between 1979 and 2009 and perform CMFGEN model fits to spectra of 1994, 2000, 2002, and 2009. The results are as follows: (1) the long-term S Dor-type variability is associated with changes of the hydrostatic radius; (2) the 1994 eruption involved changes in its bolometric luminosity and wind structure; (3)more » the emission-line strength, the wind velocity, and the continuum luminosity underwent correlated variations in the sense that a decreasing V{sub {infinity}} is associated with increasing emission line and continuum levels; and (4) the spectrum of the third star in the system (Star C) is well fit by a T{sub eff} = 32 K model atmosphere with SMC chemical abundances. For all epochs, the wind of the erupting star is optically thick at the sonic point and is thus driven mainly by the continuum opacity. We speculate that the wind switches between two stable regimes driven by the 'hot' (during the eruption) and the 'cool' (post-eruption) iron opacity bumps as defined by Lamers and Nugis and Graefener and Hamann, and thus the wind may undergo a bi-stability jump of a different nature from that which occurs in OB stars.« less

Lumbar facet anatomy changes in spondylolysis: a comparative skeletal study.

PubMed

Masharawi, Youssef; Dar, Gali; Peleg, Smadar; Steinberg, Nili; Alperovitch-Najenson, Dvora; Salame, Khalil; Hershkovitz, Israel

2007-07-01

Opinions differ as to the exact mechanism responsible for spondylolysis (SP) and whether individuals with specific morphological characteristics of the lumbar vertebral neural arch are predisposed to SP. The aim of our study was to reveal the association between SP and the architecture of lumbar articular facets and the inter-facet region. Using a Microscribe three-dimensional apparatus (Immersion Co., San Jose, CA, USA), length, width and depth of all articular facets and all inter-facet distances in the lumbar spine (L1-L5) were measured. From the Hamann-Todd Human Osteological Collection (Cleveland Museum of Natural History, OH, USA) 120 normal male skeletons with lumbar spines in the control group and 115 with bilateral SP at L5 were selected. Analysis of variance was employed to examine the differences between spondylolytic and normal spines. Three profound differences between SP and the norm appeared: (1) in individuals with SP, the size and shape of L4's neural arch had significantly greater inter-facet widths, significantly shorter inter-facet heights and significantly shorter and narrower articular facets; (2) only in the L4 vertebra in individuals with SP was the inferior inter-facet width greater in size than the superior inter-facet width of the vertebra below (L5) (38.7 mm versus 40 mm); (3) in all lumbar vertebrae, the right inferior articular facets in individuals with SP were flatter compared to the control group. Individuals with L4 "SP" characteristics are at a greater risk of developing fatigue fractures in the form of spondylolysis at L5.

Effect of dispersion on surface interactions of cobalt(II) octaethylporphyrin monolayer on Au(111) and HOPG(0001) substrates: a comparative first principles study.

PubMed

Chilukuri, Bhaskar; Mazur, Ursula; Hipps, K W

2014-07-21

A density functional theory study of a cobalt(II) octaethylporphyrin (CoOEP) monolayer on Au(111) and HOPG(0001) surfaces was performed under periodic boundary conditions. Calculations with and without dispersion corrections are performed and the effect of van der Waals forces on the interface properties is analyzed. Calculations have determined that the CoOEP molecule tends to bind at the 3-fold and the 6-fold center sites on Au(111) and HOPG(0001), respectively. Geometric optimizations at the center binding sites have indicated that the porphyrin molecules (in the monolayer) lie flat on both substrates. Calculations also reveal that the CoOEP monolayer binds slightly more strongly to Au(111) than to HOPG(0001). Charge density difference plots disclose that charge is redistributed mostly around the porphyrin plane and the first layer of the substrates. Dispersion interactions cause a larger substrate to molecule charge pushback on Au(111) than on HOPG. CoOEP adsorption tends to lower the work functions of either substrate, qualitatively agreeing with the experimental photoelectron spectroscopic data. Comparison of the density of states (DOS) of the isolated CoOEP molecule with that on gold and HOPG substrates showed significant band shifts around the Fermi energy due to intermolecular orbital hybridization. Simulated STM images were plotted with the Tersoff-Hamann approach using the local density of states, which also agree with the experimental results. This study elucidates the role of dispersion for better describing porphyrin-substrate interactions. A DFT based overview of geometric, adsorption and electronic properties of a porphyrin monolayer on conductive surfaces is presented.

Wolf-Rayet Stars

NASA Astrophysics Data System (ADS)

Hamann, Wolf-Rainer; Sander, Andreas; Todt, Helge

Nearly 150 years ago, the French astronomers Charles Wolf and Georges Rayet described stars with very conspicuous spectra that are dominated by bright and broad emission lines. Meanwhile termed Wolf-Rayet Stars after their discoverers, those objects turned out to represent important stages in the life of massive stars. As the first conference in a long time that was specifically dedicated to Wolf-Rayet stars, an international workshop was held in Potsdam, Germany, from 1.-5. June 2015. About 100 participants, comprising most of the leading experts in the field as well as as many young scientists, gathered for one week of extensive scientific exchange and discussions. Considerable progress has been reported throughout, e.g. on finding such stars, modeling and analyzing their spectra, understanding their evolutionary context, and studying their circumstellar nebulae. While some major questions regarding Wolf-Rayet stars still remain open 150 years after their discovery, it is clear today that these objects are not just interesting stars as such, but also keystones in the evolution of galaxies. These proceedings summarize the talks and posters presented at the Potsdam Wolf-Rayet workshop. Moreover, they also include the questions, comments, and discussions emerging after each talk, thereby giving a rare overview not only about the research, but also about the current debates and unknowns in the field. The Scientific Organizing Committee (SOC) included Alceste Bonanos (Athens), Paul Crowther (Sheffield), John Eldridge (Auckland), Wolf-Rainer Hamann (Potsdam, Chair), John Hillier (Pittsburgh), Claus Leitherer (Baltimore), Philip Massey (Flagstaff), George Meynet (Geneva), Tony Moffat (Montreal), Nicole St-Louis (Montreal), and Dany Vanbeveren (Brussels).

Composite Spectra of Broad Absorption Line Quasars in SDSS-III BOSS

NASA Astrophysics Data System (ADS)

Herbst, Hanna; Hamann, Fred; Paris, Isabelle; Capellupo, Daniel M.

