bluuebunny/crossref_metadata_2025 huggingface dataset:
Ground-penetrating radar profiles of the McMurdo Shear Zone, Antarctica, acquired with an unmanned rover: Interpretation of crevasses, fractures, and folds within firn and marine ice
Authors: Arcone Steven A. , Lever James H. , Ray Laura E. , Walker Benjamin S. , Hamilton Gordon , Kaluzienski Lynn
Published: September 2015

The crevassed firn of the McMurdo shear zone (SZ) within the Ross Ice Shelf may also contain crevasses deep within its meteoric and marine ice, but the surface crevassing prevents ordinary vehicle access to investigate its structure geophysically. We used a lightweight robotic vehicle to tow 200- and 400-MHz ground-penetrating radar antennas simultaneously along 100 parallel transects over a [Formula: see text] grid spanning the SZ width. Transects were generally orthogonal to the ice flow. Total firn and meteoric ice thickness was approximately 160 m. Firn crevasses profiled at 400 MHz were up to 16 m wide, under snow bridges up to 10 m thick, and with strikes near 35°–40° to the transect direction. From the top down, 200-MHz profiles revealed firn diffractions originating to a depth of approximately 40 m, no discernible structure within the meteoric ice, a discontinuous transitional horizon, and at least 20 m of stratified marine ice; 28–31 m of freeboard found more marine ice exists. Based on 10 consecutive transects covering approximately [Formula: see text], we preliminarily interpreted the transitional horizon to be a thin saline layer, and marine ice hyperbolic diffractions and reflections to be responses to localized fractures, and crevasses filled with unstratified marine ice, all at strikes from 27° to 50°. We preliminarily interpreted off-nadir, marine ice horizons to be responses to linear and folded faults, similar to some in firn. The coinciding and synchronously folded areas of fractured firn and marine ice suggested that the visibly unstructured meteoric ice beneath our grid was also fractured, but either never crevassed, crevassed and sutured without marine ice inclusions, or that any ice containing crevasses might have eroded before marine ice accretion. We will test these interpretations with analysis of all transects and by extending our grid and increasing our depth ranges.
3D modeling of buried valley geology using airborne electromagnetic data
Authors: Sapia Vincenzo , Oldenborger Greg A. , Jørgensen Flemming , Pugin André J.-M. , Marchetti Marco , Viezzoli Andrea
Published: September 2015

Buried valleys are important hydrogeologic features of glaciated terrains. They often contain valuable groundwater resources; however, they can remain undetected by borehole-based hydrogeologic mapping or prospecting campaigns. Airborne electromagnetic (AEM) surveys provide high-density information that can allow detailed features of buried valleys to be efficiently mapped over large geographic areas. Using AEM data for the Spiritwood Valley Aquifer system in Manitoba, Canada, we developed a 3D electric property model and a geologic model of the buried valley network. The 3D models were derived from voxel-based segmentation of electric resistivity obtained via spatially constrained inversion of two separate helicopter time-domain electromagnetic data sets (AeroTEM and versatile time-domain electromagnetic [VTEM]) collected over the survey area. Because the electric resistivity do not provide unequivocal information on subsurface lithology, we have used a cognitive procedure to interpret the electric property models of the aquifer complex, while simultaneously incorporating supporting information for the assignment of lithology in the 3D geologic model. For the Spiritwood model, supporting information included seismic reflection data and borehole records. These data constrained valley geometry and provided lithologic benchmarks at specific borehole sites and along seismic transects. The large-scale AeroTEM survey provided the basis for modeling the regional extent and connectivity of the Spiritwood Valley Aquifer system, whereas the local-scale VTEM survey provided higher near-surface resolution and insight into a detailed shallow architecture of individual buried valleys and their fill.
Centrifuge Testing of Model Levees atop Peat: Experimental Data
Authors: Lemnitzer Anne , Cappa Riccardo , Yniesta Samuel , Brandenberg Scott
Published: September 2015

Four large-scale centrifuge tests were performed at the NEES@UCDavis equipment site to study the cyclic behavior of levee structures resting atop soft organic peat. The model configurations using a non-liquefiable levee focused on the seismic deformation potential of peat during primary consolidation and secondary compression. The tests performed with a sandy levee studied the liquefaction potential of saturated loose sand fill overlying soft peat as well as the levee-peat-interaction under different loading conditions. The models were subjected to scaled ground motions representative of the Sacramento/San Joaquin Delta. System instrumentation consisted of linear potentiometers, pore pressure sensors and accelerometers. Slow data recorded at 1 Hz document the settlements during spin up, application of ground motions, and spin down. Fast data sampled at 4,167 Hz measured the dynamic response of the system, the excess pore pressure increase and immediate settlements. The project is archived at the NEES data repository under nees.org/warehouse/project/1161 .
LIF supports primitive endoderm expansion during pre-implantation development
Authors: Morgani Sophie M. , Brickman Joshua M.
Published: September 2015

