Elastic properties and apparent density of human edentulous maxilla and mandible.

PubMed

Seong, W-J; Kim, U-K; Swift, J Q; Heo, Y-C; Hodges, J S; Ko, C-C

2009-10-01

The aim of this study was to determine whether elastic properties and apparent density of bone differ in different anatomical regions of the maxilla and mandible. Additional analyses assessed how elastic properties and apparent density were related. Four pairs of edentulous maxilla and mandibles were retrieved from fresh human cadavers. Bone samples from four anatomical regions (maxillary anterior, maxillary posterior, mandibular anterior, mandibular posterior) were obtained. Elastic modulus (EM) and hardness (H) were measured using the nano-indentation technique. Bone samples containing cortical and trabecular bone were used to measure composite apparent density (cAD) using Archimedes' principle. Statistical analyses used repeated measures ANOVA and Pearson correlations. Bone physical properties differed between regions of the maxilla and mandible. Generally, mandible had higher physical property measurements than maxilla. EM and H were higher in posterior than in anterior regions; the reverse was true for cAD. Posterior maxillary cAD was significantly lower than that in the three other regions.

The frequency-domain approach for apparent density mapping

NASA Astrophysics Data System (ADS)

Tong, T.; Guo, L.

2017-12-01

Apparent density mapping is a technique to estimate density distribution in the subsurface layer from the observed gravity data. It has been widely applied for geologic mapping, tectonic study and mineral exploration for decades. Apparent density mapping usually models the density layer as a collection of vertical, juxtaposed prisms in both horizontal directions, whose top and bottom surfaces are assumed to be horizontal or variable-depth, and then inverts or deconvolves the gravity anomalies to determine the density of each prism. Conventionally, the frequency-domain approach, which assumes that both top and bottom surfaces of the layer are horizontal, is usually utilized for fast density mapping. However, such assumption is not always valid in the real world, since either the top surface or the bottom surface may be variable-depth. Here, we presented a frequency-domain approach for apparent density mapping, which permits both the top and bottom surfaces of the layer to be variable-depth. We first derived the formula for forward calculation of gravity anomalies caused by the density layer, whose top and bottom surfaces are variable-depth, and the formula for inversion of gravity anomalies for the density distribution. Then we proposed the procedure for density mapping based on both the formulas of inversion and forward calculation. We tested the approach on the synthetic data, which verified its effectiveness. We also tested the approach on the real Bouguer gravity anomalies data from the central South China. The top surface was assumed to be flat and was on the sea level, and the bottom surface was considered as the Moho surface. The result presented the crustal density distribution, which was coinciding well with the basic tectonic features in the study area.

Use of plasma triglyceride/high-density lipoprotein cholesterol ratio to identify increased cardio-metabolic risk in young, healthy South Asians.

PubMed

Flowers, Elena; Molina, César; Mathur, Ashish; Reaven, Gerald M

2015-01-01

Prevalence of insulin resistance and associated dyslipidaemia [high triglyceride (TG) and low high-density lipoprotein cholesterol (HDL-C) concentrations] are increased in South Asian individuals; likely contributing to their increased risk of type-2 diabetes and cardiovascular disease. The plasma concentration ratio of TG/HDL-C has been proposed as a simple way to identify apparently healthy individuals at high cardio-metabolic risk. This study was carried out to compare the cardio-metabolic risk profiles of high-risk South Asian individuals identified by an elevated TG/HDL-C ratio versus those with a diagnosis of the metabolic syndrome. Body mass index, waist circumference, blood pressure, and fasting plasma glucose, insulin, TG, and HDL-C concentrations were determined in apparently healthy men (n=498) and women (n=526). The cardio-metabolic risk profile of "high risk" individuals identified by TG/HDL-C ratios in men (≥ 3.5) and women (≥2.5) was compared to those identified by a diagnosis of the metabolic syndrome. More concentrations of all cardio-metabolic risk factors were significantly higher in "high risk" groups, identified by either the TG/HDL-C ratio or a diagnosis of the metabolic syndrome. TG, HDL-C, and insulin concentrations were not significantly different in "high risk" groups identified by either criterion, whereas plasma glucose and blood pressure were higher in those with the metabolic syndrome. Apparently healthy South Asian individuals at high cardio-metabolic risk can be identified using either the TG/HDL-C ratio or the metabolic syndrome criteria. The TG/HDL-C ratio may be used as a simple marker to identify such individuals.

Density dependence of the saturated velocity in graphene

NASA Astrophysics Data System (ADS)

Ferry, D. K.

2016-11-01

The saturated velocity of a semiconductor is an important measure in bench-marking performance for either logic or microwave applications. Graphene has been of interest for such applications due to its apparently high value of the saturated velocity. Recent experiments have suggested that this value is very density dependent and can even exceed the band limiting Fermi velocity. Some of these measurements have also suggested that the scattering is dominated by the low energy surface polar mode of the SiO2 substrate. Here, we show that the saturated velocity of graphene on SiO2 is relatively independent of the density and that the scattering is dominated by the high energy surface polar mode of the substrate.

The effects of phase on the perception of 3D shape from texture: psychophysics and modeling.

PubMed

Thaler, Lore; Todd, James T; Dijkstra, Tjeerd M H

2007-02-01

Two experiments are reported in which observers judged the apparent shapes of elliptical cylinders with eight different textures that were presented with scrambled and unscrambled phase spectra. The results revealed that the apparent depths of these surfaces varied linearly with the ground truth in all conditions, and that the overall magnitude of surface relief was systematically underestimated. In general, the apparent depth of a surface is significantly attenuated when the phase spectrum of its texture is randomly scrambled, though the magnitude of this effect varies for different types of texture. A new computational model of 3D shape from texture is proposed in which apparent depth is estimated from the relative density of edges in different local regions of an image, and the predictions of this model are highly correlated with the observers' judgments.

Rod Photopigment Kinetics After Photodisruption of the Retinal Pigment Epithelium

PubMed Central

Masella, Benjamin D.; Hunter, Jennifer J.; Williams, David R.

2014-01-01

Purpose. Advances in retinal imaging have led to the discovery of long-lasting retinal changes caused by light exposures below published safety limits, including disruption of the RPE. To investigate the functional consequences of RPE disruption, we combined adaptive optics ophthalmoscopy with retinal densitometry. Methods. A modified adaptive optics scanning light ophthalmoscope (AOSLO) measured the apparent density and regeneration rate of rhodopsin in two macaques before and after four different 568-nm retinal radiant exposures (RREs; 400–3200 J/cm2). Optical coherence tomography (OCT) was used to measure the optical path length through the photoreceptor outer segments before and after RPE disruption. Results. All tested RREs caused visible RPE disruption. Apparent rhodopsin density was significantly reduced following 1600 (P = 0.01) and 3200 J/cm2 (P = 0.007) exposures. No significant change in apparent density was observed in response to 800 J/cm2. Surprisingly, exposure to 400 J/cm2 showed a significant increase in apparent density (P = 0.047). Rhodopsin recovery rate was not significantly affected by these RREs. Optical coherence tomography measurements showed a significant decrease in the optical path length through the photoreceptor outer segments for RREs above 800 J/cm2 (P < 0.001). Conclusions. At higher RREs, optical path length through the outer segments was reduced. However, the rate of photopigment regeneration was unchanged. While some ambiguity remains as to the correlation between measured reflectivity and absolute rhodopsin density; at the lowest RREs, RPE disruption appears not to be accompanied by a loss of apparent rhodopsin density, which would have been indicative of functional loss. PMID:25316724

SU-E-T-328: Dosimetric Impact of Cobalt-Chrome Stabilization Hardware in Paraspinal Radiation Therapy

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

Tang, G; LoSasso, T; Saleh, Z

2015-06-15

Purpose: Due to saturation, high density materials Result in an apparent density of 3.2 g/cm{sup 3} in CT images. The true density of traditional titanium stabilization rods (∼4.4 g/cm{sup 3}) is typically ignored in treatment planning. This may not be acceptable for new cobalt-chrome rods with a density of 8.5 g/cm{sup 3}. This study reports the dosimetric impact of cobalt-chrome rods in paraspinal radiotherapy. Methods: For titanium and cobalt-chrome rods, two planning studies were done for both IMRT and VMAT in Varian Eclipse using AAA. 1) The effect of planning without assigning the true rod density was assessed by comparingmore » plans generated with the apparent density and recalculated with the true density for titanium and cobalt-chrome. 2) To test if TPS can compensate for high density rods during optimization. Furthermore, TPS calculation accuracy was verified using MapCheck for a single 20 x 10 cm{sup 2} field. The MapCheck was incrementally shifted to achieve measurement resolution of 1 mm. Results: PTV coverage was ∼0.3% and ∼4.7% lower in plans that were recalculated with the true rod density of titanium and cobalt-chrome, respectively. PTV coverage can be maintained if the correct density is used in optimization. Measurements showed that TPS overestimated the dose locally by up to 11% for cobalt-chrome rods and up to 4% for titanium rods if the density is incorrect. With density corrected, maximum local differences of 6% and 3% were seen for cobalt-chrome and titanium rods, respectively. At 2 cm beneath a rod, electrons scattered from the side of the rod increased the lateral dose and diminished as depth increases. TPS was not able to account for this effect properly even with the true rod density assigned. Conclusion: Neglecting the true density of cobalt-chrome rods can cause under coverage to the PTV. Assigning the correct density during treatment planning can minimize unexpected decrease in PTV dose.« less

Ossicular density in golden moles (Chrysochloridae).

PubMed

Mason, Matthew J; Lucas, Sarah J; Wise, Erica R; Stein, Robin S; Duer, Melinda J

2006-12-01

The densities of middle ear ossicles of golden moles (family Chrysochloridae, order Afrosoricida) were measured using the buoyancy method. The internal structure of the malleus was examined by high-resolution computed tomography, and solid-state NMR was used to determine relative phosphorus content. The malleus density of the desert golden mole Eremitalpa granti (2.44 g/cm3) was found to be higher than that reported in the literature for any other terrestrial mammal, whereas the ossicles of other golden mole species are not unusually dense. The increased density in Eremitalpa mallei is apparently related both to a relative paucity of internal vascularization and to a high level of mineralization. This high density is expected to augment inertial bone conduction, used for the detection of seismic vibrations, while limiting the skull modifications needed to accommodate the disproportionately large malleus. The mallei of the two subspecies of E. granti, E. g. granti and E. g. namibensis, were found to differ considerably from one another in both size and shape.

The middle and high latitude winter ionosphere at the Ariel 4 satellite altitude

NASA Technical Reports Server (NTRS)

Tulunay, Y. K.; Grebowsky, J. M.

1983-01-01

The electron (0+) density variations over the northern and southern winter high latitude ionosphere are comprehensively analyzed using the technique of Brinton et al. (1978). Two-hour Magnetic Local Time (MLT) arithmetic means of electron densities are studied in terms of invariant magnetic latitude and in terms of magnetic activity as classified by the three-hour planetary magnetic activity index. It is found that the southern hemisphere densities are significantly lower than those in the northern hemisphere. Further, the maximum electron densities observed in the northern hemisphere are located in a MLT range symmetrical about the 14-02 MLT meridian, whereas in the southern hemisphere the maxima are observed about the noon midnight magnetic meridian. A deep localized ionization hole on the nightside of the polar cap is not observed although the polar cavity is apparent.

Densities and apparent molar volumes of atmospherically important electrolyte solutions. 2. The systems H(+)-HSO4(-)-SO4(2-)-H2O from 0 to 3 mol kg(-1) as a function of temperature and H(+)-NH4(+)-HSO4(-)-SO4)2-)-H2O from 0 to 6 mol kg(-1) at 25 °C using a Pitzer ion interaction model, and NH4HSO4-H2O and (NH4)3H(SO4)2-H2O over the entire concentration range.

PubMed

Clegg, S L; Wexler, A S

2011-04-21

A Pitzer ion interaction model has been applied to the systems H(2)SO(4)-H(2)O (0-3 mol kg(-1), 0-55 °C) and H(2)SO(4)-(NH(4))(2)SO(4)-H(2)O (0-6 mol kg(-1), 25 °C) for the calculation of apparent molar volume and density. The dissociation reaction HSO(4)(-)((aq)) ↔ H(+)((aq)) + SO(4)(2-)((aq)) is treated explicitly. Apparent molar volumes of the SO(4)(2-) ion at infinite dilution were obtained from part 1 of this work, (1) and the value for the bisulfate ion was determined in this study from 0 to 55 °C. In dilute solutions of both systems, the change in the degree of dissociation of the HSO(4)(-) ion with concentration results in much larger variations of the apparent molar volumes of the solutes than for conventional strong (fully dissociated) electrolytes. Densities and apparent molar volumes are tabulated. Apparent molar volumes calculated using the model are combined with other data for the solutes NH(4)HSO(4) and (NH(4))(3)H(SO(4))(2) at 25 °C to obtain apparent molar volumes and densities over the entire concentration range (including solutions supersaturated with respect to the salts).

Highly Effective Electromagnetic Interference Shielding Materials based on Silver Nanowire/Cellulose Papers.

PubMed

Lee, Tae-Won; Lee, Sang-Eui; Jeong, Young Gyu

2016-05-25

We fabricated silver nanowire (AgNW)-coated cellulose papers with a hierarchical structure by an efficient and facile dip-coating process, and investigated their microstructures, electrical conductivity and electromagnetic interference (EMI) shielding effectiveness. SEM images confirm that AgNWs are coated dominantly on the paper surfaces, although they exist partially in the inner parts of the cellulose papers, which demonstrates that the AgNW density gradually decreases in thickness direction of the AgNW/cellulose papers. This result is supported by the anisotropic apparent electrical conductivity of the AgNW/cellulose papers depending on in-plane or thickness direction. Even for a AgNW/cellulose paper obtained by a single dip-coating cycle, the apparent electrical conductivity in the in-plane direction of 0.34 S/cm is achieved, which is far higher than the neat cellulose paper with ∼10(-11) S/cm. In addition, the apparent electrical conductivity of the papers in the in-plane direction increases significantly from 0.34 to 67.51 S/cm with increasing the number of dip-coating cycle. Moreover, although the AgNW/cellulose paper with 67.51 S/cm possesses 0.53 vol % AgNW only, it exhibits high EMI shielding performance of ∼48.6 dB at 1 GHz. This indicates that the cellulose paper structure is highly effective to form a conductive AgNW network. Overall, it can be concluded that the AgNW/cellulose papers with high flexibility and low density can be used as electrically conductive components and EMI shielding elements in advanced application areas.

Response of cackling geese (Branta hutchinsii taverneri to spatial and temporal variation in production of crowberries on the Alaska Peninsula

USGS Publications Warehouse

Hupp, Jerry W.; Safine, David E.; Nielson, Ryan M.

2013-01-01

Arctic geese often feed on berries during premigratory fattening. We hypothesized that during autumn staging on the Alaska Peninsula, the distribution of Taverne's cackling geese (Branta hutchinsii taverneri) would be correlated with spatial variation in crowberry (Empetrum nigrum) abundance. We also predicted that daily rates of fat increase among cackling geese would be higher in years when crowberries were abundant, compared to years when the crowberry crop was poor. Apparent distribution of geese based on fecal densities mirrored patterns of berry abundance, with areas that had highest densities of crowberries being used most heavily by geese. In areas where apparent use was greatest, geese consumed approximately 30 % of the berry crop between early September and mid-October. From 1999 to 2002, annual mean crowberry density in early September ranged from 205 berries m-2 (1999) to 12 berries m-2 (2002). Daily rates of lipid increase averaged 7.6 g day-1 for juvenile and 11.4 g-1 day for adult cackling geese and did not differ among years despite a >90 % difference in annual berry abundance. Although cackling geese used areas with higher densities of berries and apparently consumed a relatively large percentage of the crowberry crop, we could not detect an effect of annual variation in berry abundance on rates of fattening. Berries may have provided relatively little metabolizable biomass due to their high (90 %) water content. However, consumption of crowberries may provide geese with other physiological benefits such as water for osmoregulation or antioxidants and fatty acids that contribute to metabolic performance during migration.

Interaction of ( sup 3 H)MK-801 with multiple states of the N-methyl-D-aspartate receptor complex of rat brain

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

Javitt, D.C.; Zukin, S.R.

1989-01-01

N-Methyl-D-aspartate (N-Me-D-Asp) and phencyclidine receptors interactively mediate central nervous system processes including psychotomimetic effects of drugs as well as neurodegenerative, cognitive, and developmental events. To elucidate the mechanism of this interaction, effects of N-Me-D-Asp agonists and antagonists and of glycine-like agents upon binding of the radiolabeled phencyclidine receptor ligand ({sup 3}H)MK-801 were determined in rat brain. Scatchard analysis revealed two discrete components of ({sup 3}H)MK-801 binding after 4 hr of incubation. Incubation in the presence of L-glutamate led to an increase in apparent densities but not in affinities of both components of ({sup 3}H)MK-801 binding as well as conversion ofmore » sites from apparent low to high affinity. Incubation in the presence of combined D-serine and L-glutamate led to an increase in the apparent density of high-affinity ({sup 3}H)MK-801 binding compared with incubation in the presence of either L-glutamate or D-serine alone. These data support a model in which phencyclidine receptor ligands bind differentially to closed as well as open conformations of the N-Me-D-Asp receptor complex and in which glycine-like agents permit or facilitate agonist-induced conversion of N-Me-D-Asp receptors from closed to open conformations.« less

Primordial black holes in linear and non-linear regimes

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

Allahyari, Alireza; Abolhasani, Ali Akbar; Firouzjaee, Javad T., E-mail: allahyari@physics.sharif.edu, E-mail: j.taghizadeh.f@ipm.ir

We revisit the formation of primordial black holes (PBHs) in the radiation-dominated era for both linear and non-linear regimes, elaborating on the concept of an apparent horizon. Contrary to the expectation from vacuum models, we argue that in a cosmological setting a density fluctuation with a high density does not always collapse to a black hole. To this end, we first elaborate on the perturbation theory for spherically symmetric space times in the linear regime. Thereby, we introduce two gauges. This allows to introduce a well defined gauge-invariant quantity for the expansion of null geodesics. Using this quantity, we arguemore » that PBHs do not form in the linear regime irrespective of the density of the background. Finally, we consider the formation of PBHs in non-linear regimes, adopting the spherical collapse picture. In this picture, over-densities are modeled by closed FRW models in the radiation-dominated era. The difference of our approach is that we start by finding an exact solution for a closed radiation-dominated universe. This yields exact results for turn-around time and radius. It is important that we take the initial conditions from the linear perturbation theory. Additionally, instead of using uniform Hubble gauge condition, both density and velocity perturbations are admitted in this approach. Thereby, the matching condition will impose an important constraint on the initial velocity perturbations δ {sup h} {sub 0} = −δ{sub 0}/2. This can be extended to higher orders. Using this constraint, we find that the apparent horizon of a PBH forms when δ > 3 at turn-around time. The corrections also appear from the third order. Moreover, a PBH forms when its apparent horizon is outside the sound horizon at the re-entry time. Applying this condition, we infer that the threshold value of the density perturbations at horizon re-entry should be larger than δ {sub th} > 0.7.« less

The influence of polymer architectures on the dewetting behavior of thin polymer films: from linear chains to ring chains.

PubMed

Wang, Lina; Xu, Lin; Liu, Binyuan; Shi, Tongfei; Jiang, Shichun; An, Lijia

2017-05-03

The dewetting behavior of ring polystyrene (RPS) film and linear polystyrene (LPS) film on silanized Si substrates with different grafting densities and PDMS substrate was investigated. Results showed that polymer architectures greatly influenced the dewetting behavior of the thin polymer film. On the silanized Si substrate with 69% grafting density, RPS chains exhibited stronger adsorption compared with LPS chains, and as a result the wetting layer formed more easily. For LPS films, with a decreased annealing temperature, the stability of the polymer film changed from non-slip dewetting via apparent slip dewetting to apparently stable. However, for RPS films, the polymer film stability switched from apparent slip dewetting to apparently stable. On the silanized Si substrate with 94% grafting density, the chain adsorption became weaker and the dewetting processes were faster than that on the substrate with 69% grafting density at the same experimental temperature for both the LPS and RPS films. Moreover, on the PDMS substrate, LPS films always showed non-slip dewetting, while the dewetting kinetics of RPS films switched from non-slip dewetting to slip dewetting behaviour. Forming the wetting layer strongly influenced the stability and dewetting behavior of the thin polymer films.

Treatment of low bone density in young people with cystic fibrosis: a multicentre, prospective, open-label observational study of calcium and calcifediol followed by a randomised placebo-controlled trial of alendronate.

PubMed

Bianchi, Maria Luisa; Colombo, Carla; Assael, Baroukh M; Dubini, Antonella; Lombardo, Mariangela; Quattrucci, Serena; Bella, Sergio; Collura, Mirella; Messore, Barbara; Raia, Valeria; Poli, Furio; Bini, Rita; Albanese, Carlina V; De Rose, Virginia; Costantini, Diana; Romano, Giovanna; Pustorino, Elena; Magazzù, Giuseppe; Bertasi, Serenella; Lucidi, Vincenzina; Traverso, Gabriella; Coruzzo, Anna; Grzejdziak, Amelia D

2013-07-01

Long-term complications of cystic fibrosis include osteoporosis and fragility fractures, but few data are available about effective treatment strategies, especially in young patients. We investigated treatment of low bone mineral density in children, adolescents, and young adults with cystic fibrosis. We did a multicentre trial in two phases. We enrolled patients aged 5-30 years with cystic fibrosis and low bone mineral density, from ten cystic fibrosis regional centres in Italy. The first phase was an open-label, 12-month observational study of the effect of adequate calcium intake plus calcifediol. The second phase was a 12-month, double-blind, randomised, placebo-controlled, parallel group study of the efficacy and safety of oral alendronate in patients whose bone mineral apparent density had not increased by 5% or more by the end of the observational phase. Patients were randomly assigned to either alendronate or placebo. Both patients and investigators were masked to treatment assignment. We used dual x-ray absorptiometry at baseline and every 6 months thereafter, corrected for body size, to assess lumbar spine bone mineral apparent density. We assessed bone turnover markers and other laboratory parameters every 3-6 months. The primary endpoint was mean increase of lumbar spine bone mineral apparent density, assessed in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT01812551. We screened 540 patients and enrolled 171 (mean age 13·8 years, SD 5·9, range 5-30). In the observational phase, treatment with calcium and calcifediol increased bone mineral apparent density by 5% or more in 43 patients (25%). 128 patients entered the randomised phase. Bone mineral apparent density increased by 16·3% in the alendronate group (n=65) versus 3·1% in the placebo group (n=63; p=0·0010). 19 of 57 young people (33·3%) receiving alendronate attained a normal-for-age bone mineral apparent density Z score. In the observational phase, five patients had moderate episodes of hypercalciuria, which resolved after short interruption of calcifediol treatment. During the randomised phase, one patient taking alendronate had mild fever versus none in the placebo group; treatment groups did not differ significantly for other adverse events. Correct calcium intake plus calcifediol can improve bone mineral density in some young patients with cystic fibrosis. In those who do not respond to calcium and calcifediol alone, alendronate can safely and effectively increase bone mineral density. Telethon Foundation (Italy). Copyright © 2013 Elsevier Ltd. All rights reserved.

Microscopic Theory for the Role of Attractive Forces in the Dynamics of Supercooled Liquids.

PubMed

Dell, Zachary E; Schweizer, Kenneth S

2015-11-13

We formulate a microscopic, no adjustable parameter, theory of activated relaxation in supercooled liquids directly in terms of the repulsive and attractive forces within the framework of pair correlations. Under isochoric conditions, attractive forces can nonperturbatively modify slow dynamics, but at high enough density their influence vanishes. Under isobaric conditions, attractive forces play a minor role. High temperature apparent Arrhenius behavior and density-temperature scaling are predicted. Our results are consistent with recent isochoric simulations and isobaric experiments on a deeply supercooled molecular liquid. The approach can be generalized to treat colloidal gelation and glass melting, and other soft matter slow dynamics problems.

Infectivity and RNA patterns as functions of high- and low-dilution passage of murine sarcoma-leukemia virus: evidence for autointerference within an oncornavirus population.

PubMed

Bondurant, M C; Hackett, A J; Schaffer, F L

1973-05-01

Heterogeneity of buoyant density and RNA content of virions of Moloney murine leukemia-sarcoma complex [MSV (MLV)] was the result of passage at low dilution. Heterogeneous stocks revealed two major RNA components in the population, with the smaller component, apparent mol wt 4 x 10(6) to 5 x 10(6), becoming predominant upon serial passage at low dilution. Concomitantly, infectivity titers of both MLV and MSV decreased upon serial passage at low dilution. MSV (MLV) passaged at high dilution retained high titers and a rather homogeneous high-molecular-weight RNA population characteristic of high-buoyant-density virions. Interference of both MLV and MSV replication was demonstrated by employing mixed inocula containing both low- and high-dilution passage stocks of MSV (MLV). In contrast to results with MSV (MLV), MLV freed of MSV by limit dilution did not show heterogeneity of buoyant density or of RNA when propagated at low dilution.

Infectivity and RNA Patterns as Functions of High- and Low-Dilution Passage of Murine Sarcoma-Leukemia Virus: Evidence for Autointerference Within an Oncornavirus Population

PubMed Central

Bondurant, M. C.; Hackett, A. J.; Schaffer, F. L.

1973-01-01

Heterogeneity of buoyant density and RNA content of virions of Moloney murine leukemia-sarcoma complex [MSV (MLV)] was the result of passage at low dilution. Heterogeneous stocks revealed two major RNA components in the population, with the smaller component, apparent mol wt 4 × 106 to 5 × 106, becoming predominant upon serial passage at low dilution. Concomitantly, infectivity titers of both MLV and MSV decreased upon serial passage at low dilution. MSV (MLV) passaged at high dilution retained high titers and a rather homogeneous high-molecular-weight RNA population characteristic of high-buoyant-density virions. Interference of both MLV and MSV replication was demonstrated by employing mixed inocula containing both low- and high-dilution passage stocks of MSV (MLV). In contrast to results with MSV (MLV), MLV freed of MSV by limit dilution did not show heterogeneity of buoyant density or of RNA when propagated at low dilution. PMID:4350709

QCD In Extreme Conditions

NASA Astrophysics Data System (ADS)

Wilczek, Frank

Introduction Symmetry and the Phenomena of QCD Apparent and Actual Symmetries Asymptotic Freedom Confinement Chiral Symmetry Breaking Chiral Anomalies and Instantons High Temperature QCD: Asymptotic Properties Significance of High Temperature QCD Numerical Indications for Quasi-Free Behavior Ideas About Quark-Gluon Plasma Screening Versus Confinement Models of Chiral Symmetry Breaking More Refined Numerical Experiments High-Temperature QCD: Phase Transitions Yoga of Phase Transitions and Order Parameters Application to Glue Theories Application to Chiral Transitions Close Up on Two Flavors A Genuine Critical Point! (?) High-Density QCD: Methods Hopes, Doubts, and Fruition Another Renormalization Group Pairing Theory Taming the Magnetic Singularity High-Density QCD: Color-Flavor Locking and Quark-Hadron Continuity Gauge Symmetry (Non)Breaking Symmetry Accounting Elementary Excitations A Modified Photon Quark-Hadron Continuity Remembrance of Things Past More Quarks Fewer Quarks and Reality

Spheroidization of molybdenum powder by radio frequency thermal plasma

NASA Astrophysics Data System (ADS)

Liu, Xiao-ping; Wang, Kuai-she; Hu, Ping; Chen, Qiang; Volinsky, Alex A.

2015-11-01

To control the morphology and particle size of dense spherical molybdenum powder prepared by radio frequency (RF) plasma from irregular molybdenum powder as a precursor, plasma process parameters were optimized in this paper. The effects of the carrier gas flow rate and molybdenum powder feeding rate on the shape and size of the final products were studied. The molybdenum powder morphology was examined using high-resolution scanning electron microscopy. The powder phases were analyzed by X-ray diffraction. The tap density and apparent density of the molybdenum powder were investigated using a Hall flow meter and a Scott volumeter. The optimal process parameters for the spherical molybdenum powder preparation are 50 g/min powder feeding rate and 0.6 m3/h carrier gas rate. In addition, pure spherical molybdenum powder can be obtained from irregular powder, and the tap density is enhanced after plasma processing. The average size is reduced from 72 to 62 µm, and the tap density is increased from 2.7 to 6.2 g/cm3. Therefore, RF plasma is a promising method for the preparation of high-density and high-purity spherical powders.

Triglyceride to HDL-C ratio and increased arterial stiffness in apparently healthy individuals.

PubMed

Wen, Jiang-Hua; Zhong, Yu-Yu; Wen, Zhi-Gang; Kuang, Chao-Qun; Liao, Jie-Rong; Chen, Li-Hua; Wang, Pei-Shen; Wu, Yue-Xia; Ouyang, Chu-Jun; Chen, Zhi-Jin

2015-01-01

High triglycerides and low high density lipoprotein cholesterol are important cardiovascular risk factors. Triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) has been reported to be useful in predicting cardiovascular disease. Brachial-ankle pulse wave velocity (baPWV) is a valid and reproducible measurement by which to assess arterial stiffness and a surrogate marker of atherosclerosis. However, there is limited evidence about the relationship between them. Therefore, we tested the hypotheses that TG/HDL-C is associated with baPWV in healthy individuals. Fasting lipid profiles, baPWV and clinical data were measured in 1498 apparently healthy, medication-free subjects (926 men, 572 women) who participated in a routine health screening from 2011 to 2013. Participants were stratified into quartiles of TG/HDL-C ratio. BaPWV > 1400 cm/s was defined as abnormal baPWV, Multivariable logistic regression was used to identify associations of TG/HDL-C quartiles and baPWV, after adjusting for the presence of conventional cardiovascular risk factors. In both genders, we observed positive relationships between TG/HDL-C quartiles and BMI, systolic BP, diastolic BP, fasting glucose, total cholesterol, LDL-C, triglycerides, uric acid, and percentages of high baPWV. Multivariable logistic regression revealed that baPWV abnormality OR value of the highest TG/HDL-C quartiles was 1.91 (95% CI: 1.11-3.30, P < 0.05) and 2.91 (95% CI: 1.02-8.30, P < 0.05) in male and female after adjusting for age, systolic BP, diastolic BP, BMI, fasting plasma glucose, LDL-C, uric acid and estimated glomerular filtration rate when compared with the lowest TG/HDL-C quartiles. Increased TG/HDL-C was independently associated with baPWV abnormality in apparently healthy individuals.

Triglyceride to HDL-C ratio and increased arterial stiffness in apparently healthy individuals

PubMed Central

Wen, Jiang-Hua; Zhong, Yu-Yu; Wen, Zhi-Gang; Kuang, Chao-Qun; Liao, Jie-Rong; Chen, Li-Hua; Wang, Pei-Shen; Wu, Yue-Xia; Ouyang, Chu-Jun; Chen, Zhi-Jin

2015-01-01

Objectives: High triglycerides and low high density lipoprotein cholesterol are important cardiovascular risk factors. Triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) has been reported to be useful in predicting cardiovascular disease. Brachial-ankle pulse wave velocity (baPWV) is a valid and reproducible measurement by which to assess arterial stiffness and a surrogate marker of atherosclerosis. However, there is limited evidence about the relationship between them. Therefore, we tested the hypotheses that TG/HDL-C is associated with baPWV in healthy individuals. Methods: Fasting lipid profiles, baPWV and clinical data were measured in 1498 apparently healthy, medication-free subjects (926 men, 572 women) who participated in a routine health screening from 2011 to 2013. Participants were stratified into quartiles of TG/HDL-C ratio. BaPWV > 1400 cm/s was defined as abnormal baPWV, Multivariable logistic regression was used to identify associations of TG/HDL-C quartiles and baPWV, after adjusting for the presence of conventional cardiovascular risk factors. Results: In both genders, we observed positive relationships between TG/HDL-C quartiles and BMI, systolic BP, diastolic BP, fasting glucose, total cholesterol, LDL-C, triglycerides, uric acid, and percentages of high baPWV. Multivariable logistic regression revealed that baPWV abnormality OR value of the highest TG/HDL-C quartiles was 1.91 (95% CI: 1.11-3.30, P < 0.05) and 2.91 (95% CI: 1.02-8.30, P < 0.05) in male and female after adjusting for age, systolic BP, diastolic BP, BMI, fasting plasma glucose, LDL-C, uric acid and estimated glomerular filtration rate when compared with the lowest TG/HDL-C quartiles. Conclusion: Increased TG/HDL-C was independently associated with baPWV abnormality in apparently healthy individuals. PMID:26064351

Evaluation of the thermal and structural performance of straw bale construction

NASA Astrophysics Data System (ADS)

Beaudry, Kyle R.

This thesis is primarily divided into two distinct experimental programs evaluating: 1) the thermal performance and, 2) the structural performance of straw bale construction. The thermal performance chapter describes hot-box testing (based on ASTM C1363-11) of seven straw bale wall panels to obtain their apparent thermal conductivity values. All panels were constructed with stacked bales and cement-lime plaster skins on each side of the bales. Four panels were made with traditional, 2-string field bales of densities ranging from 89.5 kg/m3 - 131 kg/m3 and with the bales on-edge (fibres perpendicular to the heat flow). Three panels were made with manufactured high-density bales (291 kg/m3 - 372 kg/m3). The fibres of the manufactured bales were randomly oriented. The key conclusion of this work is that within the experimental error, there is no difference in the apparent thermal conductivity value for panels using normal density bales and manufactured high-density bales up to a density of 333 kg/m3. The structural performance chapter describes gravity and transverse load testing (based on ASTM E72-15) of non-plastered modular straw bale wall (DBW) panels to evaluate their strength capacity and failure modes. The out-of-plane flexural (OPF) tests exhibited a mean ultimate bending moment of 49.7 kNm. The axial compression (AC) tests exhibited a mean ultimate line load of 161.0 kN/m. The local flexural header beam (HP) tests exhibited an ultimate line load of 31.6 kN/m. The OPF and AC capacities of the DBW exceeded the capacities exhibited by a conventional 38 mm x 140 mm stud wall. However, the DBW's header beam strength and stiffness was inferior to conventional stud wall.

Effect of cell density on adipogenic differentiation of mesenchymal stem cells

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

Lu, Hongxu; Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044; Guo, Likun

2009-04-10

The effect of cell density on the adipogenic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) was investigated by using a patterning technique to induce the formation of a cell density gradient on a micropatterned surface. The adipogenic differentiation of MSCs at a density gradient from 5 x 10{sup 3} to 3 x 10{sup 4} cells/cm{sup 2} was examined. Lipid vacuoles were observed at all cell densities after 1-3 weeks of culture in adipogenic differentiation medium although the lipid vacuoles were scarce at the low cell density and abundant at the high cell density. Real-time RT-PCR analysis showed thatmore » adipogenesis marker genes encoding peroxisome proliferator-activated receptor {gamma}2 (PPAR{gamma}2), lipoprotein lipase (LPL), and fatty acid binding protein-4 (FABP4) were detected in the MSCs cultured at all cell densities. The results suggest that there was no apparent effect of cell density on the adipogenic differentiation of human MSCs.« less

Population density and seasonality effects on Sin Nombre virus transmission in North American deermice (Peromyscus maniculatus) in outdoor enclosures.

PubMed

Bagamian, Karoun H; Douglass, Richard J; Alvarado, Arlene; Kuenzi, Amy J; Amman, Brian R; Waller, Lance A; Mills, James N

2012-01-01

Surveys of wildlife host-pathogen systems often document clear seasonal variation in transmission; conclusions concerning the relationship between host population density and transmission vary. In the field, effects of seasonality and population density on natural disease cycles are challenging to measure independently, but laboratory experiments may poorly reflect what happens in nature. Outdoor manipulative experiments are an alternative that controls for some variables in a relatively natural environment. Using outdoor enclosures, we tested effects of North American deermouse (Peromyscus maniculatus) population density and season on transmission dynamics of Sin Nombre hantavirus. In early summer, mid-summer, late summer, and fall 2007-2008, predetermined numbers of infected and uninfected adult wild deermice were released into enclosures and trapped weekly or bi-weekly. We documented 18 transmission events and observed significant seasonal effects on transmission, wounding frequency, and host breeding condition. Apparent differences in transmission incidence or wounding frequency between high- and low-density treatments were not statistically significant. However, high host density was associated with a lower proportion of males with scrotal testes. Seasonality may have a stronger influence on disease transmission dynamics than host population density, and density effects cannot be considered independent of seasonality.

True density and apparent density during the drying process for vegetables and fruits: a review.

PubMed

Rodríguez-Ramírez, J; Méndez-Lagunas, L; López-Ortiz, A; Torres, S Sandoval

2012-12-01

This review presents the concepts involved in determining the density of foodstuffs, and summarizes the volumetric determination techniques used to calculate true density and apparent density in foodstuffs exposed to the drying process. The behavior of density with respect to moisture content (X) and drying temperature (T) is presented and explained with a basis in changes in structure, conformation, chemical composition, and second-order phase changes that occur in the processes of mass and heat transport, as reported to date in the literature. A review of the empirical and theoretical equations that represent density is presented, and their application in foodstuffs is discussed. This review also addresses cases with nonideal density behavior, including variations in ρ(s) and ρ(w) as a function of the inside temperature of the material, depending on drying conditions (X, T). A compilation of studies regarding the density of dehydrated foodstuffs is also presented. © 2012 Institute of Food Technologists®

Effects of Moringa oleifera silage on milk yield, nutrient digestibility and serum biochemical indexes of lactating dairy cows.

PubMed

Zeng, B; Sun, J J; Chen, T; Sun, B L; He, Q; Chen, X Y; Zhang, Y L; Xi, Q Y

2018-02-01

This study investigated the effects of Moringa oleifera (MO) as a partial substitute of alfalfa hay on milk yield, nutrient apparent digestibility and serum biochemical indexes of dairy cows. MO was harvested at 120 days post-seeding. Fresh MO was cut, mixed with chopped oat hay (425:575 on a DM basis), ensiled and stored for 60 days. Sixty healthy Holstein dairy cows were allocated to one of three groups: NM (no MO or control), LM (low MO; 25% alfalfa hay and 50% maize silage were replaced by MO silage) or HM (high MO; 50% alfalfa hay and 100% maize silage were replaced by MO silage). The feeding trial lasted 35 days. The LM and HM diets did not affect dry matter (DM) intake, milk yield or milk composition (lactose, milk fat, milk protein and somatic cell count). The apparent digestibility of DM and NDF was lower for HM group than NM group. Additionally, there were no significant differences in serum biochemical indexes between the LM and NM groups. The HM group had lower serum concentrations of total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol and higher serum concentrations of urea than the NM group. The partial replacement of alfalfa hay (≤50%) and maize silage with MO silage had no negative effects on milk yield, in vivo nutrient apparent digestibility or serum biochemical indexes of lactating cows. © 2017 Blackwell Verlag GmbH.

Experimental Determination of Air Density Using a 1 kg Mass Comparator in Vacuum

NASA Astrophysics Data System (ADS)

Gläser, M.; Schwartz, R.; Mecke, M.

1991-01-01

The density of ambient air has been determined by a straightforward experimental method. The apparent masses of two artefacts having about the same mass and surface, but different well-known volumes, have been compared by using a 1 kg balance in vacuum and in air. The differences of apparent masses and volumes yield the air density with a relative uncertainty (1σ) of 5 × 10-5. From measurements made using a third artefact, surface sorption effects caused by the change between vacuum and air conditions gave a coefficient of about 0,2 μg cm-2.

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

Khurgin, Jacob B., E-mail: jakek@jhu.edu; Bajaj, Sanyam; Rajan, Siddharth

Longitudinal optical (LO) phonons in GaN generated in the channel of high electron mobility transistors (HEMT) are shown to undergo nearly elastic scattering via collisions with hot electrons. The net result of these collisions is the diffusion of LO phonons in the Brillouin zone causing reduction of phonon and electron temperatures. This previously unexplored diffusion mechanism explicates how an increase in electron density causes reduction of the apparent lifetime of LO phonons, obtained from the time resolved Raman studies and microwave noise measurements, while the actual decay rate of the LO phonons remains unaffected by the carrier density. Therefore, themore » saturation velocity in GaN HEMT steadily declines with increased carrier density, in a qualitative agreement with experimental results.« less

Apparent isotropic electrical property for electrical brain stimulation (EBS) using magnetic resonance diffusion weighted imaging (MR-DWI)

NASA Astrophysics Data System (ADS)

Lee, Mun Bae; Kwon, Oh-In

2018-04-01

Electrical brain stimulation (EBS) is an invasive electrotherapy and technique used in brain neurological disorders through direct or indirect stimulation using a small electric current. EBS has relied on computational modeling to achieve optimal stimulation effects and investigate the internal activations. Magnetic resonance diffusion weighted imaging (DWI) is commonly useful for diagnosis and investigation of tissue functions in various organs. The apparent diffusion coefficient (ADC) measures the intensity of water diffusion within biological tissues using DWI. By measuring trace ADC and magnetic flux density induced by the EBS, we propose a method to extract electrical properties including the effective extracellular ion-concentration (EEIC) and the apparent isotropic conductivity without any auxiliary additional current injection. First, the internal current density due to EBS is recovered using the measured one component of magnetic flux density. We update the EEIC by introducing a repetitive scheme called the diffusion weighting J-substitution algorithm using the recovered current density and the trace ADC. To verify the proposed method, we study an anesthetized canine brain to visualize electrical properties including electrical current density, effective extracellular ion-concentration, and effective isotropic conductivity by applying electrical stimulation of the brain.

Ducks and passerines nesting in northern mixed-grass prairie treated with fire

USGS Publications Warehouse

Grant, Todd A.; Shaffer, Terry L.; Madden, Elizabeth M.; Berkey, Gordon B.

2011-01-01

Prescribed fire is an important, ecology-driven tool for restoration of grassland systems. However, prescribed fire remains controversial for some grassland managers because of reported reductions in bird use of recently burned grasslands. Few studies have evaluated effects of fire on grassland bird populations in the northern mixed-grass prairie region. Fewer studies yet have examined the influence of fire on nest density or survival. In our review, we found no studies that simultaneously examined effects of fire on duck and passerine nesting. During 1998—2003, we examined effects of prescribed fire on the density of upland-nesting ducks and passerines nesting in north-central North Dakota, USA. Apparent nest densities of gadwall (Anas strepera), mallard (A. platyrhynchos), and all duck species combined, were influenced by fire history of study units, although the degree of influence was not compelling. Fire history was not related to nest densities of blue-winged teal (A. discors), northern shoveler (A. clypeata), or northern pintail (A. acuta); however, apparent nest densities in relation to the number of postfire growing seasons exhibited a strikingly similar pattern among all duck species. When compared to ducks, fire history strongly influenced apparent nest densities of clay-colored sparrow (Spizella pallida), Savannah sparrow (Passerculus sandwichensis), and bobolink (Dolichonyx oryzivorus). For most species examined, apparent nest densities were lowest in recently burned units, increased during the second postfire growing season, and stabilized or, in some cases, decreased thereafter. Prescribed fire is critical for restoring the ecology of northern mixed-grass prairies and our findings indicate that reductions in nest densities are limited mostly to the first growing season after fire. Our results support the premise that upland-nesting ducks and several grassland passerine species are adapted to periodic fires occurring at a frequency similar to that of pre-Euro-American settlement of the region.

Macromolecular geometries determined with field-flow fractionation and their impact on the overlap concentration.

PubMed

Rojas, Cinthia Carola; Wahlund, Karl-Gustav; Bergenståhl, Björn; Nilsson, Lars

2008-06-01

In this paper we aim to understand the size/conformation relationship in waxy barley starch, a polydisperse and ultrahigh molar mass biomacromolecule. Characterizations are performed with asymmetrical flow field-flow fractionation (AsFlFFF). Furthermore, we study the effect of homogenization on the molar mass, rms radius (r rms) and hydrodynamic radius (r h). For the untreated sample, the macromolecules are elongated objects with low apparent density. As a result of homogenization, molar mass, and r rms decrease, while r h remains unaffected. The process also induces an increase, and scaling with size, of apparent density as well as changes in conformation, represented qualitatively by r rms/ r h. Finally, results from AsFlFFF are compared with viscosimetry and discussed in terms of concentration and close-packing in relation to macromolecular shape and conformation. Hence, the results show that AsFlFFF and our novel methodology enable the determination of several physical properties with high relevance for the solution behavior of polydisperse macromolecules.

Synthesis of 1,3-Dimethylimidazolium Chloride and Volumetric Property Investigations of Its Aqueous Solution

NASA Astrophysics Data System (ADS)

Dong, L.; Zheng, D. X.; Wei, Z.; Wu, X. H.

2009-10-01

By investigating the vapor pressure of the solvent and the affinity between ionic liquids (ILs) and the solvent, it is proposed that 1,3-dimethylimidazolium chloride ([Mmim]Cl) has the potential to be used as a novel absorbent species with the absorption cycle working fluid. Adopting a high-pressure reaction kettle, the method of gas-liquid phase reaction was used to synthesize [Mmim]Cl under the conditions of 348.15 K and 0.7 MPa. The densities of [Mmim]Cl aqueous solutions were measured for mass fractions in the range from 20% to 90% at 293.15 K, 298.15 K, 303.15 K, 308.15 K, 313.15 K, and 318.15 K with a digital vibrating-tube densimeter. The excess volume, the apparent molar volume, the partial molar volume, and the apparent molar expansibility of this system were investigated, and the influences of variations of the cation and anion on the density of several IL aqueous solutions are discussed.

Dynamics and distribution of black abalone populations at San Nicolas Island

USGS Publications Warehouse

VanBlaricom, Glenn R.; Hochberg, F.G.

1993-01-01

Dense populations of black abalones (Haliotis cracherodii Leach) were monitored in permanent intertidal plots at nine sites on San Nicolas Island from 1981 through 1990. Densities were essentially constant at all four sites along the north shore of the island throughout the study period. Densities at five sites along the south shore were more variable, possibly reflecting asynchronous variation in recruitment, mortality resulting from wave disturbance, and removal by people. Temporal variation of abalone densities apparently was not influenced by sea otters or abalone withering syndrome during this study. Abalones were strongly aggregated in space. Highest densities occurred in areas of irregular substrata, apparently as a result of preference for crevices and vertical faces. The locations of dense patches were persistent in time.

Acute microwave irradiation and cataract formation in rabbits and monkeys.

PubMed

Kramar, P; Harris, C; Emery, A F; Guy, A W

1978-09-01

Rabbits and monkeys were irradiated in the near field of a cavity-backed 2450 MHz resonant slot radiator, to determine the cataractogenic threshold. Rabbits developed cataracts at incident "apparent" power densities of 180 mW/cm2 (E2/120 pi, where E=rms/electric field strength). Monkeys sustained facial burns, but no lens damage, even at incident "apparent" power densities of 500 mW/cm2. These results were substantiated by computer thermal models.

Revisiting the Inner Magnetospheric Oxygen Torus with DE 1 RIMS

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Goldstein, J.; Craven, P. D.; Comfort, R. H.

2016-01-01

Nearly 35 years ago direct observations of cold plasmaspheric ions found enhanced O(+), O(++), and even N(+) densities in the outer plasmasphere, in particular during storm recovery conditions. Enhancements were seen inside or just outside of the plasmapause at all magnetic local times. Whereas nominal O(+) concentrations were found to be 1% or less inside the plasmasphere, enhanced O(+) in the vicinity of the plasmapause was found to reach densities comparable to H(+). Enhanced ion outflow (including oxygen) from high latitudes has also become part of our picture of storm-time phenomena. More recently it has become apparent that high latitude outflow is a source of inner magnetospheric warm ions that convect into morning and afternoon local times, to form what we now call the warm plasma cloak. Low to middle latitude ionospheric outflow and high latitude outflow are thought to result from very different processes and can be expected to contribute differently as a function of conditions and locations to the dynamic processes of energy and particle transport in the inner magnetosphere. Given the apparent proximity of their delivery to the vicinity of the plasmapause during plasmaspheric refilling conditions it becomes worthwhile to question the origin of the oxygen torus and its role in this region. While the observations do not yet exist to settle this question, there are measurements that contribute to the discussion in the new emerging context of cold plasma in the inner magnetosphere. In this paper we present and discuss DE 1 RIMS derived ion densities and temperatures that contribute to answering these outstanding questions about the origin and dynamics of the oxygen torus.