2017-01-01

We present preliminary results from a study of broad absorption line (BAL) quasars in the SDSS-III BOSS survey. We’re particularly interested in BALs because they arise from quasar outflows, which may be a source of feedback to the host galaxy. We analyze median composite spectra for BOSS QSOs in the redshift range 2.1 to 3.4 sorted by the strength of the BAL absorption troughs, parameterized by the Balnicity Index (BI), to study trends in the emission and absorption properties of BAL quasars. The wavelength coverage and high number of quasars observed in the BOSS survey allow us to examine BALs in the Lyman forest. Our main preliminary results when sorting the quasars by BI are 1) doublet absorption lines such as P V 1128A show a 1:1 ratio across all BI, indicating large column densities at all BI. This suggests that weaker BAL troughs result from smaller covering fractions rather than lower column densities. 2) The He II emission line, which is a measure of the far-UV/near-UV hardness of the ionizing continuum, is weaker in the larger BI composite spectra, indicating a far-UV spectral softening correlated with BI. This is consistent with the radiatively-driven BAL outflows being helped by intrinsically weaker ionizing continuum shapes (e.g., Baskin, Laor, and Hamann 2013). We also find a trend for slightly redder continuum slopes in the larger BI composite spectra, suggesting that the slope differences in the near-UV are also intrinsic.

Protection of obstetric dimensions in a small-bodied human sample.

PubMed

Kurki, Helen K

2007-08-01

In human females, the bony pelvis must find a balance between being small (narrow) for efficient bipedal locomotion, and being large to accommodate a relatively large newborn. It has been shown that within a given population, taller/larger-bodied women have larger pelvic canals. This study investigates whether in a population where small body size is the norm, pelvic geometry (size and shape), on average, shows accommodation to protect the obstetric canal. Osteometric data were collected from the pelves, femora, and clavicles (body size indicators) of adult skeletons representing a range of adult body size. Samples include Holocene Later Stone Age (LSA) foragers from southern Africa (n = 28 females, 31 males), Portuguese from the Coimbra-identified skeletal collection (CISC) (n = 40 females, 40 males) and European-Americans from the Hamann-Todd osteological collection (H-T) (n = 40 females, 40 males). Patterns of sexual dimorphism are similar in the samples. Univariate and multivariate analyses of raw and Mosimann shape-variables indicate that compared to the CISC and H-T females, the LSA females have relatively large midplane and outlet canal planes (particularly posterior and A-P lengths). The LSA males also follow this pattern, although with absolutely smaller pelves in multivariate space. The CISC females, who have equally small stature, but larger body mass, do not show the same type of pelvic canal size and shape accommodation. The results suggest that adaptive allometric modeling in at least some small-bodied populations protects the obstetric canal. These findings support the use of population-specific attributes in the clinical evaluation of obstetric risk. (c) 2007 Wiley-Liss, Inc.

Characterization of proximal femoral anatomy in the skeletally-immature patient.

PubMed

Beutel, B G; Girdler, S J; Collins, J A; Otsuka, N Y; Chu, A

2018-04-01

The morphology of the proximal femur has been extensively studied in the adult population. However, no literature providing a comprehensive evaluation of the anatomy in paediatric patients exists. The current study aims to characterize such anatomy in skeletally-immature patients, examine potential differences between genders, and analyze how these anatomical parameters change with age. Cadaveric femurs from the Hamann-Todd Osteological Collection were examined. Specimens with open physes and no skeletal disease or deformity were included for analysis. Age and gender were recorded for each specimen. Each femur was photographed in standardized modified axial and anteroposterior views. In all, 14 proximal femoral anatomical parameters were measured from these photographs. Comparisons between genders and age were calculated. A total of 43 femurs from ages four to 17 years met inclusion criteria. The majority were female (56%); no difference existed in age between genders (p = 0.62). The specimens had a neutral mean neck-shaft angle (130.7º) and anteversion (12.8º), and the sphericity of the ossified femoral heads was symmetrical. Male specimens had significantly higher alpha angles (p = 0.01), posterior offset (p = 0.02), neck width (p = 0.04) and head-neck length ratio (p = 0.02) values than female specimens. Strong positive correlations exist between length/size parameters and age, while negligible correlations were noted for angular measurements. This study establishes reference values for a comprehensive list of anatomical parameters for the skeletally-immature ossified proximal femur. It highlights gender differences in morphology and demonstrates that angular characteristics remain relatively stable while length parameters generally increase with age. Level III Diagnostic.

Effect of Dispersion on Surface Interactions of Cobalt(II) Octaethylporphyrin Monolayer on Au(111) and HOPG(0001) Substrates: a Comparative First Principles Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chilukuri, Bhaskar; Mazur, Ursula; Hipps, Kerry W.

A density functional theory study of a cobalt(II) octaethylporphyrin (CoOEP) monolayer on Au(111) and HOPG(0001) surfaces was performed under periodic boundary conditions. Calculations with and without dispersion corrections are performed and the effect of van der Waals forces on the interface properties is analyzed. Calculations have determined that the CoOEP molecule tends to bind at the 3-fold and the 6-fold center sites on Au(111) and HOPG(0001), respectively. Geometric optimizations at the center binding sites have indicated that the porphyrin molecules (in the monolayer) lie flat on both substrates. Calculations also reveal that the CoOEP monolayer binds slightly more strongly tomore » Au(111) than to HOPG(0001). Charge density difference plots disclose that charge is redistributed mostly around the porphyrin plane and the first layer of the substrates. Dispersion interactions cause a larger substrate to molecule charge pushback on Au(111) than on HOPG. CoOEP adsorption tends to lower the work functions of either substrate, qualitatively agreeing with the experimental photoelectron spectroscopic data. Comparison of the density of states (DOS) of the isolated CoOEP molecule with that on gold and HOPG substrates showed significant band shifts around the Fermi energy due to intermolecular orbital hybridization. Simulated STM images were plotted with the Tersoff–Hamann approach using the local density of states, which also agree with the experimental results. This study elucidates the role of dispersion for better describing porphyrin–substrate interactions. A DFT based overview of geometric, adsorption and electronic properties of a porphyrin monolayer on conductive surfaces is presented.« less

Lumbar facet anatomy changes in spondylolysis: a comparative skeletal study

PubMed Central

Dar, Gali; Peleg, Smadar; Steinberg, Nili; Alperovitch-Najenson, Dvora; Salame, Khalil; Hershkovitz, Israel