Embryonic stem cells (ESCs) are pluripotent cell lines that can be maintained indefinitely in an early developmental state. ESC culture conditions almost all require the cytokine LIF to maintain self-renewal. As ESCs are not homogeneous, but contain multiple populations reminiscent of the blastocyst, identifying the target cells of LIF is necessary to understand the propagation of pluripotency. We recently found that LIF acts under self-renewing conditions to stimulate the fraction of ESCs that express extraembryonic markers, but has little impact on pluripotent gene expression. Here we report that LIF has two distinct roles. It blocks early epiblast differentiation and supports the expansion of primitive endoderm (PrE) primed ESCs and PrE in vivo. We find that activation of JAK/STAT signalling downstream of LIF occurs initially throughout the pre-implantation embryo, but later marks the PrE. Moreover, the addition of LIF to cultured embryos increases the GATA6+ PrE population while inhibition of JAK/STAT reduces both NANOG+ epiblast (Epi) and GATA6+ PrE. The reduction of the NANOG+ Epi may be explained by its precocious differentiation to later Epi derivatives, while the increase in PrE is mediated both by an increase in proliferation and inhibition of PrE apoptosis that is normally triggered in embryos with an excess of GATA6+ cells. Thus, it appears that the relative size of the PrE is determined by the number of LIF-producing cells in the embryo. This suggests a mechanism by which the embryo adjusts the relative ratio of the primary lineages in response to experimental manipulation.
Phenotypic analysis of mice completely lacking Netrin-1
Authors: Yung Andrea R. , Nishitani Allison M. , Goodrich Lisa V.
Published: September 2015

Netrin-1 (Ntn1) is a multifunctional guidance cue expressed in the ventricular zone and floor plate of the embryonic neural tube. Though Ntn1 is best known for acting as an axon guidance cue through DCC and Neogenin receptors, it is also thought to regulate neuronal survival and blood vessel development through Unc5 family receptors. However, the Ntn1 gene trap mutant mouse does not display all the phenotypes predicted from in vitro assays or analyses of mice lacking predicted receptors. Since the gene trap strain still produces wild-type Ntn1 protein, it is unclear whether the absence of phenotypes reflects the activity of alternative cues or residual Ntn1. To resolve the full extent of Ntn1's contribution to development, we generated a null allele of Ntn1 and re-examined tissues exhibiting phenotypic discrepancies between receptor mutants and Ntn1 hypomorphs. We found that in Ntn1 null animals, commissural axons rarely cross the midline, resulting in a strongly enhanced phenotype relative to Ntn1 hypomorphs, which retain many axons with normal trajectories. Thus, low levels of Ntn1 can account for persistent attraction to the midline in hypomorphs. In contrast, Ntn1 null mice do not show all of the phenotypes reported for Unc5 receptor mutants, indicating that Ntn1 is not necessarily the dominant ligand for Unc5 family members in vivo and ruling out primary roles in survival or angiogenesis.
Polarization of the epithelial layer and apical localization of integrins are required for engulfment of apoptotic cells
Authors: Meehan Tracy L. , Kleinsorge Sarah E. , Timmons Allison K. , Taylor Jeffrey D. , McCall Kimberly
Published: September 2015

Inefficient clearance of dead cells or debris by epithelial cells can lead to or exacerbate debilitating conditions such as retinitis pigmentosa, macular degeneration, chronic obstructive pulmonary disease, and asthma. Despite the importance of engulfment by epithelial cells, little is known about the molecular changes that are required within these cells. The misregulation of integrins has previously been associated with disease states, suggesting that a better understanding of the regulation of receptor trafficking may be key to treating diseases caused by defects in phagocytosis. Here, we demonstrate that the integrin heterodimer αPS3/βPS becomes apically enriched and is required for engulfment by the epithelial follicle cells of the Drosophila ovary. We found that integrin heterodimer localization and function is largely directed by the α subunit. Moreover, proper cell polarity promotes asymmetric integrin enrichment, suggesting that αPS3/βPS trafficking occurs in a polarized fashion. We show that several genes previously known for their roles in trafficking and cell migration are also required for engulfment. Moreover, as in mammals, the same α integrin subunit is required by professional and non-professional phagocytes and migrating cells in Drosophila. Our findings suggest that migrating and engulfing cells may use common machinery and demonstrate a critical role for integrin function and polarized trafficking of integrin subunits during engulfment. This study also establishes the epithelial follicle cells of the Drosophila ovary as a powerful model for understanding the molecular changes required for engulfment by a polarized epithelium.
The ARF2–ANT–COR15A gene cascade regulates ABA-signaling-mediated resistance of large seeds to drought in Arabidopsis
Authors: Meng Lai-Sheng , Wang Zhi-Bo , Yao Shun-Qiao , Liu Aizhong
Published: September 2015

Seedlings of large-seeded plants are considered to be able to withstand abiotic stresses efficiently. The molecular mechanisms that underlie the involved signaling crosstalk between the large-seeded trait and abiotic tolerance are, however, largely unknown. Here, we demonstrate the molecular link that integrates plant abscisic acid (ABA) responses to drought stress into the regulation of seed mass. Both loss-of-function mutants of the Auxin Response Factor 2 (ARF2 encoding a transcription factor) and lines overexpressing AINTEGUMENTA (ANT; a transcription factor) under the 35S promoter exhibited large seed and drought-tolerant phenotypes as a result of abnormal ABA–auxin crosstalk signaling pathways in Arabidopsis. The target gene COLD-REGULATED15A (COR15a) was identified as participating in the regulation of seed development with ABA signaling through a negative regulation mechanism that is mediated by ANT. The molecular and genetic evidence presented indicate that ARF2, ANT and COR15A form an ABA-mediated signaling pathway to link modulation of seed mass with drought tolerance. These observations indicate that the ARF2 transcription factor serves as a molecular link that integrates plant ABA responses to drought stress into the regulation of seed mass.
Children and adults minimise activated muscle volume by selecting gait parameters that balance gross mechanical power and work demands
Authors: Hubel Tatjana Y. , Usherwood James R.
Published: September 2015