Perceived Density, Social Interaction and Morale in New South Wales Rural Communities

ERIC Educational Resources Information Center

Argent, Neil

2008-01-01

This paper explores the relationships between population density, social interaction patterns, and morale in rural communities. It tests two apparently competing hypotheses concerning rural population density, social interaction patterns and overall levels of morale: one, that low (and rapidly declining) rural densities lead to feelings of…

Current rectifying and resistive switching in high density BiFeO3 nanocapacitor arrays on Nb-SrTiO3 substrates

PubMed Central

Zhao, Lina; Lu, Zengxing; Zhang, Fengyuan; Tian, Guo; Song, Xiao; Li, Zhongwen; Huang, Kangrong; Zhang, Zhang; Qin, Minghui; SujuanWu; Lu, Xubing; Zeng, Min; Gao, Xingsen; Dai, Jiyan; Liu, Jun-Ming

2015-01-01

Ultrahigh density well-registered oxide nanocapacitors are very essential for large scale integrated microelectronic devices. We report the fabrication of well-ordered multiferroic BiFeO3 nanocapacitor arrays by a combination of pulsed laser deposition (PLD) method and anodic aluminum oxide (AAO) template method. The capacitor cells consist of BiFeO3/SrRuO3 (BFO/SRO) heterostructural nanodots on conductive Nb-doped SrTiO3 (Nb-STO) substrates with a lateral size of ~60 nm. These capacitors also show reversible polarization domain structures, and well-established piezoresponse hysteresis loops. Moreover, apparent current-rectification and resistive switching behaviors were identified in these nanocapacitor cells using conductive-AFM technique, which are attributed to the polarization modulated p-n junctions. These make it possible to utilize these nanocapacitors in high-density (>100 Gbit/inch2) nonvolatile memories and other oxide nanoelectronic devices. PMID:25853937

Down-regulation of angiotensin II receptor subtypes and desensitization of cyclic GMP production in neuroblastoma N1E-115 cells.

PubMed

Reagan, L P; Ye, X; Maretzski, C H; Fluharty, S J

1993-01-01

Murine neuroblastoma N1E-115 cells possess membranous receptors for the octapeptide angiotensin II (AngII) whose density is substantially increased by in vitro differentiation. Incubation of differentiated N1E-115 cells with AngII produced a rapid decrease in receptor density, but did not alter the affinity of these receptors for either 125I-AngII or the high-affinity antagonist 125I-[Sarc1,Ile8]-AngII. This apparent down-regulation was dose related with an ED50 of 1 nM, and maximal decreases of approximately 90% were obtained with 100 nM AngII. Receptor loss from differentiated cell membranes was unaffected by incubations of membranes obtained from agonist-exposed cells with non-hydrolyzable analogues of GTP for 60 min at 37 degrees C to ensure dissociation of the ligand. Partial loss of AngII receptors was apparent within 5 min of agonist exposure, whereas maximal declines were not observed until 30 min. This temporal pattern resulted from a preferential decrease in the AT1 receptor subtype during the first 5 min, followed by a decline in both AT1 and AT2 receptors with longer periods of agonist exposure. The loss of membranous receptors was reversible with partial recovery observed after 4 h, and with nearly full recovery observed 18 h after exposure of the cells to AngII. However, the long-term recovery of receptor density was blocked by the protein synthesis inhibitor, cycloheximide. The heptapeptide angiotensin III produced a similar down-regulation of receptors, and the high-affinity antagonist [Sarc1,Thr8]-AngII blocked agonist-induced down-regulation. Finally, the apparent loss of cell surface AngII receptors decreased the ability of AngII to stimulate cyclic GMP production within intact N1E-115 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Grassland bird productivity in warm season grass fields in southwest Wisconsin

USGS Publications Warehouse

Byers, Carolyn M.; Ribic, Christine; Sample, David W.; Dadisman, John D.; Guttery, Michael

2017-01-01

Surrogate grasslands established through federal set-aside programs, such as U.S. Department of Agriculture's Conservation Reserve Program (CRP), provide important habitat for grassland birds. Warm season grass CRP fields as a group have the potential for providing a continuum of habitat structure for breeding birds, depending on how the fields are managed and their floristic composition. We studied the nesting activity of four obligate grassland bird species, Bobolink (Dolichonyx oryzivorus), Eastern Meadowlark (Sturnella magna), Grasshopper Sparrow (Ammodramus savannarum), and Henslow's Sparrow (A. henslowii), in relation to vegetative composition and fire management in warm season CRP fields in southwest Wisconsin during 2009–2011. Intraspecific variation in apparent nest density was related to the number of years since the field was burned. Apparent Grasshopper Sparrow nest density was highest in the breeding season immediately following spring burns, apparent Henslow's Sparrow nest density was highest 1 y post burn, and apparent Bobolink and Eastern Meadowlark nest densities were higher in post fire years one to three. Grasshopper Sparrow nest density was highest on sites with more diverse vegetation, specifically prairie forbs, and on sites with shorter less dense vegetation. Bobolink, Eastern Meadowlark, and Henslow's Sparrow apparent nest densities were higher on sites with deeper litter; litter was the vegetative component that was most affected by spring burns. Overall nest success was 0.487 for Bobolink (22 d nesting period), 0.478 for Eastern Meadowlark (25 d nesting period), 0.507 for Grasshopper Sparrow (22 d nesting period), and 0.151 for Henslow's Sparrow (21 d nesting period). The major nest predators were grassland-associated species: thirteen-lined ground squirrel (Ictidomys tridecemlineatus), striped skunk (Mephitis mephitis), milk snake (Lampropeltis triangulum), American badger (Taxidea taxus), and western fox snake (Elaphe vulpina). Overall depredation rate was not affected by the number of years since the site had been burned. The diversity of vegetation on warm season CRP fields created by management using fire provides a continuum of structure for obligate grassland birds to use for breeding and habitat for a diversity of nest predators.

Population Density and Seasonality Effects on Sin Nombre Virus Transmission in North American Deermice (Peromyscus maniculatus) in Outdoor Enclosures

PubMed Central

Bagamian, Karoun H.; Douglass, Richard J.; Alvarado, Arlene; Kuenzi, Amy J.; Amman, Brian R.; Waller, Lance A.; Mills, James N.

2012-01-01

Surveys of wildlife host-pathogen systems often document clear seasonal variation in transmission; conclusions concerning the relationship between host population density and transmission vary. In the field, effects of seasonality and population density on natural disease cycles are challenging to measure independently, but laboratory experiments may poorly reflect what happens in nature. Outdoor manipulative experiments are an alternative that controls for some variables in a relatively natural environment. Using outdoor enclosures, we tested effects of North American deermouse (Peromyscus maniculatus) population density and season on transmission dynamics of Sin Nombre hantavirus. In early summer, mid-summer, late summer, and fall 2007–2008, predetermined numbers of infected and uninfected adult wild deermice were released into enclosures and trapped weekly or bi-weekly. We documented 18 transmission events and observed significant seasonal effects on transmission, wounding frequency, and host breeding condition. Apparent differences in transmission incidence or wounding frequency between high- and low-density treatments were not statistically significant. However, high host density was associated with a lower proportion of males with scrotal testes. Seasonality may have a stronger influence on disease transmission dynamics than host population density, and density effects cannot be considered independent of seasonality. PMID:22768034

Tailoring the High-Q LC Filter Arrays for Readout of Kilo-Pixel TES Arrays in the SPICA-SAFARI Instrument

NASA Astrophysics Data System (ADS)

Bruijn, M. P.; Gottardi, L.; den Hartog, R. H.; van der Kuur, J.; van der Linden, A. J.; Jackson, B. D.

2014-08-01

Following earlier presentations of arrays of high quality factor (Q 10.000) superconducting resonators in the MHz regime, we report on improvement of the packing density of resonance frequencies to 160 in the 1-3 MHz band. Spread in the spacing of resonances is found to be limited to 1 kHz (1 with the present fabrication procedure. The present packing density of frequencies and chip area approaches the requirements for the SAFARI instrument on the SPICA mission (in preparation). The a-Si:H dielectric layer in the planar S-I-S capacitors shows a presently unexplained apparent negative effective series resistance, depending on operating temperature and applied testing voltage.

Multilayer densities using a wavelet-based gravity method and their tectonic implications beneath the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xu, Chuang; Luo, Zhicai; Sun, Rong; Zhou, Hao; Wu, Yihao

2018-06-01

Determining density structure of the Tibetan Plateau is helpful in better understanding of tectonic structure and development. Seismic method, as traditional approach obtaining a large number of achievements of density structure in the Tibetan Plateau except in the centre and west, is primarily inhibited by the poor seismic station coverage. As the implementation of satellite gravity missions, gravity method is more competitive because of global homogeneous gravity coverage. In this paper, a novel wavelet-based gravity method with high computation efficiency and excellent local identification capability is developed to determine multilayer densities beneath the Tibetan Plateau. The inverted six-layer densities from 0 to 150 km depth can reveal rich tectonic structure and development of study area: (1) The densities present a clockwise pattern, nearly east-west high-low alternating pattern in the west and nearly south-north high-low alternating pattern in the east, which is almost perpendicular to surface movement direction relative to the stable Eurasia from the Global Positioning System velocity field; (2) Apparent fold structure approximately from 10 to 110 km depth can be inferred from the multilayer densities, the deformational direction of which is nearly south-north in the west and east-west in the east; (3) Possible channel flows approximately from 30 to 110 km depth can also be observed clearly during the multilayer densities. Moreover, the inverted multilayer densities are in agreement with previous studies, which verify the correctness and effectiveness of our method.

Multilayer Densities Using a Wavelet-based Gravity Method and Their Tectonic Implications beneath the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xu, Chuang; Luo, Zhicai; Sun, Rong; Zhou, Hao; Wu, Yihao

2018-03-01

Determining density structure of the Tibetan Plateau is helpful in better understanding tectonic structure and development. Seismic method, as traditional approach obtaining a large number of achievements of density structure in the Tibetan Plateau except in the center and west, is primarily inhibited by the poor seismic station coverage. As the implementation of satellite gravity missions, gravity method is more competitive because of global homogeneous gravity coverage. In this paper, a novel wavelet-based gravity method with high computation efficiency and excellent local identification capability is developed to determine multilayer densities beneath the Tibetan Plateau. The inverted 6-layer densities from 0 km to 150 km depth can reveal rich tectonic structure and development of study area: (1) The densities present a clockwise pattern, nearly east-west high-low alternating pattern in the west and nearly south-north high-low alternating pattern in the east, which is almost perpendicular to surface movement direction relative to the stable Eurasia from the Global Positioning System velocity field; (2) Apparent fold structure approximately from 10 km to 110 km depth can be inferred from the multilayer densities, the deformational direction of which is nearly south-north in the west and east-west in the east; (3) Possible channel flows approximately from 30 km to 110 km depth can be also observed clearly during the multilayer densities. Moreover, the inverted multilayer densities are in agreement with previous studies, which verify the correctness and effectiveness of our method.

Distinct Visual Evoked Potential Morphological Patterns for Apparent Motion Processing in School-Aged Children.

PubMed

Campbell, Julia; Sharma, Anu

2016-01-01

Measures of visual cortical development in children demonstrate high variability and inconsistency throughout the literature. This is partly due to the specificity of the visual system in processing certain features. It may then be advantageous to activate multiple cortical pathways in order to observe maturation of coinciding networks. Visual stimuli eliciting the percept of apparent motion and shape change is designed to simultaneously activate both dorsal and ventral visual streams. However, research has shown that such stimuli also elicit variable visual evoked potential (VEP) morphology in children. The aim of this study was to describe developmental changes in VEPs, including morphological patterns, and underlying visual cortical generators, elicited by apparent motion and shape change in school-aged children. Forty-one typically developing children underwent high-density EEG recordings in response to a continuously morphing, radially modulated, circle-star grating. VEPs were then compared across the age groups of 5-7, 8-10, and 11-15 years according to latency and amplitude. Current density reconstructions (CDR) were performed on VEP data in order to observe activated cortical regions. It was found that two distinct VEP morphological patterns occurred in each age group. However, there were no major developmental differences between the age groups according to each pattern. CDR further demonstrated consistent visual generators across age and pattern. These results describe two novel VEP morphological patterns in typically developing children, but with similar underlying cortical sources. The importance of these morphological patterns is discussed in terms of future studies and the investigation of a relationship to visual cognitive performance.

Distinct Visual Evoked Potential Morphological Patterns for Apparent Motion Processing in School-Aged Children

PubMed Central

Campbell, Julia; Sharma, Anu

2016-01-01

Measures of visual cortical development in children demonstrate high variability and inconsistency throughout the literature. This is partly due to the specificity of the visual system in processing certain features. It may then be advantageous to activate multiple cortical pathways in order to observe maturation of coinciding networks. Visual stimuli eliciting the percept of apparent motion and shape change is designed to simultaneously activate both dorsal and ventral visual streams. However, research has shown that such stimuli also elicit variable visual evoked potential (VEP) morphology in children. The aim of this study was to describe developmental changes in VEPs, including morphological patterns, and underlying visual cortical generators, elicited by apparent motion and shape change in school-aged children. Forty-one typically developing children underwent high-density EEG recordings in response to a continuously morphing, radially modulated, circle-star grating. VEPs were then compared across the age groups of 5–7, 8–10, and 11–15 years according to latency and amplitude. Current density reconstructions (CDR) were performed on VEP data in order to observe activated cortical regions. It was found that two distinct VEP morphological patterns occurred in each age group. However, there were no major developmental differences between the age groups according to each pattern. CDR further demonstrated consistent visual generators across age and pattern. These results describe two novel VEP morphological patterns in typically developing children, but with similar underlying cortical sources. The importance of these morphological patterns is discussed in terms of future studies and the investigation of a relationship to visual cognitive performance. PMID:27445738

High urban breeding densities do not disrupt genetic monogamy in a bird species.

PubMed

Rodriguez-Martínez, Sol; Carrete, Martina; Roques, Séverine; Rebolo-Ifrán, Natalia; Tella, José L

2014-01-01

Urbanization causes widespread endangerment of biodiversity worldwide. However, some species successfully colonize cities reaching higher densities than in their rural habitats. In these cases, although urban city dwellers may apparently be taking advantage of these new environments, they also face new ecological conditions that may induce behavioural changes. For example, the frequency of alternative reproductive behaviours such as extra-pair paternity and intraspecific brood parasitism might increase with breeding densities. Here, using a panel of 17 microsatellites, we tested whether increments in breeding densities such as those associated with urban invasion processes alter genetic monogamy in the burrowing owl Athene cunicularia. Our results show low rates of extra-pair paternity (1.47%), but relatively high levels of intraspecific brood parasitism (8.82%). However, we were not able to detect differences in the frequency at which either alternative reproductive behaviour occurs along a strong breeding density gradient. Further research is needed to properly ascertain the role of other social and ecological factors in the frequency at which this species presents alternative reproductive strategies. Meanwhile, our results suggest that genetic monogamy is maintained despite the increment in conspecific density associated with a recent urban invasion process.

Transformation of apparent ocean wave spectra observed from an aircraft sensor platform

NASA Technical Reports Server (NTRS)

Poole, L. R.

1976-01-01

The problem considered was transformation of a unidirectional apparent ocean wave spectrum observed from an aircraft sensor platform into the true spectrum that would be observed from a stationary platform. Spectral transformation equations were developed in terms of the linear wave dispersion relationship and the wave group speed. An iterative solution to the equations was outlined and used to transform reference theoretical apparent spectra for several assumed values of average water depth. Results show that changing the average water depth leads to a redistribution of energy density among the various frequency bands of the transformed spectrum. This redistribution is most severe when much of the energy density is expected, a priori, to reside at relatively low true frequencies.

Volumetric and acoustical behaviour of sodium saccharin in aqueous system over temperature range (20.0-45.0)°C.

PubMed

Jamal, Muhammad Asghar; Rashad, Muhammad; Khosa, Muhammad Kaleem; Bhatti, Haq Nawaz

2015-04-15

Densities and ultrasonic velocity values for aqueous solutions of sodium saccharin (SS) has been measured as a function of concentration at 20.0-45.0 °C and atmospheric pressure using DSA-5000 M. The density and ultrasonic velocity values have been further used to calculate apparent molar volume, apparent specific volume, isentropic apparent molar compressibility and compressibility hydration numbers and reported. The values for apparent molar volume obtained at given temperatures showed negative deviations from Debye-Hückel limiting law and used as a direct measure of the ion-ion and ion-solvent interactions. The apparent specific volumes of the solute were calculated and it was found that these values of the investigated solutions lie on the borderline between the values reported for sweet substances. The sweetness response of the sweeteners is then explained in terms of their solution behaviours. Furthermore, the partial molar expansibility, its second derivative, (∂(2)V°/∂T(2)) as Hepler's constant and thermal expansion coefficient have been estimated. Copyright © 2014 Elsevier Ltd. All rights reserved.

Density and Reproductive Success of California Towhees

Treesearch

Kathryn L. Purcell; Jared Verner

1998-01-01

Models of habitat selection commonly asume that higher-quality source habitats will be occupied at higher densities than sink habitats. We examined an apparent sink habitat for California Towhees (Pipilo crissalis) in which densities are greater than in nearby source habitats. We estimated territory density using spot-mapping and monitored nests of towhees in grazed...

Last Glacial Maximum Salinity Reconstruction

NASA Astrophysics Data System (ADS)

Homola, K.; Spivack, A. J.

2016-12-01

It has been previously demonstrated that salinity can be reconstructed from sediment porewater. The goal of our study is to reconstruct high precision salinity during the Last Glacial Maximum (LGM). Salinity is usually determined at high precision via conductivity, which requires a larger volume of water than can be extracted from a sediment core, or via chloride titration, which yields lower than ideal precision. It has been demonstrated for water column samples that high precision density measurements can be used to determine salinity at the precision of a conductivity measurement using the equation of state of seawater. However, water column seawater has a relatively constant composition, in contrast to porewater, where variations from standard seawater composition occur. These deviations, which affect the equation of state, must be corrected for through precise measurements of each ion's concentration and knowledge of apparent partial molar density in seawater. We have developed a density-based method for determining porewater salinity that requires only 5 mL of sample, achieving density precisions of 10-6 g/mL. We have applied this method to porewater samples extracted from long cores collected along a N-S transect across the western North Atlantic (R/V Knorr cruise KN223). Density was determined to a precision of 2.3x10-6 g/mL, which translates to salinity uncertainty of 0.002 gms/kg if the effect of differences in composition is well constrained. Concentrations of anions (Cl-, and SO4-2) and cations (Na+, Mg+, Ca+2, and K+) were measured. To correct salinities at the precision required to unravel LGM Meridional Overturning Circulation, our ion precisions must be better than 0.1% for SO4-/Cl- and Mg+/Na+, and 0.4% for Ca+/Na+, and K+/Na+. Alkalinity, pH and Dissolved Inorganic Carbon of the porewater were determined to precisions better than 4% when ratioed to Cl-, and used to calculate HCO3-, and CO3-2. Apparent partial molar densities in seawater were determined experimentally. We compare the high precision salinity profiles determined using our new method to profiles determined from the traditional chloride titrations of parallel samples. Our technique provides a more accurate reconstruction of past salinity, informing questions of water mass composition and distribution during the LGM.

Seed-predator satiation and Janzen-Connell effects vary with spatial scales for seed-feeding insects.

PubMed

Xiao, Zhishu; Mi, Xiangcheng; Holyoak, Marcel; Xie, Wenhua; Cao, Ke; Yang, Xifu; Huang, Xiaoqun; Krebs, Charles J

2017-01-01

The Janzen-Connell model predicts that common species suffer high seed predation from specialized natural enemies as a function of distance from parent trees, and consequently as a function of conspecific density, whereas the predator satiation hypothesis predicts that seed attack is reduced due to predator satiation at high seed densities. Pre-dispersal predation by insects was studied while seeds are still on parent trees, which represents a frequently overlooked stage in which seed predation occurs. Reproductive tree density and seed production were investigated from ten Quercus serrata populations located in south-west China, quantifying density-dependent pre-dispersal seed predation over two years by three insect groups. Acorn infestation was nearly twice as high in the low-seed year as that in the high-seed year, with considerable spatio-temporal variation in the direction and magnitude of density-dependent pre-dispersal seed predation evident. Across whole populations of trees, a high density of reproductive trees caused predator satiation and reduced insect attack in the high-seed year. Within individual trees, and consistent with the Janzen-Connell model, overall insect seed predation was positively correlated with seed production in the low-seed year. In addition, there was variation among insect taxa, with positive density-dependent seed predation by Curculio weevils in the high-seed year and moths in the low-seed year, but apparent density independence by Cyllorhynchites weevils in both years. The overall trend of negative density-dependent, pre-dispersal seed predation suggests that predator satiation limited the occurrence of Janzen-Connell effects across Q. serrata populations. Such effects may have large impacts on plant population dynamics and tree diversity, depending on the extent to which they are reduced by counteracting positive density-dependent predation for seeds on individual trees and other factors affecting successful recruitment. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Relationships among diet, physical activity, and dual plane dual-energy X-ray absorptiometry bone outcomes in pre-pubertalgirls.

PubMed

Ren, Jie; Brann, Lynn S; Bruening, Kay S; Scerpella, Tamara A; Dowthwaite, Jodi N

2017-12-01

In pre-pubertal girls, nutrient intakes and non-aquatic organized activity were evaluated as factors in vertebral body bone mass, structure, and strength. Activity, vitamin B 12 , and dietary fiber predicted bone outcomes most consistently. Exercise and vitamin B 12 appear beneficial, whereas high fiber intake appears to be adverse for vertebral body development. Childhood development sets the baseline for adult fracture risk. Most studies evaluate development using postero-anterior (PA) dual-energy X-ray absorptiometry (DXA) areal bone mineral density, bone mineral content, and bone mineral apparent density. In a prior analysis, we demonstrated that PA DXA reflects posterior element properties, rather than vertebral body fracture sites, such that loading is associated with subtle differences in vertebral body geometry, not 3D density. The current analysis is restricted to pre-pubertal girls, for a focused exploration of key nutrient intakes and physical activity as factors in dual plane indices of vertebral body geometry, density, and strength. This cross-sectional analysis used paired PA and supine lateral (LAT) lumbar spine DXA scans to assess "3D" vertebral body bone mineral apparent density (PALATBMAD), "3D" index of structural strength in axial compression (PALATIBS), and fracture risk index (PALATFRI). Diet data were collected using the Youth/Adolescent Questionnaire (YAQ, 1995); organized physical activity was recorded via calendar-based form. Pearson correlations and backward stepwise multiple linear regression analyzed associations among key nutrients, physical activity, and bone outcomes. After accounting for activity and key covariates, fiber, unsupplemented vitamin B 12 , zinc, carbohydrate, vitamin C, unsupplemented magnesium, and unsupplemented calcium intake explained significant variance for one or more bone outcomes (p < 0.05). After adjustment for influential key nutrients and covariates, activity exposure was associated with postero-anterior (PA) areal bone mineral density, PA bone mineral content, PA width, lateral (LAT) BMC, "3D" bone cross-sectional area (coronal plane), "3D" PALATIBS, and PALATFRI benefits (p < 0.05). Physical activity, fiber intake, and unsupplemented B 12 intake appear to influence vertebral body bone mass, density, geometry, and strength in well-nourished pre-pubertal girls; high fiber intakes may adversely affect childhood vertebral body growth.

Effects of concentration, temperature and solvent composition on density and apparent molar volume of the binary mixtures of cationic-anionic surfactants in methanol-water mixed solvent media.

PubMed

Bhattarai, Ajaya; Chatterjee, Sujeet Kumar; Niraula, Tulasi Prasad

2013-01-01

The accurate measurements on density of the binary mixtures of cetyltrimethylammonium bromide and sodium dodecyl sulphate in pure water and in methanol(1) + water (2) mixed solvent media containing (0.10, 0.20, and 0.30) volume fractions of methanol at 308.15, 318.15, and 323.15 K are reported. The concentrations are varied from (0.03 to 0.12) mol.l(-1) of sodium dodecyl sulphate in presence of ~ 5.0×10(-4) mol.l(-1) cetyltrimethylammonium bromide. The results showed almost increase in the densities with increasing surfactant mixture concentration, also the densities are found to decrease with increasing temperature over the entire concentration range, investigated in a given mixed solvent medium and these values are found to decrease with increasing methanol content in the solvent composition. The concentration dependence of the apparent molar volumes appear to be negligible over the entire concentration range, investigated in a given mixed solvent medium and the apparent molar volumes increase with increasing temperature and are found to decrease with increasing methanol content in the solvent composition.

Determinants of pika population density vs. occupancy in the Southern Rocky Mountains.

PubMed

Erb, Liesl P; Ray, Chris; Guralnick, Robert

2014-04-01

Species distributions are responding rapidly to global change. While correlative studies of local extinction have been vital to understanding the ecological impacts of global change, more mechanistic lines of inquiry are needed for enhanced forecasting. The current study assesses whether the predictors of local extinction also explain population density for a species apparently impacted by climate change. We tested a suite of climatic and habitat metrics as predictors of American pika (Ochotona princeps) relative population density in the Southern Rocky Mountains, USA. Population density was indexed as the density of pika latrine sites. Negative binomial regression and AICc showed that the best predictors of pika latrine density were patch area followed by two measures of vegetation quality: the diversity and relative cover of forbs. In contrast with previous studies of habitat occupancy in the Southern Rockies, climatic factors were not among the top predictors of latrine density. Populations may be buffered from decline and ultimately from extirpation at sites with high-quality vegetation. Conversely, populations at highest risk for declining density and extirpation are likely to be those in sites with poor-quality vegetation.

Measurement of thermal diffusivity of depleted uranium metal microspheres

NASA Astrophysics Data System (ADS)

Humrickhouse-Helmreich, Carissa J.; Corbin, Rob; McDeavitt, Sean M.

2014-03-01

The high void space of nuclear fuels composed of homogeneous uranium metal microspheres may allow them to achieve ultra-high burnup by accommodating fuel swelling and reducing fuel/cladding interactions; however, the relatively low thermal conductivity of microsphere nuclear fuels may limit their application. To support the development of microsphere nuclear fuels, an apparatus was designed in a glovebox and used to measure the apparent thermal diffusivity of a packed bed of depleted uranium (DU) microspheres with argon fill in the void spaces. The developed Crucible Heater Test Assembly (CHTA) recorded radial temperature changes due to an initial heat pulse from a central thin-diameter cartridge heater. Using thermocouple positions and time-temperature data, the apparent thermal diffusivity was calculated. The thermal conductivity of the DU microspheres was calculated based on the thermal diffusivity from the CHTA, known material densities and specific heat capacities, and an assumed 70% packing density based on prior measurements. Results indicate that DU metal microspheres have very low thermal conductivity, relative to solid uranium metal, and rapidly form an oxidation layer even in a low oxygen environment. At 500 °C, the thermal conductivity of the DU metal microsphere bed was 0.431 ± 0.0560 W/m-K compared to the literature value of approximately 32 W/m-K for solid uranium metal.

Structural properties of aqueous metoprolol succinate solutions. Density, viscosity, and refractive index at 311 K

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Kalyankar, T. M.

2013-06-01

Density, viscosity and refractive index of aqueous solutions of metoprolol succinate of different concentrations (0.005-0.05 mol dm-3) were measured at 38°C. Apparent molar volume of resultant solutions were calculated and fitted to the Masson's equation and apparent molar volume at infinite dilution was determined graphically. Viscosity data of solutions has been fitted to the Jone-Dole equation and viscosity A- and B-coefficients were determined graphically. Physicochemical data obtained were discussed in terms of molecular interactions.

Influence of sintering temperature on the characteristics of shale brick containing oil well-derived drilling waste.

PubMed

Li, Xiang-Guo; Lv, Yang; Ma, Bao-Guo; Jian, Shou-Wei; Tan, Hong-Bo

2011-11-01

The influence of sintering temperature on the physico-mechanical characteristics (such as water absorption, apparent porosity, bulk density, weight loss on ignition, firing shrinkage, and compressive strength), leachability, and microstructure of shale brick containing oil well-derived drilling waste (DW) was investigated. The experiments were conducted at a temperature ranging from 950°C to 1,050°C with 30% DW addition. The results indicate that increasing the sintering temperature decreases the water absorption and apparent porosity and increases the shrinkage, density, and compressive strength of sintered specimens. Moreover, the physico-mechanical properties of samples sintered at 1,050°C meet the requirements of the MU20 according to GB/T 5101-2003 (in China). The heavy metal concentrations of the leachate are much lower than the current regulatory limits according to GB16889-2008. The results from XRD and SEM show that increasing sintering temperature results in an increase of the high temperature liquid phase, which may have a significant effect on the densification process of the samples.

Effect of dislocations on properties of heteroepitaxial InP solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Swartz, C. K.; Curtis, H. B.; Brinker, D. J.; Jenkins, P.; Faur, M.

1991-01-01

The apparently unrelated phenomena of temperature dependency, carrier removal and photoluminescence are shown to be affected by the high dislocation densities present in heteroepitaxial InP solar cells. Using homoepitaxial InP cells as a baseline, it is found that the relatively high dislocation densities present in heteroepitaxial InP/GaAs cells lead to increased volumes of dVoc/dt and carrier removal rate and substantial decreases in photoluminescence spectral intensities. With respect to dVoc/dt, the observed effect is attributed to the tendency of dislocations to reduce Voc. Although the basic cause for the observed increase in carrier removal rate is unclear, it is speculated that the decreased photoluminescence intensity is attributable to defect levels introduced by dislocations in the heteroepitaxial cells.

Experimental evidence of a liquid-liquid transition in interfacial water

NASA Astrophysics Data System (ADS)

Zanotti, J.-M.; Bellissent-Funel, M.-C.; Chen, S.-H.

2005-07-01

At ambient pressure, bulk liquid water shows an anomalous increase of thermodynamic quantities and apparent divergences of dynamic properties on approaching a temperature Ts of 228 K. At normal pressure, supercooled water spontaneously freezes below the homogeneous nucleation temperature, TH = 235 K. Upon heating, the two forms of Amorphous Solid Water (ASW), LDA (Low Density Amorphous Ice) and HDA (High Density Amorphous Ice), crystallise above TX = 150 K. As a consequence, up to now no experiment has been able to explore the properties of liquid water in this very interesting temperature range between 150 and 235 K. We present nanosecond-time-scale measurements of local rotational and translational dynamics of interfacial, non-crystalline, water from 77 to 280 K. These experimental dynamic results are combined with calorimetric and diffraction data to show that after exhibiting a glass transition at 165 K, interfacial water experiences a first-order liquid-liquid transition at 240 K from a low-density to a high-density liquid. This is the first direct evidence of the existence of a liquid-liquid transition involving water.

Effect on structure and mechanical property of tungsten irradiated by high intensity pulsed ion beam

NASA Astrophysics Data System (ADS)

Mei, Xianxiu; Zhang, Xiaonan; Liu, Xiaofei; Wang, Younian

2017-09-01

The anti-thermal radiation performance of tungsten was investigated by high intensity pulsed ion beam technology. The ion beam was mainly composed of Cn+ (70%) and H+ (30%) at an acceleration voltage of 250 kV under different energy densities for different number of pulses. GIXRD analysis showed that no obvious phase structural changes occurred on the tungsten, and microstress generated. SEM analysis exhibited that there was no apparent irradiation damage on the surface of tungsten at the low irradiation frequency (3 times and 10 times) and at the low energy density (0.25 J/cm2 and 0.7 J/cm2). Cracks appeared on the surface of tungsten after 100-time and 300-time irradiation. Shedding phenomenon even appeared on the surface of tungsten at the energy densities of 1.4 J/cm2 and 2.0 J/cm2. The surface nano-hardness of tungsten decreased with the increase of the pulse times and the energy density. The tungsten has good anti-thermal radiation properties under certain heat load environment.

Partial-reflection studies of D-region winter variability. [electron density measurements

NASA Technical Reports Server (NTRS)

Denny, B. W.; Bowhill, S. A.

1973-01-01

D-region electron densities were measured from December, 1972, to July, 1973, at Urbana, Illinois (latitude 40.2N) using the partial-reflection technique. During the winter, electron densities at altitudes of 72, 76.5, and 81 km show cyclical changes with a period of about 5 days that are highly correlated between these altitudes, suggesting that the mechanism responsible for the winter anomaly in D-region ionization applies throughout this height region. From January 13 to February 3, a pronounced wave-like variation occurred in the partial-reflection measurements, apparently associated with a major stratospheric warming that developed in that period. During the same time period, a traveling periodic variation is observed in the 10-mb height; it is highly correlated with the partial-reflection measurements. Electron density enhancements occur approximately at the same time as increases in the 10-mb height. Comparison of AL and A3 absorption measurements with electron density measurements below 82 km indicates that the winter anomaly in D-region ionization is divided into two types. Type 1, above about 82 km, extends horizontally for about 200 km while type 2, below about 82 km, extends for a horizontal scale of at least 1000 km.

Experimental evolution reveals differences between phenotypic and evolutionary responses to population density.

PubMed

McNamara, K B; Simmons, L W

2017-09-01

Group living can select for increased immunity, given the heightened risk of parasite transmission. Yet, it also may select for increased male reproductive investment, given the elevated risk of female multiple mating. Trade-offs between immunity and reproduction are well documented. Phenotypically, population density mediates both reproductive investment and immune function in the Indian meal moth, Plodia interpunctella. However, the evolutionary response of populations to these traits is unknown. We created two replicated populations of P. interpunctella, reared and mated for 14 generations under high or low population densities. These population densities cause plastic responses in immunity and reproduction: at higher numbers, both sexes invest more in one index of immunity [phenoloxidase (PO) activity] and males invest more in sperm. Interestingly, our data revealed divergence in PO and reproduction in a different direction to previously reported phenotypic responses. Males evolving at low population densities transferred more sperm, and both males and females displayed higher PO than individuals at high population densities. These positively correlated responses to selection suggest no apparent evolutionary trade-off between immunity and reproduction. We speculate that the reduced PO activity and sperm investment when evolving under high population density may be due to the reduced population fitness predicted under increased sexual conflict and/or to trade-offs between pre- and post-copulatory traits. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Long-term habitat selection and chronic root herbivory: explaining the relationship between periodical cicada density and tree growth.

PubMed

Yang, Louie H; Karban, Richard

2009-01-01

Periodical cicadas (Magicicada spp.) are insect herbivores that feed on host tree roots, but their distribution among hosts is determined largely by the oviposition of female cicadas in the previous generation. A pattern of decreasing tree growth rates with increasing cicada densities is predicted when considering the costs of chronic root herbivory, but the opposite pattern is expected when considering adaptive habitat selection. Here, we report observations indicating that the relationship between periodical cicada densities and host tree growth rates is hump shaped. We suggest that both herbivory and habitat selection are likely to be key processes explaining this pattern, resulting in regions of positive and negative correlation. These results suggest that the effects of cicada herbivory are most apparent at relatively high cicada densities, while habitat selection tends to distribute cicada herbivory on host trees that are able to compensate for cicada root herbivory up to threshold cicada densities.

The role of grain size in He bubble formation: Implications for swelling resistance

DOE PAGES

El-Atwani, Osman; Nathaniel, II, James E.; Leff, Asher C.; ...

2016-12-07

Here, nanocrystalline metals are postulated as radiation resistant materials due to their high defect and particle (e.g. Helium) sink density. Here, the performance of nanocrystalline iron films is investigated in-situ in a transmission electron microscope (TEM) using He irradiation at 700 K. Automated crystal orientation mapping is used in concert with in-situ TEM to explore the role of grain orientation and grain boundary character on bubble density trends. Bubble density as a function of three key grain size regimes is demonstrated. While the overall trend revealed an increase in bubble density up to a saturation value, grains with areas rangingmore » from 3000 to 7500 nm 2 show a scattered distribution. An extrapolated swelling resistance based on bubble size and areal density indicated that grains with sizes less than 2000 nm 2 possess the greatest apparent resistance. Moreover, denuded zones are found to be independent of grain size, grain orientation, and grain boundary misorientation angle.« less

A thermosyphon heat pipe cooler for high power LEDs cooling

NASA Astrophysics Data System (ADS)

Li, Ji; Tian, Wenkai; Lv, Lucang

2016-08-01

Light emitting diode (LED) cooling is facing the challenge of high heat flux more seriously with the increase of input power and diode density. The proposed unique thermosyphon heat pipe heat sink is particularly suitable for cooling of high power density LED chips and other electronics, which has a heat dissipation potential of up to 280 W within an area of 20 mm × 22 mm (>60 W/cm2) under natural air convection. Meanwhile, a thorough visualization investigation was carried out to explore the two phase flow characteristics in the proposed thermosyphon heat pipe. Implementing this novel thermosyphon heat pipe heat sink in the cooling of a commercial 100 W LED integrated chip, a very low apparent thermal resistance of 0.34 K/W was obtained under natural air convection with the aid of the enhanced boiling heat transfer at the evaporation side and the enhanced natural air convection at the condensation side.

Significant locations in auxiliary data as seeds for typical use cases of point clustering

NASA Astrophysics Data System (ADS)

Kröger, Johannes

2018-05-01

Random greedy clustering and grid-based clustering are highly susceptible by their initial parameters. When used for point data clustering in maps they often change the apparent distribution of the underlying data. We propose a process that uses precomputed weighted seed points for the initialization of clusters, for example from local maxima in population density data. Exemplary results from the clustering of a dataset of petrol stations are presented.

Intraspecific competition and density dependence of food consumption and growth in Arctic charr.

PubMed

Amundsen, Per-Arne; Knudsen, Rune; Klemetsen, Anders

2007-01-01

1. Intraspecific competition for restricted food resources is considered to play a fundamental part in density dependence of somatic growth and other population characteristics, but studies simultaneously addressing the interrelationships between population density, food acquisition and somatic growth have been missing. 2. We explored the food consumption and individual growth rates of Arctic charr Salvelinus alpinus in a long-term survey following a large-scale density manipulation experiment in a subarctic lake. 3. Prior to the initiation of the experiment, the population density was high and the somatic growth rates low, revealing a severely overcrowded and stunted fish population. 4. During the 6-year period of stock depletion the population density of Arctic charr was reduced with about 75%, resulting in an almost twofold increase in food consumption rates and enhanced individual growth rates of the fish. 5. Over the decade following the density manipulation experiment, the population density gradually rose to intermediate levels, accompanied by corresponding reductions in food consumption and somatic growth rates. 6. The study revealed negative relationships with population density for both food consumption and individual growth rates, reflecting a strong positive correlation between quantitative food intake and somatic growth rates. 7. Both the growth and consumption rate relationships with population density were well described by negative power curves, suggesting that large density perturbations are necessary to induce improved feeding conditions and growth rates in stunted fish populations. 8. The findings demonstrate that quantitative food consumption represents the connective link between population density and individual growth rates, apparently being highly influenced by intraspecific competition for limited resources.

A spatio-temporal index for heat vulnerability assessment.

PubMed

Kershaw, Suzanne E; Millward, Andrew A

2012-12-01

The public health consequences of extreme heat events are felt most intensely in metropolitan areas where population density is high and the presence of the urban heat island phenomenon exacerbates the potential for prolonged exposure. This research develops an approach to map potential heat stress on humans by combining temperature and relative humidity into an index of apparent temperature. We use ordinary kriging to generate hourly prediction maps describing apparent temperature across the Greater Toronto Area, Canada. Meteorological data were obtained from 65 locations for 6 days in 2008 when extreme heat alerts were issued for the City of Toronto. Apparent temperature and exposure duration were integrated in a single metric, humidex degree hours (HDH), and mapped. The results show a significant difference in apparent temperature between built and natural locations from 3 PM to 7 AM; this discrepancy was greatest at 12 AM where built locations had a mean of 2.8 index values larger, t(71) = 5.379, p < 0.001. Spatial trends in exposure to heat stress (apparent temperature, ≥ 30°C) show the downtown core of the City of Toronto and much of Mississauga (west of Toronto) as likely to experience hazardous levels of prolonged heat and humidity (HDH ≥ 72) during a heat alert. We recommend that public health officials use apparent temperature and exposure duration to develop spatially explicit heat vulnerability assessment tools; HDH is one approach that unites these risk factors into a single metric.

Irrigation in the arid regions of Tunisia impacts the abundance and apparent density of sand fly vectors of Leishmania infantum

PubMed Central

Barhoumi, Walid; Qualls, Whitney A.; Archer, Reginald; Fuller, Douglas O.; Chelbi, Ifhem; Cherni, Saifedine; Derbali, Mohamed; Arheart, Kristopher L.; Zhioua, Elyes; Beier, John C.

2015-01-01

The distribution expansion of important human visceral leishmaniasis (HVL) and sporadic cutaneous leishmaniasis (SCL) vector species, Phlebotomus perfiliewi and P. perniciosus, throughout central Tunisia is a major public health concern. This study was designed to investigate if the expansion of irrigation influences the abundance of sand fly species potentially involved in the transmission of HVL and SCL located in arid bioclimatic regions. Geographic and remote sensing approaches were used to predict the density of visceral leishmaniasis vectors in Tunisia. Entomological investigations were performed in the governorate of Sidi Bouzid, located in the arid bioclimatic region of Tunisia. In 2012, sand flies were collected by CDC light traps located at nine irrigated and nine non-irrigated sites to determine species abundance. Eight species in two genera were collected. Among sand flies of the subgenus Larroussius, P. perfiliewi was the only species collected significantly more in irrigated areas. Trap data were then used to develop Poisson regression models to map the apparent density of important sand fly species as a function of different environmental covariates including climate and vegetation density. The density of P. perfiliewi is predicted to be moderately high in the arid regions. These results highlight that the abundance of P. perfiliewi is associated with the development of irrigated areas and suggests that the expansion of this species will continue to more arid areas of the country as irrigation sites continue to be developed in the region. The continued increase in irrigated areas in the Middle East and North Africa region deserves attention, as it is associated with the spread of L. infantum vector P. perfiliewi. Integrated vector management strategies targeting irrigation structures to reduce sand fly vector populations should be evaluated in light of these findings. PMID:25447265

Interaction between colloidal particles on an oil-water interface in dilute and dense phases.

PubMed

Parolini, Lucia; Law, Adam D; Maestro, Armando; Buzza, D Martin A; Cicuta, Pietro

2015-05-20

The interaction between micron-sized charged colloidal particles at polar/non-polar liquid interfaces remains surprisingly poorly understood for a relatively simple physical chemistry system. By measuring the pair correlation function g(r) for different densities of polystyrene particles at the decane-water interface, and using a powerful predictor-corrector inversion scheme, effective pair-interaction potentials can be obtained up to fairly high densities, and these reproduce the experimental g(r) in forward simulations, so are self consistent. While at low densities these potentials agree with published dipole-dipole repulsion, measured by various methods, an apparent density dependence and long range attraction are obtained when the density is higher. This condition is thus explored in an alternative fashion, measuring the local mobility of colloids when confined by their neighbors. This method of extracting interaction potentials gives results that are consistent with dipolar repulsion throughout the concentration range, with the same magnitude as in the dilute limit. We are unable to rule out the density dependence based on the experimental accuracy of our data, but we show that incomplete equilibration of the experimental system, which would be possible despite long waiting times due to the very strong repulsions, is a possible cause of artefacts in the inverted potentials. We conclude that to within the precision of these measurements, the dilute pair potential remains valid at high density in this system.

Population cycles: generalities, exceptions and remaining mysteries

PubMed Central

2018-01-01

Population cycles are one of nature's great mysteries. For almost a hundred years, innumerable studies have probed the causes of cyclic dynamics in snowshoe hares, voles and lemmings, forest Lepidoptera and grouse. Even though cyclic species have very different life histories, similarities in mechanisms related to their dynamics are apparent. In addition to high reproductive rates and density-related mortality from predators, pathogens or parasitoids, other characteristics include transgenerational reduced reproduction and dispersal with increasing-peak densities, and genetic similarity among populations. Experiments to stop cyclic dynamics and comparisons of cyclic and noncyclic populations provide some understanding but both reproduction and mortality must be considered. What determines variation in amplitude and periodicity of population outbreaks remains a mystery. PMID:29563267

SINEs, evolution and genome structure in the opossum.

PubMed

Gu, Wanjun; Ray, David A; Walker, Jerilyn A; Barnes, Erin W; Gentles, Andrew J; Samollow, Paul B; Jurka, Jerzy; Batzer, Mark A; Pollock, David D

2007-07-01

Short INterspersed Elements (SINEs) are non-autonomous retrotransposons, usually between 100 and 500 base pairs (bp) in length, which are ubiquitous components of eukaryotic genomes. Their activity, distribution, and evolution can be highly informative on genomic structure and evolutionary processes. To determine recent activity, we amplified more than one hundred SINE1 loci in a panel of 43 M. domestica individuals derived from five diverse geographic locations. The SINE1 family has expanded recently enough that many loci were polymorphic, and the SINE1 insertion-based genetic distances among populations reflected geographic distance. Genome-wide comparisons of SINE1 densities and GC content revealed that high SINE1 density is associated with high GC content in a few long and many short spans. Young SINE1s, whether fixed or polymorphic, showed an unbiased GC content preference for insertion, indicating that the GC preference accumulates over long time periods, possibly in periodic bursts. SINE1 evolution is thus broadly similar to human Alu evolution, although it has an independent origin. High GC content adjacent to SINE1s is strongly correlated with bias towards higher AT to GC substitutions and lower GC to AT substitutions. This is consistent with biased gene conversion, and also indicates that like chickens, but unlike eutherian mammals, GC content heterogeneity (isochore structure) is reinforced by substitution processes in the M. domestica genome. Nevertheless, both high and low GC content regions are apparently headed towards lower GC content equilibria, possibly due to a relative shift to lower recombination rates in the recent Monodelphis ancestral lineage. Like eutherians, metatherian (marsupial) mammals have evolved high CpG substitution rates, but this is apparently a convergence in process rather than a shared ancestral state.

Dietary boron does not affect tooth strength, micro-hardness, and density, but affects tooth mineral composition and alveolar bone mineral density in rabbits fed a high-energy diet.

PubMed

Hakki, Sema S; SiddikMalkoc; Dundar, Niyazi; Kayis, Seyit Ali; Hakki, Erdogan E; Hamurcu, Mehmet; Baspinar, Nuri; Basoglu, Abdullah; Nielsen, Forrest H; Götz, Werner

2015-01-01

The objective of this study was to determine whether dietary boron (B) affects the strength, density and mineral composition of teeth and mineral density of alveolar bone in rabbits with apparent obesity induced by a high-energy diet. Sixty female, 8-month-old, New Zealand rabbits were randomly assigned for 7 months into five groups as follows: (1) control 1, fed alfalfa hay only (5.91 MJ/kg and 57.5 mg B/kg); (2) control 2, high energy diet (11.76 MJ and 3.88 mg B/kg); (3) B10, high energy diet + 10 mg B gavage/kg body weight/96 h; (4) B30, high energy diet + 30 mg B gavage/kg body weight/96 h; (5) B50, high energy diet + 50 mg B gavage/kg body weight/96 h. Maxillary incisor teeth of the rabbits were evaluated for compression strength, mineral composition, and micro-hardness. Enamel, dentin, cementum and pulp tissue were examined histologically. Mineral densities of the incisor teeth and surrounding alveolar bone were determined by using micro-CT. When compared to controls, the different boron treatments did not significantly affect compression strength, and micro-hardness of the teeth, although the B content of teeth increased in a dose-dependent manner. Compared to control 1, B50 teeth had decreased phosphorus (P) concentrations. Histological examination revealed that teeth structure (shape and thickness of the enamel, dentin, cementum and pulp) was similar in the B-treated and control rabbits. Micro CT evaluation revealed greater alveolar bone mineral density in B10 and B30 groups than in controls. Alveolar bone density of the B50 group was not different than the controls. Although the B treatments did not affect teeth structure, strength, mineral density and micro-hardness, increasing B intake altered the mineral composition of teeth, and, in moderate amounts, had beneficial effects on surrounding alveolar bone.

Structure and dynamics of mixed-species flocks in a Hawaiian rain forest

USGS Publications Warehouse

Hart, P.J.; Freed, L.A.