2007-01-01

Opinions differ as to the exact mechanism responsible for spondylolysis (SP) and whether individuals with specific morphological characteristics of the lumbar vertebral neural arch are predisposed to SP. The aim of our study was to reveal the association between SP and the architecture of lumbar articular facets and the inter-facet region. Methods: Using a Microscribe three-dimensional apparatus (Immersion Co., San Jose, CA, USA), length, width and depth of all articular facets and all inter-facet distances in the lumbar spine (L1–L5) were measured. From the Hamann-Todd Human Osteological Collection (Cleveland Museum of Natural History, OH, USA) 120 normal male skeletons with lumbar spines in the control group and 115 with bilateral SP at L5 were selected. Analysis of variance was employed to examine the differences between spondylolytic and normal spines. Results: Three profound differences between SP and the norm appeared: (1) in individuals with SP, the size and shape of L4’s neural arch had significantly greater inter-facet widths, significantly shorter inter-facet heights and significantly shorter and narrower articular facets; (2) only in the L4 vertebra in individuals with SP was the inferior inter-facet width greater in size than the superior inter-facet width of the vertebra below (L5) (38.7 mm versus 40 mm); (3) in all lumbar vertebrae, the right inferior articular facets in individuals with SP were flatter compared to the control group. Conclusions: Individuals with L4 “SP” characteristics are at a greater risk of developing fatigue fractures in the form of spondylolysis at L5. PMID:17440753

Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis.

PubMed

Gebhart, Jeremy J; Bohl, Michael S; Weinberg, Douglas S; Cooperman, Daniel R; Liu, Raymond W

2015-09-01

The etiology of slipped capital femoral epiphysis (SCFE) is multifactorial, but the role of sagittal balance of the pelvis as a contributing factor to its development has not been well studied. Our primary purpose was to determine whether a smaller pelvic incidence (PI), a position-independent anatomic parameter that regulates pelvic orientation, could be a factor that increases shear stress in the epiphyseal growth plate and potentially contributes to the development of SCFE. We also set out to determine whether acetabular retroversion was associated with SCFE. We obtained 14 cadaveric pelvi from the Hamann-Todd Osteological Collection whose femurs showed evidence of post-SCFE deformity. Two hundred age-matched, sex-matched, and race-matched pelvi were used as controls. PI and acetabular version were measured using standardized lateral photographs and goniometers, respectively. T tests were performed to evaluate for differences in measured parameters between groups. The mean PI was 40.6±6.1 degrees for SCFE specimens and 47.4±9.9 degrees for normal specimens (P=0.01). The mean version of SCFE and normal acetabula was 15±7 and 17±6 degrees, respectively (P=0.39). There was also no significant difference in version between SCFE acetabula and the contralateral, uninvolved acetabular of the same specimen (15±7 vs. 17±8 degrees, P=0.33). Specimens with SCFE deformity demonstrated a smaller PI than a large cohort of normal control specimens. We found no significant difference between acetabular version of specimens with and without SCFE deformity. Contralateral or unaffected acetabuli of SCFE specimens were not more retroverted than the affected side of the same specimen. Sagittal balance of the pelvis, and particularly decreased PI, may play an important role in the development of SCFE. The influence of mechanical factors beyond the hip joint in the development of SCFE should be considered by clinicians.

Estimating Age of Mature Adults from the Degeneration of the Sternal End of the Clavicle

PubMed Central

Falys, Ceri G; Prangle, Dennis

2015-01-01

The sternal end of the clavicle has been illustrated to be useful in aging young adults, however, no studies have investigated what age-related changes occur to the sternal end post epiphyseal fusion. In this study, three morphological features (i.e., surface topography, porosity, and osteophyte formation) were examined and scored using 564 clavicles of individuals of European ancestry (n = 318 males; n = 246 females), with known ages of 40+ years, from four documented skeletal collections: Hamann-Todd, Pretoria, St. Bride's, and Coimbra. An ordinal scoring method was developed for each of the three traits. Surface topography showed the strongest correlation with age, and composite scores (formed by summing the three separate trait scores) indicated progressive degeneration of the surface with increasing chronological age. Linear regression analyses were performed on the trait scores to produce pooled-sample age estimation equations. Blind tests of the composite score method and regression formulae on 56 individuals, aged 40+ years, from Christ Church Spitalfields, suggest accuracies of 96.4% for both methods. These preliminary results display the first evidence of the utility of the sternal end of the clavicle in aging older adult individuals. However, in the current format, these criteria should only be applied to individuals already identified as over 40 years in order to refine the age ranges used for advanced age. These findings do suggest the sternal end of the clavicle has potential to aid age estimates beyond the traditional “mature adult” age category (i.e., 46+ years), and provides several suggestions for future research. Am J Phys Anthropol 156:203–214, 2015. © 2014 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc. PMID:25327699

Broad NE 8 lambda 774 emission from quasars in the HST-FOS snapshot survey (ABSNAP)

NASA Technical Reports Server (NTRS)

Hamann, Fred; Zuo, Lin; Tytler, David

1995-01-01

We discuss the strength and frequency of broad Ne VIII lambda 774 emission from quasars measured in the Hubble Space Telescope Faint Object Spectrograph (HST-FOS) snapshot survey (Absnap). Five sources in the survey have suitable redshifts (0.86 less than or equal to Z(sub em) less than or equal to 1.31), signal-to-noise ratios and no Lyman limit absorptions. Three of the five sources have a strong broad emission line near 774 A (rest), and the remaining two sources have a less securely measured line near this wavelength. We identify these lines with Ne VIII lambda 774 based on the measured wavelengths and theoretical estimates of various line fluxes (Hamann et al. 1995a). Secure Ne VIII detections occur in both radio-loud and radio-quiet sources. We tentatively conclude that broad Ne VIII lambda 774 emission is common in quasars, with typical strengths between approximately 25% and approximately 200% of O VI lambda 1034. These Ne VIII lambda 774 measurements imply that the broad emission line regions have a much hotter and more highly ionized component than previously recognized. They also suggest that quasar continua have substantial ionizing flux out to energies greater than 207 eV (greater than 15.2 ryd, lambda less than 60 A). Photoionization calculations using standard incident spectra indicate that the Ne VIII emission requires ionization parameters U greater than or = 5, total column densities N(sub H) greater than or = 10(sub 22)/sq cm and covering factors greater than or = 25%. The temperatures could be as high as approximately 10(exp 5) K. If the gas is instead collisionally ionized, strong Ne VIII would imply equilibrium temperatures in the range approximately 400,000 less than or approximately = T(sub e) less than or approximately = 10(exp 6) K. In either case, the highly ionized Ne VIII emission regions would appear as X-ray 'warm absorbers' if they lie along our line of sight to the X-ray continuum source.