Terrestrial locomotion on legs is energetically expensive. Compared with cycling, or with locomotion in swimming or flying animals, walking and running are highly uneconomical. Legged gaits that minimise mechanical work have previously been identified and broadly match walking and running at appropriate speeds. Furthermore, the ‘cost of muscle force’ approaches are effective in relating locomotion kinetics to metabolic cost. However, few accounts have been made for why animals deviate from either work-minimising or muscle-force-minimising strategies. Also, there is no current mechanistic account for the scaling of locomotion kinetics with animal size and speed. Here, we report measurements of ground reaction forces in walking children and adult humans, and their stance durations during running. We find that many aspects of gait kinetics and kinematics scale with speed and size in a manner that is consistent with minimising muscle activation required for the more demanding between mechanical work and power: spreading the duration of muscle action reduces activation requirements for power, at the cost of greater work demands. Mechanical work is relatively more demanding for larger bipeds – adult humans – accounting for their symmetrical M-shaped vertical force traces in walking, and relatively brief stance durations in running compared with smaller bipeds – children. The gaits of small children, and the greater deviation of their mechanics from work-minimising strategies, may be understood as appropriate for their scale, not merely as immature, incompletely developed and energetically sub-optimal versions of adult gaits.
Study of Porous Structures and Thermal Properties of Luminescent Polymeric Microspheres Derivatives of Naphthalene-2,7-Diol
Authors: Podkościelna Beata , Lutomski Mateusz
Published: September 2015

We studied the porous structures and thermal properties of spherical shaped cross-linked polymers. These novel polymeric microspheres were synthesized by emulsion–suspension polymerization of aromatic tetrafunctional monomer [2,7-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,7-NAF.DM)] with typical, commercially available monomers (styrene, divinylbenze ne and methyl methacrylate). The monomer 2,7-NAF.DM was obtained in the two-step process. In the first step, the epoxy resin was synthesized by treating epichlorohydrin with naphthalene-2,7-diol. In the second step, the obtained epoxy derivatives were subjected to esterification with methacrylic acid. Porous structures of the obtained microspheres in the dry state were studied by nitrogen adsorption–desorption measurements. Thermal stabilities and degradation behaviours of the obtained co-polymers were characterized by differential scanning calorimetry and thermogravimetric/derivative thermogravimetry analyses. In addition, we also present the photoluminescent properties of these microspheres.
Physicochemical Properties and Catalytic Performance of Sulphonic Resins of Various Morphological Types in Ethyl t-Butyl Ether Synthesis
Authors: Vlasenko Nina V. , Kochkin Yuri N. , Serebrii Tamila G. , Strizhak Peter E.
Published: September 2015

Physicochemical and catalytic properties of sulphonic resins of various morphological types in ethyl t-butyl ether synthesis were studied. We have found that the turnover frequency (TOF) of sulphonated cation-exchange resins reflects the effect of morphology expressed in terms of fractal geometry. The correlation between the catalytic activity of various types of sulphonated resins and their fractal dimension was established. Difference in observed TOF of sulphonic resins of various morphological types is caused by various accessibilities of acid sites. Catalysts of more ordered structure (characterized by smaller fractal dimension) provide the best conditions for the adsorption–desorption of reactants and products resulting in large values of TOF.
Adsorption of Cs+ at the Hydroxyapatite/Aqueous Electrolyte Interface
Authors: Skwarek E.
Published: September 2015

The aim of this paper is to discuss the changes in the double electrical layer at the hydroxyapatite/electrolyte solution interface during the adsorption of Cs+ and to establish the relationship between the time and adsorption on this material. The adsorbent was prepared by wet precipitation methods, and characterized by X-ray diffraction and low-temperature nitrogen adsorption–desorption methods. The specific surface area of the adsorbent was characterized and the suitable particle sizes were determined. Adsorption of 137Cs isotopes from ionic solutions was carried out at different concentrations and pH. The values of Cs+ adsorption on the hydroxyapatite were quantified and the effect of Cs on its grains (particles) size, morphology, surface charge density and zeta potential was discussed.
Structural and Functional Designs of Catalysts for Reduction of Nitrogen (I), (II) Oxides
Authors: Orlyk Svitlana M. , Boichuk Tetiana M. , Kyriienko Pavlo I. , Popovych Nataliia O.
Published: September 2015

Co- and Ag-containing catalysts on structured supports were investigated for use in DeNOx processes, in particular, in the process of combined reduction of N2O and NO with carbon monoxide and in selective catalytic reduction of NO with C2 and C4 alcohols. It was shown that doping of cobalt–cerium–zirconium oxide with 0.1 wt.% of Pd significantly lowers the temperature for achieving high conversions of N2O and NO (up to 200–300 °C) in a reaction mixture containing N2O, NO, CO and O2. The activity of Ag/Al2O3/cordierite catalysts in the selective reduction of nitrogen oxides by ethanol and butanol rises with increasing of Al2O3 loading and depends on the optimal silver content added. Silver is associated with the regulation of redox and acid–base properties of the catalyst surface.
Electrical and Physical Characteristics of Silica Nanoparticles in Aqueous Media Affected by Cations Na+, Ba2+ and Al3+
Authors: Andriyko L.S. , Zarko V.I. , Gun'ko V.M. , Marynin A.I. , Olishevskiy V.V. , Skwarek E. , Janusz W.
Published: September 2015