2003-01-01

Mixed-species flocks of native and introduced birds were studied for four years in an upper elevation Hawaiian rain forest. Those flocks were characterized by strong seasonality, large size, low species richness, high intraspecific abundance, a lack of migrants, and a general lack of territoriality or any sort of dominance hierarchy. There was high variability among years in patterns of occurrence at the species level, and high variability within years at the individual level. These flocks are loosely structured social groupings with apparently open membership. The fluid, unstable movement patterns, high degree of variability in size and composition, and lack of positive interspecific associations are not consistent with the “foraging enhancement” hypothesis for flocking. Two resident, endangered insectivores, the Akepa (Loxops coccineus) and Hawaii Creeper (Oreomystis mana) served as “nuclear” species. Flock composition was compared between two study sites that differed significantly in density of these two nuclear species. Flock size was similar at the two sites, primarily because the nuclear species were over-represented relative to their density. This observation suggests that birds are attempting to achieve a more optimal flock size at the lower density site.

Deregulation of HIF1-alpha and hypoxia-regulated pathways in hepatocellular carcinoma and corresponding non-malignant liver tissue--influence of a modulated host stroma on the prognosis of HCC.

PubMed

Simon, Frank; Bockhorn, Maximilian; Praha, Christian; Baba, Hideo A; Broelsch, Christoph E; Frilling, Andrea; Weber, Frank

2010-04-01

The aim of this study was to elucidate the role of HIF1A expression in hepatocellular carcinoma (HCC) and the corresponding non-malignant liver tissue and to correlate it with the clinical outcome of HCC patients after curative liver resection. HIF1A expression was determined by quantitative RT-PCR in HCC and corresponding non-malignant liver tissue of 53 patients surgically treated for HCC. High-density gene expression analysis and pathway analysis was performed on a selected subset of patients with high and low HIF1A expression in the non-malignant liver tissue. HIF1A over-expression in the apparently non-malignant liver tissue was a predictor of tumor recurrence and survival. The estimated 1-year and 5-year disease-free survival was significantly better in patients with low HIF1A expression in the non-malignant liver tissue when compared to those patients with high HIF1 expression (88.9% vs. 67.9% and 61.0% vs. 22.6%, respectively, p = 0.008). Based on molecular pathway analysis utilizing high-density gene-expression profiling, HIF1A related molecular networks were identified that contained genes involved in cell migration, cell homing, and cell-cell interaction. Our study identified a potential novel mechanism contributing to prognosis of HCC. The deregulation of HIF1A and its related pathways in the apparently non-malignant liver tissue provides for a modulated environment that potentially enhances or allows for HCC recurrence after curative resection.

Cytoskeletal mechanics in pressure-overload cardiac hypertrophy

NASA Technical Reports Server (NTRS)

Tagawa, H.; Wang, N.; Narishige, T.; Ingber, D. E.; Zile, M. R.; Cooper, G. 4th

1997-01-01

We have shown that the cellular contractile dysfunction characteristic of pressure-overload cardiac hypertrophy results not from an abnormality intrinsic to the myofilament portion of the cardiocyte cytoskeleton but rather from an increased density of the microtubule component of the extramyofilament portion of the cardiocyte cytoskeleton. To determine how, in physical terms, this increased microtubule density mechanically overloads the contractile apparatus at the cellular level, we measured cytoskeletal stiffness and apparent viscosity in isolated cardiocytes via magnetic twisting cytometry, a technique by which magnetically induced force is applied directly to the cytoskeleton through integrin-coupled ferromagnetic beads coated with Arg-Gly-Asp (RGD) peptide. Measurements were made in two groups of cardiocytes from cats with right ventricular (RV) hypertrophy induced by pulmonary artery banding: (1) those from the pressure-overloaded RV and (2) those from the normally loaded same-animal control left ventricle (LV). Cytoskeletal stiffness increased almost twofold, from 8.53 +/- 0.77 dyne/cm2 in the normally loaded LV cardiocytes to 16.46 +/- 1.32 dyne/cm2 in the hypertrophied RV cardiocytes. Cytoskeletal apparent viscosity increased almost fourfold, from 20.97 +/- 1.92 poise in the normally loaded LV cardiocytes to 87.85 +/- 6.95 poise in the hypertrophied RV cardiocytes. In addition to these baseline data showing differing stiffness and, especially, apparent viscosity in the two groups of cardiocytes, microtubule depolymerization by colchicine was found to return both the stiffness and the apparent viscosity of the pressure overload-hypertrophied RV cells fully to normal. Conversely, microtubule hyperpolymerization by taxol increased the stiffness and apparent viscosity values of normally loaded LV cardiocytes to the abnormal values given above for pressure-hypertrophied RV cardiocytes. Thus, increased microtubule density constitutes primarily a viscous load on the cardiocyte contractile apparatus in pressure-overload cardiac hypertrophy.

Petrologic constraints on the decompression history of magma prior to Vulcanian explosions at the Soufrière Hills volcano, Montserrat

NASA Astrophysics Data System (ADS)

Clarke, A. B.; Stephens, S.; Teasdale, R.; Sparks, R. S. J.; Diller, K.

2007-04-01

A series of 88 Vulcanian explosions occurred at the Soufrière Hills volcano, Montserrat, between August and October, 1997. Conduit conditions conducive to creating these and other Vulcanian explosions were explored via analysis of eruptive products and one-dimensional numerical modeling of magma ascent through a cylindrical conduit. The number densities and textures of plagioclase microlites were documented for twenty-three samples from the events. The natural samples all show very high number densities of microlites, and > 50% by number of microlites have areas < 20 μm 2. Pre-explosion conduit conditions and decompression history have been inferred from these data by comparison with experimental decompressions of similar groundmass compositions. Our comparisons suggest quench pressures < 30 MPa (origin depths < 2 km) and multiple rapid decompressions of > 13.75 MPa each during ascent from chamber to surface. Values are consistent with field studies of the same events and statistical analysis of explosion time-series data. The microlite volume number density trend with depth reveals an apparent transition from growth-dominated crystallization to nucleation-dominated crystallization at pressures of ˜ 7 MPa and lower. A concurrent sharp increase in bulk density marks the onset of significant open-system degassing, apparently due to a large increase in system permeability above ˜ 70% vesicularity. This open-system degassing results in a dense plug which eventually seals the conduit and forms conditions favorable to Vulcanian explosions. The corresponding inferred depth of overpressure at 250-700 m, near the base of the dense plug, is consistent with depth to center of pressure estimated from deformation measurements. Here we also illustrate that one-dimensional models representing ascent of a degassing, crystal-rich magma are broadly consistent with conduit profiles constructed via our petrologic analysis. The comparison between models and petrologic data suggests that the dense conduit plug forms as a result of high overpressure and open-system degassing through conduit walls.

Cooling of Electric Motors Used for Propulsion on SCEPTOR

NASA Technical Reports Server (NTRS)

Christie, Robert; Dubois, Authur; Derlaga, Joseph

2016-01-01

Benefits of Electric Power: Reduced energy consumption, Lower emissions, Less noise. Traction motors: Permanent magnet, Synchronous, High torque at low rotational speeds, High power density, (High concentration of heat). Annular inlet: Very compatible with PM motors, (Provides cooling where needed, No need for complicated ducting, Leads to a larger motor diameter which is beneficial for motor torque) Effect of prop wash on heat transfer coefficients: Assumed propeller induced turbulence would increase heat transfer coefficients, Holmes, Obara Yip reported 'propeller slipstream showed little if any apparent effect of the slip stream', Derlaga @ LaRC also found little change in heat transfer in the wake of the propeller.

Adsorption of benzene, toluene, and xylene by two tetramethylammonium-smectites having different charge densities

USGS Publications Warehouse

Lee, Jiunn-Fwu; Mortland, Max M.; Chiou, Cary T.; Kite, Daniel E.; Boyd, Stephen A.

1990-01-01

A high-charge smectite from Arizona [cation-exchange capacity (CEC) = 120 meq/100 g] and a low-charge smectite from Wyoming (CEC = 90 meq/100 g) were used to prepare homoionic tetramethylammonium (TMA)-clay complexes. The adsorption of benzene, toluene, and o-xylene as vapors by the dry TMA-clays and as solutes from water by the wet TMA-clays was studied. The adsorption of the organic vapors by the dry TMA-smectite samples was strong and apparently consisted of interactions with both the aluminosilicate mineral surfaces and the TMA exchange ions in the interlayers. In the adsorption of organic vapors, the closer packing of TMA ions in the dry high-charge TMA-smectite, compared with the dry low-charge TMA-smectite, resulted in a somewhat higher degree of shape-selective adsorption of benzene, toluene, and xylene. In the presence of water, the adsorption capacities of both samples for the aromatic compounds were significantly reduced, although the uptake of benzene from water by the low-charge TMA-smectite was still substantial. This lower sorption capacity was accompanied by increased shape-selectivity for the aromatic compounds. The reduction in uptake and increased selectivity was much more pronounced for the water-saturated, high-charge TMA-smectite than for the low-charge TMA-smectite. Hydration of the TMA exchange ions and/or the mineral surfaces apparently reduced the accessibility of the aromatic molecules to interlamellar regions. The resulting water-induced sieving effect was greater for the high-charge TMA-smectite due to the higher density of exchanged TMA-ions. The low-charge Wyoming TMA-smectite was a highly effective adsorbent for removing benzene from water and may be useful for purifying benzene-contaminated water.

Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel

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

Matyas, Josef; Engler, Robert K.

2013-09-01

The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents, Ag0-functionalized silica aerogels, shows great promise as a potential replacement for Ag-bearing mordenites because of its high selectivity and sorption capacity for iodine. Moreover, a feasible consolidation of iodine-loaded Ag0-functionalized silica aerogels to a durable SiO2-based waste form makes this aerogel an attractive choice for sequestering radioiodine. This report provides a preliminary assessment of the methods that can be used to consolidate iodine-loaded Ag0-functionalized silica aerogels into amore » final waste form. In particular, it focuses on experimental investigation of densification of as prepared Ag0-functionalized silica aerogels powders, with or without organic moiety and with or without sintering additive (colloidal silica), with three commercially available techniques: 1) hot uniaxial pressing (HUP), 2) hot isostatic pressing (HIP), and 3) spark plasma sintering (SPS). The densified products were evaluated with helium gas pycnometer for apparent density, with the Archimedes method for apparent density and open porosity, and with high-resolution scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) for the extent of densification and distribution of individual elements. The preliminary investigation of HUP, HIP, and SPS showed that these sintering methods can effectively consolidate powders of Ag0-functionalized silica aerogel into products of near-theoretical density. Also, removal of organic moiety and adding 5.6 mass% of colloidal silica to Ag0-functionalized silica aerogel powders before processing provided denser products. Furthermore, the ram travel data for SPS indicated that rapid consolidation of powders can be performed at temperatures below 950°C.« less

Why prostate tumour delineation based on apparent diffusion coefficient is challenging: an exploration of the tissue microanatomy.

PubMed

Borren, Alie; Moman, Maaike R; Groenendaal, Greetje; Boeken Kruger, Arto E; van Diest, Paul J; van der Groep, Petra; van der Heide, Uulke A; van Vulpen, Marco; Philippens, Marielle E P

2013-11-01

Focal boosting of prostate tumours to improve outcome, requires accurate tumour delineation. For this, the apparent diffusion coefficient (ADC) derived from diffusion-weighted MR imaging (DWI) seems a useful tool. On voxel level, the relationship between ADC and histological presence of tumour is, however, ambiguous. Therefore, in this study the relationship between ADC and histological variables was investigated on voxel level to understand the strengths and limitations of DWI for prostate tumour delineation. Twelve radical prostatectomy patients underwent a pre-operative 3.0T DWI exam and the ADC was calculated. From whole-mount histological sections cell density and glandular area were retrieved for every voxel. The distribution of all variables was described for tumour, peripheral zone (PZ) and central gland (CG) on regional and voxel level. Correlations between variables and differences between regions were calculated. Large heterogeneity of ADC on voxel level was observed within tumours, between tumours and between patients. This heterogeneity was reflected by the distribution of cell density and glandular area. On regional level, tumour was different from PZ having higher cell density (p = 0.007), less glandular area (p = 0.017) and lower ADCs (p = 0.017). ADC was correlated with glandular area (r = 0.402) and tumour volume (r = -0.608), but not with Gleason score. ADC tended to decrease with increasing cell density (r = -0.327, p = 0.073). On voxel level, correlations between ADC and histological variables varied among patients, for cell density ranging from r = -0.439 to r = 0.261 and for glandular area from r = 0.593 to r = 0.207. The variation in ADC can to a certain extent be explained by the variation in cell density and glandular area. The ADC is highly heterogeneous, which reflects the heterogeneity of malignant and benign prostate tissue. This heterogeneity might however obscure small tumours or parts of tumours. Therefore, DWI has to be used in the context of multiparametric MRI.

Separation of solids by varying the bulk density of a fluid separating medium

DOEpatents

Peterson, Palmer L.; Duffy, James B.; Tokarz, Richard D.

1978-01-01

A method and apparatus for separating objects having a density greater than a selected density value from objects having a density less than said selected density value. The method typically comprises: (a) providing a separation vessel having an upper and lower portion, said vessel containing a liquid having a density exceeding said selected density value; (b) reducing the apparent density of the liquid to said selected density value by introducing solid, bubble-like bodies having a density less than that of the liquid into the lower portion of the vessel and permitting them to rise therethrough; (c) introducing the objects to be separated into the separation vessel and permitting the objects having a density greater than the apparent density of the liquid to sink to the lower portion of the vessel, while the objects having a density less than said selected density value float in the upper portion of the vessel; and (d) separately removing the higher density objects in the lower portion and the lower density objects in the upper portion from the separation vessel. The apparatus typically comprises: (a) a vessel containing a liquid having a density such that at least part of said objects having a density exceeding said selected density value will float therein; (b) means to place said objects into said vessel; (c) means to reduce the effective density of at least a portion of said liquid to said selected density value, whereby said objects having a density exceeding said selected density value sink into said liquid and said objects having a density less than said selected density value remain afloat, said means to adjust the effective density comprising solid, bubble-like bodies having a density less than said selected density value and means for introducing said bodies into said liquid; and (d) means for separately removing said objects having a density exceeding said selected density value and said objects having a density less than said selected density value from said vessel.

Effects of Cougar Predation and Nutrition on Mule Deer Population Declines in the Intermountain Province of the Columbia Basin, 2001-2002 Annual Report.

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

Wielgus, Robert B.; Shipley, Lisa

2002-07-01

Construction of the Grand Coulee and Chief Joseph dams has resulted in inundation and loss of 29,125 total habitat units for mule deer and irrigation agriculture in many parts the Intermountain Province (IM) of the Columbia Basin. Mule deer in the Shrub-Steppe are ranked high priority target species for mitigation and management and are declining in most portions of the subbasins of the IM. Reasons for the decline are unknown but believed to be related to habitat changes resulting from dams and irrigation agriculture. White-tailed deer are not ranked as target species and are believed to be increasing throughout themore » basin because of habitat changes brought about by the dams and irrigation agriculture. Recent research (1997-2000) in the NE IM and adjacent Canadian portions of the Columbia Basin (conducted by this author and funded by the Columbia Basin Fish & Wildlife Compensation Program B.C.), suggest that the increasing white-tailed deer populations (because of dams and irrigation agriculture) are resulting in increased predation by cougars on mule deer (apparent competition or alternate prey hypothesis). The apparent competition hypothesis predicts that as alternate prey (white-tailed deer) densities increase, so do densities of predators, resulting in increased incidental predation on sympatric native prey (mule deer). Apparent competition can result in population declines and even extirpation of native prey in some cases. Such a phenomenon may account for declines of mule deer in the IM and throughout arid and semi-arid West where irrigation agriculture is practiced. We will test the apparent competition hypothesis by conducting a controlled, replicated ''press'' experiment in at least 2 treatment and 2 control areas of the IM subbasins by reducing densities of white-tailed deer and observing any changes in cougar predation on mule deer. Deer densities will be monitored by WADFW personnel using annual aerial surveys and/or other trend indices. Predation rates and population growth rates of deer will be determined using radio telemetry. Changes in cougar functional (kills/unit time), aggregative (cougars/unit area), numerical (offspring/cougar), and total (predation rate) responses on deer will also be monitored using radio telemetry. The experiment will be conducted and completed over a period of 5 years. Results will be used to determine the cause and try to halt the mule deer population declines. Results will also guide deer mitigation and management in the IM and throughout the North American West.« less

Effects of Cougar Predation and Nutrition on Mule Deer Population Declines in the IM Province of the Columbia Basin, Annual Report 2002-2003.

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

Wielgus, Robert; Shipley, Lisa; Myers, Woodrow

2003-09-01

Construction of the Grand Coulee and Chief Joseph dams has resulted in inundation and loss of 29,125 total habitat units for mule deer and irrigation agriculture in many parts the Intermountain Province (IM) of the Columbia Basin. Mule deer in the Shrub-Steppe are ranked high priority target species for mitigation and management and are declining in most portions of the sub basins of the IM. Reasons for the decline are unknown but believed to be related to habitat changes resulting from dams and irrigation agriculture. White-tailed deer are believed to be increasing throughout the basin because of habitat changes broughtmore » about by the dams and irrigation agriculture. Recent research (1997-2000) in the NE IM and adjacent Canadian portions of the Columbia Basin (conducted by this author and funded by the Columbia Basin Fish & Wildlife Compensation Program B.C.), suggest that the increasing white-tailed deer populations (because of dams and irrigation agriculture) are resulting in increased predation by cougars on mule deer (apparent competition or alternate prey hypothesis). The apparent competition hypothesis predicts that as alternate prey (white-tailed deer) densities increase, so do densities of predators, resulting in increased incidental predation on sympatric native prey (mule deer). Apparent competition can result in population declines and even extirpation of native prey in some cases. Such a phenomenon may account for declines of mule deer in the IM and throughout arid and semi-arid West where irrigation agriculture is practiced. We will test the apparent competition hypothesis by conducting a controlled, replicated 'press' experiment in at least 2 treatment and 2 control areas of the IM sub basins by reducing densities of white-tailed deer and observing any changes in cougar predation on mule deer. Deer densities will be monitored by WADFW personnel using annual aerial surveys and/or other trend indices. Predation rates and population growth rates of deer will be determined using radio telemetry. Changes in cougar functional (kills/unit time), aggregative (cougars/unit area), numerical (offspring/cougar), and total (predation rate) responses on deer will also be monitored using radio telemetry. The experiment will be conducted and completed over a period of 5 years. Results will be used to determine the cause and try to halt the mule deer population declines. Results will also guide deer mitigation and management in the IM and throughout the North American West.« less

Genetic effects on bone mass and turnover-relevance to black/white differences.

PubMed

Parfitt, A M

1997-08-01

The mass of a bone is given by its volume and its apparent density--mass per unit external volume. Most measurements of so-called density are of mass incompletely normalized by some index of bone size. Genes control about 60% to 75% of the variance of peak bone mass/density and a much smaller proportion of the variance in rate of loss. Genetic influence on bone mass/density are mediated in large part by body size, bone size, and muscle mass. Most of the fifty-fold increase in bone mass from birth to maturity is due to bone growth, which is linked to muscle growth and bodily growth. Three-D apparent bone density in the vertebrae increases about 15% during the pubertal growth spurt. The genetic potential for bone accumulation can be frustrated by insufficient calcium intake, disruption of the calendar of puberty and inadequate physical activity. The growing skeleton is much more responsive than the mature skeleton to the osteotrophic effect of exercise, which is mediated by the detection of deviations from a target value for strain, and orchestration of cellular responses that restore the target value, processes collectively termed the mechanostat. Production of metaphyseal cancellous bone and growth in length are both linked to endochondral ossification, which is driven by growth plate cartilage cell proliferation. Production of diaphyseal cortical bone and growth in width are both linked to periosteal apposition, which is driven by osteoblast precursor proliferation. During adolescence trabeculae and cortices become thicker by net endosteal apposition, which increases apparent density. Two lines of evidence support a genetic basis for black/white differences in bone mass. First, the magnitude (10% to 40%) is incommensurate with known nongenetic factors. Second, the difference is already evident in the fetus and increases progressively during growth, especially in adolescence; the difference in peak bone mass persists throughout life. The genetic determination of bone mass is mediated by two classes of gene. The first regulates growth of the body, including muscles and bones, under the control of a master gene or set of genes whose products function as the sizostat. The second regulates the increase in apparent bone density in response to load bearing, under the control of a master gene or set of genes whose products function as the mechanostat.

Profound Effects of Population Density on Fitness-Related Traits in an Invasive Freshwater Snail

PubMed Central

Zachar, Nicholas; Neiman, Maurine

2013-01-01

Population density can profoundly influence fitness-related traits and population dynamics, and density dependence plays a key role in many prominent ecological and evolutionary hypotheses. Here, we evaluated how individual-level changes in population density affect growth rate and embryo production early in reproductive maturity in two different asexual lineages of Potamopyrgus antipodarum, a New Zealand freshwater snail that is an important model system for ecotoxicology and the evolution of sexual reproduction as well as a potentially destructive worldwide invader. We showed that population density had a major influence on individual growth rate and early-maturity embryo production, effects that were often apparent even when comparing treatments that differed in population density by only one individual. While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos. The two lineages responded similarly to the treatments, indicating that these effects of population density might apply more broadly across P. antipodarum. These results indicate that there are profound and complex relationships between population density, growth rate, and early-maturity embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology. PMID:24278240

Profound effects of population density on fitness-related traits in an invasive freshwater snail.

PubMed

Zachar, Nicholas; Neiman, Maurine

2013-01-01

Population density can profoundly influence fitness-related traits and population dynamics, and density dependence plays a key role in many prominent ecological and evolutionary hypotheses. Here, we evaluated how individual-level changes in population density affect growth rate and embryo production early in reproductive maturity in two different asexual lineages of Potamopyrgus antipodarum, a New Zealand freshwater snail that is an important model system for ecotoxicology and the evolution of sexual reproduction as well as a potentially destructive worldwide invader. We showed that population density had a major influence on individual growth rate and early-maturity embryo production, effects that were often apparent even when comparing treatments that differed in population density by only one individual. While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos. The two lineages responded similarly to the treatments, indicating that these effects of population density might apply more broadly across P. antipodarum. These results indicate that there are profound and complex relationships between population density, growth rate, and early-maturity embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology.

Melting of the precipitated ice IV in LiCl aqueous solution and polyamorphism of water.

PubMed

Mishima, Osamu

2011-12-08

Melting of the precipitated ice IV in supercooled LiCl-H(2)O solution was studied in the range of 0-0.6 MPa and 160-270 K. Emulsified solution was used to detect this metastable transition. Ice IV was precipitated from the aqueous solution of 2.0 mol % LiCl (or 4.8 mol % LiCl) in each emulsion particle at low-temperature and high-pressure conditions, and the emulsion was decompressed at different temperatures. The melting of ice IV was detected from the temperature change of the emulsified sample during the decompression. There was an apparently sudden change in the slope of the ice IV melting curve (liquidus) in the pressure-temperature diagram. At the high-pressure and high-temperature side of the change, the solute-induced freezing point depression was observed. At the low-pressure and low-temperature side, ice IV transformed into ice Ih on the decompression, and the transition was almost unrelated to the concentration of LiCl. These experimental results were roughly explained by the presumed existence of two kinds of liquid water (low-density liquid water and high-density liquid water), or polyamorphism in water, and by the simple assumption that LiCl dissolved maily in high-density liquid water. © 2011 American Chemical Society

Origin of the anomalous decrease in the apparent density of polymer gels observed by multi-echo reflection ultrasound spectroscopy.

PubMed

Takeda, Kohsuke; Norisuye, Tomohisa; Tran-Cong-Miyata, Qui

2013-07-01

Multi-echo reflection ultrasound spectroscopy (MERUS), which enables one to simultaneously evaluate the attenuation coefficient α, the sound velocity v and the density ρ, has been developed for measurements of elastic moduli. In the present study, the technique was further developed to analyze systems undergoing gelation where an unphysical decrease in the apparent density was previously observed after polymerization. The main reason for this problem was that the shrinkage accompanying the gelation led to a small gap between the cell wall and the sample, resulting in the superposition of the reflected signals which were not separable into individual components. By taking into account the multiply reflecting echoes at the interface of the gap, the corrected densities were systematically obtained and compared with the results for the floating test. The present technique opens a new route to simultaneously evaluate the three parameters α, v and ρ and also the sample thickness for solid thin films. Copyright © 2013 Elsevier B.V. All rights reserved.

Protein source and nutrient density in the diets of male broilers from 8 to 21 d of age: Effects on small intestine morphology.

PubMed

Wang, X; Peebles, E D; Morgan, T W; Harkess, R L; Zhai, W

2015-01-01

In a companion study, high amino acid (AA) or apparent metabolizable energy (AME) densities in the diets of broilers from 8 to 21 d of age were found to improve feed conversion. A total of 1,120 male Ross×Ross 708 chicks were randomly allocated to 80 pens (8 treatments, 10 replications per treatment, 14 chicks per pen). A 2×2×2 factorial arrangement of treatments was used to investigate the interaction among the protein source (high distillers dried grains with solubles diet [hDDGS] or high meat and bone meal diet [hMBM]), AA density (moderate or high), and AME density (2,998 or 3,100 kcal/kg) of diets on small intestine morphology. Duodenum, jejunum, and ileum samples from 2 chicks per pen were collected and measured individually at 21 d. Jejunum sections were processed for histological analysis. Chicks fed hDDGS diets exhibited longer small intestines than did chicks fed hMBM diets. Particularly, when chicks were fed high AA density diets, jejuna were longer in groups fed hDDGS diets than groups fed hMBM diets. Dietary treatments did not affect jejunum villus height, width, area, crypt depth, villus to crypt ratio, goblet cell size, or cell density. In birds fed diets containing a moderate AA and a high AME density, jejunum muscle layers of chicks fed hDDGS diets were thicker than those fed hMBM diets. Chicks exhibited a lower feed conversion ratio (FCR) and a higher BW gain when their crypts were shorter. In conclusion, an hDDGS diet may facilitate small intestine longitudinal growth in broilers, which may subsequently improve dietary nutrient absorption. In addition, broiler chicks with shallow intestinal crypts exhibited better growth performance. © 2014 Poultry Science Association Inc.

Laser ultrasonics for bulk-density distribution measurement on green ceramic tiles

NASA Astrophysics Data System (ADS)

Revel, G. M.; Cavuto, A.; Pandarese, G.

2016-10-01

In this paper a Laser Ultrasonics (LUT) system is developed and applied to measure bulk density distribution of green ceramic tiles, which are porous materials with low heat conductivity. Bulk density of green ceramic bodies is a fundamental parameter to be kept under control in the industrial production of ceramic tiles. The LUT system proposed is based on a Nd:YAG pulsed laser for excitation and an air-coupled electro-capacitive transducer for detection. The paper reports experimental apparent bulk-density measurements on white ceramic bodies after a calibration procedures. The performances observed are better than those previously achieved by authors using air-coupled ultrasonic probes for both emission and detection, allowing to reduce average uncertainty down to about ±6 kg/m3 (±0.3%), thanks to the increase in excitation efficiency and lateral resolution, while maintaining potential flexibility for on-line application. The laser ultrasonic procedure proposed is available for both on-line and off-line application. In this last case it is possible to obtain bulk density maps with high spatial resolution by a 2D scan without interrupting the production process.

Multiband VLBI Observations of CTA102

NASA Technical Reports Server (NTRS)

Rantakyro, F. T.; Baath, L. B.; Dallacasa, D.; Jones, D. L.; Wehrle, A. E.

1995-01-01

The source CTA102, known to exhibit low frequency variability, has been observed at six epochs (three at lambda 32 cm, two at lambda 18 cm, and one at lambda l.3 cm) with intercontinental VLBI arrays. On the basis of the changes observed in the structure, we believe that the flux density variations at these wavelengths are due to intrinsic processes and not due to interstellar scintillation. This source exhibits behaviour suggestive of being expanding with a very high apparent transverse velocity.

Quartz and feldspar glasses produced by natural and experimental shock.

NASA Technical Reports Server (NTRS)

Stoeffler, D.; Hornemann, U.

1972-01-01

Refractive index, density, and infrared absorption studies of naturally and experimentally shocked-produced glasses formed from quartz, plagioclase, and alkali-feldspar confirm the existence of two main groups of amorphous forms of the framework silicates: solid-state and liquid-state glasses. These were apparently formed as metastable release products of high-pressure-phases above and below the glass transition temperatures. Solid-state glasses exhibit a series of structural states with increasing disorder caused by increasing shock pressures and temperatures. They gradually merge into the structural state of fused minerals similar to that of synthetic glasses quenched from a melt. Shock-fused alkali feldspars can, however, be distinguished from their laboratory-fused counterparts by infrared absorption and by higher density.

Determining crystal structures through crowdsourcing and coursework

NASA Astrophysics Data System (ADS)

Horowitz, Scott; Koepnick, Brian; Martin, Raoul; Tymieniecki, Agnes; Winburn, Amanda A.; Cooper, Seth; Flatten, Jeff; Rogawski, David S.; Koropatkin, Nicole M.; Hailu, Tsinatkeab T.; Jain, Neha; Koldewey, Philipp; Ahlstrom, Logan S.; Chapman, Matthew R.; Sikkema, Andrew P.; Skiba, Meredith A.; Maloney, Finn P.; Beinlich, Felix R. M.; Caglar, Ahmet; Coral, Alan; Jensen, Alice Elizabeth; Lubow, Allen; Boitano, Amanda; Lisle, Amy Elizabeth; Maxwell, Andrew T.; Failer, Barb; Kaszubowski, Bartosz; Hrytsiv, Bohdan; Vincenzo, Brancaccio; de Melo Cruz, Breno Renan; McManus, Brian Joseph; Kestemont, Bruno; Vardeman, Carl; Comisky, Casey; Neilson, Catherine; Landers, Catherine R.; Ince, Christopher; Buske, Daniel Jon; Totonjian, Daniel; Copeland, David Marshall; Murray, David; Jagieła, Dawid; Janz, Dietmar; Wheeler, Douglas C.; Cali, Elie; Croze, Emmanuel; Rezae, Farah; Martin, Floyd Orville; Beecher, Gil; de Jong, Guido Alexander; Ykman, Guy; Feldmann, Harald; Chan, Hugo Paul Perez; Kovanecz, Istvan; Vasilchenko, Ivan; Connellan, James C.; Borman, Jami Lynne; Norrgard, Jane; Kanfer, Jebbie; Canfield, Jeffrey M.; Slone, Jesse David; Oh, Jimmy; Mitchell, Joanne; Bishop, John; Kroeger, John Douglas; Schinkler, Jonas; McLaughlin, Joseph; Brownlee, June M.; Bell, Justin; Fellbaum, Karl Willem; Harper, Kathleen; Abbey, Kirk J.; Isaksson, Lennart E.; Wei, Linda; Cummins, Lisa N.; Miller, Lori Anne; Bain, Lyn; Carpenter, Lynn; Desnouck, Maarten; Sharma, Manasa G.; Belcastro, Marcus; Szew, Martin; Szew, Martin; Britton, Matthew; Gaebel, Matthias; Power, Max; Cassidy, Michael; Pfützenreuter, Michael; Minett, Michele; Wesselingh, Michiel; Yi, Minjune; Cameron, Neil Haydn Tormey; Bolibruch, Nicholas I.; Benevides, Noah; Kathleen Kerr, Norah; Barlow, Nova; Crevits, Nykole Krystyne; Dunn, Paul; Silveira Belo Nascimento Roque, Paulo Sergio; Riber, Peter; Pikkanen, Petri; Shehzad, Raafay; Viosca, Randy; James Fraser, Robert; Leduc, Robert; Madala, Roman; Shnider, Scott; de Boisblanc, Sharon; Butkovich, Slava; Bliven, Spencer; Hettler, Stephen; Telehany, Stephen; Schwegmann, Steven A.; Parkes, Steven; Kleinfelter, Susan C.; Michael Holst, Sven; van der Laan, T. J. A.; Bausewein, Thomas; Simon, Vera; Pulley, Warwick; Hull, William; Kim, Annes Yukyung; Lawton, Alexis; Ruesch, Amanda; Sundar, Anjali; Lawrence, Anna-Lisa; Afrin, Antara; Maheshwer, Bhargavi; Turfe, Bilal; Huebner, Christian; Killeen, Courtney Elizabeth; Antebi-Lerrman, Dalia; Luan, Danny; Wolfe, Derek; Pham, Duc; Michewicz, Elaina; Hull, Elizabeth; Pardington, Emily; Galal, Galal Osama; Sun, Grace; Chen, Grace; Anderson, Halie E.; Chang, Jane; Hewlett, Jeffrey Thomas; Sterbenz, Jennifer; Lim, Jiho; Morof, Joshua; Lee, Junho; Inn, Juyoung Samuel; Hahm, Kaitlin; Roth, Kaitlin; Nair, Karun; Markin, Katherine; Schramm, Katie; Toni Eid, Kevin; Gam, Kristina; Murphy, Lisha; Yuan, Lucy; Kana, Lulia; Daboul, Lynn; Shammas, Mario Karam; Chason, Max; Sinan, Moaz; Andrew Tooley, Nicholas; Korakavi, Nisha; Comer, Patrick; Magur, Pragya; Savliwala, Quresh; Davison, Reid Michael; Sankaran, Roshun Rajiv; Lewe, Sam; Tamkus, Saule; Chen, Shirley; Harvey, Sho; Hwang, Sin Ye; Vatsia, Sohrab; Withrow, Stefan; Luther, Tahra K.; Manett, Taylor; Johnson, Thomas James; Ryan Brash, Timothy; Kuhlman, Wyatt; Park, Yeonjung; Popović, Zoran; Baker, David; Khatib, Firas; Bardwell, James C. A.

2016-09-01

We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality.

Determining crystal structures through crowdsourcing and coursework.

PubMed

Horowitz, Scott; Koepnick, Brian; Martin, Raoul; Tymieniecki, Agnes; Winburn, Amanda A; Cooper, Seth; Flatten, Jeff; Rogawski, David S; Koropatkin, Nicole M; Hailu, Tsinatkeab T; Jain, Neha; Koldewey, Philipp; Ahlstrom, Logan S; Chapman, Matthew R; Sikkema, Andrew P; Skiba, Meredith A; Maloney, Finn P; Beinlich, Felix R M; Popović, Zoran; Baker, David; Khatib, Firas; Bardwell, James C A

2016-09-16

We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality.

Population cycles: generalities, exceptions and remaining mysteries.

PubMed

Myers, Judith H

2018-03-28

Population cycles are one of nature's great mysteries. For almost a hundred years, innumerable studies have probed the causes of cyclic dynamics in snowshoe hares, voles and lemmings, forest Lepidoptera and grouse. Even though cyclic species have very different life histories, similarities in mechanisms related to their dynamics are apparent. In addition to high reproductive rates and density-related mortality from predators, pathogens or parasitoids, other characteristics include transgenerational reduced reproduction and dispersal with increasing-peak densities, and genetic similarity among populations. Experiments to stop cyclic dynamics and comparisons of cyclic and noncyclic populations provide some understanding but both reproduction and mortality must be considered. What determines variation in amplitude and periodicity of population outbreaks remains a mystery. © 2018 The Author(s).

Impact of food supplementation and methionine on high densities of cotton rats: Support of the amino-acid-quality hypothesis?

USGS Publications Warehouse

Webb, R.E.; Leslie, David M.; Lochmiller, R.L.; Masters, R.E.

2005-01-01

Considerable research supports the tenet that quantity and quality of food limit vertebrate populations. We evaluated predictions that increased availabilities of food and the essential amino acid methionine were related to population limitation of the hispid cotton rat (Sigmodon hispidus). Effects of supplemental food and methionine on density, survival, and reproductive parameters of wild cotton rats were assessed in north-central Oklahoma in 1998-1999. Twelve enclosed groups of 16 adult cotton rats each (8 male, 8 female) were randomly assigned to either no supplementation (control), supplementation with a mixed ration that had methionine at slightly below maintenance levels (0.20%), or a methionine-enhanced mixed ration (1.20%). In general, densities of cotton rats were twice as high and were sustained longer with dietary supplementation, and methionine-supplemented populations maintained the highest densities. Treatment effects on survival depended on time of year, with higher survival in supplemented enclosures in October and November. Per capita recruitment was highest with methionine-enhanced food. Treatment effects on proportions of overall and female cotton rats in reproductive condition depended on sampling date, but males were most reproductively active with methionine supplementation. Methionine supplementation resulted in an earlier and longer reproductive season. Density-dependent and density-independent factors no doubt interplay to determine population dynamics of cotton rats, but our results suggest that methionine plays a role in the population dynamics of wild cotton rats, apparently by enhancing overall density, recruitment, and reproductive activity of males.

Effects of density on growth, metamorphosis, and survivorship in tadpoles of Scaphiopus holbrooki

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

Semlitsch, R.D.; Caldwell, J.P.

1982-08-01

Density-dependent aspects of growth, metamorphosis, and survivorship of Scaphiopus holbrooki tadpoles were examined in the laboratory under two experimental regimes. In the first density experiment, the growth index (W) of tadpoles decreased exponentially with density. Mean growth rate varied from 0.023 mL/d at the lowest density to 0.006 mL/d at the highest density. The mean number of days to metamorphic climax was positively associated with the initial density treatment: 27 d at the lowest density to 86 d at the highest density. The body size of tadpoles at metamorphosis showed a concave curvilinear relationship to initial density, indicating tadpoles atmore » the highest densities are apparently capable to growth recovery once released from density stress. The survival of tadpoles decreased exponentially with initial density, from 90% at the lowest density to 20% at the highest initial density. In the second experiment a cross-classified design was used to examine the effects of density and duration of treatment (time) on growth and metamorphosis. Density and time had significant effects on body size at metamorphosis and days to metamorphosis. There was no significant interaction between density and time. These results indicate that the inhibitory effect of density stress varies with the duration of the stress. Scaphiopus holbrooki tadpoles exhibit developmental traits (rapid growth, short larval period, small body size at metamorphosis) that should be favored by natural selection in high density habitats. Dispersability may be a mechanism whereby S. holbrooki can minimize the detrimental effects of density stress.« less

The interstellar medium and the highly ionized species observed in the spectrum of the nearby white dwarf G191-B2B

NASA Technical Reports Server (NTRS)

Bruhweiler, F. C.; Kondo, Y.

1981-01-01

High-resolution spectra of the nearby (48 pc) white dwarf G191-B2B, obtained with the International Ultraviolet Explorer, reveal sharp resonance lines of N V, C IV, and Si IV. The origin of these features is most likely linked to the white dwarf, possibly being formed in an expanding halo around the star. Interstellar lines of C II, N I, Mg II, Si II, and Fe II are also seen in the spectrum. Analysis of these features indicates an average neutral hydrogen number density of 0.064 for this line of sight. In combination with the recent EUV and soft X-ray results, this is interpreted to mean that the interstellar medium in the most immediate solar vicinity is of the normal density n approximately equal to 0.1/cu cm of lower ionization, while just beyond it, at least in some directions, is a hot lower density plasma. These results are apparently in conflict with the model of the interstellar medium by McKee and Ostriker (1977) in its present form.

Contact Inhibition: Also a Control for Cell Proliferation in Unicellular Algae?

PubMed

Costas, E; Aguilera, A; Gonzalez-Gil, S; López-Rodas, V

1993-02-01

According to traditional views, the proliferation of unicellular algae is controlled primarily by environmental conditions. But as in mammalian cells, other biological mechanisms, such as growth factors, cellular aging, and contact inhibition, might also control algal proliferation. Here we ask whether contact inhibition regulates growth in several species of unicellular algae as it does in mammalian cells. Laboratory cultures of the dinoflagellate Prorocentrum lima (Ehrenberg) Dodge show contact inhibition at low cell density, so this would be an autocontrol mechanism of cell proliferation that could also act in natural populations of P. lima. But, Synechocystis spp., Phaeodactylum tricornutum (Bohlin), Skeletonema costatum (Greville), and Tetraselmis spp. do not exhibit contact inhibition in laboratory cultures because they are able to grow at high cellular density. Apparently their growth is limited by nutrient depletion or catabolite accumulation instead of contact inhibition. Spirogyra insignis (Hassall) Kutz, Prorocentrum triestinum Schiller, and Alexandrium tamarense (Halim) Balech show a complex response, as they are able to grow in both low and high cell density medium. These results suggest that contact inhibition is more adaptative in benthic unicellular algae.

Decorating TiO2 Nanowires with BaTiO3 Nanoparticles: A New Approach Leading to Substantially Enhanced Energy Storage Capability of High-k Polymer Nanocomposites.

PubMed

Kang, Da; Wang, Guanyao; Huang, Yanhui; Jiang, Pingkai; Huang, Xingyi

2018-01-31

The urgent demand of high energy density and high power density devices has triggered significant interest in high dielectric constant (high-k) flexible nanocomposites comprising dielectric polymer and high-k inorganic nanofiller. However, the large electrical mismatch between polymer and nanofiller usually leads to earlier electric failure of the nanocomposites, resulting in an undesirable decrease of electrical energy storage capability. A few studies show that the introduction of moderate-k shell onto a high-k nanofiller surface can decrease the dielectric constant mismatch, and thus, the corresponding nanocomposites can withstand high electric field. Unfortunately, the low apparent dielectric enhancement of the nanocomposites and high electrical conductivity mismatch between matrix and nanofiller still result in low energy density and low efficiency. In this study, it is demonstrated that encapsulating moderate-k nanofiller with high-k but low electrical conductivity shell is effective to significantly enhance the energy storage capability of dielectric polymer nanocomposites. Specifically, using BaTiO 3 nanoparticles encapsulated TiO 2 (BaTiO 3 @TiO 2 ) core-shell nanowires as filler, the corresponding poly(vinylidene fluoride-co-hexafluoropylene) nanocomposites exhibit superior energy storage capability in comparison with the nanocomposites filled by either BaTiO 3 or TiO 2 nanowires. The nanocomposite film with 5 wt % BaTiO 3 @TiO 2 nanowires possesses an ultrahigh discharged energy density of 9.95 J cm -3 at 500 MV m -1 , much higher than that of commercial biaxial-oriented polypropylene (BOPP) (3.56 J cm -3 at 600 MV m -1 ). This new strategy and corresponding results presented here provide new insights into the design of dielectric polymer nanocomposites with high electrical energy storage capability.

The human peripheral subunit-binding domain folds rapidly while overcoming repulsive Coulomb forces

PubMed Central

Arbely, Eyal; Neuweiler, Hannes; Sharpe, Timothy D; Johnson, Christopher M; Fersht, Alan R

2010-01-01

Peripheral subunit binding domains (PSBDs) are integral parts of large multienzyme complexes involved in carbohydrate metabolism. PSBDs facilitate shuttling of prosthetic groups between different catalytic subunits. Their protein surface is characterized by a high density of positive charges required for binding to subunits within the complex. Here, we investigated folding thermodynamics and kinetics of the human PSBD (HSBD) using circular dichroism and tryptophan fluorescence experiments. HSBD was only marginally stable under physiological solvent conditions but folded within microseconds via a barrier-limited apparent two-state transition, analogous to its bacterial homologues. The high positive surface-charge density of HSBD leads to repulsive Coulomb forces that modulate protein stability and folding kinetics, and appear to even induce native-state movement. The electrostatic strain was alleviated at high solution-ionic-strength by Debye-Hückel screening. Differences in ionic-strength dependent characteristics among PSBD homologues could be explained by differences in their surface charge distributions. The findings highlight the trade-off between protein function and stability during protein evolution. PMID:20662005

The hydration structure at yttria-stabilized cubic zirconia (110)-water interface with sub-Ångström resolution

DOE PAGES

Hou, Binyang; Kim, Seunghyun; Kim, Taeho; ...

2016-06-15

The interfacial hydration structure of yttria-stabilized cubic zirconia (110) surface in contact with water was determined with ~0.5 Å resolution by high-resolution X-ray reflectivity measurement. The terminal layer shows a reduced electron density compared to the following substrate lattice layers, which indicates there are additional defects generated by metal depletion as well as intrinsic oxygen vacancies, both of which are apparently filled by water species. Above this top surface layer, two additional adsorbed layers are observed forming a characteristic interfacial hydration structure. The first adsorbed layer shows abnormally high density as pure water and likely includes metal species, whereas themore » second layer consists of pure water. The observed interfacial hydration structure seems responsible for local equilibration of the defective surface in water and eventually regulating the long-term degradation processes. As a result, the multitude of water interactions with the zirconia surface results in the complex but highly ordered interfacial structure constituting the reaction front.« less

Co-pyrolysis of biomass and plastic wastes: investigation of apparent kinetic parameters and stability of pyrolysis oils

NASA Astrophysics Data System (ADS)

Fekhar, B.; Miskolczi, N.; Bhaskar, T.; Kumar, J.; Dhyani, V.

2018-05-01

This work is dedicated to the co-pyrolysis of real waste high density polyethylene (HDPE) and biomass (rice straw) obtained from agriculture. Mixtures of raw materials were pyrolyzed in their 0%/100%, 30%/70%, 50%/50%, 70%/30%, 100%/0% ratios using a thermograph. The atmosphere was nitrogen, and a constant heating rate was used. Based on weight loss and DTG curves, the apparent reaction kinetic parameters (e.g., activation energy) were calculated using first-order kinetic approach and Arrhenius equation. It was found that decomposition of pure plastic has approximately 280 kJ/mol activation energy, while that of was considerably less in case of biomass. Furthermore, HDPE decomposition takes by one stage, while that of biomass was three stages. The larger amount of raw materials (100 g) were also pyrolyzed in the batch rig at 550°C to obtain products for analysis focussing to their long-term application. Pyrolysis oils were investigated by Fourier transformed infrared spectroscopy and standardized methods, such as density, viscosity, boiling range determination. It was concluded, that higher plastic ratio in raw material had the advantageous effect to the pyrolysis oil long-term application. E.g., the concentration of oxygenated compounds, such as aldehydes, ketones, carboxylic acids or even phenol and its derivate could be significantly decreased, which had an advantageous effect to their corrosion property. Lower average molecular weight, viscosity, and density were measured as a function of plastic content.

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats1[OPEN

PubMed Central

de Boer, Hugo J.; Drake, Paul L.; Wendt, Erin; Price, Charles A.; Schulze, Ernst-Detlef; Turner, Neil C.; Nicolle, Dean

2016-01-01

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. PMID:27784769

Characteristics of iron ore sinter with EFB addition

NASA Astrophysics Data System (ADS)

Purwanto, H.; Rozhan, A. N.; Mohamad, A. S.; Zakiyuddin, A.

2018-04-01

Utilization of EFB-derived biochar in sintering of iron ore has been conducted in this work with regards to the porosity of iron sinter. EFB has been heated up in argon atmosphere to 450°C in order to produce biochar. In the present work, the sintering process was conducted at 1150°C with variations of biochar content from 5% to 10%. In this case, the apparent density for iron sinter shows significant decrease as the biochar addition increase. The porosity of iron sinter showed a gradual increment from 5% to 7.5% and escalated at 10% biochar content. The results of porosity and apparent density were in line with the micrograph of iron sinter.

Relations between conspecific density and effects of ultraviolet-b radiation on tadpole size in the striped marsh frog.

PubMed

Mitchell, Toby; Alton, Lesley A; White, Craig R; Franklin, Craig E

2012-12-01

Global increases in ultraviolet-B radiation (UVBR) associated with stratospheric ozone depletion are potentially contributing to the decline of numerous amphibian species around the world. Exposure to UVBR alone reduces survival and induces a range of sublethal effects in embryonic and larval amphibians. When additional environmental stressors are present, UVBR can have compounding negative effects. Thus, examination of the effects of UVBR in the absence of other stressors may substantially underestimate its potential to affect amphibians in natural habitats. We examined the independent and interactive effects of increased UVBR and high conspecific density would have embryonic and larval striped marsh frogs (Limnodynastes peronii). We exposed individuals to a factorial combination of low and high UVBR levels and low, medium, and high densities of striped marsh frog tadpoles. The response variables were time to hatching, hatching success, posthatch survival, burst-swimming performance of tadpoles (maximum instantaneous swim speed following an escape response), and size and morphology of tadpoles. Consistent with results of previous studies, we found that exposure to UVBR alone increased the time to hatching of embryos and reduced the burst-swimming performance and size of tadpoles. Similarly, increasing conspecific density increased the time to hatching of embryos and reduced the size of tadpoles, but had no effect on burst-swimming performance. The negative effect of UVBR on tadpole size was not apparent at high densities of tadpoles. This result suggests that tadpoles living at higher densities may invest relatively less energy in growth and thus have more energy to repair UVBR-induced damage. Lower densities of conspecifics increased the negative effects of UVBR on developing amphibians. Thus, low-density populations, which may include declining populations, may be particularly susceptible to the detrimental effects of increased UVBR and thus may be driven toward extinction faster than might be expected on the basis of results from single-factor studies. ©2012 Society for Conservation Biology.