Facet orientation in the thoracolumbar spine: three-dimensional anatomic and biomechanical analysis.

PubMed

Masharawi, Youssef; Rothschild, Bruce; Dar, Gali; Peleg, Smadar; Robinson, Dror; Been, Ella; Hershkovitz, Israel

2004-08-15

Thoracolumbar facet orientations were measured and analyzed. To establish a comprehensive database for facet orientation in the thoracolumbar vertebrae and to determine the normal human condition. Most studies on facet orientation have based their conclusions on two-dimensional measurements, in small samples or isolated vertebrae. The amount of normal asymmetry in facet orientation is poorly addressed. Transverse and longitudinal facet angles were measured directly from 240 human vertebral columns (males/females, blacks/whites). The specimens' osteologic material is part of the Hamann-Todd Osteological Collection housed at the Cleveland Museum of Natural History (Cleveland, OH). A total of 4,080 vertebrae (T1-L5) from the vertebral columns of individuals 20 to 80 years of age were measured, using a Microscribe three-dimensional apparatus (Immersion Co., San Jose, CA). Data were recorded directly on computer software. Statistical analysis included paired t tests and analysis of variance. RESULTS.: Facet orientation is independent of gender, age, and ethnic group. Asymmetry in facet orientation is found in the thorax. All thoracolumbar facets are positioned in an oblique plane. In the transverse plane, all facets from T1 to T11 are positioned with an anterior inclination of approximately 25 degrees to 30 degrees from the frontal plane. The facets of T12-L2 are oriented closer to the midsagittal plane of the vertebral body (mean range, 25.89 degrees-33.87 degrees), while the facets of L3-L5 are oriented away from that plane (mean range, 40.40 degrees-56.30 degrees). Facet transverse orientation at the thoracolumbar junction is highly variable (approximately 80% with approximately 101 degrees and approximately 20% with 35 degrees). All facets are oriented more vertically from T1 (approximately 150 degrees) to L5 (approximately 170 degrees). The facet sagittal orientations of the lumbar zygoapophyseal joints are not equivalent. CONCLUSIONS.: Asymmetry in facet

Facet tropism and interfacet shape in the thoracolumbar vertebrae: characterization and biomechanical interpretation.

PubMed

Masharawi, Youssef; Rothschild, Bruce; Salame, Khalil; Dar, Gali; Peleg, Smadar; Hershkovitz, Israel

2005-06-01

Thoracolumbar facet and interfacet linear dimensions were measured and analyzed. To characterize and analyze the thoracolumbar facet and interfacet size and shape in relation to gender, ethnic group, and age and to detect the extent of normal facet tropism along the thoracolumbar spine. Knowledge on facet tropism and interfacet shape is limited in the literature as most data are based on 2-dimensional measurements, small samples, or isolated vertebrae. Facet shape as represented by width, length, width/length ratio and interfacet distances was obtained directly from dry vertebrae of 240 adult human spines. The specimen's osteologic material is part of the Hamann-Todd Osteological Collection housed at the Cleveland Museum of Natural History, Cleveland, OH. A total of 4080 vertebrae (T1-L5) from the vertebral columns of individuals 20 to 80 years of age were measured, using a Microscribe 3-dimensional apparatus (Immersion Co., San Jose, CA). Data were recorded directly on computer software. Statistical analysis included paired t tests and ANOVA. A significant correlation was found between all thoracolumbar facet dimensions and an individual's height and weight. Facet tropism is a major characteristic of the thoracolumbar spine, the left being longer in the thorax while the right is longer in the lumbar. In general, facet size is age-independent and greater in males compared with females with a significant ethnic component. Facet length is similar for all thoracic vertebrae, whereas it sharply and continuously increases in the lumbar vertebrae. Facet dimension manifests a bipolar distribution along the thoracolumbar vertebrae. Width/length ratio indicates that facets are longer than wider for most verte-brae. The interarticular area manifests a marked inverted trapezoidal shape at T1-T2, a rectangular shape at T3-L3, and an ordinary trapezoidal shape at L4-L5. Facet tropism is a normal characteristic in humans, yet it varies along the thoracolumbar spine.

Origin and Evolution of the Elements

NASA Astrophysics Data System (ADS)

McWilliam, Andrew; Rauch, Michael

2004-09-01

. Chemical composition of the intracluster medium Michael Loewenstein; 28. Quasar elemental abundances and host galaxy evolution Fred Hamann, Matthias Dietrich, Bassem M. Sabra, and Craig Warner; 29. Chemical abundances in the damped Lyα systems Jason X. Prochaska; 30. Intergalactic medium abundances Robert F. Carswell; 31. Conference summary Bernard E. J. Pagel.

Differences in Medial and Lateral Posterior Tibial Slope: An Osteological Review of 1090 Tibiae Comparing Age, Sex, and Race.

PubMed

Weinberg, Douglas S; Williamson, Drew F K; Gebhart, Jeremy J; Knapik, Derrick M; Voos, James E

2017-01-01

Injuries to the anterior cruciate ligament (ACL) are common, and a number of knee morphological variables have been identified as risk factors for an ACL injury, including the posterior tibial slope (TS). However, limited data exist regarding innate population differences in the TS. To (1) establish normative values for the medial and lateral posterior TS; (2) determine what differences exist between ages, sexes, and races; and (3) determine how internal or external tibial rotation (as occurs during sagittal knee motion) influences the stereotactic perception of the TS. Cross-sectional study; Level of evidence, 3. A total of 545 cadaveric specimens (1090 tibiae) were obtained from the Hamann-Todd osteological collection. Specimens were leveled in the coronal, sagittal, and axial planes using a digital laser. Virtual representations of each bone were created with a 3-dimensional digitizer apparatus. The TS of the medial and lateral tibial plateaus were measured using techniques adapted from previous radiographic protocols. Medial and lateral TS were then again measured on 200 tibiae that were internally and externally rotated by 10° (axially). The mean (±SD) medial TS was 6.9° ± 3.7° posterior, which was greater than the mean lateral TS of 4.7° ± 3.6° posterior ( P < .001). Neither the medial nor lateral TS changed with age. Women had a greater mean TS compared with men on both the medial (7.5° ± 3.8° vs 6.8° ± 3.7°, respectively; P = .03) and lateral (5.2° ± 3.5° vs 4.6° ± 3.5°, respectively; P = .04) sides. Black specimens had a greater mean medial TS (8.7° ± 3.6° vs 5.8° ± 3.3°, respectively; P < .001) and lateral TS (5.9° ± 3.3° vs 3.8° ± 3.5°, respectively; P < .001) compared with white specimens. Axial rotation was shown to increase the perception of the medial and lateral TS ( P < .001). The medial TS was shown to be greater than the lateral TS. Important sex- and race-based differences exist in the TS. This study also