The influence of metal cations which have various valences [mono-(Na+), bi-(Ba2+) and trivalent (Al3+)] at different concentrations (0.001–0.1M) on the behaviour of nanosilica (0.5%wt. and 5%wt.) in aqueous media is analyzed using both photon correlation spectroscopy (particle-size distribution) and electrophoresis (zeta potential, ζ). The zeta potential and the particle-size distribution with respect to the particle volume of nanosilica was found to strongly depend on the silica content, concentration, and valence of cations of dissolved salts. An increase in the latter can cause a change in the sign of the zeta potential.
Study on Synthesis and Characterization of Porous Microspheres with Pendant Amine Groups
Authors: Maciejewska Małgorzata , Bolbukh Yuliia M.
Published: September 2015

Porous microspheres of glycidyl methacrylate cross-linked with trimethylolpropane trimethacrylate were prepared with toluene as porogen by suspension–emulsion polymerization. With increasing molar ratio of the functional monomer to cross-linker, the epoxy group content increases significantly, whereas the parameters of porous structure (specific surface area and total pore volume) decrease. To obtain adsorbents bearing functional groups, the porous methacrylate network was modified by subsequent treatment with diethylenetriamine. Polymers capacity towards Cu(II), Zn(II), Pb(II) and Cd(II) was investigated.
Thiol-Functionalized Mesoporous Carbons as Adsorbents of Heavy-Metal Ions
Authors: Michalak-Zwierz Katarzyna , Gdula Karolina , Tyszczuk-Rotko Katarzyna , Zawadzki Witold , Dąbrowski Andrzej , Barczak Mariusz
Published: September 2015

Ordered mesoporous carbon has been obtained by hard templating using SBA-15 and subsequently, oxidized (by treatment with ammonium persulphate) and thiol-functionalized (by treatment with thiol-contained polyhedral oligomeric silsesquioxane). Pristine and thiol-functionalized carbons were characterized by nitrogen adsorption, X-ray diffractometry, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy and tested for their ability to adsorb bivalent heavy-metal ions (Cd, Cu, Pb, Zn) from the aqueous solutions. The observed static adsorption capacities are very high up to 0.76 mmol/g. Adsorption kinetics is also very fast: approximately 90% of the equilibrium amount is adsorbed after several minutes.
Adsorption of L-Histidine onto Functionalized Mesoporous SBA-15 Organosilicas
Authors: Oszust Monika , Gdula Karolina , Borowski Piotr , Dąbrowski Andrzej , Barczak Mariusz
Published: September 2015

Adsorption of L-histidine (LH) over mesoporous SBA-15 silicas functionalized by amine-, thiol- and cyano-functional groups has been studied. These organosilicas have been synthesized by co-condensation of proper monomers in the presence of a template (Pluronic P-123), and characterized by elemental analysis, nitrogen adsorption, X-ray diffraction and transmission electron microscopy. The highest LH static adsorption capacity was observed for the cyano-functionalized sample [approximately 70 mg g−1 (450 mol g−1)]; by contrast, pristine SBA-15 had a lowest adsorption capacity of approximately 25 mg g−1 (170 mol g−1).
Adsorption and Stability Properties of Aqueous Suspension of Chromium (III) Oxide in the Presence of Synthetic and Natural Polymers: Possibilities of Solid Removal
Authors: Wiśniewska Małgorzata , Ostolska Iwona , Szewczuk-Karpisz Katarzyna , Nosal-Wiercińska Agnieszka
Published: September 2015

The effects of type and content of polymer functional groups on the adsorption mechanism on the chromium (III) oxide surface were studied. Both synthetic [poly(acrylic acid) (PAA), anionic polyacrylamide (PAM), poly(aspartic acid) (ASP), block co-polymer of ASP with poly(ethylene glycol) (ASP-b-PEG)] and natural [bovine serum albumin, ovalbumin, human serum albumin, bacterial polysaccharide (exopolysaccharide EPS)] polymers were applied. For this purpose, adsorption, surface charge, zeta potential and stability measurements were carried out. The largest adsorption was found for the ASP-b-PEG (synthetic polymer) and EPS (natural polymer). The most effective destabilizers for Cr2O3 removal from the aqueous suspension were PAA 240,000 and ASP 6800.
Agriculture Cooperatives in Lithuania: development issues
Authors: Раманаускас Юлюс , Ramanauskas Julius , Сташис Римантас , Stays Rimantas
Published: September 2015

The evolution of cooperation in Lithuanian agriculture during the past century is analysed in the paper. It was found that cooperation has greatly depended on farming conditions, traditions of communication, state policy with respect to the development of agriculture and cooperation, and various economic conditions. Particularly significant are the specific features of development during transition of economic conditions: weak agricultural structures (farmer’s farms, agricultural companies); the domination of share capital in the processing industry and commerce, and the insufficiency of agricultural and foodstuffs markets.