Influence of external factors on the self-assembly of two structurally related antidepressant drugs: a thermodynamic study

NASA Astrophysics Data System (ADS)

Gutiérrez-Pichel, Manuel; Attwood, David; Taboada, Pablo; Mosquera, Víctor

Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic antidepressant drugs imipramine and desipramine hydrochlorides have been determined from density and ultrasound velocity measurements in the temperature range 288.15-313.15 K in buffered solution of pH 3.0 and 5.5. Critical concentrations for aggregation of these drugs were obtained from inflections on the plots of the sound velocity against drug concentration. Positive deviation from the Debye-Hückel limiting law of the apparent molal volume of imipramine provides evidence of limited association at concentrations below the critical concentration over the temperature range studied. Apparent molal adiabatic compressibilities of the aggregates formed by the drugs, calculated by combining the ultrasound velocity and density data, were typical of those for a stacked aggregate. The critical concentration and energy involved in the aggregation process of these drugs have been evaluated using isothermal titration calorimetry. The solvent-aggregate interactions have been discussed from compressibility and calorimetry data.

Resource recycling through artificial lightweight aggregates from sewage sludge and derived ash using boric acid flux to lower co-melting temperature.

PubMed

Hu, Shao-Hua; Hu, Shen-Chih; Fu, Yen-Pei

2012-02-01

This study focuses on artificial lightweight aggregates (ALWAs) formed from sewage sludge and ash at lowered co-melting temperatures using boric acid as the fluxing agent. The weight percentages of boric acid in the conditioned mixtures of sludge and ash were 13% and 22%, respectively. The ALWA derived from sewage sludge was synthesized under the following conditions: preheating at 400 degrees C 0.5 hr and a sintering temperature of 850 degrees C 1 hr. The analytical results of water adsorption, bulk density, apparent porosity, and compressive strength were 3.88%, 1.05 g/cm3, 3.93%, and 29.7 MPa, respectively. Scanning electron microscope (SEM) images of the ALWA show that the trends in water adsorption and apparent porosity were opposite to those of bulk density. This was due to the inner pores being sealed off by lower-melting-point material at the aggregates'surface. In the case of ash-derived aggregates, water adsorption, bulk density, apparent porosity, and compressive strength were 0.82%, 0.91 g/cm3, 0.82%, and 28.0 MPa, respectively. Both the sludge- and ash-derived aggregates meet the legal standards for ignition loss and soundness in Taiwan for construction or heat insulation materials.

Phosphorus-zinc interactive effects on growth by Selenastrum capricornutum (chlorophyta)

USGS Publications Warehouse

Kuwabara, J.S.

1985-01-01

Culturing experiments in chemically defined growth media were conducted to observe possible Zn and P interactions on Selenastrum capricornutum Printz growth indexes. Elevated Zn concentrations (7.5 ?? 10-8 and 1.5 ?? 10-7 M [Zn2+]) were highly detrimental to algal growth, affecting lag, exponential, and stationary growth phases. P behaved as a yield-limiting nutrient with maximum cell densities increasing linearly with total P. This yield limitation was intensified at elevated Zn concentrations. Although calculated cellular phosphorus concentrations increased markedly with Zn ion activity, elevated Zn concentrations had no apparent effect on rates of phosphorus uptake estimated for Selenastrum during exponential growth. Results indicated that P-Zn interactions were significant in describing Selenastrum cell yield results and are consistent with previous Zn studies on chlorophytes. These P-Zn interactions and the observed inhibitory growth effects of submicromolar Zn concentrations suggest that in nature an apparent P yield-limiting condition may result from elevated Zn concentrations.

Cell Density Affects the Detection of Chk1 Target Engagement by the Selective Inhibitor V158411.

PubMed

Geneste, Clara C; Massey, Andrew J

2018-02-01

Understanding drug target engagement and the relationship to downstream pharmacology is critical for drug discovery. Here we have evaluated target engagement of Chk1 by the small-molecule inhibitor V158411 using two different target engagement methods (autophosphorylation and cellular thermal shift assay [CETSA]). Target engagement measured by these methods was subsequently related to Chk1 inhibitor-dependent pharmacology. Inhibition of autophosphorylation was a robust method for measuring V158411 Chk1 target engagement. In comparison, while target engagement determined using CETSA appeared robust, the V158411 CETSA target engagement EC 50 values were 43- and 19-fold greater than the autophosphorylation IC 50 values. This difference was attributed to the higher cell density in the CETSA assay configuration. pChk1 (S296) IC 50 values determined using the CETSA assay conditions were 54- and 33-fold greater than those determined under standard conditions and were equivalent to the CETSA EC 50 values. Cellular conditions, especially cell density, influenced the target engagement of V158411 for Chk1. The effects of high cell density on apparent compound target engagement potency should be evaluated when using target engagement assays that necessitate high cell densities (such as the CETSA conditions used in this study). In such cases, the subsequent relation of these data to downstream pharmacological changes should therefore be interpreted with care.

Preliminary results on the apparent size of the sources of type III bursts observed at low frequencies

NASA Technical Reports Server (NTRS)

Alvarez, H.

1976-01-01

We present preliminary results on the apparent angular size of the sources of four type III bursts observed between 3500 and 50 kHz from the IMP-6 spacecraft. The observations were made with a dipole rotating in the plane of the ecliptic where the sources are assumed to be. The apparent angular sizes obtained are unexpectedly large. We discuss different explanations for the results. It seems that the scattering of radio waves by electron density inhomogeneities is the most likely cause. We report a temporal increase of the apparent angular size of the source during the burst lifetime for some bursts. From its characteristics it appears to be a real effect.

The voltage threshold for arcing for solar cells in Leo - Flight and ground test results

NASA Technical Reports Server (NTRS)

Ferguson, Dale C.

1986-01-01

Ground and flight results of solar cell arcing in low earth orbit (LEO) conditions are compared and interpreted. It is shown that an apparent voltage threshold for arcing may be produced by a storage power law dependence of arc rate on voltage, combined with a limited observation time. The change in this apparent threshold with plasma density is a reflection of the density dependence of the arc rate. A nearly linear dependence of arc rate on density is inferred from the data. A real voltage threshold for arcing for 2 by 2 cm solar cells may exist however, independent of plasma density, near -230 V relative to the plasma. Here, arc rates may change by more than an order of magnitude for a change of only 30 V in array potential. For 5.9 by 5.9 solar cells, the voltage dependence of the arc rate is steeper, and the data are insufficient to indicate the existence of an arcing increased by an atomic oxygen plasma, as is found in LEO, and by arcing from the backs of welded-through substrates.

The voltage threshold for arcing for solar cells in LEO: Flight and ground test results

NASA Technical Reports Server (NTRS)

Ferguson, D. C.

1986-01-01

Ground and flight results of solar cell arcing in low Earth orbit (LEO) conditions are compared and interpreted. It is shown that an apparent voltage threshold for arcing may be produced by a strong power law dependence of arc rate on voltage, combined with a limited observation time. The change in this apparent threshold with plasma density is a reflection of the density dependence of the arc rate. A nearly linear dependence of arc rate on density is inferred from the data. A real voltage threshold for arcing for 2 by 2 cm solar cells may exist however, independent of plasma density, near -230 V relative to the plasma. Here, arc rates may change by more than an order of magnitude for a change of only 30 V in array potential. For 5.9 by 5.9 solar cells, the voltage dependence of the arc rate is steeper, and the data are insufficient to indicate the existence of an arcing increased by an atomic oxygen plasma, as is found in LEO, and by arcing from the backs of welded-through substrates.

Triglyceride/high-density lipoprotein cholesterol (TG/HDL-C) index as a reference criterion of risk for metabolic syndrome (MetS) and low insulin sensitivity in apparently healthy subjects.

PubMed

Baez-Duarte, Blanca Guadalupe; Zamora-Gínez, Irma; González-Duarte, Ramiro; Torres-Rasgado, Enrique; Ruiz-Vivanco, Guadalupe; Pérez-Fuentes, Ricardo; Celis, The Multidisciplinary Research Group Of Diabetes

To evaluate if the TG/HDL-C index can be considered as a reference criterion of MetS and low insulin sensitivity in apparently healthy subjects. The subjects were Mexican mestizos who resided in Puebla City, Mexico, who were anthropometrically, biochemically, and clinically characterized. The TG/HDL-C index was calculated by dividing triglyceride (TG) levels by HDL-C levels. MetS was diagnosed by the Third Report from the Adult Treatment Panel-National Cholesterol Education Program (ATP-III NCEP) criteria, while insulin sensitivity was evaluated by the Quantitative Insulin sensitivity Check Index (QUICKI). The study included 813 subjects, with an average age of 38.6 ± 12.1 years, of which 564 were women and 249 men. An association was found between high TG/HDL-C index and low insulin sensitivity (Odds ratio [OR]: 4.09; p < 0.01) and with MetS (OR: 15.29; p < 0.01). A correlation was found between the TG/HDL-C index and QUICKI (rho: -0.4989; p < 0.01) and with MetS (rho: 0.6581; p < 0.01). The results indicate that the TG/HDL-C index is associated with low insulin sensitivity and MetS in apparently healthy subjects, suggesting this index as a reference criterion of risk for low insulin sensitivity and MetS.

Seasonal and altitudinal variations in populations of small mammals on Rattlesnake Mountain, Washington

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

O'Farrell, T.P.

1975-07-01

Small mammals were live-trapped for 2 years at four elevations in shrub-steppe vegetation of S-central Washington to determine seasonal and altitudinal changes in populations. Species trapped included: Perognathus parvus, Peromyscus maniculatus, Onychromys leucogaster, Lagurus curtatus, Spermophilus townsendii; Neotoma cinerea and Mustela frenata. Perognathus parvus was the most numerous, and widespread species, reaching peak densities in the Artemisia/Poa association at 500-ft elevation. Its density declined with increasing elevation. Perognathus was most numerous on a site with a high frequency of seed-producing annuals, and less numerous in perennial grasslands or where soil temperatures below 40 F were prolonged in the spring. Peromyscusmore » maniculatus were most numerous in the Artemisia/Agropyron association above 2000 ft. Peromyscus appeared to be limited by lack of succulent vegetation or free water at lower, more arid sites. Perognathus was most active and breeding between spring and autumn. Peromyscus favored the period between autumn and late spring. Interspecific competition was not apparent. Perognathus employed periods of torpor during the winter, and some evidence indicated that Peromyscus may have used hypothermia during the driest part of summer and midwinter. Average weights of male Perognathus increased with increasing altitude. The weight increase was not apparent in Peromyscus. (auth)« less

Reuse of solid petroleum waste in the manufacture of porcelain stoneware tile.

PubMed

Pinheiro, B C A; Holanda, J N F

2013-03-30

This study investigates the incorporation of solid petroleum waste as raw material into a porcelain stoneware tile body, in replacement to natural kaolin material by up to 5 wt.%. Tile formulations containing solid petroleum waste were pressed and fired at 1240 °C by using a fast-firing cycle. The tile pieces were tested to determine their properties (linear shrinkage, water absorption, apparent density, and flexural strength), sintered microstructure, and leaching toxicity. The results therefore indicated that the growing addition of solid petroleum waste into tile formulations leads to a decrease of linear shrinkage, apparent density, and flexural strength, and to an increase of water absorption of the produced tile materials. It was also found that the replacement of kaolin with solid petroleum waste, in the range up to 2.5 wt.%, allows the production of porcelain stoneware tile (group BIa, ISO 13006 standard). All concentrations of Ag, As, Ba, Cd, Cr (total), Hg, and Pb of the fired porcelain stoneware tile pieces in the leachate comply with the current regulatory limits. These results indicate that the solid petroleum waste could be used for high-quality porcelain stoneware tile production, thus giving rise to a new possibility for an environmentally friendly management of this abundant waste. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Most Massive Galaxies and Black Holes Allowed by ΛCDM

NASA Astrophysics Data System (ADS)

Behroozi, Peter; Silk, Joseph

2018-04-01

Given a galaxy's stellar mass, its host halo mass has a lower limit from the cosmic baryon fraction and known baryonic physics. At z > 4, galaxy stellar mass functions place lower limits on halo number densities that approach expected ΛCDM halo mass functions. High-redshift galaxy stellar mass functions can thus place interesting limits on number densities of massive haloes, which are otherwise very difficult to measure. Although halo mass functions at z < 8 are consistent with observed galaxy stellar masses if galaxy baryonic conversion efficiencies increase with redshift, JWST and WFIRST will more than double the redshift range over which useful constraints are available. We calculate maximum galaxy stellar masses as a function of redshift given expected halo number densities from ΛCDM. We apply similar arguments to black holes. If their virial mass estimates are accurate, number density constraints alone suggest that the quasars SDSS J1044-0125 and SDSS J010013.02+280225.8 likely have black hole mass — stellar mass ratios higher than the median z = 0 relation, confirming the expectation from Lauer bias. Finally, we present a public code to evaluate the probability of an apparently ΛCDM-inconsistent high-mass halo being detected given the combined effects of multiple surveys and observational errors.

Determining crystal structures through crowdsourcing and coursework

PubMed Central

Horowitz, Scott; Koepnick, Brian; Martin, Raoul; Tymieniecki, Agnes; Winburn, Amanda A.; Cooper, Seth; Flatten, Jeff; Rogawski, David S.; Koropatkin, Nicole M.; Hailu, Tsinatkeab T.; Jain, Neha; Koldewey, Philipp; Ahlstrom, Logan S.; Chapman, Matthew R.; Sikkema, Andrew P.; Skiba, Meredith A.; Maloney, Finn P.; Beinlich, Felix R. M.; Caglar, Ahmet; Coral, Alan; Jensen, Alice Elizabeth; Lubow, Allen; Boitano, Amanda; Lisle, Amy Elizabeth; Maxwell, Andrew T.; Failer, Barb; Kaszubowski, Bartosz; Hrytsiv, Bohdan; Vincenzo, Brancaccio; de Melo Cruz, Breno Renan; McManus, Brian Joseph; Kestemont, Bruno; Vardeman, Carl; Comisky, Casey; Neilson, Catherine; Landers, Catherine R.; Ince, Christopher; Buske, Daniel Jon; Totonjian, Daniel; Copeland, David Marshall; Murray, David; Jagieła, Dawid; Janz, Dietmar; Wheeler, Douglas C.; Cali, Elie; Croze, Emmanuel; Rezae, Farah; Martin, Floyd Orville; Beecher, Gil; de Jong, Guido Alexander; Ykman, Guy; Feldmann, Harald; Chan, Hugo Paul Perez; Kovanecz, Istvan; Vasilchenko, Ivan; Connellan, James C.; Borman, Jami Lynne; Norrgard, Jane; Kanfer, Jebbie; Canfield, Jeffrey M.; Slone, Jesse David; Oh, Jimmy; Mitchell, Joanne; Bishop, John; Kroeger, John Douglas; Schinkler, Jonas; McLaughlin, Joseph; Brownlee, June M.; Bell, Justin; Fellbaum, Karl Willem; Harper, Kathleen; Abbey, Kirk J.; Isaksson, Lennart E.; Wei, Linda; Cummins, Lisa N.; Miller, Lori Anne; Bain, Lyn; Carpenter, Lynn; Desnouck, Maarten; Sharma, Manasa G.; Belcastro, Marcus; Szew, Martin; Szew, Martin; Britton, Matthew; Gaebel, Matthias; Power, Max; Cassidy, Michael; Pfützenreuter, Michael; Minett, Michele; Wesselingh, Michiel; Yi, Minjune; Cameron, Neil Haydn Tormey; Bolibruch, Nicholas I.; Benevides, Noah; Kathleen Kerr, Norah; Barlow, Nova; Crevits, Nykole Krystyne; Dunn, Paul; Roque, Paulo Sergio Silveira Belo Nascimento; Riber, Peter; Pikkanen, Petri; Shehzad, Raafay; Viosca, Randy; James Fraser, Robert; Leduc, Robert; Madala, Roman; Shnider, Scott; de Boisblanc, Sharon; Butkovich, Slava; Bliven, Spencer; Hettler, Stephen; Telehany, Stephen; Schwegmann, Steven A.; Parkes, Steven; Kleinfelter, Susan C.; Michael Holst, Sven; van der Laan, T. J. A.; Bausewein, Thomas; Simon, Vera; Pulley, Warwick; Hull, William; Kim, Annes Yukyung; Lawton, Alexis; Ruesch, Amanda; Sundar, Anjali; Lawrence, Anna-Lisa; Afrin, Antara; Maheshwer, Bhargavi; Turfe, Bilal; Huebner, Christian; Killeen, Courtney Elizabeth; Antebi-Lerrman, Dalia; Luan, Danny; Wolfe, Derek; Pham, Duc; Michewicz, Elaina; Hull, Elizabeth; Pardington, Emily; Galal, Galal Osama; Sun, Grace; Chen, Grace; Anderson, Halie E.; Chang, Jane; Hewlett, Jeffrey Thomas; Sterbenz, Jennifer; Lim, Jiho; Morof, Joshua; Lee, Junho; Inn, Juyoung Samuel; Hahm, Kaitlin; Roth, Kaitlin; Nair, Karun; Markin, Katherine; Schramm, Katie; Toni Eid, Kevin; Gam, Kristina; Murphy, Lisha; Yuan, Lucy; Kana, Lulia; Daboul, Lynn; Shammas, Mario Karam; Chason, Max; Sinan, Moaz; Andrew Tooley, Nicholas; Korakavi, Nisha; Comer, Patrick; Magur, Pragya; Savliwala, Quresh; Davison, Reid Michael; Sankaran, Roshun Rajiv; Lewe, Sam; Tamkus, Saule; Chen, Shirley; Harvey, Sho; Hwang, Sin Ye; Vatsia, Sohrab; Withrow, Stefan; Luther, Tahra K; Manett, Taylor; Johnson, Thomas James; Ryan Brash, Timothy; Kuhlman, Wyatt; Park, Yeonjung; Popović, Zoran; Baker, David; Khatib, Firas; Bardwell, James C. A.

2016-01-01

We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality. PMID:27633552

Effects of probiotic supplementation in different nutrient density diets on growth performance, nutrient digestibility, blood profiles, fecal microflora and noxious gas emission in weaning pig.

PubMed

Lan, Ruixia; Tran, Hoainam; Kim, Inho

2017-03-01

Probiotics can serve as alternatives to antibiotics to increase the performance of weaning pigs, and the intake of probiotics is affected by dietary nutrient density. The objective of this study was to evaluate the effects of a probiotic complex in different nutrient density diets on growth performance, digestibility, blood profiles, fecal microflora and noxious gas emission in weaning pigs. From day 22 to day 42, both high-nutrient-density and probiotic complex supplementation diets increased (P < 0.05) the average daily gain. On day 42, the apparent total tract digestibility (ATTD) of dry matter, nitrogen and gross energy (GE), blood urea nitrogen concentration and NH 3 and H 2 S emissions were increased (P < 0.05) in pigs fed high-nutrient-density diets. Pigs fed probiotic complex supplementation diets had higher (P < 0.05) ATTD of GE than pigs fed non-supplemented diets. Fecal Lactobacillus counts were increased whereas Escherichia coli counts and NH 3 and H 2 S emissions were decreased (P < 0.05) in pigs fed probiotic complex supplementation diets. Interactive effects on average daily feed intake (ADFI) were observed from day 22 to day 42 and overall, where probiotic complex improved ADFI more dramatically in low-nutrient-density diets. The beneficial effects of probiotic complex (Bacillus coagulans, Bacillus licheniformis, Bacillus subtilis and Clostridium butyricum) supplementation on ADFI is more dramatic with low-nutrient-density diets. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Fabrication and Characterization of Porous MgAl₂O₄ Ceramics via a Novel Aqueous Gel-Casting Process.

PubMed

Yuan, Lei; Liu, Zongquan; Liu, Zhenli; He, Xiao; Ma, Beiyue; Zhu, Qiang; Yu, Jingkun

2017-11-30

A novel and aqueous gel-casting process has been successfully developed to fabricate porous MgAl₂O₄ ceramics by using hydratable alumina and MgO powders as raw materials and deionized water as hydration agent. The effects of different amounts of deionized water on the hydration properties, apparent porosity, bulk density, microstructure, pore size distribution and compressive strength of the samples were investigated. The results indicated that the porosity and the microstructure of porous MgAl₂O₄ ceramics were governed by the amounts of deionized water added. The porous structure was formed by the liberation of physisorbed water and the decomposition of hydration products such as bayerite, brucite and boehmite. After determining the addition amounts of deionized water, the fabricated porous MgAl₂O₄ ceramics had a high apparent porosity (52.5-65.8%), a small average pore size structure (around 1-3 μm) and a relatively high compressive strength (12-28 MPa). The novel aqueous gel-casting process with easy access is expected to be a promising candidate for the preparation of Al₂O₃-based porous ceramics.

High-affinity cannabinoid binding site in brain: A possible marijuana receptor

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

Nye, J.S.

The mechanism by which delta{sup 9} tetrahydrocannabinol (delta{sup 9}THC), the major psychoactive component of marijuana or hashish, produces its potent psychological and physiological effects is unknown. To find receptor binding sites for THC, we designed a water-soluble analog for use as a radioligand. 5{prime}-Trimethylammonium-delta{sup 8}THC (TMA) is a positively charged analog of delta-{sup 8}THC modified on the 5{prime} carbon, a portion of the molecule not important for its psychoactivity. We have studied the binding of ({sup 3}H)-5{prime}-trimethylammonium-delta-{sup 8}THC (({sup 3}H)TMA) to rat neuronal membranes. ({sup 3}H)TMA binds saturably and reversibly to brain membranes with high affinity to apparently one classmore » of sites. Highest binding site density occurs in brain, but several peripheral organs also display specific binding. Detergent solubilizes the sites without affecting their pharmacologial properties. Molecular sieve chromatography reveals a bimodal peak of ({sup 3}H)TMA binding activity of approximately 60,000 daltons apparent molecular weight.« less

Variation in the biomass density and demography of Antarctic krill in the vicinity of the South Shetland Islands during the 1999/2000 austral summer

NASA Astrophysics Data System (ADS)

Hewitt, R. P.; Kim, S.; Naganobu, M.; Gutierrez, M.; Kang, D.; Takao, Y.; Quinones, J.; Lee, Y.-H.; Shin, H.-C.; Kawaguchi, S.; Emery, J. H.; Demer, D. A.; Loeb, V. J.

2004-06-01

Vessels from Japan, Peru, and the USA conducted four sequential surveys designed to estimate the biomass density and demography of Antarctic krill in the vicinity of the South Shetland Islands between late December 1999 and early March 2000. The surveys were conducted during the same austral summer as the CCAMLR 2000 Survey in the Scotia Sea (Watkins et al., Deep-Sea Research, II, this issue [doi: 10.1016/j.dsr2.2004.06.010]), and the data were analyzed in a similar manner. Biomass densities were not significantly different between the surveys and averaged 49 g m -2. Maps of krill biomass indicate three areas of consistently high density: one near the eastern end of Elephant Island, one mid-way between Elephant Island and King George Island, and one near Cape Shirreff on the north side of Livingston Island. The areas of highest krill density appeared to move closer to the shelf break as the season progressed. This apparent movement was accompanied by a change in the demographic structure of the population, with smaller krill absent and a larger proportion of sexually mature animals present in late summer.

Jupiter plasma wave observations: an initial voyager 1 overview.

PubMed

Scarf, F L; Gurnett, D A; Kurth, W S

1979-06-01

The Voyager I plasma wave instrument detected low-frequency radio emissions, ion acoustic waves, and electron plasma oscillations for a period of months before encountering Jupiter's bow shock. In the outer magnetosphere, measurements of trapped radio waves were used to derive an electron density profile. Near and within the Io plasma torus the instrument detected high-frequency electrostatic waves, strong whistler mode turbulence, and discrete whistlers, apparently associated with lightning. Some strong emissions in the tail region and some impulsive signals have not yet been positively identified.

Observations of SO in dark and molecular clouds

NASA Technical Reports Server (NTRS)

Rydbeck, O. E. H.; Hjalmarson, A.; Rydbeck, G.; Ellder, J.; Kollberg, E.; Irvine, W. M.

1980-01-01

The 1(0)-0(1) transition of SO at 30 GHz has been observed in several sources, including the first detection of sulfur monoxide in cold dark clouds without apparent internal energy sources. The SO transition appears to be an excellent tracer of structure in dark clouds, and the data support suggestions that self-absorption is important in determining emission profiles in such regions for large line-strength transitions. Column densities estimated from a comparison of the results for the two isotopic species indicate a high fractional abundance of SO in dark clouds.

Putting density back into the habitat-quality equation: case study of an open-nesting forest bird.

PubMed

Pérot, Aurore; Villard, Marc-André

2009-12-01

Ecological traps and other cases of apparently maladaptive habitat selection cast doubt on the relevance of density as an indicator of habitat quality. Nevertheless, the prevalence of these phenomena remains poorly known, and density may still reflect habitat quality in most systems. We examined the relationship between density and two other parameters of habitat quality in an open-nesting passerine species: the Ovenbird (Seiurus aurocapilla). We hypothesized that the average individual bird makes a good decision when selecting its breeding territory and that territory spacing reflects site productivity or predation risk. Therefore, we predicted that density would be positively correlated with productivity (number of young fledged per unit area). Because individual performance is sensitive to events partly determined by chance, such as nest predation, we further predicted density would be weakly correlated or uncorrelated with the proportion of territories fledging young. We collected data in 23 study sites (25 ha each), 16 of which were located in untreated mature northern hardwood forest and seven in stands partially harvested (treated) 1-7 years prior to the survey. Density explained most of the variability in productivity (R(2)= 0.73), and there was no apparent decoupling between density and productivity in treated plots. In contrast, there was no significant relationship between density and the proportion of territories fledging >or=1 young over the entire breeding season. These results suggest that density reflects habitat quality at the plot scale in this study system. To our knowledge this is one of the few studies testing the value of territory density as an indicator of habitat quality in an open-nesting bird species on the basis of a relatively large number of sizeable study plots.

Plume propagation direction determination with SO2 cameras

NASA Astrophysics Data System (ADS)

Klein, Angelika; Lübcke, Peter; Bobrowski, Nicole; Kuhn, Jonas; Platt, Ulrich

2017-03-01

SO2 cameras are becoming an established tool for measuring sulfur dioxide (SO2) fluxes in volcanic plumes with good precision and high temporal resolution. The primary result of SO2 camera measurements are time series of two-dimensional SO2 column density distributions (i.e. SO2 column density images). However, it is frequently overlooked that, in order to determine the correct SO2 fluxes, not only the SO2 column density, but also the distance between the camera and the volcanic plume, has to be precisely known. This is because cameras only measure angular extents of objects while flux measurements require knowledge of the spatial plume extent. The distance to the plume may vary within the image array (i.e. the field of view of the SO2 camera) since the plume propagation direction (i.e. the wind direction) might not be parallel to the image plane of the SO2 camera. If the wind direction and thus the camera-plume distance are not well known, this error propagates into the determined SO2 fluxes and can cause errors exceeding 50 %. This is a source of error which is independent of the frequently quoted (approximate) compensation of apparently higher SO2 column densities and apparently lower plume propagation velocities at non-perpendicular plume observation angles.Here, we propose a new method to estimate the propagation direction of the volcanic plume directly from SO2 camera image time series by analysing apparent flux gradients along the image plane. From the plume propagation direction and the known location of the SO2 source (i.e. volcanic vent) and camera position, the camera-plume distance can be determined. Besides being able to determine the plume propagation direction and thus the wind direction in the plume region directly from SO2 camera images, we additionally found that it is possible to detect changes of the propagation direction at a time resolution of the order of minutes. In addition to theoretical studies we applied our method to SO2 flux measurements at Mt Etna and demonstrate that we obtain considerably more precise (up to a factor of 2 error reduction) SO2 fluxes. We conclude that studies on SO2 flux variability become more reliable by excluding the possible influences of propagation direction variations.

Kinetic Analysis of Isothermal Decomposition Process of Sodium Bicarbonate Using the Weibull Probability Function—Estimation of Density Distribution Functions of the Apparent Activation Energies

NASA Astrophysics Data System (ADS)

Janković, Bojan

2009-10-01

The decomposition process of sodium bicarbonate (NaHCO3) has been studied by thermogravimetry in isothermal conditions at four different operating temperatures (380 K, 400 K, 420 K, and 440 K). It was found that the experimental integral and differential conversion curves at the different operating temperatures can be successfully described by the isothermal Weibull distribution function with a unique value of the shape parameter ( β = 1.07). It was also established that the Weibull distribution parameters ( β and η) show independent behavior on the operating temperature. Using the integral and differential (Friedman) isoconversional methods, in the conversion (α) range of 0.20 ≤ α ≤ 0.80, the apparent activation energy ( E a ) value was approximately constant ( E a, int = 95.2 kJmol-1 and E a, diff = 96.6 kJmol-1, respectively). The values of E a calculated by both isoconversional methods are in good agreement with the value of E a evaluated from the Arrhenius equation (94.3 kJmol-1), which was expressed through the scale distribution parameter ( η). The Málek isothermal procedure was used for estimation of the kinetic model for the investigated decomposition process. It was found that the two-parameter Šesták-Berggren (SB) autocatalytic model best describes the NaHCO3 decomposition process with the conversion function f(α) = α0.18(1-α)1.19. It was also concluded that the calculated density distribution functions of the apparent activation energies ( ddfE a ’s) are not dependent on the operating temperature, which exhibit the highly symmetrical behavior (shape factor = 1.00). The obtained isothermal decomposition results were compared with corresponding results of the nonisothermal decomposition process of NaHCO3.

Repeatability Measurements of Apparent Thermal Conductivity of Multilayer Insulation (MLI)

NASA Astrophysics Data System (ADS)

Vanderlaan, M.; Stubbs, D.; Ledeboer, K.; Ross, J.; Van Sciver, S.; Guo, W.

2017-12-01

This report presents and discusses the results of repeatability experiments gathered from the multi-layer insulation thermal conductivity experiment (MIKE) for the measurement of the apparent thermal conductivity of multi-layer insulation (MLI) at variable boundary temperatures. Our apparatus uses a calibrated thermal link between the lower temperature shield of a concentric cylinder insulation assembly and the cold head of a cryocooler to measure the heat leak. In addition, thermocouple readings are taken in-between the MLI layers. These measurements are part of a multi-phase NASA-Yetispace-FSU collaboration to better understand the repeatability of thermal conductivity measurements of MLI. NASA provided five 25 layer coupons and requested boundary temperatures of 20 K and 300 K. Yetispace provided ten 12-layer coupons and requested boundary temperatures of 77 K and 293 K. Test conditions must be met for a duration of four hours at a steady state variance of less than 0.1 K/hr on both cylinders. Temperatures from three Cernox® temperature sensors on each of the two cylinders are averaged to determine the boundary temperatures. A high vacuum, less than 10-5 torr, is maintained for the duration of testing. Layer density varied from 17.98 - 26.36 layers/cm for Yetispace coupons and 13.05 - 17.45 layers/cm for the NASA coupons. The average measured heat load for the Yetispace coupons was 2.40 W for phase-one and 2.92 W for phase-two. The average measured heat load for the NASA coupons was 1.10 W. This suggests there is still unknown variance of MLI performance. It has been concluded, variations in the insulation installation heavy effect the apparent thermal conductivity and are not solely dependent on layer density.

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

D`Agostino, A.E.; Jordan, D.W.; Jordan, D.W.

Shanmugam and Moiola (1995) put forth a new interpretation of sandstone depositional processes in the Jackfork Group exposed in the spillway at DeGray Lake, near Arkadelphia, Arkansas. Their novel interpretation of deposition dominated by sandy, matrix-supported debris flows is at odds with nearly every other investigation of the Jackfork to date. One key to their interpretation is their contention that the Jackfork sandstones have a high matrix content (as high as 25%). The high matrix content is critical to their arguments about the textural characteristics and flow properties of debris flows vs. turbidites. In our guidebook, we presented a largemore » volume of petrographic data collected from samples taken from the Jackfork exposed on the east and west sides of the Spillway at DeGray Lake (and other locations as well). D`Agostino performed nearly al of the petrographic analyses presented in that guidebook. We disagree strongly with the reinterpretations of Shanmugam and Moiola and believe we can confidently address issues of petrography and matrix content. Specifically, we wish to address four points: (1) the amount of petrographic sampling done by Shanmugam and Moiola (1995); i.e., sampling density in a 327-m- (1072-ft) thick section, (2) overall matrix content of Jackfork sandstones, and Shanmugam and Moiola`s misrepresentation of our data, plus their apparent unfamiliarity with pertinent published data on the petrography of the Jackfork, (3) the distinction among authigenic clay, density in a 327-m- (1072-ft-) thick section, (2) overall matrix content of Jackfork sandstones, and Shanmugam and Moiola`s misrepresentation of our data, plus their apparent unfamiliarity with pertinent published data on the petrography of the Jackfork, (3) the distinction among authigenic clay, detrital clay, and other matrix materials, which Shanmugam and Moiola do not adequately discuss, and (4) the relationship of matrix content to their own facies classification scheme.« less

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats.

PubMed

de Boer, Hugo J; Drake, Paul L; Wendt, Erin; Price, Charles A; Schulze, Ernst-Detlef; Turner, Neil C; Nicolle, Dean; Veneklaas, Erik J

2016-12-01

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO 2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (d x ) is equal to the distance from these veins to the epidermis (d y ), expressed as d x :d y ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce d x :d y below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing d x beyond d y using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in d x :d y ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing d x beyond d y is to offset the reduction in leaf gas exchange that would result from maintaining d x :d y at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. © 2016 American Society of Plant Biologists. All Rights Reserved.

Effects of forest management on density, survival, and population growth of wood thrushes

USGS Publications Warehouse

Powell, L.A.; Lang, J.D.; Conroy, M.J.; Krementz, D.G.

2000-01-01

Loss and alteration of breeding habitat have been proposed as causes of declines in several Neotropical migrant bird populations. We conducted a 4-year study to determine the effects of winter prescribed burning and forest thinning on breeding wood thrush (Hylocichla mustelina) populations at the Piedmont National Wildlife Refuge (PNWR) in Georgia. We estimated density, adult and juvenile survival rates, and apparent annual survival using transect surveys, radiotelemetry, and mist netting. Burning and thinning did not cause lower densities (P = 0.25); wood thrush density ranged from 0.15 to 1.30 pairs/10 ha. No radiomarked male wood thrushes (n = 68) died during the 4 years, but female (n = 63) weekly survival was 0.981 ? 0.014 (SE) for females (n = 63) and 0.976 ? 0.010 for juveniles (n = 38). Apparent annual adult survival was 0.579 (SE = 0.173). Thinning and prescribed burning did not reduce adult or juvenile survival during the breeding season or apparent annual adult survival. Annual population growth (lambda) at PNWR was 1.00 (95% confidence interval = 0.32--1.63), and the considerable uncertainty in this prediction underscores the need for long term monitoring to effectively manage Neotropical migrants. Population growth increased on experimental compartments after the burn and thin (95% CI before = 0.91--0.97, after = 0.98--1.05), while control compartment declined (before = 0.98--1.05, after = 0.87--0.92). We found no evidence that the current management regime at PNWR, designed to improve red-cockaded woodpecker (Picoides borealis) habitat, negatively affected wood thrushes.

Combined natural gamma ray spectral/litho-density measurements applied to complex lithologies

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

Quirein, J.A.; Gardner, J.S.; Watson, J.T.

1982-09-01

Well log data has long been used to provide lithological descriptions of complex formations. Historically, most of the approaches used have been restrictive because they assumed fixed, known, and distinct lithologies for specified zones. The approach described in this paper attempts to alleviate this restriction by estimating the ''probability of a model'' for the models suggested as most likely by the reservoir geology. Lithological variables are simultaneously estimated from response equations for each model and combined in accordance with the probability of each respective model. The initial application of this approach has been the estimation of calcite, quartz, and dolomitemore » in the presence of clays, feldspars, anhydrite, or salt. Estimations were made by using natural gamma ray spectra, photoelectric effect, bulk density, and neutron porosity information. For each model, response equations and parameter selections are obtained from the thorium vs potassium crossplot and the apparent matrix density vs apparent volumetric photoelectric cross section crossplot. The thorium and potassium response equations are used to estimate the volumes of clay and feldspar. The apparent matrix density and volumetric cross section response equations can then be corrected for the presence of clay and feldspar. A test ensures that the clay correction lies within the limits for the assumed lithology model. Results are presented for varying lithologies. For one test well, 6,000 feet were processed in a single pass, without zoning and without adjusting more than one parameter pick. The program recognized sand, limestone, dolomite, clay, feldspar, anhydrite, and salt without analyst intervention.« less

Sustaining hypercitrullinemia, hypercholesterolemia and augmented oxidative stress in Japanese children with aspartate/glutamate carrier isoform 2-citrin-deficiency even during the silent period.

PubMed

Nagasaka, Hironori; Okano, Yoshiyuki; Tsukahara, Hirokazu; Shigematsu, Yosuke; Momoi, Toru; Yorifuji, Junko; Miida, Takashi; Ohura, Toshihiro; Kobayashi, Keiko; Saheki, Takeyori; Hirano, Kenichi; Takayanagi, Masaki; Yorifuji, Tohru

2009-05-01

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) shows diverse metabolic abnormalities such as urea cycle dysfunction together with citrullinemia, galactosemia, and suppressed gluconeogenesis. Such abnormalities apparently resolve during the first year of life. However, metabolic profiles of the silent period remain unknown. We analyzed oxidative stress markers and profiles of amino acids, carbohydrates, and lipids in 20 asymptomatic children with aspartate/glutamate carrier isoform 2-citrin-deficiency aged 1-10 years, for whom tests showed normal liver function. Despite normal plasma ammonia levels, the affected children showed higher blood levels of ornithine (p<0.001) and citrulline (p<0.01)--amino acids involved in the urea cycle--than healthy children. Blood levels of nitrite/nitrate, metabolites of nitric oxide (NO), and asymmetric dimethylarginine inhibiting NO production from arginine were not different between these two groups. Blood glucose, galactose, pyruvate, and lactate levels after 4-5h fasting were not different between these groups, but the affected group showed a significantly higher lactate to pyruvate ratio. Low-density and high-density lipoprotein cholesterol levels in the affected group were 1.5 times higher than those in the controls. Plasma oxidized low-density lipoprotein apparently increased in the affected children; their levels of urinary oxidative stress markers such as 8-hydroxy-2'-deoxyguanosine and acrolein-lysine were significantly higher than those in the controls. Results of this study showed, even during the silent period, sustained hypercitrullinemia, hypercholesterolemia, and augmented oxidative stress in children with citrin deficiency.

Diffusion of rhodamine B and bovine serum albumin in fibrin gels seeded with primary endothelial cells.

PubMed

Shkilnyy, Andriy; Proulx, Pierre; Sharp, Jamie; Lepage, Martin; Vermette, Patrick

2012-05-01

Scaffolds with adequate mass transport properties are needed in many tissue engineering applications. Fibrin is considered a good biological material to fabricate such scaffolds. However, very little is known about mass transport in fibrin. Therefore, a method based on the analysis of fluorescence intensity for measuring the apparent diffusion coefficient of rhodamine B and fluorescein-labelled bovine serum albumin (FITC-BSA) is described. The experiments are performed in fibrin gels with and without human umbilical vein endothelial cells (HUVEC). The apparent diffusion coefficients of rhodamine B and FITC-BSA in fibrin (fibrinogen concentration of 4 mg/mL) with different cell densities are reported. A LIVE/DEAD(®) assay is performed to confirm the viability of HUVEC seeded at high densities. Diffusion coefficients for rhodamine B remain more or less constant up to 5×10(5) cells/mL and correlate well with literature values measured by other methods in water systems. This indicates that the presence of HUVEC in the fibrin gels (up to 5×10(5) cells/mL) has almost no effect on the diffusion coefficients. Higher cell densities (>5×10(5) cells/mL) result in a decrease of the diffusion coefficients. Diffusion coefficients of rhodamine B and FITC-BSA obtained by this method agree with diffusion coefficients in water predicted by the Stokes-Einstein equation. The experimental design used in this study can be applied to measure diffusion coefficients in different types of gels seeded or not with living cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Domain wall pinning on strain relaxation defects (stacking faults) in nanoscale FePd (001)/MgO thin films

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

Hsiao, C. H.; Ouyang, Chuenhou, E-mail: wei0208@gmail.com, E-mail: houyang@mx.nthu.edu.tw; Yao, Y. D.

FePd (001) films, prepared by an electron beam deposition system on MgO(100), exhibit a perpendicular magnetic anisotropy (1.7 × 10{sup 7 }erg/cc) with a high order parameter (0.92). The relation between stacking faults induced by the strain relaxation, which act as strong domain wall pinning sites, and the perpendicular coercivity of (001) oriented L1{sub 0} FePd films prepared at different temperatures have been investigated. Perpendicular coercivity can be apparently enhanced by raising the stacking fault densities, which can be elevated by climbing dissociation of total dislocation. The increased stacking fault densities (1.22 nm{sup −2}) with large perpendicular coercivity (6000 Oe) are obtained for samples preparedmore » at 650 °C. This present work shows through controlling stacking fault density in FePd film, the coercivity can be manipulated, which can be applied in future magnetic devices.« less

Mechanical properties of cancellous bone in the human mandibular condyle are anisotropic.

PubMed

Giesen, E B; Ding, M; Dalstra, M; van Eijden, T M

2001-06-01

The objective of the present study was (1) to test the hypothesis that the elastic and failure properties of the cancellous bone of the mandibular condyle depend on the loading direction, and (2) to relate these properties to bone density parameters. Uniaxial compression tests were performed on cylindrical specimens (n=47) obtained from the condyles of 24 embalmed cadavers. Two loading directions were examined, i.e., a direction coinciding with the predominant orientation of the plate-like trabeculae (axial loading) and a direction perpendicular to the plate-like trabeculae (transverse loading). Archimedes' principle was applied to determine bone density parameters. The cancellous bone was in axial loading 3.4 times stiffer and 2.8 times stronger upon failure than in transverse loading. High coefficients of correlation were found among the various mechanical properties and between them and the apparent density and volume fraction. The anisotropic mechanical properties can possibly be considered as a mechanical adaptation to the loading of the condyle in vivo.

Growing Platinum-Ruthenium-Tin ternary alloy nanoparticles on reduced graphene oxide for strong ligand effect toward enhanced ethanol oxidation reaction.

PubMed

Xia, Qing Qing; Zhang, Lian Ying; Zhao, Zhi Liang; Li, Chang Ming

2017-11-15

Uniform Pt 1 Ru 0.5 Sn 0.5 ternary alloy nanoparticles are in situ deposited on reduced graphene oxide (Pt 1 Ru 0.5 Sn 0.5 -RGO) through its functional groups and defects as nucleation sites to greatly electrocatalyze ethanol oxidation reaction for much higher mass current densities, larger apparent specific current densities and better stability than commercial Pt-C catalyst (Pt-C(commer)). Mechanistic studies indicate that the excellent electrocatalytic activity and anti-poisoning are resulted from a strong ligand effect of the ternary alloy components, in which the charge transfer is boosted while decreasing the density of states close to the Fermi level of Pt to reduce bond energy between Pt and CO-like adsorbates for greatly improved anti-poisoning ability. This work holds a great promise to fabricate a high performance anode catalyst with a low Pt loading for direct ethanol fuel cells. Copyright © 2017. Published by Elsevier Inc.

High Performance Li4Ti5O12/Si Composite Anodes for Li-Ion Batteries

PubMed Central

Chen, Chunhui; Agrawal, Richa; Wang, Chunlei

2015-01-01

Improving the energy capacity of spinel Li4Ti5O12 (LTO) is very important to utilize it as a high-performance Li-ion battery (LIB) electrode. In this work, LTO/Si composites with different weight ratios were prepared and tested as anodes. The anodic and cathodic peaks from both LTO and silicon were apparent in the composites, indicating that each component was active upon Li+ insertion and extraction. The composites with higher Si contents (LTO:Si = 35:35) exhibited superior specific capacity (1004 mAh·g−1) at lower current densities (0.22 A·g−1) but the capacity deteriorated at higher current densities. On the other hand, the electrodes with moderate Si contents (LTO:Si = 50:20) were able to deliver stable capacity (100 mAh·g−1) with good cycling performance, even at a very high current density of 7 A·g−1. The improvement in specific capacity and rate performance was a direct result of the synergy between LTO and Si; the former can alleviate the stresses from volumetric changes in Si upon cycling, while Si can add to the capacity of the composite. Therefore, it has been demonstrated that the addition of Si and concentration optimization is an easy yet an effective way to produce high performance LTO-based electrodes for lithium-ion batteries. PMID:28347076

Reconstruction of apparent orthotropic conductivity tensor image using magnetic resonance electrical impedance tomography

NASA Astrophysics Data System (ADS)

Sajib, Saurav Z. K.; Kim, Ji Eun; Jeong, Woo Chul; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

2015-03-01

Magnetic resonance electrical impedance tomography visualizes current density and/or conductivity distributions inside an electrically conductive object. Injecting currents into the imaging object along at least two different directions, induced magnetic flux density data can be measured using a magnetic resonance imaging scanner. Without rotating the object inside the scanner, we can measure only one component of the magnetic flux density denoted as Bz. Since the biological tissues such as skeletal muscle and brain white matter show strong anisotropic properties, the reconstruction of anisotropic conductivity tensor is indispensable for the accurate observations in the biological systems. In this paper, we propose a direct method to reconstruct an axial apparent orthotropic conductivity tensor by using multiple Bz data subject to multiple injection currents. To investigate the anisotropic conductivity properties, we first recover the internal current density from the measured Bz data. From the recovered internal current density and the curl-free condition of the electric field, we derive an over-determined matrix system for determining the internal absolute orthotropic conductivity tensor. The over-determined matrix system is designed to use a combination of two loops around each pixel. Numerical simulations and phantom experimental results demonstrate that the proposed algorithm stably determines the orthotropic conductivity tensor.

High-ionic-strength electroosmotic flows in uncharged hydrophobic nanochannels.

PubMed

Kim, Daejoong; Darve, Eric

2009-02-01

We report molecular dynamics simulation results of high-ionic-strength electroosmotic flows inside uncharged nanochannels. The possibility of this unusual electrokinetic phenomenon has been discussed by Dukhin et al. [A. Dukhin, S. Dukhin, P. Goetz, Langmuir 21 (2005) 9990]. Our computed velocity profiles clearly indicate the presence of a net flow with a maximum velocity around 2 m/s. We found the apparent zeta potential to be -29.7+/-6.8 mV, using the Helmholtz-Smoluchowski relation and the measured mean velocity. This value is comparable to experimentally measured values in Dukhin et al. and references therein. We also investigate the orientations of water molecules in response to an electric field by computing polarization density. Water molecules in the bulk region are oriented along the direction of the external electric field, while their near-wall orientation shows oscillations. The computation of three-dimensional density distributions of sodium and chloride ions around each individual water molecule show that chloride ions tend to concentrate near a water molecule, whereas sodium ions are diffusely distributed.

Effects of a high-gradient magnetic field on the migratory behavior of primary crystal silicon in hypereutectic Al–Si alloy

PubMed Central

Jin, Fangwei; Ren, Zhongming; Ren, Weili; Deng, Kang; Zhong, Yunbo; Yu, Jianbo

2008-01-01

The migration of primary Si grains during the solidification of Al–18 wt%Si alloy under a high-gradient magnetic field has been investigated experimentally. It was found that under a gradient magnetic field, the primary Si grains migrated toward one end of the specimen, forming a Si-rich layer, and the thickness of the Si-rich layer increased with increasing magnetic flux density. No movement of Si grains was apparent under a magnetic field below 2.3 T. For magnetic fields above 6.6 T, however, the thickness of the Si-rich layer was almost constant. It was shown that the static field also played a role in impeding the movement of the grains. The primary Si grains were refined in the Si layer, even though the primary silicon grains were very dense. The effect of the magnetic flux density on the migratory behavior is discussed. PMID:27877953

Observation and modeling of deflagration-to-detonation transition (DDT) in low-density HMX

NASA Astrophysics Data System (ADS)

Tringe, Joseph W.; Vandersall, Kevin S.; Reaugh, John E.; Levie, Harold W.; Henson, Bryan F.; Smilowitz, Laura B.; Parker, Gary R.