A big data geospatial analytics platform - Physical Analytics Integrated Repository and Services (PAIRS)

NASA Astrophysics Data System (ADS)

Hamann, H.; Jimenez Marianno, F.; Klein, L.; Albrecht, C.; Freitag, M.; Hinds, N.; Lu, S.

2015-12-01

A big data geospatial analytics platform:Physical Analytics Information Repository and Services (PAIRS)Fernando Marianno, Levente Klein, Siyuan Lu, Conrad Albrecht, Marcus Freitag, Nigel Hinds, Hendrik HamannIBM TJ Watson Research Center, Yorktown Heights, NY 10598A major challenge in leveraging big geospatial data sets is the ability to quickly integrate multiple data sources into physical and statistical models and be run these models in real time. A geospatial data platform called Physical Analytics Information and Services (PAIRS) is developed on top of open source hardware and software stack to manage Terabyte of data. A new data interpolation and re gridding is implemented where any geospatial data layers can be associated with a set of global grid where the grid resolutions is doubling for consecutive layers. Each pixel on the PAIRS grid have an index that is a combination of locations and time stamp. The indexing allow quick access to data sets that are part of a global data layers and allowing to retrieve only the data of interest. PAIRS takes advantages of parallel processing framework (Hadoop) in a cloud environment to digest, curate, and analyze the data sets while being very robust and stable. The data is stored on a distributed no-SQL database (Hbase) across multiple server, data upload and retrieval is parallelized where the original analytics task is broken up is smaller areas/volume, analyzed independently, and then reassembled for the original geographical area. The differentiating aspect of PAIRS is the ability to accelerate model development across large geographical regions and spatial resolution ranging from 0.1 m up to hundreds of kilometer. System performance is benchmarked on real time automated data ingestion and retrieval of Modis and Landsat data layers. The data layers are curated for sensor error, verified for correctness, and analyzed statistically to detect local anomalies. Multi-layer query enable PAIRS to filter different data

Differential diagnostic perspectives provided by en face microscopic examination of articular surface defects.

PubMed

Rothschild, Bruce M

2018-03-01

Surface defects have a central position in diagnosis of articular pathology. Recognizing the limitations of standard radiologic techniques and those imposed by positioning and averaging artifacts on CT evaluation, direct visualization of surface defects was pursued to identify disease characteristics that would facilitate interpretation of radiologic findings. Epi-illumination surface microscopy was utilized to examine macroscopically recognized articular surface defects in individuals in the Hamann-Todd, Terry, and Huntington human skeletal collections with previously verified diagnoses of rheumatoid arthritis, spondyloarthropathy, juvenile inflammatory arthritis (JIA), calcium pyrophosphate deposition disease (CPPD), gout, metastatic cancer, multiple myeloma, septic arthritis, tuberculosis, fungal arthritis, histiocytosis and sickle cell anemia (Rothschild and Rothschild Clin Infect Dis 20(5):1402-1408, 1995; Rothschild et al. Amer J Phys Anthropol 82(4):441-449, 1990; Rothschild and Rothschild Amer J Phys Anthropol 96(4):357-563, 1995; Rothschild and Woods Clin Exp Rheumatol 10(2):117-122, 1992; Barrett and Keat Radiographics 24(6):1679-1691, 2004; Rothschild and Heathcote Amer J Phys Anthropol 98(4):519-525, 1995; Rothschild and Woods Am J Phys Anthropol 85:25-34, 1991; Hershkovitz et al. Amer J Phys Anthropol 106(1):47-60, 1998; Winland et al. Amer J Phys Anthropol 24:S243, 1997; Rothschild et al. Clin Exp Rheumatol 10(6):557-564, 1992; Rothschild and Martin , 2006; Rothschild et al. Amer J Phys Anthropol 102(2):249-264, 1997). Observed alterations were compared with standard radiographs. Fronts of resorption distinguished inflammatory arthritis from those caused by the other disorders studied. Multiple myeloma, fungal disease, and gout are expansile character; the latter accompanied by reactive new bone formation more prominent than that noted with spondyloarthropathy and JIA. Those were clearly distinguished from the crumbling alterations found with CPPD

Latinas' heritage language as a source of resiliency: impact on academic achievement in STEM fields

NASA Astrophysics Data System (ADS)

Stevenson, Alma D.; Gallard Martínez, Alejandro José; Brkich, Katie Lynn; Flores, Belinda Bustos; Claeys, Lorena; Pitts, Wesley

2017-03-01

This article highlights how the preservation of heritage languages is essential in the construction of three Georgia Latina participants' cultural identities and the creation of support networks that allow them to develop resiliency and achieve academically. We conceptualize resiliency as a strategy developed by the Latina participants using contextually mitigating factors during their STEM education. The findings presented in this manuscript are part of a larger, ongoing study of Latina resiliency and their paths to success in STEM fields in two states: Georgia and Texas. Following James Spradley's guidelines, data were collected via three separate semi-structured interviews with each participant. Intrinsic, multiple case studies were used to find both commonalities and differences, as well as to deepen our understanding of the role of the participants' heritage language in their development of resiliency in each particular case. The findings presented here were not part of a preconceived research hypothesis, but rather a theme that emerged while analyzing data collected in the state of Georgia. Georgia is not home to a long-established Hispanic/Latino population, but rather is part of the New Latino Diaspora (Wortham, Murillo and Hamann in Education in the new Latino diaspora: policy and the politics of identity. Ablex Publishing, New York, 2002), and therefore local natives do not necessarily perceive Latino immigrants and the Spanish language either as long-standing or permanent features of the state. In fact, in response to the growing diversity of the state during the past generation, Georgia has implemented multiple educational policies hostile toward immigrants and linguistic diversity (Beck and Allexsaht-Snider in Education in the new Latino diaspora: policy and the politics of identity. Ablex Press, Westport, 2002). Our findings suggest that the Latina participants' heritage languages allow them to engage in cultural traditions, encouraged by their

Growth Patterns of the Neurocentral Synchondrosis (NCS) in Immature Cadaveric Vertebra.