The basis of analysis in this paper are the theoretical preconditions for the principles of development of the activity of cooperatives. It was determined that most prospective preconditions for development of cooperation at present and in the near future emphasize the comparitive weight of the cost of production of raw materials, i.e. cooperatives of facilities, realisation, finance and representation of interests.
Spatial and spatiotemporal models of unemployment rate in Poland
Authors: Müller-Frączek Iwona , Pietrzak Michał Bernard
Published: September 2015

The article show interest in modelling of economic processes which are characterized by spatial dependence. An unemployment rate indicating a level of socio-economic development of regions constitutes one of such processes. The correct quantitative description of this process, as one of more important negative socio-economic phenomena, is an important task of econometrics, in particular, of spatial econometrics. The purpose of the article is to provide a spatial analysis of the unemployment rate registered at the end of each year in Polish poviats. The research covers the period of 2004-2009. Two approaches to modelling are used - spatial and spatiotemporal. The neighbourhood matrix based on the common border of poviats is applied to reflect the strength and direction of spatial relations. There are used two exogenous variables: investments and entities of the economy recorded, both per capita. In the spatial as well as in the spatiotemporal approach the main tendencies of the change of the unemployment rate are described with a spatial linear trend. All of the received models have good economic and statistic properties and they could be used for further analysis.
The monetary transmission mechanism in Polish economy
Authors: Waszkowski Adam
Published: September 2015

The aim of this article is to define the monetary transmission mechanism of the Polish economy and to identify the impact of shocks from the monetary policy on macroeconomic indicators such as price levels or GDP. In this regard there were used a theoretical vector autoregression model and conducted its recursive structure proposed by Sims (1980) using Cholesky decomposition. This allowed to isolate the impact of shocks: a supply, a demand, monetary and exchange rate on the value and output growth, inflation and exchange rate. Thanks to this it was visualized in the Polish economy a phenomenon of output and price puzzle.
Merchant Commodity Storage Practice Revisited
Authors: Secomandi Nicola
Published: September 2015

Commodity merchants use various heuristics to value leasing contracts on storage facilities as real options and make inventory trading decisions. Two prominent heuristics sequentially reoptimize simple models, leading to the so-called rolling intrinsic (RI) policy and rolling basket of spread options (RSO) policy. The extant literature numerically demonstrates that these two policies are nearly optimal in many realistic settings and can be used with Monte Carlo simulation to obtain fairly accurate estimates of the value of storage contracts. This paper provides a theoretical basis for the observed benefit of reoptimization with these heuristics and additional numerical evidence for the near optimal performance of the RI and RSO policies in several practical cases, but shows that the RI policy significantly outperforms the RSO policy in some of these cases. This research also proves that the RSO policy has a double basestock target structure, a known property of an optimal policy that is trivially true for the RI policy. Moreover, this work develops efficient and effective dual bounds to assess the performance of merchant commodity storage heuristics. In particular, these bounds are immediately relevant to the developers and users of the two considered heuristics.
Graph energy change due to any single edge deletion
Authors: Wang Wen-Huan , So Wasin
Published: September 2015

The energy of a graph is the sum of the absolute values of its eigenvalues. We propose a new problem on graph energy change due to any single edge deletion. Then we survey the literature for existing partial solution of the problem, and mention a conjecture based on numerical evidence. Moreover, we prove in three different ways that the energy of a cycle graph decreases when an arbitrary edge is deleted except for the order of 4.
Method for Identification of Spectral Targets in Discrete Frequency Infrared Spectroscopy for Clinical Diagnostics
Authors: Lloyd Gavin Rhys , Stone Nicholas
Published: September 2015

Spectroscopic imaging with discrete frequency infrared (DF-IR) has the potential to have a major impact on the clinical utility of IR imaging techniques for biochemical detection of disease. This can be achieved in real time using imaging at selected wavenumbers tuned to molecular absorptions of interest enabling tissue and disease-specific contrast to be obtained from the sample. However, selecting the appropriate wavenumbers to measure for DF-IR is critical, since vital diagnostic information could be missed. Here we demonstrate the application of partial least squares discriminant analysis (PLS-DA) and variable importance for projection (VIP) to identify key diagnostic wavenumber targets for the detection of dysplasia in human colon polyp sections. A small dataset, including 41 regions of interest (25 benign, 16 dysplastic; 5175 spectra in total), was selected from Fourier transform infrared (FT-IR) images of human colon polyp sections. PLS-DA was used to differentiate between benign and cancerous human colon polyp sections (sensitivity 95%, specificity 93% cross-validated), and VIP scores were calculated for all wavenumbers. A second PLS-DA model was then calculated using only variables that VIP identified as significant, reducing the number of wavenumbers to ∼25% of the full dataset. The resulting cross-validated sensitivity and specificity (93 and 90%, respectively) indicate that the VIP method selects the key diagnostic wavenumbers for this dataset. Finally, a robust subset of variables was identified by selecting wavenumbers that exceeded the minimum VIP score in 95% of our validation iterations. A cross-validated PLS-DA model using only the robustly selected wavenumber targets (∼20% of the original wavenumbers) resulted in sensitivity and specificity of 91 and 82%, respectively, indicating that PLS-DA and VIP are suitable approaches for the selection of wavenumber targets in DF-IR.
Laser-Induced Fluorescence from N2+ Ions Generated by a Corona Discharge in Ambient Air
Authors: Konthasinghe Kumarasiri , Fitzmorris Kristin , Peiris Manoj , Hopkins Adam J. , Petrak Benjamin , Killinger Dennis K. , Muller Andreas
Published: September 2015