2017-01-01

We employ simultaneous flash x-ray radiography and streak imaging, together with a multi-phase finite element model, to understand deflagration-to-detonation transition (DDT) phenomena in low-density (˜1.2 gm/cm3) powder of the explosive cyclotetramethylene-tetranitramine (HMX). HMX powder was lightly hand-tamped in a 12.7 mm diameter column, relatively lightly-confined in an optically-transparent polycarbonate cylinder with wall thickness 25.4 mm. We observe apparent compaction of the powder in advance of the detonation transition by the motion of small steel spheres pre-emplaced throughout the length of explosive. High-speed imaging along the explosive cylinder length provides a more temporally continuous record of the transition that is correlated with the high-resolution x-ray image record. Preliminary simulation of these experiments with the HERMES model implemented in the ALE3D code enables improved understanding of the explosive particle burning, compaction and detonation phenomena which are implied by the observed reaction rate and transition location within the cylinder.

New Evidence for a Large Local Void From the UKIDSS LAS + SDSS

NASA Astrophysics Data System (ADS)

Keenan, Ryan; Barger, A. J.

2013-01-01

Recent cosmological modeling efforts have shown that a local under-density on scales of a few hundred Mpc (out to z ~ 0.1) could produce the apparent acceleration of the expansion of the universe observed via type Ia supernovae. Several studies of galaxy counts in the near-infrared (NIR) have found that the local universe appears underdense by ~25 - 50% compared with regions a few hundred Mpc distant (e.g. Keenan et al., 2010). An accurate characterization of any such under-density will be important for studies seeking to understand the nature of dark energy. If the space density of galaxies is rising as a function of redshift, then the luminosity density, as measured via the NIR galaxy luminosity function (LF), should be rising as well. In Keenan et al. (2012), we presented a study of the NIR LF at z ~ 0.2 and found that the product φ*L* (the peak of the luminosity density distribution) at z ~ 0.2 is roughly ~ 30% higher than that measured at z ~ 0.05. Here we present the results from a study of the NIR LF derived from galaxies selected from the UKIRT Infrared Deep Sky Large Area Survey (UKIDSS LAS) combined with spectroscopy from the Sloan Digital Sky Survey (SDSS). We confirm the apparent rise in luminosity density found in Keenan et al. (2012) from z = 0.05 to z = 0.1 and provide the first self-consistent measurements of the NIR luminosity density out to z ~ 0.15.

Background-Oriented Schlieren used in a hypersonic inlet test at NASA GRC

NASA Technical Reports Server (NTRS)

Clem, Michelle; Woike, Mark; Saunders, John

2016-01-01

Background Oriented Schlieren (BOS) is a derivative of the classical schlieren technology, which is used to visualize density gradients, such as shock wave structures in a wind tunnel. Changes in refractive index resulting from density gradients cause light rays to bend, resulting in apparent motion of a random background pattern. The apparent motion of the pattern is determined using cross-correlation algorithms (between no-flow and with-flow image pairs) producing a schlieren-like image. One advantage of BOS is its simplified setup which enables a larger field-of-view (FOV) than traditional schlieren systems. In the present study, BOS was implemented into the Combined Cycle Engine Large-Scale Inlet Mode Transition Experiment (CCE LIMX) in the 10x10 Supersonic Wind Tunnel at NASA Glenn Research Center. The model hardware for the CCE LIMX accommodates a fully integrated turbine based combined cycle propulsion system. To date, inlet mode transition between turbine and ramjet operation has been successfully demonstrated. High-speed BOS was used to visualize the behavior of the flow structures shock waves during unsteady inlet unstarts, a phenomenon known as buzz. Transient video images of inlet buzz were recorded for both the ramjet flow path (high speed inlet) and turbine flow path (low speed inlet). To understand the stability limits of the inlet, operation was pushed to the point of unstart and buzz. BOS was implemented in order to view both inlets simultaneously, since the required FOV was beyond the capability of the current traditional schlieren system. An example of BOS data (Images 1-6) capturing inlet buzz are presented.

Near Surface Investigation of Agricultural Soils using a Multi-Frequency Electromagnetic Sensor

NASA Astrophysics Data System (ADS)

Sadatcharam, K.; Unc, A.; Krishnapillai, M.; Cheema, M.; Galagedara, L.

2017-12-01

Electromagnetic induction (EMI) sensors have been used as precision agricultural tools over decades. They are being used to measure spatiotemporal variability of soil properties and soil stratification in the sense of apparent electrical conductivity (ECa). We mapped the ECa variability by horizontal coplanar (HCP) and by vertical coplanar (VCP) orientation of a multi-frequency EMI sensor and identified its interrelation with physical properties of soil. A broadband, multi-frequency handheld EMI sensor (GEM-2) was used on a loamy sand soil cultivated with silage-corn in western Newfoundland, Canada. Log and line spaced, three frequency ranges (weak, low, and high), based on the factory calibration were tested using HCP and VCP orientation to produce spatiotemporal data of ECa. In parallel, we acquired data on soil moisture content, texture and bulk density. We then assessed the statistical significance of the relationship between ECa and soil physical properties. The test site had three areas of distinct soil properties corresponding to the elevation, in particular. The same spatial variability was also identified by ECa mapping at different frequencies and the two modes of coil orientations. Data analysis suggested that the high range frequency (38 kHz (log-spaced) and 49 kHz (line-spaced)) for both HCP and VCP orientations produced accurate ECa maps, better than the weak and low range frequencies tested. Furthermore, results revealed that the combined effects of soil texture, moisture content and bulk density affect ECameasurements as obtained by both frequencies and two coil orientations. Keywords: Apparent electrical conductivity, Electromagnetic induction, Horizontal coplanar, Soil properties, Vertical coplanar

Correlation between some technological parameters and properties of composite material based on recycled tires and polymer binder

NASA Astrophysics Data System (ADS)

Plesuma, Renate; Malers, Laimonis

2015-04-01

The present article is dedicated to the determination of a possible connection between the composition, specific properties of the composite material and molding pressure as an important technological parameter. Apparent density, Shore C hardness, compressive modulus of elasticity and compressive stress at 10% deformation was determined for composite material samples. Definite formation conditions - varying molding pressure conditions at ambient temperature and corresponding relative air humiditywere realized. The results obtained showed a significant effect of molding pressure on the apparent density, mechanical properties of composite material as well as on the compressive stress change at a cyclic mode of loading. Some general regularities were determined - mechanical properties of the composite material, as well as values of Shore C hardness increases with an increase of molding pressure.

Preparation of sintered foam materials by alkali-activated coal fly ash.

PubMed

Zhao, Yelong; Ye, Junwei; Lu, Xiaobin; Liu, Mangang; Lin, Yuan; Gong, Weitao; Ning, Guiling

2010-02-15

Coal fly ash from coal fired power stations is a potential raw material for the production of ceramic tiles, bricks and blocks. Previous works have demonstrated that coal fly ash consists mainly of glassy spheres that are relatively resistant to reaction. An objective of this research was to investigate the effect of alkali on the preparation process of the foam material. Moreover, the influence of foam dosage on the water absorption, apparent density and compressive strength was evaluated. The experimental results showed that homogenous microstructures of interconnected pores could be obtained by adding 13 wt.% foaming agent at 1050 degrees C, leading to foams presenting water absorption, apparent density and compressive strength values of about 126.5%, 0.414 g/cm(3), 6.76 MPa, respectively.

Mechanism and models for zinc metal morphology in alkaline media

NASA Technical Reports Server (NTRS)

May, C. E.; Kautz, H. E.

1981-01-01

Based on experimental observations, a mechanism is presented to explain existence of the different morphologies of electrodeposited zinc in alkaline solution. The high current density dendrites appear to be due to more rapid growth on the nonbasal crystallographic planes than on the basal plane. The low current density moss apparently results from dissolution from the nonbasal planes at low cathodic voltages. Electrochemical models were sought which would produce such a phenomenon. The fundamental plating mechanism alone accounts only for different rates on different planes, not for zinc dissolution from a plane in the cathodic region. Fourteen models were explored; two models were in accord with the proposed mechanism. One involves rapid disproportionation of the zinc +1 species on the nonbasal planes. The other involves a redox reaction (corrosion) between the zinc-zincate and hydrogen-water systems.

Influence of bone mineral density measurement on fracture risk assessment tool® scores in postmenopausal Indian women.

PubMed

Daswani, Bhavna; Desai, Meena; Mitra, Sumegha; Gavali, Shubhangi; Patil, Anushree; Kukreja, Subhash; Khatkhatay, M Ikram

2016-03-01

Fracture risk assessment tool® calculations can be performed with or without addition of bone mineral density; however, the impact of this addition on fracture risk assessment tool® scores has not been studied in Indian women. Given the limited availability and high cost of bone mineral density testing in India, it is important to know the influence of bone mineral density on fracture risk assessment tool® scores in Indian women. Therefore, our aim was to assess the contribution of bone mineral density in fracture risk assessment tool® outcome in Indian women. Apparently healthy postmenopausal Indian women (n = 506), aged 40-72 years, without clinical risk factors for bone disease, were retrospectively selected, and their fracture risk assessment tool® scores calculated with and without bone mineral density were compared. Based on WHO criteria, 30% women were osteoporotic, 42.9% were osteopenic and 27.1% had normal bone mineral density. Fracture risk assessment tool® scores for risk of both major osteoporotic fracture and hip fracture significantly increased on including bone mineral density (P < 0.0001). When criteria of National Osteoporosis Foundation, US was applied number of participants eligible for medical therapy increased upon inclusion of bone mineral density, (for major osteoporotic fracture risk number of women eligible without bone mineral density was 0 and with bone mineral density was 1, P > 0.05, whereas, for hip fracture risk number of women eligible without bone mineral density was 2 and with bone mineral density was 17, P < 0.0001). Until the establishment of country-specific medication intervention thresholds, bone mineral density should be included while calculating fracture risk assessment tool® scores in Indian women. © The Author(s) 2016.

On the dependence of charge density on surface curvature of an isolated conductor

NASA Astrophysics Data System (ADS)

Bhattacharya, Kolahal

2016-03-01

A study of the relation between the electrostatic charge density at a point on a conducting surface and the curvature of the surface (at that point) is presented. Two major papers in the scientific literature on this topic are reviewed and the apparent discrepancy between them is resolved. Hence, a step is taken towards obtaining a general analytic formula for relating the charge density with surface curvature of conductors. The merit of this formula and its limitations are discussed.

Relevance of the triglyceride-to-high-density lipoprotein cholesterol ratio as an important lipid fraction in apparently healthy, young, and middle-aged Indian men

PubMed Central

Kohli, Aparna; Siddhu, Anupa; Pandey, Ravindra M.; Reddy, K. Srinath

2017-01-01

Context: Cardiovascular disease (CVD) is the largest cause of mortality in Indians. Insulin resistance and related dyslipidemia of increased triglyceride (TG), small dense low-density lipoprotein (sd-LDL) particles, and decreased high-density lipoprotein-cholesterol (HDL-C) are associated with increased risk of CVD. TG/HDL-C ratio could be a potential surrogate marker for this South Asian phenotype. Data are scarce on the relevance of TG/HDL-C ratio as a useful lipid marker among Indians. Aims: To study the prevalence of TG/HDL-C ratio among healthy, young, and middle-aged Indian men (25–44 years) and its relationship with other lipid and nonlipid factors. Subjects and Methods: In this cross-sectional analysis, fasting blood samples from 236 healthy participants recruited from an urban community setting were tested for TG/HDL-C ratio, HDL-C, TG, total cholesterol (TC), non-HDL-C, TC/HDL-C, high-sensitivity C-reactive protein, body mass index (BMI), and body fat. Results: Mean (standard deviation) age of participants was 34.7 (7.7) years; median (interquartile range) TG/HDL-C ratio was 4 (2.85-5.2). More than half (51.3%) the participants (n = 121) recorded abnormal TG/HDL-C ratio (≥4.0). Across tertiles of TG/HDL-C ratio, there was a significant trend of higher conventional lipid parameters such as non-HDL-C*, TC/HDL-C ratio*, TG*, HDL-C*, TC**; and non-lipid parameters body-fat* and BMI*** (*P < 0.001, **P = 0.015, ***P = 0.002). LDL-C showed moderate and nonsignificant (P = 0.646) increase across tertiles. Conclusion: In a sample of apparently healthy, young, and middle-aged Indian men abnormal TG/HDL-C ratio levels were observed among more than half the participants. The TG/HDL-C ratio was closely associated with other lipid parameters and measures of adiposity, such as BMI and body fat, apart from its previously documented unique association with sd-LDL particles. TG/HDL-C ratio should be evaluated in future for risk prediction of incident CVD among Indians. PMID:28217509

Relevance of the triglyceride-to-high-density lipoprotein cholesterol ratio as an important lipid fraction in apparently healthy, young, and middle-aged Indian men.

PubMed

Kohli, Aparna; Siddhu, Anupa; Pandey, Ravindra M; Reddy, K Srinath

2017-01-01

Cardiovascular disease (CVD) is the largest cause of mortality in Indians. Insulin resistance and related dyslipidemia of increased triglyceride (TG), small dense low-density lipoprotein (sd-LDL) particles, and decreased high-density lipoprotein-cholesterol (HDL-C) are associated with increased risk of CVD. TG/HDL-C ratio could be a potential surrogate marker for this South Asian phenotype. Data are scarce on the relevance of TG/HDL-C ratio as a useful lipid marker among Indians. To study the prevalence of TG/HDL-C ratio among healthy, young, and middle-aged Indian men (25-44 years) and its relationship with other lipid and nonlipid factors. In this cross-sectional analysis, fasting blood samples from 236 healthy participants recruited from an urban community setting were tested for TG/HDL-C ratio, HDL-C, TG, total cholesterol (TC), non-HDL-C, TC/HDL-C, high-sensitivity C-reactive protein, body mass index (BMI), and body fat. Mean (standard deviation) age of participants was 34.7 (7.7) years; median (interquartile range) TG/HDL-C ratio was 4 (2.85-5.2). More than half (51.3%) the participants ( n = 121) recorded abnormal TG/HDL-C ratio (≥4.0). Across tertiles of TG/HDL-C ratio, there was a significant trend of higher conventional lipid parameters such as non-HDL-C*, TC/HDL-C ratio*, TG*, HDL-C*, TC**; and non-lipid parameters body-fat* and BMI*** (* P < 0.001, ** P = 0.015, *** P = 0.002). LDL-C showed moderate and nonsignificant ( P = 0.646) increase across tertiles. In a sample of apparently healthy, young, and middle-aged Indian men abnormal TG/HDL-C ratio levels were observed among more than half the participants. The TG/HDL-C ratio was closely associated with other lipid parameters and measures of adiposity, such as BMI and body fat, apart from its previously documented unique association with sd-LDL particles. TG/HDL-C ratio should be evaluated in future for risk prediction of incident CVD among Indians.

Controls on the spatial variability of key soil properties: comparing field data with a mechanistic soilscape evolution model

NASA Astrophysics Data System (ADS)

Vanwalleghem, T.; Román, A.; Giraldez, J. V.

2016-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of a geostatistical versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

The most massive galaxies and black holes allowed by ΛCDM

NASA Astrophysics Data System (ADS)

Behroozi, Peter; Silk, Joseph

2018-07-01

Given a galaxy's stellar mass, its host halo mass has a lower limit from the cosmic baryon fraction and known baryonic physics. At z> 4, galaxy stellar mass functions place lower limits on halo number densities that approach expected Lambda Cold Dark Matter halo mass functions. High-redshift galaxy stellar mass functions can thus place interesting limits on number densities of massive haloes, which are otherwise very difficult to measure. Although halo mass functions at z < 8 are consistent with observed galaxy stellar masses if galaxy baryonic conversion efficiencies increase with redshift, JWST(James Webb Space Telescope) and WFIRST(Wide-Field InfraRed Survey Telescope) will more than double the redshift range over which useful constraints are available. We calculate maximum galaxy stellar masses as a function of redshift given expected halo number densities from ΛCDM. We apply similar arguments to black holes. If their virial mass estimates are accurate, number density constraints alone suggest that the quasars SDSS J1044-0125 and SDSS J010013.02+280225.8 likely have black hole mass to stellar mass ratios higher than the median z = 0 relation, confirming the expectation from Lauer bias. Finally, we present a public code to evaluate the probability of an apparently ΛCDM-inconsistent high-mass halo being detected given the combined effects of multiple surveys and observational errors.

Spatial mapping of humeral head bone density.

PubMed

Alidousti, Hamidreza; Giles, Joshua W; Emery, Roger J H; Jeffers, Jonathan

2017-09-01

Short-stem humeral replacements achieve fixation by anchoring to the metaphyseal trabecular bone. Fixing the implant in high-density bone can provide strong fixation and reduce the risk of loosening. However, there is a lack of data mapping the bone density distribution in the proximal humerus. The aim of the study was to investigate the bone density in proximal humerus. Eight computed tomography scans of healthy cadaveric humeri were used to map bone density distribution in the humeral head. The proximal humeral head was divided into 12 slices parallel to the humeral anatomic neck. Each slice was then divided into 4 concentric circles. The slices below the anatomic neck, where short-stem implants have their fixation features, were further divided into radial sectors. The average bone density for each of these regions was calculated, and regions of interest were compared using a repeated-measures analysis of variance with significance set at P < .05. Average apparent bone density was found to decrease from proximal to distal regions, with the majority of higher bone density proximal to the anatomic neck of the humerus (P < .05). Below the anatomic neck, bone density increases from central to peripheral regions, where cortical bone eventually occupies the space (P < .05). In distal slices below the anatomic neck, a higher bone density distribution in the medial calcar region was also observed. This study indicates that it is advantageous with respect to implant fixation to preserve some bone above the anatomic neck and epiphyseal plate and to use the denser bone at the periphery. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Evaluation of foaming polypropylene modified with ramified polymer

NASA Astrophysics Data System (ADS)

Demori, Renan; de Azeredo, Ana Paula; Liberman, Susana A.; Mauler, Raquel S.

2015-05-01

Polypropylene foams have great industrial interest because of balanced physical and mechanical properties, recyclability as well as low material cost. During the foaming process, the elongational forces applied to produce the expanded polymer are strong enough to rupture cell walls. As a result, final foam has a high amount of coalesced as well as opened cells which decreases mechanical and also physical properties. To increase melt strength and also avoid the coalescence effect, one of the current solution is blend PP with ramified polymers as well as branched polypropylene (LCBPP) or ethylene-octene copolymer (POE). In this research to provide extensional properties and achieve uniform cellular structures of expanded PP, 20 phr of LCBPP or POE was added into PP matrix. The blend of PP with ramified polymers was prepared by twin-screw extrusion. Injection molding process was used to produce PP foams using azodicarbonamide (ACA) as chemical blowing agent. The morphological results of the expanded PP displayed a non-uniform geometrical cell, apparent density of 0.48 g/cm3 and cell density of 13.9.104 cell/cm3. Otherwise, the expanded PP blended with LCBPP or POE displayed a homogeneous cell structure and increased the amount of smaller cells (50-100 μm of size). The apparent density slightly increased with addition of LCBPP or POE, 0.64 and 0.57 g/cm3, respectively. Thus, the cell density reduced to 65% in PP/LCBPP 100/20 and 75% in the sample PP/POE 100/20 compared to expanded PP. The thermo-mechanical properties (DMTA) of PP showed specific stiffness of 159 MPa.cm-3.g-1, while the sample PP/LCBPP 100/20 increased the stiffness values of 10%. Otherwise, the expanded PP/POE 100/20 decreased the specific stiffness values at -30%, in relation to expanded PP. In summary, blending PP with ramified polymers showed increasing of the homogenous cellular structure as well as the amount of smaller cells in the expanded material.

Photoaffinity labeling of protoporphyrinogen oxidase, the molecular target of diphenylether-type herbicides.

PubMed

Camadro, J M; Matringe, M; Thome, F; Brouillet, N; Mornet, R; Labbe, P

1995-05-01

Diphenylether-type herbicides are extremely potent inhibitors of protoporphyrinogen oxidase, a membrane-bound enzyme involved in the heme and chlorophyll biosynthesis pathways. Tritiated acifluorfen and a diazoketone derivative of tritiated acifluorfen were specifically bound to a single class of high-affinity binding sites on yeast mitochondrial membranes with apparent dissociation constants of 7 nM and 12.5 nM, respectively. The maximum density of specific binding sites, determined by Scatchard analysis, was 3 pmol.mg-1 protein. Protoporphyrinogen oxidase specific activity was estimated to be 2500 nmol protoporphyrinogen oxidized h-1.mol-1 enzyme. The diazoketone derivative of tritiated acifluorfen was used to specifically photolabel yeast protoporphyrinogen oxidase. The specifically labeled polypeptide in wild-type mitochondrial membranes had an apparent molecular mass of 55 kDa, identical to the molecular mass of the purified enzyme. This photolabeled polypeptide was not detected in a protoporphyrinogen-oxidase-deficient yeast strain, but the membranes contained an equivalent amount of inactive immunoreactive protoporphyrinogen oxidase protein.

Ultrasound promoted catalytic liquid-phase dehydrogenation of isopropanol for Isopropanol-Acetone-Hydrogen chemical heat pump.

PubMed

Xu, Min; Xin, Fang; Li, Xunfeng; Huai, Xiulan; Liu, Hui

2015-03-01

The apparent kinetic of the ultrasound assisted liquid-phase dehydrogenation of isopropanol over Raney nickel catalyst was determined in the temperature range of 346-353 K. Comparison of the effects of ultrasound and mechanical agitation on the isopropanol dehydrogenation was investigated. The ultrasound assisted dehydrogenation rate was significantly improved when relatively high power density was used. Moreover, the Isopropanol-Acetone-Hydrogen chemical heat pump (IAH-CHP) with ultrasound irradiation, in which the endothermic reaction is exposure to ultrasound, was proposed. A mathematical model was established to evaluate its energy performance in term of the coefficient of performance (COP) and the exergy efficiency, into which the apparent kinetic obtained in this work was incorporated. The operating performances between IAH-CHP with ultrasound and mechanical agitation were compared. The results indicated that the superiority of the IAH-CHP system with ultrasound was present even if more than 50% of the power of the ultrasound equipment was lost. Copyright © 2014 Elsevier B.V. All rights reserved.

High- and low-temperature unfolding of human high-density apolipoprotein A-2.

PubMed Central

Gursky, O.; Atkinson, D.

1996-01-01

Human plasma apolipoprotein A-2 (apoA-2) is the second major protein of the high-density lipoproteins that mediate the transport and metabolism of cholesterol. Using CD spectroscopy and differential scanning calorimetry, we demonstrate that the structure of lipid-free apoA-2 in neutral low-salt solutions is most stable at approximately 25 degrees C and unfolds reversibly both upon heating and cooling from 25 degrees C. High-temperature unfolding of apoA-2, monitored by far-UV CD, extends from 25-85 degrees C with midpoint Th = 56 +/- 2 degrees C and vant Hoff's enthalpy delta H(Th) = 17 +/- 2 kcal/mol that is substantially lower than the expected enthalpy of melting of the alpha-helical structure. This suggests low-cooperativity apoA-2 unfolding. The apparent free energy of apoA-2 stabilization inferred from the CD analysis of the thermal unfolding, delta G(app)(25 degrees) = 0.82 +/- 0.15 kcal/mol, agrees with the value determined from chemical denaturation. Enhanced low-temperature stability of apoA-2 observed upon increase in Na2HPO4 concentration from 0.3 mM to 50 mM or addition of 10% glycerol may be linked to reduced water activity. The close proximity of the heat and cold unfolding transitions, that is consistent with low delta G(app)(25 degrees), indicates that lipid-free apoA-2 has a substantial hydrophobic core but is only marginally stable under near-physiological solvent conditions. This suggests that in vivo apoA-2 transfer is unlikely to proceed via the lipid-free state. Low delta H(Th) and low apparent delta Cp approximately 0.52 kcal/mol.K inferred from the far-UV CD analysis of apoA-2 unfolding, and absence of tertiary packing interactions involving Tyr groups suggested by near-UV CD, are consistent with a molten globular-like state of lipid-free apoA-2. PMID:8880911

Effect of Theobromine Consumption on Serum Lipoprotein Profiles in Apparently Healthy Humans with Low HDL-Cholesterol Concentrations

PubMed Central

Jacobs, Doris M.; Smolders, Lotte; Lin, Yuguang; de Roo, Niels; Trautwein, Elke A.; van Duynhoven, John; Mensink, Ronald P.; Plat, Jogchum; Mihaleva, Velitchka V.

2017-01-01

Scope: Theobromine is a major active compound in cocoa with allegedly beneficial effect on high-density-lipoprotein-cholesterol (HDL-CH). We have investigated the effect of theobromine (TB) consumption on the concentrations of triglyceride (TG) and cholesterol (CH) in various lipoprotein (LP) subclasses. Methods: In a randomized, double-blind, placebo-controlled, cross-over study, 44 apparently healthy women and men (age: 60 ± 6 years, BMI: 29 ± 3 kg/m2) with low baseline HDL-CH concentrations consumed a drink supplemented with 500 mg/d theobromine for 4 weeks. TG and CH concentrations in 15 LP subclasses were predicted from diffusion-edited 1H NMR spectra of fasting serum. Results: The LP phenotype of the subjects was characterized by low CH concentrations in the large HDL particles and high TG concentrations in large VLDL and chylomicron (CM) particles, which clearly differed from a LP phenotype of subjects with normal HDL-CH. TB only reduced CH concentrations in the LDL particles by 3.64 and 6.79%, but had no effect on TG and CH in any of the HDL, VLDL and CM subclasses. Conclusion: TB was not effective on HDL-CH in subjects with a LP phenotype characterized by low HDL-CH and high TG in VLDL. PMID:28971099

Density, ages, and growth rates in old-growth and young-growth forests in coastal Oregon

USGS Publications Warehouse

Tappeiner, J. C.; Huffman, D.; Spies, T.; Bailey, John D.

1997-01-01

We studied the ages and diameter growth rates of trees in former Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco) old-growth stands on 10 sites and compared them with young-growth stands (50-70 years old, regenerated after timber harvest) in the Coast Range of western Oregon. The diameters and diameter growth rates for the first 100 years of trees in the old-growth stands were significantly greater than those in the young-growth stands. Growth rates in the old stands were comparable with those from long-term studies of young stands in which density is about 100-120 trees/ha; often young-growth stand density is well over 500 trees/ha. Ages of large trees in the old stands ranged from 100 to 420 years; ages in young stands varied by only about 5 to 10 years. Apparently, regeneration of old-growth stands on these sites occurred over a prolonged period, and trees grew at low density with little self-thinning; in contrast, after timber harvest, young stands may develop with high density of trees with similar ages and considerable self-thinning. The results suggest that thinning may be needed in dense young stands where the management objective is to speed development of old-growth characteristics.

Bone Mineral Density and Respiratory Muscle Strength in Male Individuals with Mental Retardation (with and without Down Syndrome)

ERIC Educational Resources Information Center

da Silva, Vinicius Zacarias Maldaner; Barros, Jonatas de Franca; de Azevedo, Monique; de Godoy, Jose Roberto Pimenta; Arena, Ross; Cipriano, Gerson, Jr.

2010-01-01

The purpose of this study was to assess the respiratory muscle strength (RMS) in individuals with mental retardation (MR), with or without Down Syndrome (DS), and its association with bone mineral density (BMD). Forty-five male individuals (15 with DS, 15 with mental retardation (MR) and 15 apparently healthy controls), aged 20-35, participated in…

Analysis and visualization of chromosomal abnormalities in SNP data with SNPscan

PubMed Central

Ting, Jason C; Ye, Ying; Thomas, George H; Ruczinski, Ingo; Pevsner, Jonathan

2006-01-01

Background A variety of diseases are caused by chromosomal abnormalities such as aneuploidies (having an abnormal number of chromosomes), microdeletions, microduplications, and uniparental disomy. High density single nucleotide polymorphism (SNP) microarrays provide information on chromosomal copy number changes, as well as genotype (heterozygosity and homozygosity). SNP array studies generate multiple types of data for each SNP site, some with more than 100,000 SNPs represented on each array. The identification of different classes of anomalies within SNP data has been challenging. Results We have developed SNPscan, a web-accessible tool to analyze and visualize high density SNP data. It enables researchers (1) to visually and quantitatively assess the quality of user-generated SNP data relative to a benchmark data set derived from a control population, (2) to display SNP intensity and allelic call data in order to detect chromosomal copy number anomalies (duplications and deletions), (3) to display uniparental isodisomy based on loss of heterozygosity (LOH) across genomic regions, (4) to compare paired samples (e.g. tumor and normal), and (5) to generate a file type for viewing SNP data in the University of California, Santa Cruz (UCSC) Human Genome Browser. SNPscan accepts data exported from Affymetrix Copy Number Analysis Tool as its input. We validated SNPscan using data generated from patients with known deletions, duplications, and uniparental disomy. We also inspected previously generated SNP data from 90 apparently normal individuals from the Centre d'Étude du Polymorphisme Humain (CEPH) collection, and identified three cases of uniparental isodisomy, four females having an apparently mosaic X chromosome, two mislabelled SNP data sets, and one microdeletion on chromosome 2 with mosaicism from an apparently normal female. These previously unrecognized abnormalities were all detected using SNPscan. The microdeletion was independently confirmed by fluorescence in situ hybridization, and a region of homozygosity in a UPD case was confirmed by sequencing of genomic DNA. Conclusion SNPscan is useful to identify chromosomal abnormalities based on SNP intensity (such as chromosomal copy number changes) and heterozygosity data (including regions of LOH and some cases of UPD). The program and source code are available at the SNPscan website . PMID:16420694

Effects of dietary copper and amino acid density on growth performance, apparent metabolizable energy, and nutrient digestibility in Eimeria acervulina-challenged broilers.

PubMed

Rochell, S J; Usry, J L; Parr, T M; Parsons, C M; Dilger, R N

2017-03-01

The objective of this experiment was to evaluate the influence of copper supplementation in diets varying in amino acid (AA) density on growth performance, apparent metabolizable energy (AMEn), apparent ileal nutrient digestibility (AID), and plasma carotenoids in broilers infected with Eimeria acervulina. Ross 308 male broilers (480 total) were housed in battery cages and allotted to 8 experimental treatments in a factorial arrangement of 2 dietary AA densities [1.00% (LAA) or 1.20% (HAA) digestible Lys], 2 supplemental copper concentrations (zero or 116 mg/kg), and 2 E. acervulina infection states (uninfected or infected). Essential AA ratios relative to digestible Lys were similar in both the LAA and HAA diets, and copper was provided by 200 mg/kg of tribasic copper chloride (58% copper). Chicks received experimental diets from 2 to 21 d post hatch and 6 replicate cages of 10 birds per cage were assigned to each treatment. Broilers were inoculated with zero or 6.3 × 105 sporulated E. acervulina oocysts at 15 d and blood and ileal digesta were collected at 21 days. From 2 to 15 d, body weight gain and G:F of broilers were improved (P < 0.05) with increasing AA density, and an AA density × copper interaction was observed (P < 0.05) for feed intake. Eimeria infection reduced (P < 0.05) plasma carotenoids, growth performance, dietary AMEn, and AID of organic matter, nitrogen, and total AA. There were no interactive effects of dietary treatments with E. acervulina infection on broiler growth performance or dietary AMEn. An AA density × copper supplementation interaction was observed (P < 0.05) for AID of total AA, whereby copper supplementation increased AID of total AA for birds fed the LAA diet and decreased AID of total AA for birds fed the HAA diet. In summary, E. acervulina-induced reductions in nutrient digestibility were dependent on dietary copper and AA status, but changes in digestibility had minimal impact on growth performance of broilers during the E. acervulina infection period. © 2016 Poultry Science Association Inc.

Inter-decadal patterns of population and dietary change in sea otters at Amchitka Island, Alaska

USGS Publications Warehouse

Watt, J.; Siniff, D.B.; Estes, J.A.

2000-01-01

After having been hunted to near-extinction in the Pacific maritime fur trade, the sea otter population at Amchitka Island, Alaska increased from very low numbers in the early 1900s to near equilibrium density by the 1940s. The population persisted at or near equilibrium through the 1980s, but declined sharply in the 1990s in apparent response to increased killer whale predation. Sea otter diet and foraging behavior were studied at Amchitka from August 1992 to March 1994 and the data compared with similar information obtained during several earlier periods. In contrast with dietary patterns in the 1960s and 1970s, when the sea otter population was at or near equilibrium density and kelp-forest fishes were the dietary mainstay, these fishes were rarely eaten in the 1990s. Benthic invertebrates, particularly sea urchins, dominated the otter's diet from early summer to midwinter, then decreased in importance during late winter and spring when numerous Pacific smooth lumpsuckers (a large and easily captured oceanic fish) were eaten. The occurrence of spawning lumpsuckers in coastal waters apparently is episodic on a scale of years to decades. The otters' recent dietary shift away from kelp-forest fishes is probably a response to the increased availability of lumpsuckers and sea urchins (both high-preference prey). Additionally, increased urchin densities have reduced kelp beds, thus further reducing the availability of kelp-forest fishes. Our findings suggest that dietary patterns reflect changes in population status and show how an ecosystem normally under top-down control and limited by coastal zone processes can be significantly perturbed by exogenous events.

Electron temperatures and densities in the venus ionosphere: pioneer venus orbiter electron temperature probe results.

PubMed

Brace, L H; Theis, R F; Krehbiel, J P; Nagy, A F; Donahue, T M; McElroy, M B; Pedersen, A

1979-02-23

Altitude profiles of electron temperature and density in the ionosphere of Venus have been obtained by the Pioneer Venus orbiter electron temperatutre probe. Elevated temperatutres observed at times of low solar wind flux exhibit height profiles that are consistent with a model in which less than 5 percent of the solar wind energy is deposited at the ionopause and is conducted downward through an unmagnetized ionosphere to the region below 200 kilomneters where electron cooling to the neutral atmosphere proceeds rapidly. When solar wind fluxes are higher, the electron temperatures and densities are highly structured and the ionopause moves to lower altitudes. The ionopause height in the late afternoon sector observed thus far varies so widely from day to (day that any height variation with solar zenith angle is not apparent in the observations. In the neighborhood of the ionopause, measuremnents of plasma temperatures and densities and magnetic field strength indicate that an induced magnetic barrier plays an important role in the pressure transfer between the solar wind and the ionosphere. The bow, shock is marked by a distinct increase in electron current collected by the instrument, a featutre that provides a convenient identification of the bow shock location.

Efficiently dense hierarchical graphene based aerogel electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Xin; Lu, Chengxing; Peng, Huifen; Zhang, Xin; Wang, Zhenkun; Wang, Gongkai

2016-08-01

Boosting gravimetric and volumetric capacitances simultaneously at a high rate is still a discrepancy in development of graphene based supercapacitors. We report the preparation of dense hierarchical graphene/activated carbon composite aerogels via a reduction induced self-assembly process coupled with a drying post treatment. The compact and porous structures of composite aerogels could be maintained. The drying post treatment has significant effects on increasing the packing density of aerogels. The introduced activated carbons play the key roles of spacers and bridges, mitigating the restacking of adjacent graphene nanosheets and connecting lateral and vertical graphene nanosheets, respectively. The optimized aerogel with a packing density of 0.67 g cm-3 could deliver maximum gravimetric and volumetric capacitances of 128.2 F g-1 and 85.9 F cm-3, respectively, at a current density of 1 A g-1 in aqueous electrolyte, showing no apparent degradation to the specific capacitance at a current density of 10 A g-1 after 20000 cycles. The corresponding gravimetric and volumetric capacitances of 116.6 F g-1 and 78.1 cm-3 with an acceptable cyclic stability are also achieved in ionic liquid electrolyte. The results show a feasible strategy of designing dense hierarchical graphene based aerogels for supercapacitors.

A random-walk algorithm for modeling lithospheric density and the role of body forces in the evolution of the Midcontinent Rift

USGS Publications Warehouse

Levandowski, William Brower; Boyd, Oliver; Briggs, Richard; Gold, Ryan D.

2015-01-01

We test this algorithm on the Proterozoic Midcontinent Rift (MCR), north-central U.S. The MCR provides a challenge because it hosts a gravity high overlying low shear-wave velocity crust in a generally flat region. Our initial density estimates are derived from a seismic velocity/crustal thickness model based on joint inversion of surface-wave dispersion and receiver functions. By adjusting these estimates to reproduce gravity and topography, we generate a lithospheric-scale model that reveals dense middle crust and eclogitized lowermost crust within the rift. Mantle lithospheric density beneath the MCR is not anomalous, consistent with geochemical evidence that lithospheric mantle was not the primary source of rift-related magmas and suggesting that extension occurred in response to far-field stress rather than a hot mantle plume. Similarly, the subsequent inversion of normal faults resulted from changing far-field stress that exploited not only warm, recently faulted crust but also a gravitational potential energy low in the MCR. The success of this density modeling algorithm in the face of such apparently contradictory geophysical properties suggests that it may be applicable to a variety of tectonic and geodynamic problems. 

Visceral obesity: a "civilization syndrome".

PubMed

Björntorp, P

1993-05-01

The controversial question of the relationship between obesity and disease has been considerably clearer after the demonstration in several prospective, epidemiological studies that the subgroup of central, visceral obesity is particularly prone to develop cardiovascular disease, stroke, and non-insulin dependent diabetes mellitus. Visceral obesity is associated with multiple central endocrine aberrations. The hypothalamo-adrenal axis is apparently sensitive to stimuli, sex steroid hormone secretion blunted, and hyperandrogenicity is found in women. In addition, there seem to be signs of central dysfunctions in the regulation of hemodynamic factors after stress, and growth hormone secretion appears to be particularly blunted. Several of these endocrine abnormalities are associated with insulin resistance, particularly glycogen synthesis in muscle. Fiber composition with low type I/type II ratio might be secondary to the prevailing hyperinsulinemia, but low capillary density in muscle may well be of importance. In combination with elevated turn-over of free fatty acids (FFA) this will probably provide powerful mechanisms whereby insulin resistance is created. Portal FFA, from the highly lipolytic visceral depots may, in addition, affect hepatic metabolism to induce increased gluconeogenesis, production of very low density lipoproteins as well as to perhaps inhibit clearance of insulin. By these mechanisms a Metabolic Syndrome Visceral adipocytes seem to have a high density of several steroid hormone receptors, directing steroid hormone effects particularly to these depots. The net effect of cortisol is apparently a stimulation of lipid storage, with opposing effects of sex steroid hormones which also facilitate lipid mobilization, regulations most often found at the gene transcription level. Growth hormone inhibits cortisol effects on lipid accumulation, and amplifies the lipid mobilizing effects of steroid hormones. The combined perturbations of hormonal secretions will therefore probably direct triglycerides toward visceral depots. Circulatory and nervous regulatory mechanisms require, however, more attention. The multiple central endocrine and nervous aberrations of visceral obesity suggest neuroendocrine dysregulations, and have features characteristic of the hypothalamic arousal seen after certain types of stress, alcohol intake, and smoking. Such factors can be traced to subjects with visceral fat accumulation. Standardized stress, eliciting a "defeat reaction" in primates is followed by an apparently identical syndrome. This integrated picture of the multiple symptoms of visceral obesity is based on epidemiological, clinical, experimental, cellular, and molecular evidence. The ingredients of positive energy balance, including physical inactivity, stress, smoking, and alcohol consumption are frequent features of modern, urbanized society. Visceral obesity may therefore be an expression of a "Civilization Syndrome."

Controlled Growth of NiCo2O4 Nanorods and Ultrathin Nanosheets on Carbon Nanofibers for High-performance Supercapacitors

PubMed Central

Zhang, Genqiang; (David) Lou, Xiong Wen

2013-01-01

Two one-dimensional hierarchical hybrid nanostructures composed of NiCo2O4 nanorods and ultrathin nanosheets on carbon nanofibers (CNFs) are controllably synthesized through facile solution methods combined with a simple thermal treatment. The structure of NiCo2O4 can be easily controlled to be nanorods or nanosheets by using different additives in the synthesis. These two different nanostructures are evaluated as electrodes for high performance supercapacitors, in view of their apparent advantages, such as high electroactive surface area, ultrathin and porous features, robust mechanical strength, shorter ion and electron transport path. Their electrochemical performance is systematically studied, and both of these two hierarchical hybrid nanostructures exhibit high capacitance and excellent cycling stability. The remarkable electrochemical performance will undoubtedly make these hybrid structures attractive for high-performance supercapacitors with high power and energy densities. PMID:23503561

Fabrication and Characterization of Porous MgAl2O4 Ceramics via a Novel Aqueous Gel-Casting Process

PubMed Central

Yuan, Lei; Liu, Zongquan; Liu, Zhenli; He, Xiao; Ma, Beiyue; Zhu, Qiang; Yu, Jingkun

2017-01-01

A novel and aqueous gel-casting process has been successfully developed to fabricate porous MgAl2O4 ceramics by using hydratable alumina and MgO powders as raw materials and deionized water as hydration agent. The effects of different amounts of deionized water on the hydration properties, apparent porosity, bulk density, microstructure, pore size distribution and compressive strength of the samples were investigated. The results indicated that the porosity and the microstructure of porous MgAl2O4 ceramics were governed by the amounts of deionized water added. The porous structure was formed by the liberation of physisorbed water and the decomposition of hydration products such as bayerite, brucite and boehmite. After determining the addition amounts of deionized water, the fabricated porous MgAl2O4 ceramics had a high apparent porosity (52.5–65.8%), a small average pore size structure (around 1–3 μm) and a relatively high compressive strength (12–28 MPa). The novel aqueous gel-casting process with easy access is expected to be a promising candidate for the preparation of Al2O3-based porous ceramics. PMID:29189734

Using nonlinear programming to correct leakage and estimate mass change from GRACE observation and its application to Antarctica

NASA Astrophysics Data System (ADS)

Tang, Jingshi; Cheng, Haowen; Liu, Lin

2012-11-01

The Gravity Recovery And Climate Experiment (GRACE) mission has been providing high quality observations since its launch in 2002. Over the years, fruitful achievements have been obtained and the temporal gravity field has revealed the ongoing geophysical, hydrological and other processes. These discoveries help the scientists better understand various aspects of the Earth. However, errors exist in high degree and order spherical harmonics, which need to be processed before use. Filtering is one of the most commonly used techniques to smooth errors, yet it attenuates signals and also causes leakage of gravity signal into surrounding areas. This paper reports a new method to estimate the true mass change on the grid (expressed in equivalent water height or surface density). The mass change over the grid can be integrated to estimate regional or global mass change. This method assumes the GRACE-observed apparent mass change is only caused by the mass change on land. By comparing the computed and observed apparent mass change, the true mass change can be iteratively adjusted and estimated. The problem is solved with nonlinear programming (NLP) and yields solutions which are in good agreement with other GRACE-based estimates.

Analysis and Testing of High Temperature Fibrous Insulation for Reusable Launch Vehicles

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran

1999-01-01

Analytical models were developed to model the heat transfer through high-temperature fibrous insulation used in metallic thermal protection systems on reusable launch vehicles. The optically thick approximation was used to simulate radiation heat transfer through the insulation. Different models for gaseous conduction and solid conduction in the fibers, and for combining the various modes of heat transfer into a local, volume-averaged, thermal conductivity were considered. The governing heat transfer equations were solved numerically, and effective thermal conductivities were calculated from the steady-state results. An experimental apparatus was developed to measure the apparent thermal conductivity of insulation subjected to pressures, temperatures and temperature gradients representative of re-entry conditions for launch vehicles. The apparent thermal conductivity of an alumina fiber insulation was measured at nominal densities of 24, 48 and 96 kg/cu m. Data were obtained at environmental pressures from 10(exp 4) to 760 torr, with the insulation cold side maintained at room temperature and its hot side temperature varying up to 1000 C. The experimental results were used to evaluate the analytical models. The best analytical model resulted in effective thermal conductivity predictions that were within 8% of experimental results.

Maximum density echogram analysis : a novel approach to study the characteristics of oblique echoes observed by MARSIS/Mars Express

NASA Astrophysics Data System (ADS)

P, M.; Narukull, V. R.; Rao, S. V. B.

2017-12-01

The ionograms of the Mars Advance Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard Mars Express spacecraft show vertical and oblique echoes from the Martian ionosphere. The vertical echoes are from the normal ionosphere while the oblique echoes are believed to be from ionization bulges that occur in regions of strong vertical magnetic fields. These oblique echoes appear as downward facing hyperbolas when plotted as radargram (at 1.9 MHz), which is a color coded plot of apparent altitude as a function of time at a single frequency. In order to extract further information from these ionization bulges, we considered the peak density of the oblique echoes and plotted them in a format similar to a radargram and called it as a 'maximum density radargram' (MDR). Thus, an MDR shows the peak densities in entire ionization bulge. This analysis revealed several new aspects of the ionization bulges. We found that there is an asymmetry in the ionization bulge so that the density on one side of the hyperbola is different than the other side. In some cases, the density on the same side of the hyperbola, between the edge and apex, changes. Occasionally, the radargrams show only one side of the hyperbola, while the MDRs show a full hyperbola. When the density structures are repeatedly observed over the same location with a few days interval, the MDR analysis shows that the density inside the bulge varies from one pass to another. Finally, the ionization bulges in the MDR displays are clearly observed on several nights. Several of these nighttime bulges were not apparent in radargram analysis. These observations are discussed in the light of current understanding on the ionization bulges.

Gonadotropin stimulation of cyclic adenosine monophosphate and testosterone production without detectable high-affinity binding sites in purified Leydig cells from rat testis

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

Browne, E.S.; Bhalla, V.K.

1991-02-01

Rat testicular interstitial cells were separated by three different gradient-density procedures and, with each, two biochemically and morphologically distinct cell fractions were isolated. The lighter density cells in fraction-I bound iodine 125-labeled human chorionic gonadotropin (hCG) with high-affinity (apparent equilibrium dissociation constant, Kd, approximately 10{sup {minus} 10} M) without producing either cyclic adenosine monophosphate or testosterone in response to hormone action. The heavier-density cells displayed morphologic features typical of Leydig cells and produced cyclic adenosine monophosphate and testosterone in the presence of hCG without detectable {sup 125}I-labeled hCG high-affinity binding. These cell fractions were further characterized by studies using deglycosylatedmore » hCG, a known antagonist to hCG action. Cell concentration-dependent studies with purified Leydig cells revealed that maximal testosterone production was achieved when lower cell concentrations (0.5 x 10(6) cells/250 microliters) were used for in vitro hCG stimulation assays. Under these conditions, the {sup 125}I-labeled hCG binding was barely detectable (2.24 fmol; 2,698 sites/cell). Furthermore, these studies revealed that the hCG-specific binding in Leydig cells is overestimated by the classic method for nonspecific binding correction using excess unlabeled hormone. An alternate method is presented.« less

Solute-solvent interactions in solutions of 2-hydroxy-5-chloro-3-nitroacetophenone isonicotinoylhydrazone in N, N-dimethylformamide at 298-313 K according to ultrasonic and viscometric data

NASA Astrophysics Data System (ADS)

Dikkar, A. B.; Pethe, G. B.; Aswar, A. S.

2015-12-01

Density (ρ), speed of sound ( u), and viscosity (η), measurements have been carried on 2-hydroxy- 5-chloro-3-nitroacetophenone isonicotinoylhydrazone (HCNAIH) in N, N-dimethylformamide at 298.15, 303.15, 308.15, and 313.15 K. Adiabatic compressibility (βs), intermolecular free length ( L f), acoustic impedance ( Z), internal pressure ( P int), the apparent molar volume ( V w), limiting apparent molar volume ( V w 0), partial molar expansibility (wE 0), apparent molar adiabatic compressibility ( K w), limiting apparent molar adiabatic compressibility ( K w 0), viscosity B coefficients of Jones-Dole equation have been calculated. The activation free energy (Δμ 2 0 *) for viscous flow in solution have been calculated from B coefficient and partial molar volume data. The calculated parameters are used to interpret the solute-solvent interactions and structure forming/breaking ability of solute in DMF.