PubMed

Blakemore, Laurel; Schwend, Richard; Akbarnia, Behrooz A; Dumas, Megan; Schmidt, John

2018-03-01

Gross anatomic study of osteological specimens. To evaluate the age of closure for the neurocentral synchondrosis (NCS) in all 3 regions of the spine in children aged 1 to 18 years old. The ossification of the human vertebra begins from a vertebral body ossification center and a pair of neural ossification centers located within the centrum called the NCS. These bipolar cartilaginous centers of growth contribute to the growth of the vertebral body, spinal canal, and posterior elements of the spine. The closure of the synchondroses is dependent upon location of the vertebra and previous studies range from 2 to 16 years of age. Although animal and cadaveric studies have been performed regarding NCS growth and early instrumentation's effect on its development, the effects of NCS growth disturbances are still not completely understood. The vertebrae of 32 children (1 to 18 y old) from the Hamann-Todd Osteological collection were analyzed (no 2 or 9 y old specimens available). Vertebrae studied ranged from C1 to L5. A total of 768 vertebral specimens were photographed on a background grid to allow for measurement calibration. Measurements of the right and left NCS, pedicle width at the NCS, and spinal canal area were taken using Scandium image-analysis software (Olympus Soft Imaging Solutions, Germany). The percentage of the growth plate still open was found by dividing the NCS by the pedicle width and multiplying by 100. Data were analyzed with JMP 11 software (SAS Institute Inc., Cary, NC). The NCS was 100% open in all 3 regions of the spine in the 1- to 3-year age group. The cervical NCS closed first with completion around 5 years of age. The lumbar NCS was nearly fully closed by age 11. Only the thoracic region remained open through age 17 years. The left and right NCS closed simultaneously as there was no statistical difference between them. In all regions of the spine, the NCS appeared to close sooner in males than in females. Spinal canal area increased with age

Techno-economic analysis for the evaluation of three UCG synthesis gas end use approaches

NASA Astrophysics Data System (ADS)

Nakaten, Natalie; Kempka, Thomas; Burchart-Korol, Dorota; Krawczyk, Piotr; Kapusta, Krzysztof; Stańczyk, Krzysztof

2016-04-01

production, the UCG synthesis gas should have a calorific value of at least 7 MJ/Nm³. However, UCG feedstock production in view of the underlying geological and chemical boundary conditions can compete on the market. Kempka, T., Plötz, M.L., Hamann, J., Deowan, S.A., Azzam, R. (2010) Carbon dioxide utilisation for carbamide production by application of the coupled UCG-urea process. Energy Procedia 4: 2200-2205. Nakaten, N., Schlüter, R., Azzam, R., Kempka, T. (2014) Development of a techno-economic model for dynamic calculation of COE, energy demand and CO2 emissions of an integrated UCG-CCS process. Energy (in print). Doi 10.1016/j.energy.2014.01.014

Techno-economic analysis of integrated onshore and offshore UCG-CCS systems to produce electricity, SNG and urea

NASA Astrophysics Data System (ADS)

Nakaten, Natalie; Kapusta, Krzysztof; Burchart-Korol, Dorota; Kempka, Thomas

2017-04-01

profitable in view of the expected future development of natural gas prices. [1] Stanczyk, K., Howaniec, N., Smolinski, A., Swiadrowski, J., Kapusta, K., Wiatowski, M., Grabowski, J., Rogut, J. (2011): Gasification of lignite and hard coal with air and oxygen enriched air in a pilot scale ex-situ reactor for underground gasification. Fuel, 90, p. 1953-1962, doi:10.1016/j.fuel.2010.12.007. [2] Kempka, T., Schlüter, R., Hamann, J., Deowan, S., Azzam, R. (2011): Carbon dioxide utilisation for carbamide production by application of the coupled UCG-Urea process. Energy Procedia, 4, p. 2200-2205, doi.org/10.1016/j.egypro.2011.02.107. [3] Nakaten, N.C., Schlüter, R., Azzam, R. and Kempka, T. (2014): Development of a techno-economic model for dynamic calculation of COE, energy demand and CO2 emissions of an integrated UCG-CCS process. Energy, 66, p. 779-790, doi: 10.1016/j.energy.2014.01.014.

Underground coal gasification with extended CO2 utilization as economic and carbon neutral approach to address energy and fertilizer supply shortages in Bangladesh

NASA Astrophysics Data System (ADS)

Nakaten, Natalie; Islam, Rafiqul; Kempka, Thomas

2014-05-01

injected in the scope of the scheduled EGR operation. Our techno-economic modeling results considering EGR reservoir simulations demonstrate that an economic and carbon neutral operation of UCG combined with fertilizer production and CCS is feasible. The suggested approach may provide a bridging technology to tackle fertilizer and power supply shortages in Bangladesh, and in addition support further production from depleting natural gas deposits. References Kempka, T., Plötz, M.L., Hamann, J., Deowan, S.A., Azzam, R. (2010) Carbon dioxide utilisation for carbamide production by application of the coupled UCG-urea process. Energy Procedia 4: 2200-2205. Nakaten, N., Schlüter, R., Azzam, R., Kempka, T. (2014) Development of a techno-economic model for dynamic calculation of COE, energy demand and CO2 emissions of an integrated UCG-CCS process. Energy (in print). Doi 10.1016/j.energy.2014.01.014

Changes in Clavicle Length and Maturation in Americans: 1840-1980.