In this work, we present the measurement of laser-induced fluorescence from N2+ ions via the B2Σ+ u − X2Σ+ g band system in the near-ultraviolet. The ions were generated continuously by a plasma glow discharge in low pressure N2 and by a corona discharge in ambient air. The fluorescence decay time was found to rapidly decrease with increasing pressure leading to an extrapolated decay rate of ≈10 10 s−1 at atmospheric pressure. In spite of this quenching, we were able to observe laser induced fluorescence in ambient air by means of a time-gated spectral measurement. In the process of comparing the emission signal with that of N2 spontaneous Raman scattering, ion concentrations in ambient air of order 10 8 -10 10 cm−3 were determined. With moderate increases in laser power and collection efficiency, ion concentrations of less than 10 6 cm−3 may be measurable, potentially enabling applications in atmospheric standoff detection of ionizing radiation from hazardous radioactive sources.
Stray Light Correction in the Optical Spectroscopy of Crystals
Authors: Hendler Richard W. , Meuse Curtis W. , Gallagher Travis , Labahn Joerg , Kubicek Jan , Smith Paul D. , Kakareka John W.
Published: September 2015

It has long been known in spectroscopy that light not passing through a sample, but reaching the detector (i.e., stray light), results in a distortion of the spectrum known as absorption flattening. In spectroscopy with crystals, one must either include such stray light or take steps to exclude it. In the former case, the derived spectra are not accurate. In the latter case, a significant amount of the crystal must be masked off and excluded. In this paper, we describe a method that allows use of the entire crystal by correcting the distorted spectrum.
Joint Baseline-Correction and Denoising for Raman Spectra
Authors: Liu Hai , Zhang Zhaoli , Liu Sanya , Yan Luxin , Liu Tingting , Zhang Tianxu
Published: September 2015

Laser instruments often suffer from the problem of baseline drift and random noise, which greatly degrade spectral quality. In this article, we propose a variation model that combines baseline correction and denoising. First, to guide the baseline estimation, morphological operations are adopted to extract the characteristics of the degraded spectrum. Second, to suppress noise in both the spectrum and baseline, Tikhonov regularization is introduced. Moreover, we describe an efficient optimization scheme that alternates between the latent spectrum estimation and the baseline correction until convergence. The major novel aspect of the proposed algorithms is the estimation of a smooth spectrum and removal of the baseline simultaneously. Results of a comparison with state-of-the-art methods demonstrate that the proposed method outperforms them in both qualitative and quantitative assessments.
Oxygen Rotational Temperature Determination Using Empirical Analyses of C3Π(v′ = 2) ← X3Σ(v″ = 0) Transitions
Authors: Adams Steven F. , Wu Yue , Zhang Zhili
Published: September 2015

The spectra of molecular oxygen through C3Π(v′ = 2) ← X3Σ(v″ = 0) transitions have been obtained by coherent microwave Rayleigh scattering (radar) from resonance-enhanced multiphoton ionization (REMPI). Measurements of rotational temperatures of molecular oxygen have been demonstrated based on the empirical analyses of the O2 spectra without the requirement of highly resolved rotational features. Three methods, including (1) linewidth fitting, (2) linear fitting, and (3) area fitting have been investigated for temperature measurements within pure oxygen, ambient air, and H2–air and CH4–air flame environments. The first two methods were applied in a moderately low temperature environment with measurement uncertainties less than 11% and 26%, respectively. The area fitting method covered a wider temperature range, from room temperature (∼300 K) to flame temperature (∼1700 K), with minimal dependence on the fine structures of the O2 spectra. Less elaborate than Boltzmann plot analyses of ultrafine rotational lines from congested upper rotational energy levels in O2(C3Π(v′ = 2)), these empirical analyses are predictably sensitive to the thermal distribution of molecular oxygen and have been successfully demonstrated as simple and quick methods for remote gas-phase temperature measurement.
Revisiting Time-Resolved Protein Phosphorescence
Authors: Draganski Andrew R. , Corradini Maria G. , Ludescher Richard D.
Published: September 2015

Analysis of time-resolved phosphorescence data from proteins presents certain problems. Care must be taken in establishing that the analysis is not confounded in the early part of the decay by other emitting species. These species may include tyrosine, impurities found in the solvent, or impurities bound to the protein. In this paper, analysis of the phosphorescence of simple mixtures of tryptophan, tyrosine, and tryptophan + tyrosine in glycerol–water solvent has demonstrated the necessity of accounting for tyrosine emission in the analysis of protein phosphorescence. The tyrosine emission is especially strong at cold temperatures and becomes negligible above approximately 185 K in this solvent. Two fitting procedures have been developed to describe the bimodal emission that results from a single-tryptophan protein that contains a significant number of tyrosine residues. The methods utilize either a maximum entropy method-derived lifetime distribution or the stretched exponential function. In both cases some prior information regarding the expected decay characteristics of the tryptophan residue is applied to guide the separation of the tryptophan component from the tyrosine component. This prior information is obtained by comparing the tail of the protein decay to decays of free-tryptophan in solvent at a variety of temperatures until a match is found having close overlap on a log-intensity decay plot.
Fourier Transform Infrared Spectral Detection of Life in Polar Subsurface Environments and its Application to Mars Exploration
Authors: Preston Louisa J. , Johnson Diane , Cockell Charles S. , Grady Monica M.
Published: September 2015