Ultrasonic speed, densities and viscosities of xylitol in water and in aqueous tyrosine and phenylalanine solutions at different temperatures

NASA Astrophysics Data System (ADS)

Ali, A.; Bidhuri, P.; Uzair, S.

2014-07-01

Ultrasonic speed u, densities ρ and viscosities η of xylitol in water and in 0.001 m aqueous l-tyrosine (Tyr) and l-phenylalanine (Phe) have been measured at different temperatures. From the density and ultrasonic speed measurements apparent molar isentropic compression κ_{φ}, apparent molar isentropic compressions at infinite dilution κ_{{S,φ}}0 , experimental slope S K , hydration number n H , transfer partial molar isentropic compressibility Δ_{tr} κ_{{S,φ}}0 of xylitol from water to aqueous Tyr and Phe have been obtained. From the viscosity data, B-coefficient and B-coefficient of transfer Δ tr B of xylitol from water to aqueous Phe and Tyr at different temperatures have also been estimated. Gibbs free energies of activation of viscous flow per mole of solvent Δ μ 1 0# and per mole of solute Δ μ 2 0# have been calculated by using Feakins transition state theory for the studied systems. The calculated parameters have been interpreted in terms of solute-solute and solute-solvent interactions and hydration behavior of xylitol.

Molecular dynamics simulation of the plastic behavior anisotropy of shock-compressed monocrystal nickel

NASA Astrophysics Data System (ADS)

Chen, Ya-Zhou; Zhou, Liu-Cheng; He, Wei-Feng; Sun, Yu; Li, Ying-Hong; Jiao, Yang; Luo, Si-Hai

2017-01-01

Molecular dynamics simulations were used to study the plastic behavior of monocrystalline nickel under shock compression along the [100] and [110] orientations. The shock Hugoniot relation, local stress curve, and process of microstructure development were determined. Results showed the apparent anisotropic behavior of monocrystalline nickel under shock compression. The separation of elastic and plastic waves was also obvious. Plastic deformation was more severely altered along the [110] direction than the [100] direction. The main microstructure phase transformed from face-centered cubic to body-centered cubic and generated a large-scale and low-density stacking fault along the family of { 111 } crystal planes under shock compression along the [100] direction. By contrast, the main mechanism of plastic deformation in the [110] direction was the nucleation of the hexagonal, close-packed phase, which generated a high density of stacking faults along the [110] and [1̅10] directions.

Optical analogues of the Newton-Schrödinger equation and boson star evolution.

PubMed

Roger, Thomas; Maitland, Calum; Wilson, Kali; Westerberg, Niclas; Vocke, David; Wright, Ewan M; Faccio, Daniele

2016-11-14

Many gravitational phenomena that lie at the core of our understanding of the Universe have not yet been directly observed. An example in this sense is the boson star that has been proposed as an alternative to some compact objects currently interpreted as being black holes. In the weak field limit, these stars are governed by the Newton-Schrodinger equation. Here we present an optical system that, under appropriate conditions, identically reproduces such equation in two dimensions. A rotating boson star is experimentally and numerically modelled by an optical beam propagating through a medium with a positive thermal nonlinearity and is shown to oscillate in time while also stable up to relatively high densities. For higher densities, instabilities lead to an apparent breakup of the star, yet coherence across the whole structure is maintained. These results show that optical analogues can be used to shed new light on inaccessible gravitational objects.

Optical analogues of the Newton–Schrödinger equation and boson star evolution

PubMed Central

Roger, Thomas; Maitland, Calum; Wilson, Kali; Westerberg, Niclas; Vocke, David; Wright, Ewan M.; Faccio, Daniele

2016-01-01

Many gravitational phenomena that lie at the core of our understanding of the Universe have not yet been directly observed. An example in this sense is the boson star that has been proposed as an alternative to some compact objects currently interpreted as being black holes. In the weak field limit, these stars are governed by the Newton–Schrodinger equation. Here we present an optical system that, under appropriate conditions, identically reproduces such equation in two dimensions. A rotating boson star is experimentally and numerically modelled by an optical beam propagating through a medium with a positive thermal nonlinearity and is shown to oscillate in time while also stable up to relatively high densities. For higher densities, instabilities lead to an apparent breakup of the star, yet coherence across the whole structure is maintained. These results show that optical analogues can be used to shed new light on inaccessible gravitational objects. PMID:27841261

Optical analogues of the Newton-Schrödinger equation and boson star evolution

NASA Astrophysics Data System (ADS)

Roger, Thomas; Maitland, Calum; Wilson, Kali; Westerberg, Niclas; Vocke, David; Wright, Ewan M.; Faccio, Daniele

2016-11-01

Many gravitational phenomena that lie at the core of our understanding of the Universe have not yet been directly observed. An example in this sense is the boson star that has been proposed as an alternative to some compact objects currently interpreted as being black holes. In the weak field limit, these stars are governed by the Newton-Schrodinger equation. Here we present an optical system that, under appropriate conditions, identically reproduces such equation in two dimensions. A rotating boson star is experimentally and numerically modelled by an optical beam propagating through a medium with a positive thermal nonlinearity and is shown to oscillate in time while also stable up to relatively high densities. For higher densities, instabilities lead to an apparent breakup of the star, yet coherence across the whole structure is maintained. These results show that optical analogues can be used to shed new light on inaccessible gravitational objects.

High dielectric constant and energy density induced by the tunable TiO2 interfacial buffer layer in PVDF nanocomposite contained with core-shell structured TiO2@BaTiO3 nanoparticles

NASA Astrophysics Data System (ADS)

Hu, Penghao; Jia, Zhuye; Shen, Zhonghui; Wang, Peng; Liu, Xiaoru

2018-05-01

To realize application in high-capacity capacitors and portable electric devices, large energy density is eagerly desired for polymer-based nanocomposite. The core-shell structured nanofillers with inorganic buffer layer are recently supposed to be promising in improving the dielectric property of polymer nanocomposite. In this work, core-shell structured TO@BT nanoparticles with crystalline TiO2 buffer layer coated on BaTiO3 nanoparticle were fabricated via solution method and heat treatment. The thickness of the TO buffer layer can be tailored by modulating the additive amount of the titanate coupling agent in preparation process, and the apparent dielectric properties of nanocomposite are much related to the thickness of the TO layer. The relatively thin TO layer prefer to generate high polarization to increase dielectric constant while the relatively thick TO layer would rather to homogenize field to maintain breakdown strength. Simulation of electric field distribution in the interfacial region reveals the improving effect of the TO buffer layer on the dielectric properties of nanocomposite which accords with the experimental results well. The optimized nanoparticle TO@BT-2 with a mean thickness of 3-5 nm buffer layer of TO is effective in increasing both the ε and Eb in the PVDF composite film. The maximal discharged energy density of 8.78 J/cm3 with high energy efficiency above 0.6 is obtained in TO@BT-2/PVDF nanocomposite with 2.5 vol% loading close to the breakdown strength of 380 kV/mm. The present study demonstrates the approach to optimize the structure of core-shell nanoparticles by modulating buffer layer and provides a new way to further enlarge energy density in polymer nanocomposite.

Large-scale galaxy flow from a non-gravitational impulse

NASA Technical Reports Server (NTRS)

Hogan, Craig J.; Kaiser, Nick

1989-01-01

A theory is presented describing linear perturbations of an expanding universe containing multiple, independently perturbed, collisionless, gravitationally coupled constituents. Solutions are found in the limit where one initially unperturbed component dominates the total density. The theory is applied to perturbations generated by a nongravitational process in one or more of the light components, as would occur in explosive or radiation-pressure-instability theories of galaxy formation. The apparent dynamical density parameter and correlations between density and velocity amplitude for various populations, are evaluated as a function of cosmic scale factor.

Modeled Seasonal Variations of Firn Density Induced by Steady State Surface Air Temperature Cycle

NASA Technical Reports Server (NTRS)

Jun, Li; Zwally, H. Jay; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Seasonal variations of firn density in ice-sheet firn layers have been attributed to variations in deposition processes or other processes within the upper firn. A recent high-resolution (mm scale) density profile, measured along a 181 m core from Antarctica, showed small-scale density variations with a clear seasonal cycle that apparently was not-related to seasonal variations in deposition or known near-surface processes (Gerland and others 1999). A recent model of surface elevation changes (Zwally and Li, submitted) produced a seasonal variation in firn densification, and explained the seasonal surface elevation changes observed by satellite radar altimeters. In this study, we apply our 1-D time-dependent numerical model of firn densification that includes a temperature-dependent formulation of firn densification based on laboratory measurements of grain growth. The model is driven by a steady-state seasonal surface temperature and a constant accumulation rate appropriate for the measured Antarctic ice core. The modeled seasonal variations in firn density show that the layers of snow deposited during spring to mid-summer with the highest temperature history compress to the highest density, and the layers deposited during later summer to autumn with the lowest temperature history compress to the lowest density. The initial amplitude of the seasonal difference of about 0.13 reduces to about 0.09 in five years and asymptotically to 0.92 at depth, which is consistent with the core measurements.

Correlation of wave propagation modes in helicon plasma with source tube lengths

NASA Astrophysics Data System (ADS)

Niu, Chen; Zhao, Gao; Wang, Yu; Liu, Zhongwei; Chen, Qiang

2017-01-01

Helicon wave plasma demonstrates lots of advantages in high coupling efficiency, high density, and low magnetic field. However, the helicon wave plasma still meets challenges in applications of material deposition, surface treatment, and electromagnetic thrusters owing to the changeable coupled efficiency and the remarkable non-uniformity. In this paper, we explore the wave propagation characterization by the B-dot probe in various lengths of source tubes. We find that in a long source tube the standing wave appears under the antenna zone, while the traveling wave is formed out of the antenna region. The apparent modulation of wave amplitude is formed in upstream rather than in downstream of the antenna. In a short source tube, however, there is only standing wave propagation.

Spatio-temporal pattern of viral meningitis in Michigan, 1993-2001

NASA Astrophysics Data System (ADS)

Greene, Sharon K.; Schmidt, Mark A.; Stobierski, Mary Grace; Wilson, Mark L.

2005-05-01

To characterize Michigan's high viral meningitis incidence rates, 8,803 cases from 1993-2001 were analyzed for standard epidemiological indices, geographic distribution, and spatio-temporal clusters. Blacks and infants were found to be high-risk groups. Annual seasonality and interannual variability in epidemic magnitude were apparent. Cases were concentrated in southern Michigan, and cumulative incidence was correlated with population density at the county level (r=0.45, p<0.001). Kulldorff's Scan test identified the occurrence of spatio-temporal clusters in Lower Michigan during July-October 1998 and 2001 (p=0.01). More extensive data on cases, laboratory isolates, sociodemographics, and environmental exposures should improve detection and enhance the effectiveness of a Space-Time Information System aimed at prevention.

Dynamics of 17alpha-ethynylestradiol exposure in rainbow trout (Oncorhynchus mykiss): absorption, tissue distribution, and hepatic gene expression pattern.

PubMed

Skillman, Ann D; Nagler, James J; Hook, Sharon E; Small, Jack A; Schultz, Irvin R

2006-11-01

17alpha-Ethynylestradiol (EE2) is a synthetic estrogen identified in sewage effluents. To understand better the absorption kinetics of EE2 and the induction of vitellogenin (VTG) and estrogen receptor alpha (ERalpha) mRNA, we subjected male rainbow trout (Onchorynchus mykiss) to continuous water exposures of 125 ng/L of EE2 for up to 61 d. Trout were either repetitively sampled for blood plasma or serially killed at selected time intervals. Vitellogenin, ERalpha mRNA, and EE2 were measured using enzyme-linked immunosorbent assay and using quantitative polymerase chain reaction and gas chromatography-mass spectrometry, respectively. In separate experiments, trout were exposed to EE2 for 7 d, and hepatic gene expression was assessed using a low- and high-density cDNA microarray. The EE2 was rapidly absorbed by the trout, with an apparent equilibrium at 16 h in plasma and liver. The ERalpha mRNA levels also increased rapidly, reaching near-peak levels by 48 h. In contrast, plasma levels of VTG continuously increased for 19 d. After 61 d, tissues with the highest levels of VTG were the liver, kidney, and testes. Microarray-based gene expression studies provided unexpected results. In some cases, known estrogen-responsive genes (e.g., ERalpha) were unresponsive, whereas many of the genes that have no apparent link to estrogen function or EE2 toxicity were significantly altered in expression. Of the two microarray approaches tested in the present study, the high-density array appeared to be superior because of the improved quality of the hybridization signal and the robustness of the response in terms of the number of genes identified as being EE2 responsive.

DYNAMICS OF 17α-ETHYNYLESTRADIOL EXPOSURE IN RAINBOW TROUT (ONCORHYNCHUS MYKISS): ABSORPTION, TISSUE DISTRIBUTION, AND HEPATIC GENE EXPRESSION PATTERN

PubMed Central

Skillman, Ann D.; Nagler, James J.; Hook, Sharon E.; Small, Jack A.; Schultz, Irvin R.

2008-01-01

17α-Ethynylestradiol (EE2) is a synthetic estrogen identified in sewage effluents. To understand better the absorption kinetics of EE2 and the induction of vitellogenin (VTG) and estrogen receptor α (ERα) mRNA, we subjected male rainbow trout (Onchorynchus mykiss) to continuous water exposures of 125 ng/L of EE2 for up to 61 d. Trout were either repetitively sampled for blood plasma or serially killed at selected time intervals. Vitellogenin, ERα mRNA, and EE2 were measured using enzyme-linked immunosorbent assay and using quantitative polymerase chain reaction and gas chromatography–mass spectrometry, respectively. In separate experiments, trout were exposed to EE2 for 7 d, and hepatic gene expression was assessed using a low- and high-density cDNA microarray. The EE2 was rapidly absorbed by the trout, with an apparent equilibrium at 16 h in plasma and liver. The ERα mRNA levels also increased rapidly, reaching near-peak levels by 48 h. In contrast, plasma levels of VTG continuously increased for 19 d. After 61 d, tissues with the highest levels of VTG were the liver, kidney, and testes. Microarray-based gene expression studies provided unexpected results. In some cases, known estrogen-responsive genes (e.g., ERα) were unresponsive, whereas many of the genes that have no apparent link to estrogen function or EE2 toxicity were significantly altered in expression. Of the two microarray approaches tested in the present study, the high-density array appeared to be superior because of the improved quality of the hybridization signal and the robustness of the response in terms of the number of genes identified as being EE2 responsive. PMID:17089724

Selected physical properties of rocks from the Baid al Jimalah West tungsten deposit, Kingdom of Saudi Arabia, and recommendations for geophysical surveys

USGS Publications Warehouse

Gettings, M.E.

1983-01-01

Bulk density and magnetic susceptibility of 11 outcrop samples representing the Proterozoic lithologic units at the Baid al Jimalah West tungsten deposit, Kingdom of Saudi Arabia were measured. Induced polarization response, apparent resistivity, and electromagnetic conductivity were determined for four specimens of the sample suite. Measurements show that there is a negative density contrast of about -0.17 g-cm^-3 between metasedimentary rocks of the Murdama group and the Bald al Jimalah graaite and that this contrast decreases with increasing mineralization of the granite. Similarly, the bulk magnetic susceptibility of the granite is about one-third that of the Murdama rocks for this sample suite; however, magnetic susceptibility increases with increasing mineralization in the granite specimens. Electromagnetic conductivities are uniformly low, in part because the specimens are weathered, but probably also because intense silicification accompanies the mineralization. Induced polarization chargeability increases in the granitic specimens with increasing mineralization and reflects higher percentages of sulfide minerals. Chargeability for the mineralized rocks is about four times higher than for the Murdama host rocks, and apparent resistivity values are about one-fifth the values of host rocks. Based on these results, it is recommended that during reconnaissance exploration of the area 15 detailed high-precision gravity profiles at 10 m to 50 m station spacing and eight induced polarization dipole-dipole profiles at 25 m dipole spacing and maximum 'n' of 6 be measured. To help define subsurface structure, a high-precision, ground-magnetic survey (map at 2-gamma contour interval) and a four-channel gamma ray spectrometric survey on a 25x50 m grid covering the area of the profiles are recommended.

Biomechanics of North Atlantic Right Whale Bone: Mandibular Fracture as a Fatal Endpoint for Blunt Vessel-Whale Collision Modeling

DTIC Science & Technology

2007-09-01

Calibration curves for CT number ( Hounsfield unit )s vs. mineral density (g /c c...12 3 Figure 3.4. Calibration curves for CT number ( Hounsfield units ) vs. apparent density (g /c c...named Hounsfield units (HU) after Sir Godfrey Hounsfield . The CT number is K([i- iw]/pw), where K = a magnifying constant, which depends on the make of CT

The 2009-2010 MU radar head echo observation programme for sporadic and shower meteors: radiant densities and diurnal rates

NASA Astrophysics Data System (ADS)

Kero, J.; Szasz, C.; Nakamura, T.; Meisel, D. D.; Ueda, M.; Fujiwara, Y.; Terasawa, T.; Nishimura, K.; Watanabe, J.

2012-09-01

The aim of this paper is to give an overview of the monthly meteor head echo observations (528.8 h) conducted between 2009 June and 2010 December using the Shigaraki Middle and Upper atmosphere radar in Japan (34°.85 N, 136°.10 E). We present diurnal detection rates and radiant density plots from 18 separate observational campaigns, each lasting for at least one diurnal cycle. Our data comprise more than 106 000 meteors. All six recognized apparent sporadic meteor sources are discernable and their average orbital distributions are presented in terms of geocentric velocity, semimajor axis, inclination and eccentricity. The north and south apex have radiant densities an order of magnitude higher than other apparent source regions. The diurnal detection rates show clear seasonal dependence. The main cause of the seasonal variation is the tilt of the Earth's axis, causing the elevation of the Earth's apex above the local horizon to change as the Earth revolves around the Sun. Yet, the meteor rate variation is not symmetric with respect to the equinoxes. When comparing the radiant density at different times of the year, and thus at different solar longitudes along the Earth's orbit, we have found that the north and south apex source regions fluctuate in strength.

Initial stage corrosion of nanocrystalline copper particles and thin films

NASA Astrophysics Data System (ADS)

Tao, Weimin

1997-12-01

Corrosion behavior is an important issue in nanocrystalline materials research and development. A very fine grain size is expected to have significant effects on the corrosion resistance of these novel materials. However, both the macroscopic corrosion properties and the corresponding structure evolution during corrosion have not been fully studied. Under such circumstances, conducting fundamental research in this area is important and necessary. In this study, high purity nanocrystalline and coarse-grained copper were selected as our sample material, sodium nitrite aqueous solution at room temperature and air at a high temperature were employed as corrosive environments. The weight loss testing and electrochemical methods were used to obtain the macroscopic corrosion properties, whereas the high resolution transmission electron microscope was employed for the structure analysis. The weight loss tests indicate that the corrosion rate of nanocrystalline copper is about 5 times higher than that of coarse-grained copper at the initial stage of corrosion. The electrochemical measurements show that the corrosion potential of the nanocrystalline copper has a 230 mV negative shift in comparison with that of the coarse-grained copper. The nanocrystalline copper also exhibits a significantly higher exchange current density than the coarse-grained copper. High resolution TEM revealed that the surface structure changes at the initial stage of corrosion. It was found that the first copper oxide layer formed on the surface of nanocrystalline copper thin film contains a large density of high angle grain boundaries, whereas that formed on the surface of coarse-grained copper shows highly oriented oxide nuclei and appears to show a strong tendency for forming low angle grain boundaries. A correlation between the macroscopic corrosion properties and the structure characteristics is proposed for the nanocrystalline copper based on the concept of the "apparent" exchange current density associated with mass transport of ions in the oxide layer. A hypothesis is developed that the high corrosion rate of the nanocrystalline copper is closely associated with the structure of the copper oxide layer. Therefore, a high "apparent" exchange current density for the nanocrystalline copper is associated with the high angle grain boundary structure in the initial oxide layer. Additional structure analysis was also carried out: (a) High resolution TEM imaging has provided a cross sectional view of the epitaxial interface between nanocrystalline copper and copper (I) oxide and explicitly discloses the presence of interface defects such as misfit dislocations. Based on this observation, a mechanism was proposed to explain the Cu/Cusb2O interface misfit accommodation. This appears to be the first time this interface has been directly examined. (b) A nanocrystalline analogue to a cross-section of Gwathmey's copper single crystal sphere was revealed by high resolution TEM imaging. A partially oxidized nanocrystalline copper particle is used to examine the variation of the Cu/Cusb2O orientation relationship with respect to changes in surface orientation. A new orientation relationship, Cu (011) //Cusb2O (11), ˜ Cu(011)//Cusb2O(111), was found for the oxidation of nanocrystalline copper.

Carbohydrate Partitioning and the Capacity of Apparent Nitrogen Fixation of Soybean Plants Grown Outdoors

PubMed Central

Millhollon, Eddie P.; Williams, Larry E.

1986-01-01

Patterns of leaf carbohydrate partitioning and nodule activity in soybean plants grown under natural conditions and the irradiance level required to produce sufficient carbohydrate to obtain maximum rates of apparent N2-fixation (acetylene reduction) were measured. Soybean plants, grown outdoors, maintained constant levels of leaf soluble sugars while leaf starch pools varied diurnally. When root temperature was kept at 25°C and shoot temperature was allowed to vary with ambient temperature, the plants maintained constant rates of apparent N2-fixation and root+nodule respiration. Results from a second experiment, in which the entire plant was kept at 25°C, were similar to those of the first experiment. Shoot carbon exchange rate of plants from the second experiment was light saturated at photosynthetic photon flux densities between 400 and 600 micromoles per square meter per second. When plants were subjected to an extended 40-hour dark period to deplete carbohydrate reserves, apparent N2-fixation was unaffected during the first 10 hours of darkness, decreased rapidly between 10 and 16 hours, and plateaued at one-third the initial level thereafter. After the extended dark period, plants were exposed to photosynthetic photon flux density from 200 to 1000 micromoles per square meter per second for 10 hours. Photosynthetic photon flux densities of 200 micromoles per square meter per second and greater resulted in maximum leaf soluble sugar content and nodule activity. Leaf starch content increased with irradiance levels up to 600 micromoles per square meter per second with no further increase at higher irradiance levels. Results presented here indicate that maximum nodule activity occurs at irradiance levels that do not saturate the plant's photosynthetic apparatus. This response would allow for maximum N2-fixation to occur in a nodulated legume during periods of inclement weather. PMID:16664789

Effect of a novel phytase on growth performance, apparent metabolizable energy, and the availability of minerals and amino acids in a low-phosphorus corn-soybean meal diet for broilers.

PubMed

Rutherfurd, S M; Chung, T K; Thomas, D V; Zou, M L; Moughan, P J

2012-05-01

The addition of microbial phytase to diets for broiler chickens has been shown to improve the availability of phytate P, total P, some other minerals, and amino acids. In this study, the effect of a novel microbial phytase expressed by synthetic genes in Aspergillus oryzae on amino acid and mineral availability was assessed. Phytase was incorporated (1,000 and 2,000 U/kg) into low-P corn-soybean meal-based diets for broilers. Broilers received the experimental diets for 3 wk, and excreta were collected from d 18 to 21 for the determination of AME and mineral retention. On the 22nd day, the broilers were killed and the left leg removed and ileal digesta collected. Ileal phytate P and total P absorption, ileal amino acid digestibility, as well as the bone mineral content and bone mineral density were determined. Ileal phytate P absorption and absorbed phytate P content of the low-P corn-soybean meal diet were significantly (P < 0.05) higher after dietary inclusion of the novel phytase (49-60% and 65-77% higher, respectively). Apparent ileal total P absorption and apparent total P retention was 12 to 16% and 14 to 19% higher (P < 0.05), respectively, after dietary inclusion of phytase. The bone mineral content and bone mineral density in the tibia were 32 to 35% and 19 to 21% higher (P < 0.05), respectively, after dietary phytase inclusion. The apparent ileal digestibility of threonine, tyrosine, and histidine increased significantly (P < 0.05) by 14, 9, and 7%, respectively, after dietary inclusion of microbial phytase. Overall, the inclusion of a novel microbial phytase into a low-P corn-soybean meal diet for broiler chickens greatly increased phytate P and total P absorption, bone mineral content and density, as well as the digestibility of some amino acids.

Effect of molecular structure on the hydration of structurally related antidepressant drugs

NASA Astrophysics Data System (ADS)

Cheema, M. A.; Taboada, P.; Barbosa, S.; Siddiq, M.; Mosquera, V.

Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic cationic antidepressant drugs butriptyline and doxepin hydrochlorides have been determined from density and ultrasound velocity measurements in the temperature range 20-50°C. Critical concentrations for aggregation of these drugs were obtained from ultrasound velocity measurements. Negative deviations from the Debye-Hückel limiting law of the apparent molal volume were obtained from both drugs in all temperature ranges, except for doxepin at 50°C, which provides evidence of no pre-association at concentrations below the critical concentration. Apparent molal adiabatic compressibilities of the aggregates formed by these drugs were typical of those corresponding for an aggregate formed by a stacking process.

Potential energy landscape of the apparent first-order phase transition between low-density and high-density amorphous ice.

PubMed

Giovambattista, Nicolas; Sciortino, Francesco; Starr, Francis W; Poole, Peter H

2016-12-14

The potential energy landscape (PEL) formalism is a valuable approach within statistical mechanics to describe supercooled liquids and glasses. Here we use the PEL formalism and computer simulations to study the pressure-induced transformations between low-density amorphous ice (LDA) and high-density amorphous ice (HDA) at different temperatures. We employ the ST2 water model for which the LDA-HDA transformations are remarkably sharp, similar to what is observed in experiments, and reminiscent of a first-order phase transition. Our results are consistent with the view that LDA and HDA configurations are associated with two distinct regions (megabasins) of the PEL that are separated by a potential energy barrier. At higher temperature, we find that low-density liquid (LDL) configurations are located in the same megabasin as LDA, and that high-density liquid (HDL) configurations are located in the same megabasin as HDA. We show that the pressure-induced LDL-HDL and LDA-HDA transformations occur along paths that interconnect these two megabasins, but that the path followed by the liquid is different from the path followed by the amorphous solid. At higher pressure, we also study the liquid-to-ice-VII first-order phase transition, and find that the behavior of the PEL properties across this transition is qualitatively similar to the changes found during the LDA-HDA transformation. This similarity supports the interpretation that the LDA-HDA transformation is a first-order phase transition between out-of-equilibrium states. Finally, we compare the PEL properties explored during the LDA-HDA transformations in ST2 water with those reported previously for SPC/E water, for which the LDA-HDA transformations are rather smooth. This comparison illuminates the previous work showing that, at accessible computer times scales, a liquid-liquid phase transition occurs in the case of ST2 water, but not for SPC/E water.

Potential energy landscape of the apparent first-order phase transition between low-density and high-density amorphous ice

NASA Astrophysics Data System (ADS)

Giovambattista, Nicolas; Sciortino, Francesco; Starr, Francis W.; Poole, Peter H.

2016-12-01

The potential energy landscape (PEL) formalism is a valuable approach within statistical mechanics to describe supercooled liquids and glasses. Here we use the PEL formalism and computer simulations to study the pressure-induced transformations between low-density amorphous ice (LDA) and high-density amorphous ice (HDA) at different temperatures. We employ the ST2 water model for which the LDA-HDA transformations are remarkably sharp, similar to what is observed in experiments, and reminiscent of a first-order phase transition. Our results are consistent with the view that LDA and HDA configurations are associated with two distinct regions (megabasins) of the PEL that are separated by a potential energy barrier. At higher temperature, we find that low-density liquid (LDL) configurations are located in the same megabasin as LDA, and that high-density liquid (HDL) configurations are located in the same megabasin as HDA. We show that the pressure-induced LDL-HDL and LDA-HDA transformations occur along paths that interconnect these two megabasins, but that the path followed by the liquid is different from the path followed by the amorphous solid. At higher pressure, we also study the liquid-to-ice-VII first-order phase transition, and find that the behavior of the PEL properties across this transition is qualitatively similar to the changes found during the LDA-HDA transformation. This similarity supports the interpretation that the LDA-HDA transformation is a first-order phase transition between out-of-equilibrium states. Finally, we compare the PEL properties explored during the LDA-HDA transformations in ST2 water with those reported previously for SPC/E water, for which the LDA-HDA transformations are rather smooth. This comparison illuminates the previous work showing that, at accessible computer times scales, a liquid-liquid phase transition occurs in the case of ST2 water, but not for SPC/E water.

Systematic temporal patterns in the relationship between housing development and forest bird biodiversity.

PubMed

Pidgeon, Anna M; Flather, Curtis H; Radeloff, Volker C; Lepczyk, Christopher A; Keuler, Nicholas S; Wood, Eric M; Stewart, Susan I; Hammer, Roger B

2014-10-01

As people encroach increasingly on natural areas, one question is how this affects avian biodiversity. The answer to this is partly scale-dependent. At broad scales, human populations and biodiversity concentrate in the same areas and are positively associated, but at local scales people and biodiversity are negatively associated with biodiversity. We investigated whether there is also a systematic temporal trend in the relationship between bird biodiversity and housing development. We used linear regression to examine associations between forest bird species richness and housing growth in the conterminous United States over 30 years. Our data sources were the North American Breeding Bird Survey and the 2000 decennial U.S. Census. In the 9 largest forested ecoregions, housing density increased continually over time. Across the conterminous United States, the association between bird species richness and housing density was positive for virtually all guilds except ground nesting birds. We found a systematic trajectory of declining bird species richness as housing increased through time. In more recently developed ecoregions, where housing density was still low, the association with bird species richness was neutral or positive. In ecoregions that were developed earlier and where housing density was highest, the association of housing density with bird species richness for most guilds was negative and grew stronger with advancing decades. We propose that in general the relationship between human settlement and biodiversity over time unfolds as a 2-phase process. The first phase is apparently innocuous; associations are positive due to coincidence of low-density housing with high biodiversity. The second phase is highly detrimental to biodiversity, and increases in housing density are associated with biodiversity losses. The long-term effect on biodiversity depends on the final housing density. This general pattern can help unify our understanding of the relationship of human encroachment and biodiversity response. © 2014 Society for Conservation Biology.

Implications of crater distributions on Venus

NASA Technical Reports Server (NTRS)

Kaula, W. M.

1993-01-01

The horizontal locations of craters on Venus are consistent with randomness. However, (1) randomness does not make crater counts useless for age indications; (2) consistency does not imply necessity or optimality; and (3) horizontal location is not the only reference frame against which to test models. Re (1), the apparent smallness of resurfacing areas means that a region on the order of one percent of the planet with a typical number of craters, 5-15, will have a range of feature ages of several 100 My. Re (2), models of resurfacing somewhat similar to Earth's can be found that are also consistent and more optimal than random: i.e., resurfacing occurring in clusters, that arise and die away in lime intervals on the order of 50 My. These agree with the observation that there are more areas of high crater density, and fewer of moderate density, than optimal for random. Re (3), 799 crater elevations were tested; there are more at low elevations and fewer at high elevations than optimal for random: i.e., 54.6 percent below the median. Only one of 40 random sets of 799 was as extreme.

Incommensurate Phonon Anomaly and the Nature of Charge Density Waves in Cuprates

DOE PAGES

Miao, H.; Ishikawa, D.; Heid, R.; ...

2018-01-18

While charge density wave (CDW) instabilities are ubiquitous to superconducting cuprates, the different ordering wave vectors in various cuprate families have hampered a unified description of the CDW formation mechanism. Here, we investigate the temperature dependence of the low-energy phonons in the canonical CDW-ordered cuprate La 1.875Ba 0.125CuO 4. We discover that the phonon softening wave vector associated with CDW correlations becomes temperature dependent in the high-temperature precursor phase and changes from a wave vector of 0.238 reciprocal lattice units (r.l.u.) below the ordering transition temperature to 0.3 r.l.u. at 300 K. This high-temperature behavior also shows that “214”-type cupratesmore » can host CDW correlations at a similar wave vector to previously reported CDW correlations in non-214-type cuprates such as YBa 2Cu 3O 6+δ. This indicates that cuprate CDWs may arise from the same underlying instability despite their apparently different low-temperature ordering wave vectors.« less

Synthesis of graphene aerogel for adsorption of bisphenol A

NASA Astrophysics Data System (ADS)

Trinh, Truong Thi Phuong Nguyet Xuan; Long, Nguyen Huynh Bach Son; Quang, Dong Thanh; Hieu, Nguyen Huu

2018-04-01

In this research, graphene aerogel (GA) was synthesized by chemical reduction method using ethylene diamine as a reducing agent. The morphology and properties of GA were characterized by calculating apparent density, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and Brunauer-Emmett-Teller (BET) specific surface area. High-performance liquid chromatography (HPLC) was used to quantify the amount of the residual bisphenol A (BPA) concentration. The analysis results showed that GA exhibited low density ranging from 4-8 mg/cm3, hydrophobicity, high porosity, and specific surface area of 1883 m2/g according to BET. The obtained GA was used as an adsorbent for BPA. The effects of pH, contact time, and initial BPA concentration on the adsorption were investigated. The adsorption equilibrium time could be reached within 240 minutes. The adsorption data were well-fitted to pseudo-second-order kinetic equation and Langmuir isotherm model. The maximum adsorption capacity of GA for BPA calculated by the Langmuir model was 185.185 mg/g at pH 7. Accordingly, GA could be considered as promising adsorbents for BPA in water.

Incommensurate Phonon Anomaly and the Nature of Charge Density Waves in Cuprates

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

Miao, H.; Ishikawa, D.; Heid, R.

While charge density wave (CDW) instabilities are ubiquitous to superconducting cuprates, the different ordering wave vectors in various cuprate families have hampered a unified description of the CDW formation mechanism. Here, we investigate the temperature dependence of the low-energy phonons in the canonical CDW-ordered cuprate La 1.875Ba 0.125CuO 4. We discover that the phonon softening wave vector associated with CDW correlations becomes temperature dependent in the high-temperature precursor phase and changes from a wave vector of 0.238 reciprocal lattice units (r.l.u.) below the ordering transition temperature to 0.3 r.l.u. at 300 K. This high-temperature behavior also shows that “214”-type cupratesmore » can host CDW correlations at a similar wave vector to previously reported CDW correlations in non-214-type cuprates such as YBa 2Cu 3O 6+δ. This indicates that cuprate CDWs may arise from the same underlying instability despite their apparently different low-temperature ordering wave vectors.« less

Quasar evolution - Not a deficit at 'low' redshifts

NASA Technical Reports Server (NTRS)

Avni, Y.; Schiller, N.

1983-01-01

Hawkins and Stewart (1981) have argued that the conventional interpretation of complete quasar samples in terms of a cosmological evolution of quasars is not unique. It has been suggested that these data can also be interpreted as due to a deficit in the density of quasars. Hawkins and Stewart have argued that such a deficit could be either apparent, due to an observational selection which biases against the inclusion of low-z quasars, or real, due to a lower density of quasars at low redshifts. The present investigation is concerned with this new interpretation. In order to test the interpretation of Hawkins and Stewart (1981) as directly as possible, the investigation is restricted to the same type of quasar samples considered by Hawkins and Stewart. It is found that the obtained results contradict clearly Hawkins and Stewart's assertion. Quasar evolution is not just a deficit of quasars at low redshifts, neither apparent nor real.

The effect of baking and enzymatic treatment on the structural properties of wheat starch.

PubMed

Fuentes, Catalina; Zielke, Claudia; Prakash, Manish; Kumar, Puneeth; Peñarrieta, J Mauricio; Eliasson, Ann-Charlotte; Nilsson, Lars

2016-12-15

In this study, bread was baked with and without the addition of α-amylase. Starch was extracted from the baked bread and its molecular properties were characterized using (1)H NMR and asymmetric flow field-flow fractionation (AF4) connected to multi-angle light scattering (MALS) and other detectors. The approach allows determination of molar mass, root- mean-square radius and apparent density as well as the average degree of branching of amylopectin. The results show that starch size and structure is affected as a result of the baking process. The effect is larger when α-amylase is added. The changes include both a decrease molar mass and size as well as an increase in apparent density. Moreover, an increase in average degree of branching and the number of reducing ends H-1(β-r) and H-1(α-r) can be observed. Copyright © 2016. Published by Elsevier Ltd.

Study of intermolecular interactions in binary mixtures of 2'-chloro-4-methoxy-3-nitro benzil in various solvents and at different concentrations by the measurement of acoustic properties.

PubMed

Nithya, G; Thanuja, B; Kanagam, Charles C

2013-01-01

Density (ρ), ultrasonic velocity (u), adiabatic compressibility (β), apparent molar volume (Ø), acoustic impedance (Z), intermolecular free length (L(f)), relative association (RA) of binary mixtures of 2'-chloro-4-methoxy-3-nitro benzil (abbreviated as 2CBe) in ethanol, acetonitrile, chloroform, dioxane and benzene were measured at different concentrations at 298 K. Several useful parameters such as excess density, excess ultrasonic velocity, excess adiabatic compressibility, excess apparent molar volume, excess acoustic impedance and excess intermolecular free length have been calculated. These parameters are used to explain the nature of intermolecular interactions taking place in the binary mixture. The above study is useful in understanding the solute--solvent interactions occurring in different concentrations at room temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

Thysanoptera infestation on skin and periorbital cellulitis in ostriches (Struthio camelus) aged 14 months.

PubMed

Cooper, R G

2007-06-01

To report the infestation of Thysanoptera (Limothrips denticornis) on ostriches (Struthio camelus) and to determine their relative density. A farm in Poland was studied on which ostriches aged 14 months were severely infested with L. denticornis (thrips). Thrips were collected and their density on the neck, torso and legs (10 cm2) of 85 ostriches determined at 0600, 1200 and 1800 h, respectively, over 7 days. At the same times, apparent densities of thrips/m2 were determined in adjacent grassy areas (120 m2) on a muslin cloth impregnated with permethrin. Thrips were mounted onto slides in Hoyer's medium, for identification. The apparent density of thrips was greatest at 1200 h, and was greater on the neck than the torso and legs (p=0.03). In adjacent surroundings, densities were also highest at 1200 h (mean 199 (SE 9.3) thrips/m2) and were similar to the maximum densities recorded on the necks of ostriches at that time (mean 205 (SE 6.4) thrips/m2). Ostriches engaged in excessive preening and attempted to scratch their head/neck with their feet. Numerous small, pale red papules were observed on the skin. Observations of periorbital cellulitis, conjunctivitis, blepharitis, watery discharge, inflammation, and sclerotic discolouration were noted in 65 ostriches. Observations were commensurate with L. denticornis infestation. Infestation may exacerbate stress levels and subsequently lead to a reduction in feed intake and performance. The infestation and subsequent irritation from thrips impacts negatively on the general health of ostriches by damaging skin and irritating eyes.

Thermal and volumetric properties of complex aqueous electrolyte solutions using the Pitzer formalism - The PhreeSCALE code

NASA Astrophysics Data System (ADS)

Lach, Adeline; Boulahya, Faïza; André, Laurent; Lassin, Arnault; Azaroual, Mohamed; Serin, Jean-Paul; Cézac, Pierre

2016-07-01

The thermal and volumetric properties of complex aqueous solutions are described according to the Pitzer equation, explicitly taking into account the speciation in the aqueous solutions. The thermal properties are the apparent relative molar enthalpy (Lϕ) and the apparent molar heat capacity (Cp,ϕ). The volumetric property is the apparent molar volume (Vϕ). Equations describing these properties are obtained from the temperature or pressure derivatives of the excess Gibbs energy and make it possible to calculate the dilution enthalpy (∆HD), the heat capacity (cp) and the density (ρ) of aqueous solutions up to high concentrations. Their implementation in PHREEQC V.3 (Parkhurst and Appelo, 2013) is described and has led to a new numerical tool, called PhreeSCALE. It was tested first, using a set of parameters (specific interaction parameters and standard properties) from the literature for two binary systems (Na2SO4-H2O and MgSO4-H2O), for the quaternary K-Na-Cl-SO4 system (heat capacity only) and for the Na-K-Ca-Mg-Cl-SO4-HCO3 system (density only). The results obtained with PhreeSCALE are in agreement with the literature data when the same standard solution heat capacity (Cp0) and volume (V0) values are used. For further applications of this improved computation tool, these standard solution properties were calculated independently, using the Helgeson-Kirkham-Flowers (HKF) equations. By using this kind of approach, most of the Pitzer interaction parameters coming from literature become obsolete since they are not coherent with the standard properties calculated according to the HKF formalism. Consequently a new set of interaction parameters must be determined. This approach was successfully applied to the Na2SO4-H2O and MgSO4-H2O binary systems, providing a new set of optimized interaction parameters, consistent with the standard solution properties derived from the HKF equations.

Volumetric and calorimetric properties of aqueous ionene solutions

PubMed Central

Lukšič, Miha; Hribar-Lee, Barbara

2016-01-01

The volumetric (partial and apparent molar volumes) and calorimetric properties (apparent heat capacities) of aqueous cationic polyelectrolyte solutions – ionenes – were studied using the oscillating tube densitometer and differential scanning calorimeter. The polyion’s charge density and the counterion properties were considered as variables. The special attention was put to evaluate the contribution of electrostatic and hydrophobic effects to the properties studied. The contribution of the CH2 group of the polyion’s backbone to molar volumes and heat capacities was estimated. Synergistic effect between polyion and counterions was found. PMID:28503012

New Wrinkles in Retinal Densitometry

PubMed Central

Masella, Benjamin D.; Hunter, Jennifer J.; Williams, David R.

2014-01-01

Purpose. Retinal densitometry provides objective information about retinal function. But, a number of factors, including retinal reflectance changes that are not directly related to photopigment depletion, complicate its interpretation. We explore these factors and suggest a method to minimize their impact. Methods. An adaptive optics scanning light ophthalmoscope (AOSLO) was used to measure changes in photoreceptor reflectance in monkeys before and after photopigment bleaching with 514-nm light. Reflectance measurements at 514 nm and 794 nm were recorded simultaneously. Several methods of normalization to extract the apparent optical density of the photopigment were compared. Results. We identified stimulus-related fluctuations in 794-nm reflectance that are not associated with photopigment absorptance and occur in both rods and cones. These changes had a magnitude approaching those associated directly with pigment depletion, precluding the use of infrared reflectance for normalization. We used a spatial normalization method instead, which avoided the fluctuations in the near infrared, as well as a confocal AOSLO designed to minimize light from layers other than the receptors. However, these methods produced a surprisingly low estimate of the apparent rhodopsin density (animal 1: 0.073 ± 0.006, animal 2: 0.032 ± 0.003). Conclusions. These results confirm earlier observations that changes in photopigment absorption are not the only source of retinal reflectance change during dark adaptation. It appears that the stray light that has historically reduced the apparent density of cone photopigment in retinal densitometry arises predominantly from layers near the photoreceptors themselves. Despite these complications, this method provides a valuable, objective measure of retinal function. PMID:25316726

Density of basalt core from Hilo drill hole, Hawaii

USGS Publications Warehouse

Moore, J.G.

2001-01-01

Density measurements of 1600 samples of core from 889 to 3097 m depth below sea level in the Hawaii Scientific Drilling Program hole near Hilo, Hawaii show marked differences between the basaltic rock types and help define stratigraphy in the hole. Water-saturated densities of subaerial lava flows (occurring above 1079 m depth) have the broadest range because of the large density variation within a single lava flow. Water-saturated densities commonly range from 2.0 to 3.0 with an average of 2.55 ?? 0.24 g/cc. Dikes and sills range from 2.8 to 3.1 g/cc). Densities of hyaloclastite commonly range from 2.3 to 2.7, with an overall average of about 2.5 g/cc. The low-density of most hyaloclastite is due primarily to palagonitization of abundant glass and presence of secondary minerals in the interstices between fragments. Four principal zones of pillow lava, separated by hyaloclastite, occur in the drill core. The shallowest (1983-2136 m) is paradoxically the densest, averaging 3.01 ?? 0.10 g/cc. The second (2234-2470 m) is decidedly the lightest, averaging 2.67 ?? 0.13 g/cc. The third (2640-2790 m) and fourth (2918-bottom at 3097 m) are high, averaging 2.89 ?? 0.17 and 2.97 ?? 0.08 g/cc, respectively. The first pillow zone includes degassed pillows i.e. lava erupted on land that flowed into the sea. These pillows are poor in vesicles, because the subaerial, one-atmosphere vesicles were compressed when the flow descended to deeper water and higher pressure. The second (low-density, non-degassed) pillow zone is the most vesicle-rich, apparently because it was erupted subaqueously at a shallow depth. The higher densities of the third and fourth zones result from a low vesicularity of only a few percent and an olivine content averaging more than 5% for the third zone and about 10% for the fourth zone. The uppermost hyaloclastite extending about 400 m below the bottom of the subaerial basalt is poorly cemented and absorbs up to 6 wt% of water when immersed. Progressing downward the hyaloclastite absorbs less water and becomes better cemented. This change is apparently due to palagonitization of glass and addition of secondary minerals in the deeper older hyaloclastite, a process favored by the increase of temperature with depth. The cementation is largely complete at 1800 m depth where the temperature attains about 20??C. The zone of freshest, uncemented hyaloclastite represents the weakest rock in the drill hole and is a likely level for tectonic or landslide disruption. ?? 2001 Published by Elsevier Science B.V.

Hypocholesterolemic effect of emodin by simultaneous determination of in vitro and in vivo bile salts binding.

PubMed

Wang, Jiaoying; Ji, Jun; Song, Zijing; Zhang, Wenjun; He, Xin; Li, Fei; Zhang, Chunfeng; Guo, Changrun; Wang, Chongzhi; Yuan, Chunsu

2016-04-01

Emodin is an active anthraquinone derivative from Rheum palmatum and some other Chinese herbs and it is traditionally used for treating a variety of diseases. In this study, we investigated the hypocholesterolemic effects and mechanism of emodin on hypercholesterolemia rats. In vitro, capability of emodin binding to sodium deoxycholate which is one kind of bile salts (BAs) was evaluated by detection of surplus content of sodium deoxycholate. In vivo, hypocholesterolemic effects were assessed by determining total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) level of serum and TC, TG level of the liver. Oil red O staining was employed to determine lipid droplet of the liver. The mechanism was explored by BAs in feces, the liver and small intestine. Furthermore, cholesterol 7α-hydroxylase (CYP7A1) activity was measured to evaluate cholesterol's transforming to BAs. The results indicated that TC level of emodin group apparently decreased comparing with model group (p<0.05). Emodin could bind to BAs both in vivo (p<0.05) and in vitro. CYP7A1 activity in emodin group apparently increased comparing with model group (p<0.05). Data suggested that emodin had the potential value for treatment of hypercholesterolemia. The underlying mechanism is probably associated with binding capability to BAs and subsequent increasing expression of CYP7A1. Copyright © 2016 Elsevier B.V. All rights reserved.

Distinguishing Error from Chaos in Ecological Time Series

NASA Astrophysics Data System (ADS)

Sugihara, George; Grenfell, Bryan; May, Robert M.

1990-11-01

Over the years, there has been much discussion about the relative importance of environmental and biological factors in regulating natural populations. Often it is thought that environmental factors are associated with stochastic fluctuations in population density, and biological ones with deterministic regulation. We revisit these ideas in the light of recent work on chaos and nonlinear systems. We show that completely deterministic regulatory factors can lead to apparently random fluctuations in population density, and we then develop a new method (that can be applied to limited data sets) to make practical distinctions between apparently noisy dynamics produced by low-dimensional chaos and population variation that in fact derives from random (high-dimensional)noise, such as environmental stochasticity or sampling error. To show its practical use, the method is first applied to models where the dynamics are known. We then apply the method to several sets of real data, including newly analysed data on the incidence of measles in the United Kingdom. Here the additional problems of secular trends and spatial effects are explored. In particular, we find that on a city-by-city scale measles exhibits low-dimensional chaos (as has previously been found for measles in New York City), whereas on a larger, country-wide scale the dynamics appear as a noisy two-year cycle. In addition to shedding light on the basic dynamics of some nonlinear biological systems, this work dramatizes how the scale on which data is collected and analysed can affect the conclusions drawn.