PubMed

Langley, Natalie R; Cridlin, Sandra

2016-01-01

Secular changes refer to short-term biological changes ostensibly due to environmental factors. Two well-documented secular trends in many populations are earlier age of menarche and increasing stature. This study synthesizes data on maximum clavicle length and fusion of the medial epiphysis in 1840-1980 American birth cohorts to provide a comprehensive assessment of developmental and morphological change in the clavicle. Clavicles from the Hamann-Todd Human Osteological Collection (n = 354), McKern and Stewart Korean War males (n = 341), Forensic Anthropology Data Bank (n = 1,239), and the McCormick Clavicle Collection (n = 1,137) were used in the analysis. Transition analysis was used to evaluate fusion of the medial epiphysis (scored as unfused, fusing, or fused). Several statistical treatments were used to assess fluctuations in maximum clavicle length. First, Durbin-Watson tests were used to evaluate autocorrelation, and a local regression (LOESS) was used to identify visual shifts in the regression slope. Next, piecewise regression was used to fit linear regression models before and after the estimated breakpoints. Multiple starting parameters were tested in the range determined to contain the breakpoint, and the model with the smallest mean squared error was chosen as the best fit. The parameters from the best-fit models were then used to derive the piecewise models, which were compared with the initial simple linear regression models to determine which model provided the best fit for the secular change data. The epiphyseal union data indicate a decline in the age at onset of fusion since the early twentieth century. Fusion commences approximately four years earlier in mid- to late twentieth-century birth cohorts than in late nineteenth- and early twentieth-century birth cohorts. However, fusion is completed at roughly the same age across cohorts. The most significant decline in age at onset of epiphyseal union appears to have occurred since the mid

Committees and organizers

NASA Astrophysics Data System (ADS)

2011-07-01

(Orsay) S Hamann (Bochum)R Varga (Košice) U Hannemann (Dresden)P Vavassori (San Sebastian) L Havela (Prague)W Wulfhekel (Karlsruhe) O Heczko (Prague)M Yamashita (Sendai) B Hernando (Oviedo)R Zdyb (Lublin) O Isnard (Grenoble)A Zhukov (San Sebastián) Z Kąkol (Kraków)A K Zvezdin (Moscow) N-T H Kim-Ngan (Kraków) International Advisory Committee (2011): Dominique Givord, President (Grenoble)Ludwig Schultz, Former President (Dresden) Manfred Albrecht (Chemnitz)Burkard Hillebrands (Kaiserslautern) Agnés Barthélémy (Paris)Andrei Kirilyuk (Nijmegen) Roy Chantrell (York)Ron Jansen (Tsukuba) Russell Cowburn (London)Nicoleta Lupu (Iasi) Tomasz Dietl (Warszawa)Caroline A Ross (Cambridge, MA) Claudia Felser (Mainz)Stefano Sanvito (Dublin) Josef Fidler (Wien)Vladimir Sechovsky (Praha) Dino Fiorani (Roma)Roberta Sessoli (Firenze) Pietro Gambardella (Bellaterra)Jozef Spałek (Kraków) Alberto Guimarães (Rio de Janeiro)

The onset of Wolf-Rayet wind outflow and the nature of the hot component in the symbiotic nova PU Vulpecula

NASA Technical Reports Server (NTRS)

Sion, Edward M.; Shore, Steven N.; Ready, Christian J.; Scheible, Maureen P.

1993-01-01

, 1402). We have carried out a rough quantitative analysis of the He II wind emission by using the theoretical He II Wolf-Rayet profiles of Hamann & Schmutz (1987). We obtain a lower limit to the He II net emission equivalent width of approximately 1 A, a hot component temperature in the range 25,000 to 35,000 K, a hot component radius in the range 5 solar radius to 30 solar radius, a maximum wind velocity of approximately equals -600 km/s and a rough upper limit to the mass-loss rate of less than 1 x 10(exp -5) solar mass/yr. To our knowledge, this is the first quantitative wind analysis, albeit crude, to be carried out for the hot component of a symbiotic nova or symbiotic variable.

Observed and simulated time evolution of HCl, ClONO2, and HF total columns

NASA Astrophysics Data System (ADS)

Ruhnke, Roland; Geomon, Ndacc Infrared, Modelling Working Group

2010-05-01

GEOmon, NDACC Infrared, and Modelling Working Group: M.P. Chipperfield (2), M. De Mazière (3), J. Notholt (4), S. Barthlott (1), R.L. Batchelor (5,17), R.D. Blatherwick (16), Th. Blumenstock (1), M.T. Coffey (17), P. Duchatelet (6), H. Fast (7), W. Feng (2), A. Goldman (16), D.W.T. Griffith (8), K. Hamann (1), J.W. Hannigan (17), F. Hase (1), N.B. Jones (8), A. Kagawa (9,10), Y. Kasai (9), O. Kirner (19), R. Kohlhepp (1), W. Kouker (1), I. Kramer (1), R. Lindenmaier (5), E. Mahieu (6), R.L. Mittermeier (7), B. Monge-Sanz (2), I. Murata (12), H. Nakajima (13), I. Morino (11), M. Palm (4), C. Paton-Walsh (8), Th. Reddmann (1), M. Rettinger (15), C.P. Rinsland (18), M. Schneider (1), C. Senten (3), B.-M. Sinnhuber (4), D. Smale (14), K. Strong (5), R. Sussmann (15), J.R. Taylor (5), G. Vanhaelewyn (3), T. Warneke (4), C. Whaley (5), M. Wiehle (1), and S.W. Wood (14) (1) Karlsruhe Institute of Technology (KIT), IMK-ASF, Karlsruhe, Germany, (2) University of Leeds, Leeds, United Kingdom, (3) Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium, (4) University of Bremen, Institute of Environmental Physics, Bremen, Germany, (5) Department of Physics, University of Toronto, Toronto, Ontario, Canada, (6) University of Liège, Institute of Astrophysics and Geophysics, Liège, Belgium, (7) Environment Canada, Toronto, Ontario, Canada, (8) Centre for Atmospheric Chemistry, University of Wollongong, Wollongong, Australia, (9) National Institute of Information and Communications Technology, Tokyo, Japan, (10) Fujitsu FIP Corporation, Tokyo, Japan, (11) Center for Global Environmental Research, National Institute for Environmental Studies (NIES), Japan, (12) Department of Environmental Studies, Graduate School of Environmental Studies, Tohoku University, Japan, (13) Atmospheric Environment Division, National Institute for Environmental Studies, Japan, (14) National Institute of Water and Atmospheric Research Ltd (NIWA), Lauder, New Zealand, (15) Karlsruhe

Scientific Visualization for Atmospheric Data Analysis in Collaborative Virtual Environments

NASA Astrophysics Data System (ADS)

Engelke, Wito; Flatken, Markus; Garcia, Arturo S.; Bar, Christian; Gerndt, Andreas

2016-04-01

. Bartelmann, "Healpix: a framework for high-resolution discretization and fast analysis of data distributed on the sphere," The Astrophysical Journal, vol. 622, no. 2, p. 759, 2005. [5] R. Westerteiger, A. Gerndt, and B. Hamann, "Spherical terrain render- ing using the hierarchical healpix grid," VLUDS, vol. 11, pp. 13-23, 2011. [6] W. Schroeder, K. Martin, and B. Lorensen, The Visualization Toolkit. Kitware, 4 ed., 2006. [7] T. van Reimersdahl, T. Kuhlen, A. Gerndt, J. Henrichs, and C. Bischof, "ViSTA: a multimodal, platform-independent VR-toolkit based on WTK, VTK, and MPI," in Proceedings of the 4th International Immersive Projection Technology Workshop (IPT), 2000.