Cryptoendolithic lichen communities of the Dry Valleys, Antarctica, survive in an extremely inhospitable environment, finding refuge in microscopic niches where conditions suitable for life exist. Such “within-rock” communities may have evolved on Mars when conditions for life on the surface deteriorated to such an extent that they could no longer survive. Fourier transform infrared spectroscopy of unprepared whole-rock Antarctic Beacon sandstones was used to vertically profile molecular vibrations of fatty acids, proteins, and carboxylic acids created by endolithic communities. Spectral biosignatures were found localized to lichen-rich areas and were absent in crustal regions and the bulk rock substrate. These cryptoendolithic profiles will aid similar spectroscopic investigations of organic biosignatures during future Martian subsurface studies and will help in the identification of similar communities in other localities across the Earth.
A Prototype Stationary Fourier Transform Spectrometer for Near-Infrared Absorption Spectroscopy
Authors: Li Jinyang , Lu Dan-Feng , Qi Zhi-Mei
Published: September 2015

A prototype stationary Fourier transform spectrometer (FTS) was constructed with a fiber-coupled lithium niobate (LiNbO3) wave-guide Mach-Zehnder interferometer (MZI) for the purpose of rapid on-site spectroscopy of biological and chemical measurands. The MZI contains push-pull electrodes for electro-optic modulation, and its interferogram as a plot of intensity against voltage was obtained by scanning the modulating voltage from −60 to +60 V in 50 ms. The power spectrum of input signal was retrieved by Fourier transform processing of the interferogram combined with the wavelength dispersion of half-wave voltage determined for the MZI used. The prototype FTS operates in the single-mode wavelength range from 1200 to 1700 nm and allows for reproducible spectroscopy. A linear concentration dependence of the absorbance at Λmax = 1451 nm for water in ethanolic solution was obtained using the prototype FTS. The near-infrared spectroscopy of solid samples was also implemented, and the different spectra obtained with different materials evidenced the chemical recognition capability of the prototype FTS. To make this prototype FTS practically applicable, work on improving its spectral resolution by increasing the maximum optical path length difference is in progress.
Monte Carlo Simulations of Subsurface Analysis of Painted Layers in Micro-Scale Spatially Offset Raman Spectroscopy
Authors: Matousek Pavel , Conti Claudia , Colombo Chiara , Realini Marco
Published: September 2015

A recently developed micrometer-scale spatially offset Raman spectroscopy (micro-SORS) method provides a new analytical capability for investigating nondestructively the chemical composition of subsurface, micrometer-scale-thick, diffusely scattering layers at depths beyond the reach of conventional confocal Raman microscopy. Here we provide, for the first time, the theoretical foundations for the micro-SORS defocusing concept based on Monte Carlo simulations. Specifically, we investigate a defocusing variant of micro-SORS that we used in our recent proof-of-concept study in conditions involving thin, diffusely scattering layers on top of an extended, diffusely scattering substrate. This configuration is pertinent, for example, for the subsurface analysis of painted layers in cultural heritage studies. The depth of the origin of Raman signal and the relative micro-SORS enhancement of the sublayer signals reached are studied as a function of layer thickness, sample photon transport length, and absorption. The model predicts that sublayer enhancement initially rapidly increases with increasing defocusing, ultimately reaching a plateau. The magnitude of the enhancement was found to be larger for thicker layers. The simulations also indicate that the penetration depths of micro-SORS can be between one and two orders of magnitude larger than those reached using conventional confocal Raman microscopy. The model provides a deeper insight into the underlying Raman photon migration mechanisms permitting the more effective optimization of experimental conditions for specific sample parameters.
Perspektiven einer anderen Natur
Authors: Becker Andreas
Published: September 2015

Mit der Möglichkeit der Raffung und Dehnung von Zeit eröffnet der Film Einblicke in Dimensionen, die der Alltag verwehrt. Eine Pflanze erblüht in wenigen Momenten, unscheinbare Gesten werden auf Minutendauer gestreckt. Bewegungen und Abläufe erschließen sich durch diese zeitliche Perspektivierung neu. Sie können redigiert und überformt werden. Der Band zeichnet am Beispiel des dokumentarischen Films die historische Entwicklung dieser Verfahren nach und beschreibt - im Anschluss an Theorien Roman Ingardens, Walter Benjamins und Siegfried Kracauers - deren ästhetische Wirkung. Gezeigt wird, wie sich das Verständnis der Verfahren im Laufe der Filmgeschichte gewandelt hat. Behandelt werden unter anderem Werke und Positionen Eadweard Muybridges, Leni Riefenstahls, Godfrey Reggios und die Zeitrafferexperimente Alexander Kluges.
Optische Magie
Authors: Gronemeyer Nicole
Published: September 2015

»Optische Magie« ist der Titel einer Reihe von Publikationen, die im 17. Jahrhundert von jesuitischen Gelehrten verfasst wurden, um das Gebiet der Optik mittels kunstfertiger Inszenierungen darzustellen. Durch neuartige Medien wie der Laterna magica oder der Anamorphose wurden Illusionen erzeugt, mit denen ein Publikum unterhalten und gebildet werden sollte. Dieser besondere Umgang mit visuellen Techniken durch Autoren wie Schott und Kircher wird in der vorliegenden Studie in medien- und kulturgeschichtlicher Hinsicht untersucht und als Teil einer barocken Kultur des Scheins bestimmt, die sich zwischen Repräsentation, Manipulation und Schaulust bewegt hat.
Aggressive Medien
Authors: Otto Isabell
Published: September 2015