Dynamical arrest with zero complexity: The unusual behavior of the spherical Blume-Emery-Griffiths disordered model

NASA Astrophysics Data System (ADS)

Rainone, Corrado; Ferrari, Ulisse; Paoluzzi, Matteo; Leuzzi, Luca

2015-12-01

The short- and long-time dynamics of model systems undergoing a glass transition with apparent inversion of Kauzmann and dynamical arrest glass transition lines is investigated. These models belong to the class of the spherical mean-field approximation of a spin-1 model with p -body quenched disordered interaction, with p >2 , termed spherical Blume-Emery-Griffiths models. Depending on temperature and chemical potential the system is found in a paramagnetic or in a glassy phase and the transition between these phases can be of a different nature. In specific regions of the phase diagram coexistence of low-density and high-density paramagnets can occur, as well as the coexistence of spin-glass and paramagnetic phases. The exact static solution for the glassy phase is known to be obtained by the one-step replica symmetry breaking ansatz. Different scenarios arise for both the dynamic and the thermodynamic transitions. These include: (i) the usual random first-order transition (Kauzmann-like) for mean-field glasses preceded by a dynamic transition, (ii) a thermodynamic first-order transition with phase coexistence and latent heat, and (iii) a regime of apparent inversion of static transition line and dynamic transition lines, the latter defined as a nonzero complexity line. The latter inversion, though, turns out to be preceded by a dynamical arrest line at higher temperature. Crossover between different regimes is analyzed by solving mode-coupling-theory equations near the boundaries of paramagnetic solutions and the relationship with the underlying statics is discussed.

Apparent Fibre Density: a novel measure for the analysis of diffusion-weighted magnetic resonance images.

PubMed

Raffelt, David; Tournier, J-Donald; Rose, Stephen; Ridgway, Gerard R; Henderson, Robert; Crozier, Stuart; Salvado, Olivier; Connelly, Alan

2012-02-15

This article proposes a new measure called Apparent Fibre Density (AFD) for the analysis of high angular resolution diffusion-weighted images using higher-order information provided by fibre orientation distributions (FODs) computed using spherical deconvolution. AFD has the potential to provide specific information regarding differences between populations by identifying not only the location, but also the orientations along which differences exist. In this work, analytical and numerical Monte-Carlo simulations are used to support the use of the FOD amplitude as a quantitative measure (i.e. AFD) for population and longitudinal analysis. To perform robust voxel-based analysis of AFD, we present and evaluate a novel method to modulate the FOD to account for changes in fibre bundle cross-sectional area that occur during spatial normalisation. We then describe a novel approach for statistical analysis of AFD that uses cluster-based inference of differences extended throughout space and orientation. Finally, we demonstrate the capability of the proposed method by performing voxel-based AFD comparisons between a group of Motor Neurone Disease patients and healthy control subjects. A significant decrease in AFD was detected along voxels and orientations corresponding to both the corticospinal tract and corpus callosal fibres that connect the primary motor cortices. In addition to corroborating previous findings in MND, this study demonstrates the clear advantage of using this type of analysis by identifying differences along single fibre bundles in regions containing multiple fibre populations. Copyright © 2011 Elsevier Inc. All rights reserved.

Outdoor temperature is associated with serum HDL and LDL.

PubMed

Halonen, Jaana I; Zanobetti, Antonella; Sparrow, David; Vokonas, Pantel S; Schwartz, Joel

2011-02-01

While exposures to high and low air temperatures are associated with cardiovascular mortality, the underlying mechanisms are poorly understood. The risk factors for cardiovascular disease include high levels of total cholesterol and low-density lipoprotein (LDL), and low levels of high-density lipoprotein (HDL). We investigated whether temperature was associated with changes in circulating lipid levels, and whether this might explain part of the association with increased cardiovascular events. The study cohort consisted of 478 men in the greater Boston area with a mean age of 74.2 years. They visited the clinic every 3-5 years between 1995 and 2008 for physical examination and to complete questionnaires. We excluded from analyses all men taking statin medication and all days with missing data, resulting in a total of 862 visits. Associations between three temperature variables (ambient, apparent, and dew point temperature) and serum lipid levels (total cholesterol, HDL, LDL, and triglycerides) were studied with linear mixed models that included possible confounders such as air pollution and a random intercept for each subject. We found that HDL decreased -1.76% (95% CI: from -3.17 to -0.32, lag 2 days), and -5.58% (95% CI: from -8.87 to -2.16, moving average of 4 weeks) for each 5°C increase in mean ambient temperature. For the same increase in mean ambient temperature, LDL increased by 1.74% (95% CI: 0.07-3.44, lag 1 day) and 1.87% (95% CI: 0.14-3.63, lag 2 days). These results were also similar for apparent and dew point temperatures. No changes were found in total cholesterol or triglycerides in relation to temperature increase. Changes in HDL and LDL levels associated with an increase in ambient temperature may be among the underlying mechanisms of temperature-related cardiovascular mortality. Copyright © 2010 Elsevier Inc. All rights reserved.

MRI appearance of posterior cruciate ligament tears.

PubMed

Rodriguez, William; Vinson, Emily N; Helms, Clyde A; Toth, Alison P

2008-10-01

There is little in the radiology literature regarding the MRI appearance of a torn posterior cruciate ligament (PCL). The purpose of this study was to describe the MRI appearance of surgically proven PCL tears and to emphasize previously unreported signs. The PCL is usually injured as the result of stretching deformation; on MRI, the ligament maintains continuity as a single structure with apparent thickening. On sagittal T2-weighted images, an anteroposterior diameter of 7 mm or more is highly suggestive of a torn PCL. Increased intrasubstance signal intensity in the PCL on proton-density images with lower signal intensity on T2-weighted images is another common feature.

High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

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

Gatu Johnson, M., E-mail: gatu@psfc.mit.edu; Frenje, J. A.; Li, C. K.

2016-11-15

The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility measures the DT neutron spectrum from cryogenically layered inertial confinement fusion implosions. Yield, areal density, apparent ion temperature, and directional fluid flow are inferred from the MRS data. This paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ∼200 keV FWHM.

Resistance of polyamide-6 against long time effects of various media at various temperatures

NASA Technical Reports Server (NTRS)

Debski, W.; Przylecka, M.

1988-01-01

During the first phase of tempering of polyamide-6, there are temporary changes which are apparently related to the lamella structure of the material. Test specimens at high temperature show that the mechanical properties of polyamide-6 are changed permanently, and mostly at 80 C. From the results of density tests and X-ray analysis, it follows that these changes depend on environmental influences and differ in gaseous and liquid media. The results of the test specimens of the mechanical properties as a function of temperature and the medium give information about the practical applications of polyamide-6.

Medulloblastomics: The End of the Beginning

PubMed Central

Northcott, Paul A; Jones, David TW; Kool, Marcel; Robinson, Giles W; Gilbertson, Richard J; Cho, Yoon-Jae; Pomeroy, Scott L; Korshunov, Andrey; Lichter, Peter; Taylor, Michael D; Pfister, Stefan M

2013-01-01

Subgrouping of medulloblastoma by microarray expression profiling has dramatically changed our perspective of this malignant childhood brain tumour. Now, the availability of next-generation sequencing and complementary high-density genomic technologies has unmasked novel driver mutations in each medulloblastoma subgroup. The implications of these findings for the management of patients are readily apparent, pinpointing previously unappreciated diagnostic and therapeutic targets. Here, we summarize the ’explosion’ of data emerging from the application of modern genomics to medulloblastoma, and in particular the recurrent targets of mutation in medulloblastoma subgroups. These data are making their way into contemporary clinical trials as we seek to integrate conventional and molecularly targeted therapies. PMID:23175120

High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

DOE PAGES

Gatu Johnson, M.; Frenje, J. A.; Bionta, R. M.; ...

2016-08-09

The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility measures the DT neutron spectrum from cryogenically layered inertial confinement fusion implosions. Yield, areal density, apparent ion temperature, and directional fluid flow are inferred from the MRS data. Here, this paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ~200 keV FWHM.

High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility.

PubMed

Gatu Johnson, M; Frenje, J A; Bionta, R M; Casey, D T; Eckart, M J; Farrell, M P; Grim, G P; Hartouni, E P; Hatarik, R; Hoppe, M; Kilkenny, J D; Li, C K; Petrasso, R D; Reynolds, H G; Sayre, D B; Schoff, M E; Séguin, F H; Skulina, K; Yeamans, C B

2016-11-01

The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility measures the DT neutron spectrum from cryogenically layered inertial confinement fusion implosions. Yield, areal density, apparent ion temperature, and directional fluid flow are inferred from the MRS data. This paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ∼200 keV FWHM.

Resolving the structure and properties of τ1-Cr-Ni-Al for high temperature protective applications

NASA Astrophysics Data System (ADS)

Simonson, J. W.; Nicasio, J. E.; Ilyas, H.; Pabla, J.; Horvat, K.; Misuraca, J. C.

Increasing the temperature of the steam in turbine power plants enhances thermal efficiency while reducing CO2 emissions. Exposed steel components, however, must be coated to withstand the harsh environments present in next-generation advanced ultra-supercritical plants. Proposed coating materials must exhibit low density, high hardness, high toughness, excellent oxidation resistance, and low thermal conductivity. With an eye towards satisfying this diverse array of requirements, we report the properties of the so-called τ1 phase of Cr-Ni-Al. We resolve the previously controversial composition and crystal structure of this material. The complex structure is composed of distorted icosahedra and octahedra of Al, with nearest-neighbor transition metal-Al bond lengths as short as 2.4 Å, far shorter than typical distances in Ni-Al and Cr-Al binaries. Accordingly, Vickers hardness is 6 . 88 +/- 0 . 13 GPa, as hard as extra-high-hardness armor plating at only 45% the density. We discuss these properties in light of the result of transport and oxidation resistance measurements. The apparent dependencies of these properties on crystal structure suggests new criteria for materials research. Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund, for support of this research under contract 56764-UNI10.

Critical current density of high-quality Bi2Sr2Ca2Cu3Ox thin films prepared by metalorganic chemical-vapor deposition

NASA Astrophysics Data System (ADS)

Yamasaki, H.; Endo, K.; Nakagawa, Y.; Umeda, M.; Kosaka, S.; Misawa, S.; Yoshida, S.; Kajimura, K.

1992-10-01

Critical current densities Jc were measured in as-deposited, c-axis-oriented Bi2Sr2Ca2Cu3Ox thin films with Tc values as high as 97 K, which were prepared by metalorganic chemical-vapor deposition. These films showed high Jc (≳109 A/m2) at 77.3 K in high magnetic fields (≥1 T, H∥a-b plane). The best values are 3.3×109 A/m2 at 1 T and 9.1×108 A/m2 at 8 T, which are the highest Jc for Bi-oxide thin films among those reported so far. There were no signs of weak links in the Jc(H) behavior, and the surface morphology examined by scanning electron microscopy showed no apparent grain boundaries. The values of Jc decreased sharply when the applied field deviated from the a-b plane, and went to zero at the angles where the field component in the c direction is nearly equal to the irreversibility field Hc2* parallel to the c axis. The angular dependence of Jc of these films is most reasonably explained by the theory of intrinsic pinning.

Estimation of the Number of Compartments Associated With the Apparent Diffusion Coefficient in MRI: The Theoretical and Experimental Investigations.

PubMed

Ashoor, Mansour; Khorshidi, Abdollah

2016-03-01

The goal of the present study was to estimate the number of compartments and the mean apparent diffusion coefficient (ADC) value with the use of the DWI signal curve. A useful new mathematic model that includes internal correlation among subcompartments with a distinct number of compartments was proposed. The DWI signal was simulated to estimate the approximate association between the number of subcompartments and the molecular density, with density corresponding to the ratio of the ADC values of the compartments, as determined using the Monte Carlo method. Various factors, such as energy depletion, temperature, intracellular water accumulation, changes in the tortuosity of the extracellular diffusion paths, and changes in cell membrane permeability, have all been implicated as factors contributing to changes in the ADC of water (ADCw); therefore, one may consider them as pseudocompartments in the new model proposed in this study. The lower the coefficient is, the lower the contribution of the compartment to the net signal will be. The results of the simulation indicate that when the number of compartments increases, the signal will become significantly lower, because the gradient factor (i.e., the b value) will increase. In other words, the signal curve is approximately linear at all b values when the number of compartments in which the tissues have been severely damaged is low; however, when the number of compartments is high, the curve will become constant at high b values, and the perfusion parameters will prevail on the diffusion parameters at low b values. Therefore, normal tissues will be investigated when the number of compartments and the ADC values are high and the b values are low, whereas damaged tissues will be evaluated when the number of compartments and the ADC values are low and the b values are high. The present study investigates damaged tissues at high b values for which the effect of eddy currents will also be compensated. These b values will probably be used in functional MRI.

Bone mineral loss in young women with amenorrhoea.

PubMed Central

Davies, M C; Hall, M L; Jacobs, H S

1990-01-01

OBJECTIVE--To examine the impact of amenorrhoea on bone mineral density in women of reproductive age. DESIGN--Cross sectional study of 200 amenorrhoeic women compared with normally menstruating controls. SETTING--Teaching hospital outpatient clinic specialising in reproductive medicine. SUBJECTS--200 Women aged 16-40 with a past or current history of amenorrhoea from various causes and of a median duration of three years, and a control group of 57 age matched normal volunteers with no history of menstrual disorder. MAIN OUTCOME MEASURE--Bone mineral density in the lumbar spine (L1-L4) as measured by dual energy x ray absorptiometry. RESULTS--The amenorrhoeic group showed a mean reduction in bone mineral density of 15% (95% confidence interval 12% to 18%) as compared with controls (mean bone mineral density 0.89 (SD 0.12) g/cm2 v 1.05 (0.09) g/cm2 in controls). Bone loss was related to the duration of amenorrhoea and the severity of oestrogen deficiency rather than to the underlying diagnosis. Patients with a history of fracture had significantly lower bone density than those without a history of fracture. Ten patients had suffered an apparently atraumatic fracture. CONCLUSIONS--Amenorrhoea in young women should be investigated and treated to prevent bone mineral loss. Menopausal women with a past history of amenorrhoea should be considered to be at high risk of osteoporosis. PMID:2224267

Automatic Quantification of X-ray Computed Tomography Images of Cores: Method and Application to Shimokita Cores (Northeast Coast of Honshu, Japan)

NASA Astrophysics Data System (ADS)

Gaillot, P.

2007-12-01

X-ray computed tomography (CT) of rock core provides nondestructive cross-sectional or three-dimensional core representations from the attenuation of electromagnetic radiation. Attenuation depends on the density and the atomic constituents of the rock material that is scanned. Since it has the potential to non-invasively measure phase distribution and species concentration, X-ray CT offers significant advantages to characterize both heterogeneous and apparently homogeneous lithologies. In particular, once empirically calibrated into 3D density images, this scanning technique is useful in the observation of density variation. In this paper, I present a procedure from which information contained in the 3D images can be quantitatively extracted and turned into very-high resolution core logs and core image logs including (1) the radial and angular distributions of density values, (2) the histogram of distribution of the density and its related statistical parameters (average, 10- 25- 50, 75 and 90 percentiles, and width at half maximum), and (3) the volume, the average density and the mass contribution of three core fractions defined by two user-defined density thresholds (voids and vugs < 1.01 g/cc ≤ damaged core material < 1.25 g/cc < non-damaged core material). In turn, these quantitative outputs (1) allow the recognition of bedding and sedimentary features, as well as natural and coring-induced fractures, (2) provide a high-resolution bulk density core log, and (3) provide quantitative estimates of core voids and core damaged zones that can further be used to characterize core quality and core disturbance, and apply, where appropriate, volume correction on core physical properties (gamma-ray attenuation density, magnetic susceptibility, natural gamma radiation, non-contact electrical resistivity, P-wave velocity) acquired via Multi- Sensors Core loggers (MSCL). The procedure is illustrated on core data (XR-CT images, continuous MSCL physical properties and discrete Moisture and Density measurements) from the Hole C9001C drilled off-shore Shimokita (northeast coast of Honshu, Japan) during the shake-down cruise (08-11/2006) of the scientific drilling vessel, Chikyu.

Photographic mark-recapture analysis of local dynamics within an open population of dolphins.

PubMed

Fearnbach, H; Durban, J; Parsons, K; Claridge, D

2012-07-01

Identifying demographic changes is important for understanding population dynamics. However, this requires long-term studies of definable populations of distinct individuals, which can be particularly challenging when studying mobile cetaceans in the marine environment. We collected photo-identification data from 19 years (1992-2010) to assess the dynamics of a population of bottlenose dolphins (Tursiops truncatus) restricted to the shallow (<7 m) waters of Little Bahama Bank, northern Bahamas. This population was known to range beyond our study area, so we adopted a Bayesian mixture modeling approach to mark-recapture to identify clusters of individuals that used the area to different extents, and we specifically estimated trends in survival, recruitment, and abundance of a "resident" population with high probabilities of identification. There was a high probability (p= 0.97) of a long-term decrease in the size of this resident population from a maximum of 47 dolphins (95% highest posterior density intervals, HPDI = 29-61) in 1996 to a minimum of just 24 dolphins (95% HPDI = 14-37) in 2009, a decline of 49% (95% HPDI = approximately 5% to approximately 75%). This was driven by low per capita recruitment (average approximately 0.02) that could not compensate for relatively low apparent survival rates (average approximately 0.94). Notably, there was a significant increase in apparent mortality (approximately 5 apparent mortalities vs. approximately 2 on average) in 1999 when two intense hurricanes passed over the study area, with a high probability (p = 0.83) of a drop below the average survival probability (approximately 0.91 in 1999; approximately 0.94, on average). As such, our mark-recapture approach enabled us to make useful inference about local dynamics within an open population of bottlenose dolphins; this should be applicable to other studies challenged by sampling highly mobile individuals with heterogeneous space use.

A deliberate tracer experiment in Santa Monica Basin. [for ocean density strata diffusion

NASA Technical Reports Server (NTRS)

Ledwell, J. R.; Broecker, W. S.; Watson, A. J.

1986-01-01

A tracer technique was developed for measurements of diffusion across oceanic density strata using SF6 and perfluorodecalin (PFD) tracers in the Santa Monica Basin. Fifty days after injection, the tracers were found to have mixed along the isopycnal surface to nearly every part of the basin. The diapycnal spreading of the tracer distributions yielded an apparent eddy diffusivity of 0.33 + or - 0.08 sq cm/s at the ambient density gradient of 4.0 + or - 0.5 x 10 to the -9th g/cm to the 4th.

Accurate bulk density determination of irregularly shaped translucent and opaque aerogels

NASA Astrophysics Data System (ADS)

Petkov, M. P.; Jones, S. M.

2016-05-01

We present a volumetric method for accurate determination of bulk density of aerogels, calculated from extrapolated weight of the dry pure solid and volume estimates based on the Archimedes' principle of volume displacement, using packed 100 μm-sized monodispersed glass spheres as a "quasi-fluid" media. Hard particle packing theory is invoked to demonstrate the reproducibility of the apparent density of the quasi-fluid. Accuracy rivaling that of the refractive index method is demonstrated for both translucent and opaque aerogels with different absorptive properties, as well as for aerogels with regular and irregular shapes.

Region-specific tritium enrichment, and not differential beta-absorption, is the major cause of 'quenching' in film autoradiography.

PubMed

McEachron, D L; Nissanov, J; Tretiak, O J

1997-06-01

Tritium quenching refers to the situation in which estimates of tritium content generated by film autoradiography depend on the chemical composition of the tissue as well as on the concentration of the radioisotope. When analysing thin brain sections, for example, regions rich in lipid content generate reduced optical densities on x-ray film compared with lipid-poor regions even when the total tissue concentration of tritium in those regions is identical. We hypothesize that the dried thickness of regions within sections depends upon the relative concentrations and types of lipid within the regions. Areas low in white matter dry thinner than areas high in white matter, leading to a relative enrichment of tritium in the thinner regions. To test this model, a series of brain pastes were made with different concentrations of grey and white matter and impregnated with equal amounts of tritium. The thickness of dried sections was compared with percentage of white matter and apparent radioactive content as determined by autoradiogram analysis. The results demonstrated that thickness increased, and apparent radioactivity decreased, with higher percentages of white matter. In the second experiment, thickness measurements from dried sections were successfully used to correct the apparent radioisotope content of autoradiograms created from tritium containing white- and grey-matter tissue slices. We conclude that within-section thickness variation is the major physical cause for 'tritium quenching'.

Universe opacity and CMB

NASA Astrophysics Data System (ADS)

Vavryčuk, Václav

2018-07-01

A cosmological model, in which the cosmic microwave background (CMB) is a thermal radiation of intergalactic dust instead of a relic radiation of the big bang, is revived and revisited. The model suggests that a virtually transparent local Universe becomes considerably opaque at redshifts z > 2-3. Such opacity is hardly to be detected in the Type Ia supernova data, but confirmed using quasar data. The opacity steeply increases with redshift because of a high proper density of intergalactic dust in the previous epochs. The temperature of intergalactic dust increases as (1 + z) and exactly compensates the change of wavelengths due to redshift, so that the dust radiation looks apparently like the radiation of the blackbody with a single temperature. The predicted dust temperature is TD = 2.776 K, which differs from the CMB temperature by 1.9 per cent only, and the predicted ratio between the total CMB and extragalactic background light (EBL) intensities is 13.4 which is close to 12.5 obtained from observations. The CMB temperature fluctuations are caused by EBL fluctuations produced by galaxy clusters and voids in the Universe. The polarization anomalies of the CMB correlated with temperature anisotropies are caused by the polarized thermal emission of needle-shaped conducting dust grains aligned by large-scale magnetic fields around clusters and voids. A strong decline of the luminosity density for z > 4 is interpreted as the result of high opacity of the Universe rather than of a decline of the global stellar mass density at high redshifts.

Native protein mapping and visualization of protein interactions in the area of human plasma high-density lipoprotein by combining nondenaturing micro 2DE and quantitative LC-MS/MS.

PubMed

Jin, Ya; Bu, Shujie; Zhang, Jun; Yuan, Qi; Manabe, Takashi; Tan, Wen

2014-07-01

A human plasma sample was subjected to nondenaturing micro 2DE and a gel area (5 mm × 18 mm) that includes high-density lipoprotein (HDL) was cut into 1 mm × 1 mm squares, then the proteins in the 90 gel pieces were analyzed by quantitative LC-MS/MS. Grid-cutting of the gel was employed to; (i) ensure the total analysis of the proteins in the area, (ii) standardize the conditions of analysis by LC-MS/MS, (iii) reconstruct the protein distribution patterns from the quantity data. Totally 154 proteins were assigned in the 90 gel pieces and the quantity distribution of each was reconstructed as a color density pattern (a native protein map). The map of apolipoprotein (Apo) A-I showed a wide apparent mass distribution characteristic to HDL and was compared with the maps of the other 153 proteins. Eleven proteins showed maps of wide distribution that overlapped with the map of Apo A-I, and all have been reported to be the components of HDL. Further, seven minor proteins associated with HDL were detected at the gel positions of high Apo A-I quantity. These results for the first time visualized the localization of HDL apolipoproteins on a nondenaturing 2DE gel and strongly suggested their interactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Universe opacity and CMB

NASA Astrophysics Data System (ADS)

Vavryčuk, Václav

2018-04-01

A cosmological model, in which the cosmic microwave background (CMB) is a thermal radiation of intergalactic dust instead of a relic radiation of the Big Bang, is revived and revisited. The model suggests that a virtually transparent local Universe becomes considerably opaque at redshifts z > 2 - 3. Such opacity is hardly to be detected in the Type Ia supernova data, but confirmed using quasar data. The opacity steeply increases with redshift because of a high proper density of intergalactic dust in the previous epochs. The temperature of intergalactic dust increases as (1 + z) and exactly compensates the change of wavelengths due to redshift, so that the dust radiation looks apparently like the radiation of the blackbody with a single temperature. The predicted dust temperature is TD = 2.776 K, which differs from the CMB temperature by 1.9% only, and the predicted ratio between the total CMB and EBL intensities is 13.4 which is close to 12.5 obtained from observations. The CMB temperature fluctuations are caused by EBL fluctuations produced by galaxy clusters and voids in the Universe. The polarization anomalies of the CMB correlated with temperature anisotropies are caused by the polarized thermal emission of needle-shaped conducting dust grains aligned by large-scale magnetic fields around clusters and voids. A strong decline of the luminosity density for z > 4 is interpreted as the result of high opacity of the Universe rather than of a decline of the global stellar mass density at high redshifts.

High-density lipoprotein cholesterol and cardiovascular disease. Four prospective American studies.

PubMed

Gordon, D J; Probstfield, J L; Garrison, R J; Neaton, J D; Castelli, W P; Knoke, J D; Jacobs, D R; Bangdiwala, S; Tyroler, H A

1989-01-01

The British Regional Heart Study (BRHS) reported in 1986 that much of the inverse relation of high-density lipoprotein cholesterol (HDLC) and incidence of coronary heart disease was eliminated by covariance adjustment. Using the proportional hazards model and adjusting for age, blood pressure, smoking, body mass index, and low-density lipoprotein cholesterol, we analyzed this relation separately in the Framingham Heart Study (FHS), Lipid Research Clinics Prevalence Mortality Follow-up Study (LRCF) and Coronary Primary Prevention Trial (CPPT), and Multiple Risk Factor Intervention Trial (MRFIT). In CPPT and MRFIT (both randomized trials in middle-age high-risk men), only the control groups were analyzed. A 1-mg/dl (0.026 mM) increment in HDLC was associated with a significant coronary heart disease risk decrement of 2% in men (FHS, CPPT, and MRFIT) and 3% in women (FHS). In LRCF, where only fatal outcomes were documented, a 1-mg/dl increment in HDLC was associated with significant 3.7% (men) and 4.7% (women) decrements in cardiovascular disease mortality rates. The 95% confidence intervals for these decrements in coronary heart and cardiovascular disease risk in the four studies overlapped considerably, and all contained the range 1.9-2.9%. HDLC levels were essentially unrelated to non-cardiovascular disease mortality. When differences in analytic methodology were eliminated, a consistent inverse relation of HDLC levels and coronary heart disease event rates was apparent in BRHS as well as in the four American studies.

Changes in the microarchitecture of the pancreatic cancer stroma are linked to neutrophil-dependent reprogramming of stellate cells and reflected by diffusion-weighted magnetic resonance imaging

PubMed Central

Mayer, Philipp; Dinkic, Christine; Jesenofsky, Ralf; Klauss, Miriam; Schirmacher, Peter; Dapunt, Ulrike; Hackert, Thilo; Uhle, Florian; Hänsch, G. Maria; Gaida, Matthias M.

2018-01-01

In pancreatic cancer (PDAC) intratumor infiltration of polymorphonuclear neutrophils (PMN) is associated with histologically apparent alterations of the tumor growth pattern. The aim of this study was to examine possible associations between PMN infiltration, tumor microarchitecture, and water diffusivity in diffusion-weighted magnetic resonance imaging (DW-MRI), and to further asses the underlying mechanisms. Methods: DW-MRI was performed in 33 PDAC patients prior to surgery. In parallel, tissue specimen were examined histologically for growth pattern, azurocidin-positive PMN infiltrates, and the presence of alpha-smooth muscle actin (α-SMA) and metalloproteinase 9 (MMP9)-positive myofibroblastic cells. For confirmation of the histological findings, a tissue microarray of a second cohort of patients (n=109) was prepared and examined similarly. For in vitro studies, the pancreatic stellate cell line RLT was co-cultivated either with isolated PMN, PMN-lysates, or recombinant azurocidin and characterized by Western blot, flow cytometry, and proteome profiler arrays. Results: Tumors with high PMN density showed restricted water diffusion in DW-MRI and histologic apparent alterations of the tumor microarchitecture (microglandular, micropapillary, or overall poorly differentiated growth pattern) as opposed to tumors with scattered PMN. Areas with altered growth pattern lacked α-SMA-positive myofibroblastic cells. Tissue microarrays confirmed a close association of high PMN density with alterations of the tumor microarchitecture and revealed a significant association of high PMN density with poor histologic grade of differentiation (G3). In vitro experiments provided evidence for direct effects of PMN on stellate cells, where a change to a spindle shaped cell morphology in response to PMN and to PMN-derived azurocidin was seen. Azurocidin incorporated into stellate cells, where it associated with F-actin. Down-regulation of α-SMA was seen within hours, as was activation of the p38-cofilin axis, up-regulation of MMP9, and acquisition of intracellular lipid droplets, which together indicate a phenotype switch of the stellate cells. Conclusion: In PDAC, PMN infiltrates are associated with alterations of the tumor microarchitecture. As a causal relationship, we propose a reprogramming of stellate cells by PMN-derived azurocidin towards a phenotype, which affects the microarchitecture of the tumor. PMID:29290790

CMB-induced radio quenching of high-redshift jetted AGNs with highly magnetic hotspots

NASA Astrophysics Data System (ADS)

Wu, Jianfeng; Ghisellini, Gabriele; Hodges-Kluck, Edmund; Gallo, Elena; Ciardi, Benedetta; Haardt, Francesco; Sbarrato, Tullia; Tavecchio, Fabrizio

2017-06-01

In an effort to understand the cause of the apparent depletion in the number density of radio-loud active galactic nuclei (AGNs) at z > 3, this work investigates the viability of the so-called cosmic microwave background (CMB) quenching mechanism of intrinsically jetted, high-z AGNs, whereby inverse Compton scattering of CMB photons off electrons within the extended lobes results in a substantial dimming of the lobe synchrotron emission at GHz frequencies, while simultaneously boosting their diffuse X-ray signal. We focus on five z > 3.5 radio galaxies that have sufficiently deep Chandra exposure (>50 ks) to warrant a meaningful investigation of any extended X-ray emission. For those objects with evidence for statistically significant extended X-ray lobes (4C 41.17 and 4C 03.24), we combine the Chandra measurements with literature data at lower frequencies to assemble the systems' spectral energy distributions (SEDs), and utilize state-of-the-art SED modelling - including emission from the disc, torus, jet, hotspots and lobes - to infer their physical parameters. For both radio galaxies, the magnetic energy density in the hotspots is found to exceed the energy density in CMB photons, whereas the opposite is true for the lobes. This implies that any extended synchrotron emission likely originates from the hotspots themselves, rather than the lobes. Conversely, inverse Compton scattering of CMB photons dominates the extended X-ray emission from the lobes, which are effectively 'radio-quenched'. As a result, CMB quenching is effective in these systems in spite of the fact that the observed X-ray to radio luminosity ratio does not bear the signature (1 + z)4 dependence of the CMB energy density.

Food habits and nutrient density of diets of Pakistani children living in different urban and rural settings.

PubMed

Hakeem, Rubina; Thomas, Jane; Badruddin, Salma H

2002-09-01

Food habits and nutrient density of diets of six groups of rural and urban school children aged 10-12 years were compared. Data were collected from three-day food records. In the UK, data were collected during October-November 1994 and in Pakistan during April-May 1995. Based on the apparent level of urbanism, the six groups were arbitrarily assigned urbanization rank 1-6. Patterns of their food and intake of nutrients were different from each other in various aspects and were not always associated with the apparent level of urbanism of the group. With urbanization, the intake of fat and sugar increased steadily. The intake of carbohydrate, fibre, riboflavin, and vitamin E decreased with urbanization. The intake of vitamin C, vitamin B12, and folates was higher among group 4, 5, and 6 than other groups. Due to various factors, in terms of micronutrient density, diets of various urban groups could have more differences than similarities. While these differences point toward the need for comprehensive nutrition education and community nutrition surveys, they also indicate the possibility of having healthy diets in urban settings.

Self-Expansion Construction of Ultralight Carbon Nanotube Aerogels with a 3D and Hierarchical Cellular Structure.

PubMed

Luo, Yufeng; Luo, Shu; Wu, Hengcai; Li, Mengya; Wang, Ke; Yan, Lingjia; Jiang, Kaili; Li, Qunqing; Fan, Shoushan; Wang, Jiaping

2017-07-01

A novel and simple strategy is developed to construct ultralight and 3D pure carbon nanotube (CNT) aerogels by the spontaneous expansion of superaligned CNT films soaked in a piranha (mixed H 2 SO 4 and H 2 O 2 ) solution, followed by cryodesiccation. The macroscopic CNT aerogels have an extremely low apparent density (0.12 mg cm -3 ), ultrahigh porosity (99.95%), high specific surface area (298 m 2 g -1 ), and a hierarchical cellular structure with giant and ultrathin CNT sheets as cell walls. The pure CNT aerogels show high adsorption abilities for various kinds of solvents, and have great potential in widespread applications such as energy storage, catalysis, and bioengineering. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the apparent power law in CDM halo pseudo-phase space density profiles

NASA Astrophysics Data System (ADS)

Nadler, Ethan O.; Oh, S. Peng; Ji, Suoqing

2017-09-01

We investigate the apparent power-law scaling of the pseudo-phase space density (PPSD) in cold dark matter (CDM) haloes. We study fluid collapse, using the close analogy between the gas entropy and the PPSD in the fluid approximation. Our hydrodynamic calculations allow for a precise evaluation of logarithmic derivatives. For scale-free initial conditions, entropy is a power law in Lagrangian (mass) coordinates, but not in Eulerian (radial) coordinates. The deviation from a radial power law arises from incomplete hydrostatic equilibrium (HSE), linked to bulk inflow and mass accretion, and the convergence to the asymptotic central power-law slope is very slow. For more realistic collapse, entropy is not a power law with either radius or mass due to deviations from HSE and scale-dependent initial conditions. Instead, it is a slowly rolling power law that appears approximately linear on a log-log plot. Our fluid calculations recover PPSD power-law slopes and residual amplitudes similar to N-body simulations, indicating that deviations from a power law are not numerical artefacts. In addition, we find that realistic collapse is not self-similar; scalelengths such as the shock radius and the turnaround radius are not power-law functions of time. We therefore argue that the apparent power-law PPSD cannot be used to make detailed dynamical inferences or extrapolate halo profiles inwards, and that it does not indicate any hidden integrals of motion. We also suggest that the apparent agreement between the PPSD and the asymptotic Bertschinger slope is purely coincidental.

Nutritional geometry of calcium and phosphorus nutrition in broiler chicks. The effect of different dietary calcium and phosphorus concentrations and ratios on nutrient digestibility.

PubMed

Wilkinson, S J; Bradbury, E J; Thomson, P C; Bedford, M R; Cowieson, A J

2014-07-01

A total of 600 Ross 308-day-old male broiler chicks were used in a 28 day digestibility study to investigate the interaction between dietary calcium (Ca) and non-phytate phosphorus (nPP) on the digestibility of minerals and amino acids. Diets were formulated to be nutritionally adequate except for Ca and nPP. Fifteen mash diets based on corn and soya bean meal with varying concentrations of Ca (6.4 to 12.0 g/kg) and nPP (2.4 to 7.0 g/kg) were used. Diets were clustered around total densities of Ca and nPP of 12, 13.5 or 15.0 (g/kg) and within each density, a range of five Ca : nPP ratios (1.14 : 1, 1.5 : 1, 2.0 : 1, 2.75 : 1 and 4.0 : 1) were fed. Birds had free access to feed and water throughout the study. At day 28, birds were euthanised for the determination of apparent ileal mineral and amino acid digestibility. Data were modelled in R version 2.15 using a linear mixed-effects model and interrogation of the data was performed by fitting a low order polynomial function. At high Ca concentrations, increasing nPP led to an increase in the apparent digestibility of minerals. Apparent ileal digestibility of phosphorus (P) was enhanced with increasing dietary nPP up to 5.5 g/kg beyond which no improvements were found. Maximal Ca digestibility was found in diets with >8.0 g/kg Ca with concomitant low concentrations of nPP. Diets with a broader Ca : nPP ratio improved the digestibility of Ca but were deleterious to the digestibility of P. In this study, apparent digestibility of amino acids was broadly unaffected by dietary Ca and nPP concentrations. However, interactions between Ca and nPP were observed for the digestibility of glutamine, tyrosine and methionine (all P<0.001). Nitrogen digestibility showed discrete optima around 10.0 and 5.0 g/kg nPP and Na digestibility was maximised around 8 to 9.0 g/kg Ca and 4.5 to 5.4 g/kg nPP. These data show that the ratio of Ca : nPP is more influential to mineral digestibility than the absolute dietary concentration of each macro mineral.

Causality, apparent ``superluminality,'' and reshaping in barrier penetration

NASA Astrophysics Data System (ADS)

Sokolovski, D.

2010-04-01

We consider tunneling of a nonrelativistic particle across a potential barrier. It is shown that the barrier acts as an effective beam splitter which builds up the transmitted pulse from the copies of the initial envelope shifted in the coordinate space backward relative to the free propagation. Although along each pathway causality is explicitly obeyed, in special cases reshaping can result an overall reduction of the initial envelope, accompanied by an arbitrary coordinate shift. In the case of a high barrier the delay amplitude distribution (DAD) mimics a Dirac δ function, the transmission amplitude is superoscillatory for finite momenta and tunneling leads to an accurate advancement of the (reduced) initial envelope by the barrier width. In the case of a wide barrier, initial envelope is accurately translated into the complex coordinate plane. The complex shift, given by the first moment of the DAD, accounts for both the displacement of the maximum of the transmitted probability density and the increase in its velocity. It is argued that analyzing apparent “superluminality” in terms of spacial displacements helps avoid contradiction associated with time parameters such as the phase time.

Relationships of Initial Population Densities of Meloidogyne incognita and M. hapla to Yield of Tomato

PubMed Central

Barker, K. R.; Shoemaker, P. B.; Nelson, L. A.

1976-01-01

Microplots 80 × 100 cm, infested with varying initial population densities (Pi) of Meloidogyne incognita or M. hapla, were planted to tomato at two locations. Experiments were conducted in a sandy loam soil at Fletcher, N. C. (mountains) where the mean temperature for May to September is ca 20.7 C, and in a loamy saml at Clayton, N. C. (coastal plain) where the mean temperature for May to Septemher is ca 24.8 C. In these experimentally infested plots, M. incognita and M. hapla caused maximunt yield losses of 20-30%, at lhe mountain site with Pi of 0-12,500 eggs and larvae/500 cm³ of soil. In the coaslal plain, M. incognita suppressed yields up to 85%, and M. hapla suppressed yields up to 50% in comparison with the noninfested control. A part of the high losses at this site apparently was due to M. incognita predisposing tomato to the early blight fungus. In a second experintent, in which a nematicide was used to obtain a range of Pis (with Pi as high as 25,000/50 cm³ of soil) at Fletcher, losses due to M. incognita were as great as 50%, but similar densities of M. hapla suppressed yields by only 10-25%. Approximate threshold densities for both species ranged from 500 to 1,000 larvae and eggs (higher for surviving larvae) for the mountain site, whereas nutnbers as low as 20 larvae/500 cm³ of soil of either species caused signiticant damage in the coastal plain. Chemical soil treatments proved useful in obtaining various initial population densities; however, problems were encountered in measuring effective inoculum after such treatments, especially in the heavier soil. PMID:19308228

Population density determines the direction of the association between ambient ultraviolet radiation and type 1 diabetes incidence.

PubMed

Elliott, Jane C; Lucas, Robyn M; Clements, Mark S; Bambrick, Hilary J

2010-09-01

Type 1 diabetes incidence has increased rapidly over the last 20 years, and ecological studies show inverse latitudinal gradients for both incidence and prevalence. Some studies have found season of birth or season of diagnosis effects. Together these findings suggest an important role for environmental factors in disease etiology. To examine whether type 1 diabetes incidence varies in relation to ambient ultraviolet radiation (UVR) in Australian children. We used case records of 4773 children aged 0-14 yr from the Australian National Diabetes Register to estimate type 1 diabetes incidence in relation to residential ambient UVR, both as a continuous variable and in four categories. We examined season of birth and season of diagnosis and variation in these parameters and in age at diagnosis, in relation to ambient UVR. Overall incidence was 20 per 100 000 population with no sex difference. There was a statistically significant trend toward winter diagnosis (adjusted RR = 1.22, 95% CI 1.13-1.33, p<0.001) but no apparent season of birth effect. Incidence in the highest UVR category was significantly lower than in the lowest UVR category (RR = 0.85, 95% CI 0.75-0.96). We found an inverse association between incidence and ambient UVR that was present only at low population densities; at high population densities type 1 diabetes incidence increased with increasing ambient UVR. In low population density, largely rural environments, ambient UVR may better reflect the personal UV dose, with the latter being protective for the development of type 1 diabetes. This effect is lost or reversed in high population density, largely urban, environments.

Can Process Understanding Help Elucidate The Structure Of The Critical Zone? Comparing Process-Based Soil Formation Models With Digital Soil Mapping.

NASA Astrophysics Data System (ADS)

Vanwalleghem, T.; Román, A.; Peña, A.; Laguna, A.; Giráldez, J. V.

2017-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties in the critical zone. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of traditional digital soil mapping versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

Sedimentation dynamics and equilibrium profiles in multicomponent mixtures of colloidal particles.

PubMed

Spruijt, E; Biesheuvel, P M

2014-02-19

In this paper we give a general theoretical framework that describes the sedimentation of multicomponent mixtures of particles with sizes ranging from molecules to macroscopic bodies. Both equilibrium sedimentation profiles and the dynamic process of settling, or its converse, creaming, are modeled. Equilibrium profiles are found to be in perfect agreement with experiments. Our model reconciles two apparently contradicting points of view about buoyancy, thereby resolving a long-lived paradox about the correct choice of the buoyant density. On the one hand, the buoyancy force follows necessarily from the suspension density, as it relates to the hydrostatic pressure gradient. On the other hand, sedimentation profiles of colloidal suspensions can be calculated directly using the fluid density as apparent buoyant density in colloidal systems in sedimentation-diffusion equilibrium (SDE) as a result of balancing gravitational and thermodynamic forces. Surprisingly, this balance also holds in multicomponent mixtures. This analysis resolves the ongoing debate of the correct choice of buoyant density (fluid or suspension): both approaches can be used in their own domain. We present calculations of equilibrium sedimentation profiles and dynamic sedimentation that show the consequences of these insights. In bidisperse mixtures of colloids, particles with a lower mass density than the homogeneous suspension will first cream and then settle, whereas particles with a suspension-matched mass density form transient, bimodal particle distributions during sedimentation, which disappear when equilibrium is reached. In all these cases, the centers of the distributions of the particles with the lowest mass density of the two, regardless of their actual mass, will be located in equilibrium above the so-called isopycnic point, a natural consequence of their hard-sphere interactions. We include these interactions using the Boublik-Mansoori-Carnahan-Starling-Leland (BMCSL) equation of state. Finally, we demonstrate that our model is not limited to hard spheres, by extending it to charged spherical particles, and to dumbbells, trimers and short chains of connected beads.

Climatic variation and tortoise survival: has a desert species met its match?

USGS Publications Warehouse

Lovich, Jeffrey E.; Yackulic, Charles B.; Freilich, Jerry; Agha, Mickey; Austin, Meaghan; Meyer, Katherine P.; Arundel, Terence R.; Hansen, Jered; Vamstad, Michael S.; Root, Stephanie A.

2014-01-01

While demographic changes in short-lived species may be observed relatively quickly in response to climate changes, measuring population responses of long-lived species requires long-term studies that are not always available. We analyzed data from a population of threatened Agassiz’s desert tortoises (Gopherus agassizii) at a 2.59 km2 study plot in the Sonoran Desert ecosystem of Joshua Tree National Park, California, USA from 1978 to 2012 to examine variation in apparent survival and demography in this long-lived species. Transect-based, mark-recapture surveys were conducted in 10 of those years to locate living and dead tortoises. Previous modeling suggested that this area would become unsuitable as tortoise habitat under a warming and drying climate scenario. Estimated adult population size declined greatly from 1996 to 2012. The population appeared to have high apparent survival from 1978 to 1996 but apparent survival decreased from 1997 to 2002, concurrent with persistent drought. The best model relating apparent survivorship of tortoises ≥18 cm over time was based on a three year moving average of estimated winter precipitation. The postures and positions of a majority of dead tortoises found in 2012 were consistent with death by dehydration and starvation. Some live and many dead tortoises found in 2012 showed signs of predation or scavenging by mammalian carnivores. Coyote (Canis latrans) scats and other evidence from the site confirmed their role as tortoise predators and scavengers. Predation rates may be exacerbated by drought if carnivores switch from preferred mammalian prey to tortoises during dry years. Climate modeling suggests that the region will be subjected to even longer duration droughts in the future and that the plot may become unsuitable for continued tortoise survival. Our results showing wide fluctuations in apparent survival and decreasing tortoise density over time may be early signals of that possible outcome.

Utilization of sewage sludge in the manufacture of lightweight aggregate.

PubMed

Franus, Małgorzata; Barnat-Hunek, Danuta; Wdowin, Magdalena

2016-01-01

This paper presents a comprehensive study on the possibility of sewage sludge management in a sintered ceramic material such as a lightweight aggregate. Made from clay and sludge lightweight aggregates were sintered at two temperatures: 1100 °C (name of sample LWA1) and 1150 °C (name of sample LWA2). Physical and mechanical properties indicate that the resulting expanded clay aggregate containing sludge meets the basic requirements for lightweight aggregates. The presence of sludge supports the swelling of the raw material, thereby causing an increase in the porosity of aggregates. The LWA2 has a lower value of bulk particle density (0.414 g/cm(3)), apparent particle density (0.87 g/cm(3)), and dry particle density (2.59 g/cm(3)) than it is in the case of LWA1 where these parameters were as follows: bulk particle density 0.685 g/cm(3), apparent particle density 1.05 g/cm(3), and dry particle density 2.69 g/cm(3). Water absorption and porosity of LWA1 (WA = 14.4 %, P = 60 %) are lower than the LWA2 (WA = 16.2 % and P = 66 %). This is due to the higher heating temperature of granules which make the waste gases, liberating them from the decomposition of organic sewage sludge. The compressive strength of LWA2 aggregate is 4.64 MPa and for LWA1 is 0.79 MPa. Results of leaching tests of heavy metals from examined aggregates have shown that insoluble metal compounds are placed in silicate and aluminosilicate structure of the starting materials (clays and sludges), whereas soluble substances formed crystalline skeleton of the aggregates. The thermal synthesis of lightweight aggregates from clay and sludge mixture is a waste-free method of their development.

Phosphorene Co-catalyst Advancing Highly Efficient Visible-Light Photocatalytic Hydrogen Production.

PubMed

Ran, Jingrun; Zhu, Bicheng; Qiao, Shi-Zhang

2017-08-21

Transitional metals are widely used as co-catalysts boosting photocatalytic H 2 production. However, metal-based co-catalysts suffer from high cost, limited abundance and detrimental environment impact. To date, metal-free co-catalyst is rarely reported. Here we for the first time utilized density functional calculations to guide the application of phosphorene as a high-efficiency metal-free co-catalyst for CdS, Zn 0.8 Cd 0.2 S or ZnS. Particularly, phosphorene modified CdS shows a high apparent quantum yield of 34.7 % at 420 nm. This outstanding activity arises from the strong electronic coupling between phosphorene and CdS, as well as the favorable band structure, high charge mobility and massive active sites of phosphorene, supported by computations and advanced characterizations, for example, synchrotron-based X-ray absorption near edge spectroscopy. This work brings new opportunities to prepare highly-active, cheap and green photocatalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of insulin deficiency on the plasma clearance and exchange of high-density-lipoprotein phosphatidylcholine in rats.

PubMed Central

Martins, I J; Redgrave, T G

1992-01-01

Triolein/cholesteryl oleate/cholesterol/phosphatidylcholine emulsions designed to model the lipid composition of chylomicrons were injected intravenously into control and streptozotocin-treated insulin-deficient rats. As previously described for lymph chylomicrons, the emulsion triolein was hydrolysed and phosphatidylcholine was transferred to the plasma high-density lipoproteins (HDL). This mechanism was used to introduce a phospholipid label into HDL in vivo. The subsequent clearance of phospholipid radioactivity from the plasma of insulin-deficient rats was significantly slower than in controls (P less than 0.025). Plasma clearance was similarly slower in insulin-deficient rats after injection of HDL that was previously labelled with radioactive phospholipids. After injection, the phospholipid label redistributed rapidly between the large-particle fraction of plasma lipoproteins (very-low- and low-density lipoproteins), and the lighter and heavier fractions of HDL. Compared with control rats, in insulin-deficient rats less of the phospholipid label was distributed to the lighter HDL fraction and more to the heavier HDL fraction, and this difference was not due to changes in activity of lecithin: cholesterol acyltransferase or in the apparent activity of phospholipid transfer protein. In insulin-deficient rats the changes in HDL phospholipid clearance and exchange appeared to be secondary to the associated hypertriglyceridaemia and the related changes in distribution of phospholipids between classes of plasma lipoproteins. PMID:1536661

Bone mineral density in elite adolescent female figure skaters

USDA-ARS?s Scientific Manuscript database

Elite adolescent figure skaters must accommodate both the physical demands of competitive training and the accelerated rate of bone growth that is associated with adolescence. Although, these athletes apparently undergo sufficient physical activity to develop healthy bones, it is possible that other...