Low Energy Electrons as Probing Tool for Astrochemical Reaction Mechanisms

NASA Astrophysics Data System (ADS)

Hendrik Bredehöft, Jan; Swiderek, Petra; Hamann, Thorben

. Faraday Discuss., 133 (2006), 393-401 [7] Snow T.P. and Bierbaum V.M.: Ion chemistry in the interstellar medium. Ann. Rev. Analyt. Chem. 1 (2008), 229-259. [8] Nuevo M., Meierhenrich U.J., Muñoz Caro G.M., Dartois E., d'Hendecourt L., Deboffle D., n Auger G., Blanot D., Bredehüft J.H. and Nahon L.: The effects of circularly polarized light on amino acid enantiomers produced by the UV irradiation of interstellar ice analogs. AA 457 (2006), 741-751 [9] Shimamura I and Takayanagi K. (eds): Electron-Molecule Collisions. Plenum Press, New York, USA (1984) [10] Hamann T., Bühler E., Swiderek P.: Low-energy-electron-induced hydroamination of an alkene. Angew Chem Int Ed Engl. 48(25) (2009), 4643-4645.

Obituary: Jörn Rossa (1969-2009)

NASA Astrophysics Data System (ADS)

Veras, Dimitri

2009-12-01

evolve into ellipticals. Joern then moved to the University of Florida (UF) in 2006 to work as a core team member of the Flamingos 2 Extra-Galactic Survey. This survey aims at deriving the star formation histories, masses and metallicities of star formation galaxies at redshifts between 2.0-2.5 and also at deriving the properties (e.g., black hole masses) of AGN and at studying the optically obscured AGN at intermediate to high redshifts (z > 1.5). Joern was largely responsible for the target selection strategies for both samples (star-forming galaxies and AGN), for coordinating the weekly group meetings, and for designing a web-page for the extragalactic group. He was interested in using the survey to answer several cosmological questions in collaboration with Vicki Sarajedini, Rafael Guzmän, Fred Hamann, Anthony Gonzalez, the Flamingos-2 instrument PI, Stephen Eikenberry (all from UF), and with additional collaborators from the Complutense University of Madrid, Spain. Joern also worked with Vicki Sarajedini on SED fitting of variability-selected AGN in the Chandra Deep Field South. Joern was a very versatile observer, complementing his belief that understanding of the star-formation activity in galaxies can be only achieved through a multi-wavelength study of various galaxy types. In addition to research, Joern had a strong desire to be involved in the logistical aspects of science. At STScI he participated in the support group for the time allocation committee and at UF he was the postdoctoral representative of the space allocation committee. He photographed the UF staff for the departmental webpage and was a designated photographer at a local conference and other events. He also participated in the public Museum nights at UF. He was always eager to provide his feedback on the scientific and practical issues of astronomy and filled in many surveys distributed to the astronomical community. His colleagues and friends could always count on Joern to be extremely

EDITORIAL: Focus on Iron-Based Superconductors FOCUS ON IRON-BASED SUPERCONDUCTORS

NASA Astrophysics Data System (ADS)

Hosono, Hideo; Ren, Zhi-An

2009-02-01

-L Drechsler, N Kozlova, M Bartkowiak, J E Hamann-Borrero, G Behr, K Nenkov, H-H Klauss, H Maeter, A Amato, H Luetkens, A Kwadrin, R Khasanov, J Freudenberger, A Köhler, M Knupfer, E Arushanov, H Rosner, B Büchner and L Schultz Low-energy spin dynamics in the antiferromagnetic phase of CaFe2As2 N J Curro, A P Dioguardi, N ApRoberts-Warren, A C Shockley and P Klavins Muon spin rotation study of magnetism and superconductivity in BaFe2-xCoxAs2 and Pr1-xSrxFeAsO C Bernhard, A J Drew, L Schulz, V K Malik, M Rössle, Ch Niedermayer, Th Wolf, G D Varma, G Mu, H-H Wen, H Liu, G Wu and X H Chen Magnetic impurities in the pnictide superconductor Ba1-xKxFe2As2 Sutirtha Mukhopadhyay, Sangwon Oh, A M Mounce, Moohee Lee, W P Halperin, N Ni, S L Bud'ko, P C Canfield, A P Reyes and P L Kuhns Neutron scattering investigation of the magnetic order in single crystalline BaFe2As2 M Kofu, Y Qiu, Wei Bao, S-H Lee, S Chang, T Wu, G Wu and X H Chen An NMR study on the F-doping evolution of the iron oxypnictide LaFeAs(O1-xFx) Y Nakai, S Kitagawa, K Ishida, Y Kamihara, M Hirano and H Hosono The peculiar physical properties and phase diagram of BaFe2-xCoxAs2 single crystals X F Wang, T Wu, G Wu, R H Liu, H Chen, Y L Xie and X H Chen Synthesis of LnFeAsO1-y superconductors (Ln=La and Nd) using the high-pressure technique Kiichi Miyazawa, Kunihiro Kihou, Motoyuki Ishikado, Parasharam M Shirage, Chul-Ho Lee, Nao Takeshita, Hiroshi Eisaki, Hijiri Kito and Akira Iyo Correlation effects in the iron pnictides Qimiao Si, Elihu Abrahams, Jianhui Dai and Jian-Xin Zhu Competition/coexisitence of magnetism and superconductivity in iron pnictides probed by muon spin rotation Soshi Takeshita and Ryosuke Kadono Impurity-induced in-gap state and Tc in sign-reversing s-wave superconductors: analysis of iron oxypnictide superconductors Yuko Senga and Hiroshi Kontani Intrinsic magnetic properties of the superconductor NdFeAsO0.9F0.1 from local and global measurements R Prozorov, M E Tillman, E D Mun and P C Canfield