Mediengewalt ist immer wieder ein Thema öffentlicher Debatten. Insbesondere nach spektakulären Amokläufen taucht regelmäßig die Frage auf, ob Medien ihre Nutzer zu Gewalttätern programmiert und so die Tat verursacht haben. Dabei ist der kausale Zusammenhang alles andere als geklärt: Obwohl die empirische Mediengewaltforschung mit großem Aufwand betrieben wird, hat sie bis heute keine konsensfähige Antwort gefunden. Diese Studie sucht keine weitere Lösung, sondern fragt, wie sich die Kausalformel »Mediengewalt« historisch herausgebildet hat und welcher Gewinn darin liegt, die Mediengewalt-Debatte beständig mit ungeklärtem Wissen zu versorgen.
Digitaler Realismus
Authors: Richter Sebastian
Published: September 2015

Digitale Doppelgänger und animierte Hollywoodstars, Fahrten durch Nervenbahnen und Hautporen, unmögliche Kameraperspektiven und Bildräume, die sich unendlich fortsetzen - in aktuellen Spielfilmen sind gefilmte Bildanteile und Computeranimationen oft ununterscheidbar miteinander verschmolzen. Eine neue Kategorie von »hybriden Bewegungsbildern« ist entstanden, die eine Bildästhetik jenseits des Effekt-Kinos hervorgebracht hat. Ihre Inszenierungsstrategien unterwandern unsere Vorstellung realistischer Darstellungen - sie beeinflussen unsere Wahrnehmung nachhaltig und prägen unsere Sicht auf die Welt mit. Das Buch verbindet die Darstellung der technischen Voraussetzungen dieser neuen Bildwelten mit einer eingehenden Untersuchung ihrer ästhetischen Implikationen. Es schließt damit eine Lücke in der wissenschaftlichen Auseinandersetzung mit der Digitalisierung der Bildproduktion.
Computerexperimente
Authors: Gramelsberger Gabriele
Published: September 2015

Seit der Einführung des Computers als Forschungs-, Experimentier- und Prognoseinstrument erleben die Wissenschaften einen tief greifenden Wandel. Nicht nur die Praktiken und Infrastrukturen wissenschaftlichen Arbeitens verändern sich, sondern auch die Logik der Forschung unterliegt einer grundlegenden Transformation. Neben Theorie, Experiment und Messung eröffnen Computerexperimente ein neues Feld der Wissensproduktion und verändern radikal die Experimentalkultur der Naturwissenschaften. Am Beispiel der Klimaforschung rekonstruiert das Buch diesen Wandel der Wissenschaften »from science to computational sciences«.
Diffusion of dust particles emitted from a fixed source
Authors: Al-mashrafi Khaled
Published: September 2015

In this paper, we investigate the mathematical model for the diffusion of dust particles emitted from a fixed source. Mathematically, the time-dependent diffusion equation in the presence of a point source whose strength is dependent on time is solved. The solution in closed form for a source of general time dependence is obtained. A number of special cases, in which the source function of time is explicitly given and special values of the diffusion parameters are taken are examined in detail. The numerical calculations show the strong dependence of the concentration of dust on the speed of the wind, the source, and its position in the vertical direction. It is also found that the diffusion parameters play an important role in the spread of the dust particles in the atmosphere. When diffusion is present only in the vertical direction, it is found that for small times the dust spreads with a front that travels with the speed of the wind.
Between the national and transnational logics: the case of Kichwa Otavalo migration
Authors: Ruiz Balzola Andrea
Published: September 2015

The aim of the present article is to describe a process of mobility and construction of the territory that challenges the logics of borders and the categories related to the nation-state. This is well illustrated by the case study of the transnational trade of the kichwa otavalo. From here, we examine the challenges that processes like the later represent for the analytical framework that explains migratory movements within a territorial logic associated with the classical notion of citizenship.
Active Transient Sound Radiation Control from a Smart Piezocomposite Hollow Cylinder
Authors: Hasheminejad Seyyed M. , Rabbani Vahid
Published: September 2015

The linear 3D piezoelasticity theory along with active damping control (ADC) strategy are applied for non-stationary vibroacoustic response suppression of a doubly fluid-loaded functionally graded piezolaminated (FGPM) composite hollow cylinder of infinite length under general time-varying excitations. The control gain parameters are identified and tuned using Genetic Algorithm (GA) with a multi-objective performance index that constrains the key elasto-acoustic system parameters and control voltage. The uncontrolled and controlled time response histories due to a pair of equal and opposite impulsive external point loads are calculated by means of Durbin’s numerical inverse Laplace transform algorithm. Numerical simulations demonstrate the superior (good) performance of the GA-optimized distributed active damping control system in effective attenuation of sound pressure transients radiated into the internal (external) acoustic space for two basic control configurations. Also, some interesting features of the transient fluid-structure interaction control problem are illustrated via proper 2D time domain images and animations of the 3D sound field. Limiting cases are considered and accuracy of the formulation is established with the aid of a commercial finite element package as well as comparisons with the current literature.