The Survival of the Core Fundamental Plane against Galactic Mergers

NASA Astrophysics Data System (ADS)

Holley-Bockelmann, Kelly; Richstone, Douglas

1999-05-01

The basic dimensional properties of the centers of elliptical galaxies, such as length scale, luminosity, and velocity dispersion, lie on a fundamental plane similar to that of elliptical galaxies as a whole. The orientation of this plane, and the distribution of core parameters within it, point to a strong correlation of core density with either core or total luminosity, and indicate that low-luminosity ellipticals are much denser than high-luminosity galaxies (Hubble Space Telescope data suggest that this relationship may be as steep as ρc~L-2). In addition, low-luminosity ellipticals have a much smaller length scale than their high-luminosity counterparts. Since we think that small galaxies are occasionally accreted by big ones, the high density of these galaxies and their likely durability against the time-varying tidal field of the bigger ones suggests that they will survive substantially intact in the cores of larger galaxies and would be easily visible. Their presence would destroy the observed correlation. Motivated by this apparent inconsistency between an observed fact and a simple physical argument, we have developed an effective simulation method and applied it to the problem of the accretion of very dense secondary companions by tenuous primaries. We have studied the accretion of objects of varying luminosity ratios, with sizes and densities drawn from the fundamental plane under the assumption that the mass distribution in the central parts of the galaxies follows the light. The results indicate that in mergers with mass ratios greater than 10, chosen with an appropriate central density dependence on luminosity, the smaller object is only stripped down to the highest density encountered in the primary during the accretion process. Thus, the form of the core fundamental plane suggests that the mass distribution in galaxy centers is different from the light distribution, or that an understanding of secondary survival requires more than the dynamics of visible stars.

Calculation of the spin-polarized electronic structure of an interstitial iron impurity in silicon

NASA Astrophysics Data System (ADS)

Katayama-Yoshida, H.; Zunger, Alex

1985-06-01

We apply our self-consistent, all-electron, spin-polarized Green's-function method within an impurity-centered, dynamic basis set to study the interstitial iron impurity in silicon. We use two different formulations of the interelectron interactions: the local-spin-density (LSD) formalism and the self-interaction-corrected (SIC) local-spin-density (SIC-LSD) formalism. We find that the SIC-LSD approach is needed to obtain the correct high-spin ground state of Si:Fe+. We propose a quantitative explanation to the observed donor ionization energy and the high-spin ground states for Si:Fe+ within the SIC-LSD approach. For both Si:Fe0 and Si:Fe+, this approach leads to a hyperfine field, contact spin density, and ionization energy in better agreement with experiments than the simple LSD approach. The apparent dichotomy between the covalently delocalized nature of Si:Fe as suggested on the one hand by its reduced hyperfine field (relative to the free atom) and extended spin density and by the occurrence of two closely spaced, stable charge states (within 0.4 eV) and on the other hand by the atomically localized picture (suggested, for example, by the stability of a high-spin, ground-state configuration) is resolved. We find a large reduction in the hyperfine field and contact spin density due to the covalent hybridization between the impurity 3d orbitals and the tails of the delocalized sp3 hybrid orbitals of the surrounding silicon atoms. Using the calculated results, we discuss (i) the underlying mechanism for the stability and plurality of charged states, (ii) the covalent reduction in the hyperfine field, (iii) the remarkable constancy of the impurity Mössbauer isomer shift for different charged states, (iv) comparison with the multiple charged states in ionic crystals, and (v) some related speculation about the mechanism of (Fe2+/Fe3+) oxidation-reduction ionizations in heme proteins and electron-transporting biological systems.

Tailored benzoxazines as novel resin systems for printed circuit boards in high temperature e-mobility applications

NASA Astrophysics Data System (ADS)

Troeger, K.; Darka, R. Khanpour; Neumeyer, T.; Altstaedt, V.

2014-05-01

This study focuses on the development of Bisphenol-F-benzoxazine resins blended with different ratios of a trifunctional epoxy resin suitable as matrix for substrates for high temperature printed circuit board (HT-PCB) applications. With the benzoxazine blends glass transition temperatures of more than 190 °C could be achieved in combination with a coefficient of thermal expansion in thickness direction (z-CTE) of less than 60 ppm/K without adding any fillers. This shows the high potential of the benzoxazine-epoxy blend systems as substrate materials for HT-PCBs. To understand the thermal behavior of the different formulations, the apparent crosslink density was calculated based on data from Dynamic Mechanical Analysis. Laminates in laboratory scale were prepared and characterized to demonstrate the transformation of the neat resin properties into real electronic substrate properties. The produced laminates exhibit a z-CTE below 40 ppm/K.

Tailored benzoxazines as novel resin systems for printed circuit boards in high temperature e-mobility applications

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

Troeger, K., E-mail: altstaedt@uni-bayreuth.de; Darka, R. Khanpour, E-mail: altstaedt@uni-bayreuth.de; Neumeyer, T., E-mail: altstaedt@uni-bayreuth.de

2014-05-15

This study focuses on the development of Bisphenol-F-benzoxazine resins blended with different ratios of a trifunctional epoxy resin suitable as matrix for substrates for high temperature printed circuit board (HT-PCB) applications. With the benzoxazine blends glass transition temperatures of more than 190 °C could be achieved in combination with a coefficient of thermal expansion in thickness direction (z-CTE) of less than 60 ppm/K without adding any fillers. This shows the high potential of the benzoxazine-epoxy blend systems as substrate materials for HT-PCBs. To understand the thermal behavior of the different formulations, the apparent crosslink density was calculated based on datamore » from Dynamic Mechanical Analysis. Laminates in laboratory scale were prepared and characterized to demonstrate the transformation of the neat resin properties into real electronic substrate properties. The produced laminates exhibit a z-CTE below 40 ppm/K.« less

Does size and buoyancy affect the long-distance transport of floating debris?

NASA Astrophysics Data System (ADS)

Ryan, Peter G.

2015-08-01

Floating persistent debris, primarily made from plastic, disperses long distances from source areas and accumulates in oceanic gyres. However, biofouling can increase the density of debris items to the point where they sink. Buoyancy is related to item volume, whereas fouling is related to surface area, so small items (which have high surface area to volume ratios) should start to sink sooner than large items. Empirical observations off South Africa support this prediction: moving offshore from coastal source areas there is an increase in the size of floating debris, an increase in the proportion of highly buoyant items (e.g. sealed bottles, floats and foamed plastics), and a decrease in the proportion of thin items such as plastic bags and flexible packaging which have high surface area to volume ratios. Size-specific sedimentation rates may be one reason for the apparent paucity of small plastic items floating in the world’s oceans.

The drift-diffusion interpretation of the electron current within the organic semiconductor characterized by the bulk single energy trap level

NASA Astrophysics Data System (ADS)

Cvikl, B.

2010-01-01

The closed solution for the internal electric field and the total charge density derived in the drift-diffusion approximation for the model of a single layer organic semiconductor structure characterized by the bulk shallow single trap-charge energy level is presented. The solutions for two examples of electric field boundary conditions are tested on room temperature current density-voltage data of the electron conducting aluminum/tris(8-hydroxyquinoline aluminum/calcium structure [W. Brütting et al., Synth. Met. 122, 99 (2001)] for which jexp∝Va3.4, within the interval of bias 0.4 V≤Va≤7. In each case investigated the apparent electron mobility determined at given bias is distributed within a given, finite interval of values. The bias dependence of the logarithm of their lower limit, i.e., their minimum values, is found to be in each case, to a good approximation, proportional to the square root of the applied electric field. On account of the bias dependence as incorporated in the minimum value of the apparent electron mobility the spatial distribution of the organic bulk electric field as well as the total charge density turn out to be bias independent. The first case investigated is based on the boundary condition of zero electric field at the electron injection interface. It is shown that for minimum valued apparent mobilities, the strong but finite accumulation of electrons close to the anode is obtained, which characterize the inverted space charge limited current (SCLC) effect. The second example refers to the internal electric field allowing for self-adjustment of its boundary values. The total electron charge density is than found typically to be of U shape, which may, depending on the parameters, peak at both or at either Alq3 boundary. It is this example in which the proper SCLC effect is consequently predicted. In each of the above two cases, the calculations predict the minimum values of the electron apparent mobility, which substantially exceed the corresponding published measurements. For this reason the effect of the drift term alone is additionally investigated. On the basis of the published empirical electron mobilities and the diffusion term revoked, it is shown that the steady state electron current density within the Al/Alq3 (97 nm)/Ca single layer organic structure may well be pictured within the drift-only interpretation of the charge carriers within the Alq3 organic characterized by the single (shallow) trap energy level. In order to arrive at this result, it is necessary that the nonzero electric field, calculated to exist at the electron injecting Alq3/Ca boundary, is to be appropriately accounted for in the computation.

Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

NASA Astrophysics Data System (ADS)

de Boer, Hugo; Drake, Paul; Veneklaas, Erik

2017-04-01

The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on transpiration, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Critical is that leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈1. Although this theory is supported by observations on many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis we assembled leaf hydraulic, morphological and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent over-investment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf lifespan, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. Our results highlight the need to consider the specific leaf hydraulic architecture of aridity-adapted plants when studying ecohydrological processes in arid ecosystems.

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

S.K. Kawatra; B. Anamerie; T.C. Eisele

The pig iron nugget process was developed as an alternative to the traditional blast furnace process by Kobe Steel. The process aimed to produce pig iron nuggets, which have similar chemical and physical properties to blast furnace pig iron, in a single step. The pig iron nugget process utilizes coal instead of coke and self reducing and fluxing dried green balls instead of pellets and sinters. In this process the environmental emissions caused by coke and sinter production, and energy lost between pellet induration (heat hardening) and transportation to the blast furnace can be eliminated. The objectives of this researchmore » were to (1) produce pig iron nuggets in the laboratory, (2) characterize the pig iron nugget produced and compare them with blast furnace pig iron, (3) investigate the furnace temperature and residence time effects on the pig iron nugget production, and (4) optimize the operational furnace temperatures and residence times. The experiments involved heat treatment of self reducing and fluxing dried green balls at various furnace temperatures and residence times. Three chemically and physically different products were produced after the compete reduction of iron oxides to iron depending on the operational furnace temperatures and/or residence times. These products were direct reduced iron (DRI), transition direct reduced iron (TDRI), and pig iron nuggets. The increase in the carbon content of the system as a function of furnace temperature and/or residence time dictated the formation of these products. The direct reduced iron, transition direct reduced iron, and pig iron nuggets produced were analyzed for their chemical composition, degree of metallization, apparent density, microstructure and microhardness. In addition, the change in the carbon content of the system with the changing furnace temperature and/or residence time was detected by optical microscopy and Microhardness measurements. The sufficient carbon dissolution required for the production of pig iron nuggets was determined. It was determined that pig iron nuggets produced had a high apparent density (6.7-7.2 gr/cm3), highly metallized, slag free structure, high iron content (95-97%), high microhardness values (> 325 HVN) and microstructure similar to white cast iron. These properties made them a competitive alternative to blast furnace pig iron.« less

Empirical analysis of vegetation dynamics and the possibility of a catastrophic desertification transition

PubMed Central

Kent, Rafi; Michael, Yaron; Shnerb, Nadav M.

2017-01-01

The process of desertification in the semi-arid climatic zone is considered by many as a catastrophic regime shift, since the positive feedback of vegetation density on growth rates yields a system that admits alternative steady states. Some support to this idea comes from the analysis of static patterns, where peaks of the vegetation density histogram were associated with these alternative states. Here we present a large-scale empirical study of vegetation dynamics, aimed at identifying and quantifying directly the effects of positive feedback. To do that, we have analyzed vegetation density across 2.5 × 106 km2 of the African Sahel region, with spatial resolution of 30 × 30 meters, using three consecutive snapshots. The results are mixed. The local vegetation density (measured at a single pixel) moves towards the average of the corresponding rainfall line, indicating a purely negative feedback. On the other hand, the chance of spatial clusters (of many “green” pixels) to expand in the next census is growing with their size, suggesting some positive feedback. We show that these apparently contradicting results emerge naturally in a model with positive feedback and strong demographic stochasticity, a model that allows for a catastrophic shift only in a certain range of parameters. Static patterns, like the double peak in the histogram of vegetation density, are shown to vary between censuses, with no apparent correlation with the actual dynamical features. Our work emphasizes the importance of dynamic response patterns as indicators of the state of the system, while the usefulness of static modality features appears to be quite limited. PMID:29261678

Traumatic brain injury causes an FK506-sensitive loss and an overgrowth of dendritic spines in rat forebrain.

PubMed

Campbell, John N; Register, David; Churn, Severn B

2012-01-20

Traumatic brain injury (TBI) causes both an acute loss of tissue and a progressive injury through reactive processes such as excitotoxicity and inflammation. These processes may worsen neural dysfunction by altering neuronal circuitry beyond the focally-damaged tissue. One means of circuit alteration may involve dendritic spines, micron-sized protuberances of dendritic membrane that support most of the excitatory synapses in the brain. This study used a modified Golgi-Cox technique to track changes in spine density on the proximal dendrites of principal cells in rat forebrain regions. Spine density was assessed at 1 h, 24 h, and 1 week after a lateral fluid percussion TBI of moderate severity. At 1 h after TBI, no changes in spine density were observed in any of the brain regions examined. By 24 h after TBI, however, spine density had decreased in ipsilateral neocortex in layer II and III and dorsal dentate gyrus (dDG). This apparent loss of spines was prevented by a single, post-injury administration of the calcineurin inhibitor FK506. These results, together with those of a companion study, indicate an FK506-sensitive mechanism of dendritic spine loss in the TBI model. Furthermore, by 1 week after TBI, spine density had increased substantially above control levels, bilaterally in CA1 and CA3 and ipsilaterally in dDG. The apparent overgrowth of spines in CA1 is of particular interest, as it may explain previous reports of abnormal and potentially epileptogenic activity in this brain region.

Empirical analysis of vegetation dynamics and the possibility of a catastrophic desertification transition.

PubMed

Weissmann, Haim; Kent, Rafi; Michael, Yaron; Shnerb, Nadav M

2017-01-01

The process of desertification in the semi-arid climatic zone is considered by many as a catastrophic regime shift, since the positive feedback of vegetation density on growth rates yields a system that admits alternative steady states. Some support to this idea comes from the analysis of static patterns, where peaks of the vegetation density histogram were associated with these alternative states. Here we present a large-scale empirical study of vegetation dynamics, aimed at identifying and quantifying directly the effects of positive feedback. To do that, we have analyzed vegetation density across 2.5 × 106 km2 of the African Sahel region, with spatial resolution of 30 × 30 meters, using three consecutive snapshots. The results are mixed. The local vegetation density (measured at a single pixel) moves towards the average of the corresponding rainfall line, indicating a purely negative feedback. On the other hand, the chance of spatial clusters (of many "green" pixels) to expand in the next census is growing with their size, suggesting some positive feedback. We show that these apparently contradicting results emerge naturally in a model with positive feedback and strong demographic stochasticity, a model that allows for a catastrophic shift only in a certain range of parameters. Static patterns, like the double peak in the histogram of vegetation density, are shown to vary between censuses, with no apparent correlation with the actual dynamical features. Our work emphasizes the importance of dynamic response patterns as indicators of the state of the system, while the usefulness of static modality features appears to be quite limited.

The long-term intensity behavior of Centaurus X-3

NASA Technical Reports Server (NTRS)

Schreier, E. J.; Swartz, K.; Giacconi, R.; Fabbiano, G.; Morin, J.

1976-01-01

In three years of observation, the X-ray source Cen X-3 appears to alternate between 'high states', with an intensity of 150 counts/s (2-6 keV) or greater, and 'low states', where the source is barely detectable. The time scale of this behavior is of the order of months, and no apparent periodicity has been observed. Analysis of two transitions between these states is reported. During two weeks in July 1972, the source increased from about 20 counts/s to 150 counts/s. The detailed nature of this turn-on is interpreted in terms of a model in which the supergiant's stellar wind decreases in density. A second transition, a turnoff in February 1973, is similarly analyzed and found to be consistent with a simple decrease in accretion rate. The presence of absorption dips during transitions at orbital phases 0.4-0.5 as well as at phase 0.75 is discussed. The data are consistent with a stellar-wind accretion model and with different kinds of extended lows caused by increased wind density masking the X-ray emission or by decreased wind density lowering the accretion rate.

Vapor-deposited organic glasses exhibit enhanced stability against photodegradation.

PubMed

Qiu, Yue; Dalal, Shakeel S; Ediger, M D

2018-04-18

Photochemically stable solids are in demand for applications in organic electronics. Previous work has established the importance of the molecular packing environment by demonstrating that different crystal polymorphs of the same compound react at different rates when illuminated. Here we show, for the first time, that different amorphous packing arrangements of the same compound photodegrade at different rates. For these experiments, we utilize the ability of physical vapor deposition to prepare glasses with an unprecedented range of densities and kinetic stabilities. Indomethacin, a pharmaceutical molecule that can undergo photodecarboxylation when irradiated by UV light, is studied as a model system. Photodegradation is assessed through light-induced changes in the mass of glassy thin films due to the loss of CO2, as measured by a quartz crystal microbalance (QCM). Glasses prepared by physical vapor deposition degraded more slowly under UV illumination than did the liquid-cooled glass, with the difference as large as a factor of 2. Resistance to photodegradation correlated with glass density, with the vapor-deposited glasses being up to 1.3% more dense than the liquid-cooled glass. High density glasses apparently limit the local structural changes required for photodegradation.

Selecting habitat to survive: the impact of road density on survival in a large carnivore.

PubMed

Basille, Mathieu; Van Moorter, Bram; Herfindal, Ivar; Martin, Jodie; Linnell, John D C; Odden, John; Andersen, Reidar; Gaillard, Jean-Michel

2013-01-01

Habitat selection studies generally assume that animals select habitat and food resources at multiple scales to maximise their fitness. However, animals sometimes prefer habitats of apparently low quality, especially when considering the costs associated with spatially heterogeneous human disturbance. We used spatial variation in human disturbance, and its consequences on lynx survival, a direct fitness component, to test the Hierarchical Habitat Selection hypothesis from a population of Eurasian lynx Lynx lynx in southern Norway. Data from 46 lynx monitored with telemetry indicated that a high proportion of forest strongly reduced the risk of mortality from legal hunting at the home range scale, while increasing road density strongly increased such risk at the finer scale within the home range. We found hierarchical effects of the impact of human disturbance, with a higher road density at a large scale reinforcing its negative impact at a fine scale. Conversely, we demonstrated that lynx shifted their habitat selection to avoid areas with the highest road densities within their home ranges, thus supporting a compensatory mechanism at fine scale enabling lynx to mitigate the impact of large-scale disturbance. Human impact, positively associated with high road accessibility, was thus a stronger driver of lynx space use at a finer scale, with home range characteristics nevertheless constraining habitat selection. Our study demonstrates the truly hierarchical nature of habitat selection, which aims at maximising fitness by selecting against limiting factors at multiple spatial scales, and indicates that scale-specific heterogeneity of the environment is driving individual spatial behaviour, by means of trade-offs across spatial scales.

Demographic and socioeconomic disparity in nutrition: application of a novel Correlated Component Regression approach

PubMed Central

Alkerwi, Ala'a; Vernier, Céderic; Sauvageot, Nicolas; Crichton, Georgina E; Elias, Merrill F

2015-01-01

Objectives This study aimed to examine the most important demographic and socioeconomic factors associated with diet quality, evaluated in terms of compliance with national dietary recommendations, selection of healthy and unhealthy food choices, energy density and food variety. We hypothesised that different demographic and socioeconomic factors may show disparate associations with diet quality. Study design A nationwide, cross-sectional, population-based study. Participants A total of 1352 apparently healthy and non-institutionalised subjects, aged 18–69 years, participated in the Observation of Cardiovascular Risk Factors in Luxembourg (ORISCAV-LUX) study in 2007–2008. The participants attended the nearest study centre after a telephone appointment, and were interviewed by trained research staff. Outcome measures Diet quality as measured by 5 dietary indicators, namely, recommendation compliance index (RCI), recommended foods score (RFS), non-recommended foods score (non-RFS), energy density score (EDS), and dietary diversity score (DDS). The novel Correlated Component Regression (CCR) technique was used to determine the importance and magnitude of the association of each socioeconomic factor with diet quality, in a global analytic approach. Results Increasing age, being male and living below the poverty threshold were predominant factors associated with eating a high energy density diet. Education level was an important factor associated with healthy and adequate food choices, whereas economic resources were predominant factors associated with food diversity and energy density. Conclusions Multiple demographic and socioeconomic circumstances were associated with different diet quality indicators. Efforts to improve diet quality for high-risk groups need an important public health focus. PMID:25967988

Partial Molar Volumes of 15-Crown-5 Ether in Mixtures of N,N-Dimethylformamide with Water.

PubMed

Tyczyńska, Magdalena; Jóźwiak, Małgorzata

2014-01-01

The density of 15-crown-5 ether (15C5) solutions in the mixtures of N,N -dimethylformamide (DMF) and water (H 2 O) was measured within the temperature range 293.15-308.15 K using an Anton Paar oscillatory U-tube densimeter. The results were used to calculate the apparent molar volumes ( V Φ ) of 15C5 in the mixtures of DMF + H 2 O over the whole concentration range. Using the apparent molar volumes and Redlich and Mayer equation, the standard partial molar volumes of 15-crown-5 were calculated at infinite dilution ([Formula: see text]). The limiting apparent molar expansibilities ( α ) were also calculated. The data are discussed from the point of view of the effect of concentration changes on interactions in solution.

The effect of weight change on changes in breast density measures over menopause in a breast cancer screening cohort.

PubMed

Wanders, Johanna Olga Pauline; Bakker, Marije Fokje; Veldhuis, Wouter Bernard; Peeters, Petra Huberdina Maria; van Gils, Carla Henrica

2015-05-30

High weight and high percentage mammographic breast density are both breast cancer risk factors but are negatively correlated. Therefore, we wanted to obtain more insight into this apparent paradox. We investigated in a longitudinal study how weight change over menopause is related to changes in mammographic breast features. Five hundred ninety-one participants of the EPIC-NL cohort were divided into three groups according to their prospectively measured weight change over menopause: (1) weight loss (more than -3.0 %), (2) stable weight (between -3.0 % and +3.0 %), and (3) weight gain (more than 3.0 %). SPSS GLM univariate analysis was used to determine both the mean breast measure changes in, and the trend over, the weight change groups. Over a median period of 5 years, the mean changes in percent density in these groups were -5.0 % (95 % confidence interval (CI) -8.0; -2.1), -6.8 % (95 % CI -9.0; -4.5), and -10.2 % (95 % CI -12.5; -7.9), respectively (P-trend = 0.001). The mean changes in dense area were -16.7 cm(2) (95 % CI -20.1; -13.4), -16.4 cm(2) (95 % CI -18.9; -13.9), and -18.1 cm(2) (95 % CI -20.6; -15.5), respectively (P-trend = 0.437). Finally, the mean changes in nondense area were -6.1 cm(2) (95 % CI -11.9; -0.4), -0.6 cm(2) (95 % CI -4.9; 3.8), and 5.3 cm(2) (95 % CI 0.9; 9.8), respectively (P-trend < 0.001). Going through menopause is associated with a decrease in both percent density and dense area. Owing to an increase in the nondense tissue, the decrease in percent density is largest in women who gain weight. The decrease in dense area is not related to weight change. So the fact that both high percent density and high weight or weight gain are associated with high postmenopausal breast cancer risk can probably not be explained by an increase (or slower decrease) of dense area in women gaining weight compared with women losing weight or maintaining a stable weight. These results suggest that weight and dense area are presumably two independent postmenopausal breast cancer risk factors.

Species-Independent Modeling of High-Frequency Ultrasound Backscatter in Hyaline Cartilage.

PubMed

Männicke, Nils; Schöne, Martin; Liukkonen, Jukka; Fachet, Dominik; Inkinen, Satu; Malo, Markus K; Oelze, Michael L; Töyräs, Juha; Jurvelin, Jukka S; Raum, Kay

2016-06-01

Apparent integrated backscatter (AIB) is a common ultrasound parameter used to assess cartilage matrix degeneration. However, the specific contributions of chondrocytes, proteoglycan and collagen to AIB remain unknown. To reveal these relationships, this work examined biopsies and cross sections of human, ovine and bovine cartilage with 40-MHz ultrasound biomicroscopy. Site-matched estimates of collagen concentration, proteoglycan concentration, collagen orientation and cell number density were employed in quasi-least-squares linear regression analyses to model AIB. A positive correlation (R(2) = 0.51, p < 10(-4)) between AIB and a combination model of cell number density and collagen concentration was obtained for collagen orientations approximately perpendicular (>70°) to the sound beam direction. These findings indicate causal relationships between AIB and cartilage structural parameters and could aid in more sophisticated future interpretations of ultrasound backscatter. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Ca II and Na I absorption in the QSO S4 0248 + 430 due to an intervening galaxy

NASA Technical Reports Server (NTRS)

Womble, Donna S.; Junkkarinen, Vesa T.; Cohen, Ross D.; Burbidge, E. Margaret

1990-01-01

Observations of the QSO S4 0248 + 430 and a nearby anonymous galaxy are presented. Two absorption components are found in both Ca II H and K and Na I D1 and D2 at z(a) = 0.0515, 0.0523. Column densities of log N(Ca II) = 13.29, 13.50, and log N(Na I) = 13.79, 14.18 are found for z(a) = 0.0515, 0.0523 absorption systems, respectively. The column density ratios imply considerable calcium depletion and disk-type absorbing gas. At least one and possibly both absorption components are produced by high-velocity gas. A broadband image of the field shows an asymmetrical armlike feature or possible tidal tail covering and extending past the position of the QSO. The presence of this extended feature and the apparent difference between the absorption velocities and galaxy rotation velocity suggest that the absorbing gas is not ordinary disk gas, but rather is a result of tidal disruption.

Interplanetary Magnetic Field Power Spectrum Variations: A VHO Enabled Study

NASA Astrophysics Data System (ADS)

Szabo, A.; Koval, A.; Merka, J.; Narock, T. W.

2010-12-01

The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the solar wind key parameter search capability of the Virtual Heliospheric Observatory (VHO) affords an opportunity to study magnetic field power spectral density variations as a function of solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the ~2 Hz limit above which digitization noise becomes apparent. The power spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions . The time periods of fixed solar wind conditions are obtained from VHO searches that greatly simplify the process. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes.

PubMed

Lee, Derek E; Kissui, Bernard M; Kiwango, Yustina A; Bond, Monica L

2016-12-01

In long-distance migratory systems, local fluctuations in the predator-prey ratio can exhibit extreme variability within a single year depending upon the seasonal location of migratory species. Such systems offer an opportunity to empirically investigate cyclic population density effects on short-term food web interactions by taking advantage of the large seasonal shifts in migratory prey biomass.We utilized a large-mammal predator-prey savanna food web to evaluate support for hypotheses relating to the indirect effects of "apparent competition" and "apparent mutualism" from migratory ungulate herds on survival of resident megaherbivore calves, mediated by their shared predator. African lions ( Panthera leo ) are generalist predators whose primary, preferred prey are wildebeests ( Connochaetes taurinus ) and zebras ( Equus quagga ), while lion predation on secondary prey such as giraffes ( Giraffa camelopardalis ) may change according to the relative abundance of the primary prey species.We used demographic data from five subpopulations of giraffes in the Tarangire Ecosystem of Tanzania, East Africa, to test hypotheses relating to direct predation and indirect effects of large migratory herds on calf survival of a resident megaherbivore. We examined neonatal survival via apparent reproduction of 860 adult females, and calf survival of 449 giraffe calves, during three precipitation seasons over 3 years, seeking evidence of some effect on neonate and calf survival as a consequence of the movements of large herds of migratory ungulates.We found that local lion predation pressure (lion density divided by primary prey density) was significantly negatively correlated with giraffe neonatal and calf survival probabilities. This supports the apparent mutualism hypothesis that the presence of migratory ungulates reduces lion predation on giraffe calves.Natural predation had a significant effect on giraffe calf and neonate survival, and could significantly affect giraffe population dynamics. If wildebeest and zebra populations in this ecosystem continue to decline as a result of increasingly disrupted migrations and poaching, then giraffe calves will face increased predation pressure as the predator-prey ratio increases. Our results suggest that the widespread population declines observed in many migratory systems are likely to trigger demographic impacts in other species due to indirect effects like those shown here.

Effect of surface coating with magnesium stearate via mechanical dry powder coating approach on the aerosol performance of micronized drug powders from dry powder inhalers.

PubMed

Zhou, Qi Tony; Qu, Li; Gengenbach, Thomas; Larson, Ian; Stewart, Peter J; Morton, David A V

2013-03-01

The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by laser diffraction and supported by a twin-stage impinger. High degrees of coating coverage were achieved after mechanofusion, as measured by X-ray photoelectron spectroscopy. Concomitant significant increases occurred in powder bulk densities and in aerosol performance after coating. The apparent optimum performance corresponded with using 2% w/w magnesium stearate. In contrast, traditional blending resulted in no significant changes in either bulk or aerosolization behaviour compared to the untreated sample. It is believed that conventional low-shear blending provides insufficient energy levels to expose host micronized particle surfaces from agglomerates and to distribute guest coating material effectively for coating. A simple ultra-high-shear mechanical dry powder coating step was shown as highly effective in producing ultra-thin coatings on micronized powders and to substantially improve the powder aerosolization efficiency.

[Effect of vibration caused by time-varying magnetic fields on diffusion-weighted MRI].

PubMed

Ogura, Akio; Maeda, Fumie; Miyai, Akira; Hayashi, Kohji; Hongoh, Takaharu

2006-04-20

Diffusion-weighted images (DWIs) with high b-factor in the body are often used to detect and diagnose cancer at MRI. The echo planar imaging (EPI) sequence and high motion probing gradient pulse are used at diffusion weighted imaging, causing high table vibration. The purpose of this study was to assess whether the diffusion signal and apparent diffusion coefficient (ADC) values are influenced by this vibration because of time-varying magnetic fields. Two DWIs were compared. In one, phantoms were fixed on the MRI unit's table transmitting the vibration. In the other, phantoms were supported in air, in the absence of vibration. The phantoms called "solution phantoms" were made from agarose of a particular density. The phantoms called "jelly phantoms" were made from agarose that was heated. The diffusion signal and ADC value of each image were compared. The results showed that the signal of DWI units using the solution phantom was not affected by vibration. However, the signal of DWI and ADC were increased in the low-density jelly phantom as a result of vibration, causing the jelly phantom to vibrate. The DWIs of vibrating regions such as the breast maybe be subject to error. A countermeasure seems to be to support the region adequately.

Suppression of high-energy electrons generated in both disrupting and sustained MST tokamak plasmas

NASA Astrophysics Data System (ADS)

Pandya, M. D.; Chapman, B. E.; Munaretto, S.; Cornille, B. S.; McCollam, K. J.; Sovinec, C. R.; Dubois, A. M.; Almagri, A. F.; Goetz, J. A.

2017-10-01

High-energy electrons appearing during MST tokamak plasma disruptions are rapidly lost from the plasma due apparently to internal MHD activity. Work has just recently begun on generating and diagnosing disruptions in MST tokamak plasmas. Initial measurements show the characteristic drop in central temperature and density preceding a quench of the plasma current. This corresponds to a burst of dominantly n=1 MHD activity, which is accompanied by a short-lived burst of high-energy electrons. The short-lived nature of these electrons is suspected to be due to stochastic transport associated with the increased MHD. Earlier work shows that runaway electrons generated in low density, sustained plasmas are suppressed by a sufficiently large m=3 RMP in plasmas with q(a) <3. RMPs of various poloidal mode number can be generated with an array of saddle coils wound around the vertical insulated gap in MST's thick conducting shell. With an m=3 RMP, the degree of runaway suppression increases with RMP amplitude, while an m=1 RMP has little effect on the runaways. Nonlinear MHD modeling with NIMROD of these MST plasmas indicates increased stochasticity with an m=3 RMP, while no such increase in stochasticity is observed with an m=1 RMP. Work supported by US DOE.

Simulation of Layered Magma Chambers.

ERIC Educational Resources Information Center

Cawthorn, Richard Grant

1991-01-01

The principles of magma addition and liquid layering in magma chambers can be demonstrated by dissolving colored crystals. The concepts of density stratification and apparent lack of mixing of miscible liquids is convincingly illustrated with hydrous solutions at room temperature. The behavior of interstitial liquids in "cumulus" piles…

Modeling solvation effects in real-space and real-time within density functional approaches

NASA Astrophysics Data System (ADS)

Delgado, Alain; Corni, Stefano; Pittalis, Stefano; Rozzi, Carlo Andrea

2015-10-01

The Polarizable Continuum Model (PCM) can be used in conjunction with Density Functional Theory (DFT) and its time-dependent extension (TDDFT) to simulate the electronic and optical properties of molecules and nanoparticles immersed in a dielectric environment, typically liquid solvents. In this contribution, we develop a methodology to account for solvation effects in real-space (and real-time) (TD)DFT calculations. The boundary elements method is used to calculate the solvent reaction potential in terms of the apparent charges that spread over the van der Waals solute surface. In a real-space representation, this potential may exhibit a Coulomb singularity at grid points that are close to the cavity surface. We propose a simple approach to regularize such singularity by using a set of spherical Gaussian functions to distribute the apparent charges. We have implemented the proposed method in the Octopus code and present results for the solvation free energies and solvatochromic shifts for a representative set of organic molecules in water.

Modeling solvation effects in real-space and real-time within density functional approaches

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

Delgado, Alain; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, Calle 30 # 502, 11300 La Habana; Corni, Stefano

2015-10-14

The Polarizable Continuum Model (PCM) can be used in conjunction with Density Functional Theory (DFT) and its time-dependent extension (TDDFT) to simulate the electronic and optical properties of molecules and nanoparticles immersed in a dielectric environment, typically liquid solvents. In this contribution, we develop a methodology to account for solvation effects in real-space (and real-time) (TD)DFT calculations. The boundary elements method is used to calculate the solvent reaction potential in terms of the apparent charges that spread over the van der Waals solute surface. In a real-space representation, this potential may exhibit a Coulomb singularity at grid points that aremore » close to the cavity surface. We propose a simple approach to regularize such singularity by using a set of spherical Gaussian functions to distribute the apparent charges. We have implemented the proposed method in the OCTOPUS code and present results for the solvation free energies and solvatochromic shifts for a representative set of organic molecules in water.« less

Co-melting technology in resource recycling of sludge derived from stone processing.

PubMed

Hu, Shao-Hua; Hu, Shen-Chih; Fu, Yen-Pei

2012-12-01

Stone processing sludge (SPS) is a by-product of stone-processing wastewater treatment; it is suitable for use as a raw material for making artificial lightweight aggregates (ALWAs). In this study, boric acid was utilized as a flux to lower sintering temperature. The formation of the viscous glassy phase was observed by DTA curve and changes in XRD patterns. Experiments were conducted to find the optimal combination of sintering temperature, sintering time, and boric acid dosage to produce an ALWA of favorable characteristics in terms of water absorption, bulk density, apparent porosity, compressive strength and weight loss to satisfy Taiwan's regulatory requirements for construction and insulation materials. Optimal results gave a sintering temperature of 850 degrees C for 15 min at a boric acid dosage of 15% by weight of SPS. Results for ALWA favorable characteristics were: 0.21% (water absorption), 0.35% (apparent porosity), 1.67 g/cm3 (bulk density), 66.94 MPa (compressive strength), and less than 0.1% (weight loss).

Co-melting technology in resource recycling of sludge derived from stone processing.

PubMed

Hu, Shao-Hua; Hu, Shen-Chih; Fu, Yen-Pei

2012-12-01

Stone processing sludge (SPS) is a by-product of stone-processing wastewater treatment; it is suitable for use as a raw material for making artificial lightweight aggregates (ALWAs). In this study, boric acid was utilized as a flux to lower sintering temperature. The formation of the viscous glassy phase was observed by DTA curve and changes in XRD patterns. Experiments were conducted to find the optimal combination of sintering temperature, sintering time, and boric acid dosage to produce an ALWA of favorable characteristics in terms of water absorption, bulk density, apparent porosity, compressive strength and weight loss to satisfy Taiwan's regulatory requirements for construction and insulation materials. Optimal results gave a sintering temperature of 850 °C for 15 min at a boric acid dosage of 15 % by weight of SPS. Results for ALWA favorable characteristics were: 0.21 % (water absorption), 0.35 %(apparent porosity), 1.67 g/cm3 (bulk density), 66.94 MPa (compressive strength), and less than 0.1% (weight loss). [Box: see text].

Surviving Coral Bleaching Events: Porites Growth Anomalies on the Great Barrier Reef

PubMed Central

Cantin, Neal E.; Lough, Janice M.

2014-01-01

Mass coral bleaching affected large parts of the Great Barrier Reef (GBR) in 1998 and 2002. In this study, we assessed if signatures of these major thermal stress events were recorded in the growth characteristics of massive Porites colonies. In 2005 a suite of short (<50 cm) cores were collected from apparently healthy, surviving Porites colonies, from reefs in the central GBR (18–19°S) that have documented observations of widespread bleaching. Sites included inshore (Nelly Bay, Pandora Reef), annually affected by freshwater flood events, midshelf (Rib Reef), only occasionally affected by freshwater floods and offshore (Myrmidon Reef) locations primarily exposed to open ocean conditions. Annual growth characteristics (extension, density and calcification) were measured in 144 cores from 79 coral colonies and analysed over the common 24-year period, 1980–2003. Visual examination of the annual density bands revealed growth hiatuses associated with the bleaching years in the form of abrupt decreases in annual linear extension rates, high density stress bands and partial mortality. The 1998 mass-bleaching event reduced Porites calcification by 13 and 18% on the two inshore locations for 4 years, followed by recovery to baseline calcification rates in 2002. Evidence of partial mortality was apparent in 10% of the offshore colonies in 2002; however no significant effects of the bleaching events were evident in the calcification rates at the mid shelf and offshore sites. These results highlight the spatial variation of mass bleaching events and that all reef locations within the GBR were not equally stressed by the 1998 and 2002 mass bleaching events, as some models tend to suggest, which enabled recovery of calcification on the GBR within 4 years. The dynamics in annual calcification rates and recovery displayed here should be used to improve model outputs that project how coral calcification will respond to ongoing warming of the tropical oceans. PMID:24586377

Surviving coral bleaching events: porites growth anomalies on the Great Barrier Reef.

PubMed

Cantin, Neal E; Lough, Janice M

2014-01-01

Mass coral bleaching affected large parts of the Great Barrier Reef (GBR) in 1998 and 2002. In this study, we assessed if signatures of these major thermal stress events were recorded in the growth characteristics of massive Porites colonies. In 2005 a suite of short (<50 cm) cores were collected from apparently healthy, surviving Porites colonies, from reefs in the central GBR (18-19°S) that have documented observations of widespread bleaching. Sites included inshore (Nelly Bay, Pandora Reef), annually affected by freshwater flood events, midshelf (Rib Reef), only occasionally affected by freshwater floods and offshore (Myrmidon Reef) locations primarily exposed to open ocean conditions. Annual growth characteristics (extension, density and calcification) were measured in 144 cores from 79 coral colonies and analysed over the common 24-year period, 1980-2003. Visual examination of the annual density bands revealed growth hiatuses associated with the bleaching years in the form of abrupt decreases in annual linear extension rates, high density stress bands and partial mortality. The 1998 mass-bleaching event reduced Porites calcification by 13 and 18% on the two inshore locations for 4 years, followed by recovery to baseline calcification rates in 2002. Evidence of partial mortality was apparent in 10% of the offshore colonies in 2002; however no significant effects of the bleaching events were evident in the calcification rates at the mid shelf and offshore sites. These results highlight the spatial variation of mass bleaching events and that all reef locations within the GBR were not equally stressed by the 1998 and 2002 mass bleaching events, as some models tend to suggest, which enabled recovery of calcification on the GBR within 4 years. The dynamics in annual calcification rates and recovery displayed here should be used to improve model outputs that project how coral calcification will respond to ongoing warming of the tropical oceans.

A Tale of Two Faint Bursts: GRB 050223 and GRB 050911

NASA Astrophysics Data System (ADS)

Page, K. L.; Barthelmy, S. D.; Beardmore, A. P.; Burrows, D. N.; Campana, S.; Chincharini, G.; Cummings, J. R.; Cusumano, G.; Gehrels, N.; Giommi, P.; Goad, M. R.; Godet, O.; Graham, J.; Kaneko, Y.; Kennea, J. A.; Mangano, V.; Markwardt, C. B.; O'Brien, P. T.; Osborne, J. P.; Reichart, D. E.; Rol, E.; Sakamoto, T.; Tagliaferri, G.; Tanvir, N. R.; Wells, A. A.; Zhang, B.

2006-05-01

GRBs 050223 and 050911 were discovered by the Swift Burst Alert Telescope (BAT) on 23rd February and 11th September 2005 respectively. The observation of GRB 050223 showed a faint, fading X-ray source, which was identified as the afterglow; GRB 050911, however, was not detected, making any X-ray afterglow extremely faint. The faintness of the afterglow of GRB 050223 could be explained by a large opening or viewing angle, or by the burst being at high redshift. The non-detection of GRB 050911 may indicate the burst occurred in a low-density environment, or, alternatively, was due to a compact object merger, in spite of the apparent long duration of the burst.

Discharge pulse phenomenology

NASA Technical Reports Server (NTRS)

Frederickson, A. R.

1985-01-01

A model was developed which places radiation induced discharge pulse results into a unified conceptual framework. Only two phenomena are required to interpret all space and laboratory results: (1) radiation produces large electrostatic fields inside insulators via the trapping of a net space charge density; and (2) the electrostatic fields initiate discharge streamer plasmas similar to those investigated in high voltage electrical insulation materials; these streamer plasmas generate the pulsing phenomena. The apparent variability and diversity of results seen is an inherent feature of the plasma streamer mechanism acting in the electric fields which is created by irradiation of the dielectrics. The implications of the model are extensive and lead to constraints over what can be done about spacecraft pulsing.

Organic matter and the geotechnical properties of submarine sediments

NASA Astrophysics Data System (ADS)

Keller, George H.

1982-09-01

Continental slope deposits off Peru and Oregon where coastal upwelling is a pronounced oceanographic process possess significant concentrations of organic carbon. Geotechnical properties are altered to varying degrees by the organic matter. Organic matter absorbs water and causes clay-size particles to aggregate forming an open fabric. This causes unusually high water contents and plasticity and exceptionally low wet bulk densities. Some of these deposits show notable increases in shear strength, sensitivity and degree of apparent overconsolidation. Owing to the unique geotechnical properties, sediment stability characteristics are considered to be poor in situations of excess pore pressures. Failure appears to take the form of a fluidized flow somewhat similar to the quick clays of Scandinavia.

Myxomatosis on the Western Plains of Victoria.

PubMed Central

Tighe, F. G.; Edmonds, J. W.; Nolan, I. F.; Shepherd, R. C.; Gocs, A.

1977-01-01

Myxomatosis on the Western Plains is an enzootic disease in contrast with the epizootic pattern which is general in eastern Australia. The most unusual aspects are the presence of significant numbers of diseased rabbits throughout the winter and the continuously low percentage of rabbits with antibodies to myxoma virus. Climatic and topographic conditions are unsuited to the production of the high densities of mosquitoes necessary for widespread epizootics. Under these conditions the effects of less efficient methods of myxomatosis transmission are apparent. The unusual epidemiology of myxomatosis has resulted in selection for virulence of the virus similar to that which has occurred under summer epizootic conditions. All field strains are now in the mid range of virulence. PMID:20473

Myxomatosis on the Western Plains of Victoria.

PubMed

Tighe, F G; Edmonds, J W; Nolan, I F; Shepherd, R C; Gocs, A

1977-10-01

Myxomatosis on the Western Plains is an enzootic disease in contrast with the epizootic pattern which is general in eastern Australia. The most unusual aspects are the presence of significant numbers of diseased rabbits throughout the winter and the continuously low percentage of rabbits with antibodies to myxoma virus. Climatic and topographic conditions are unsuited to the production of the high densities of mosquitoes necessary for widespread epizootics. Under these conditions the effects of less efficient methods of myxomatosis transmission are apparent. The unusual epidemiology of myxomatosis has resulted in selection for virulence of the virus similar to that which has occurred under summer epizootic conditions. All field strains are now in the mid range of virulence.

Comparison of intersecting pedestrian flows based on experiments

NASA Astrophysics Data System (ADS)

Zhang, J.; Seyfried, A.

2014-07-01

Intersections of pedestrian flows feature multiple types, varying in the numbers of flow directions as well as intersecting angles. In this article results from intersecting flow experiments with two different intersecting angles are compared. To analyze the transport capabilities the Voronoi method is used to resolve the fine structure of the resulting velocity-density relations and spatial dependence of the measurements. The fundamental diagrams of various flow types are compared and show no apparent difference with respect to the intersecting angle 90° and 180°. This result indicates that head-on conflicts of different types of flow have the same influence on the transport properties of the system, which demonstrates the high self-organization capabilities of pedestrians.

Metrics for comparison of crystallographic maps

DOE PAGES

Urzhumtsev, Alexandre; Afonine, Pavel V.; Lunin, Vladimir Y.; ...

2014-10-01

Numerical comparison of crystallographic contour maps is used extensively in structure solution and model refinement, analysis and validation. However, traditional metrics such as the map correlation coefficient (map CC, real-space CC or RSCC) sometimes contradict the results of visual assessment of the corresponding maps. This article explains such apparent contradictions and suggests new metrics and tools to compare crystallographic contour maps. The key to the new methods is rank scaling of the Fourier syntheses. The new metrics are complementary to the usual map CC and can be more helpful in map comparison, in particular when only some of their aspects,more » such as regions of high density, are of interest.« less

Impact of oil-based drill mud disposal on benthic foraminiferal assemblages on the continental margin off Angola

NASA Astrophysics Data System (ADS)

Jorissen, F. J.; Bicchi, E.; Duchemin, G.; Durrieu, J.; Galgani, F.; Cazes, L.; Gaultier, M.; Camps, R.

2009-12-01

In order to assess the possible environmental impact of oily cuttings discharged during oil exploration activities, we studied the benthic foraminiferal faunas in a five-station, 4-km-long sampling transect around a cuttings disposal site at about 670 m depth offshore Angola (W Africa), where drilling activities started 1.5 years before sampling. Living (Rose Bengal stained) and dead foraminiferal faunas were sampled in March 2006. The faunal patterns mirror the spatial distribution of hydrocarbons, which are dispersed into a southeastern direction. Four different areas can be distinguished on the basis of the investigated faunal parameters (density, diversity and species composition of the living fauna, and comparison with subrecent dead faunas). The fauna at station S31, 300 m SE of the oil cuttings disposal site, appears to be clearly impacted: the faunal density and diversity are maximal, but evenness is minimal. Taxa sensitive to organic enrichment, such as Uvigerina peregrina, Cancris auriculus and Cribrostomoides subglobosus, have largely disappeared, whereas the low-oxygen-resistant taxon Chilostomella oolina and opportunistic buliminids and bolivinids attain relatively high densities. At station S32, 500 m SE of the disposal site, environmental impact is still perceptible. The faunal density is slightly increased, and U. peregrina, apparently the most sensitive species, is still almost absent. The faunas found at 1 and 1.8 km SE of the disposal site are apparently no longer impacted by the drill mud disposal. Faunal density and diversity are low, and the faunal composition is typical for a mesotrophic to eutrophic upper slope environment. Finally, Station S35, 2 km NW of the disposal site, contains an intermediate fauna, where both the low-oxygen-resistant C. oolina and the more sensitive taxa ( U. peregrina, C. auriculus and C. subglobosus) are present. All taxa live close to the sediment-water interface here, indicating a reduced oxygen penetration into the sediment. Since the hydrocarbon concentration is low at this station, it appears that the faunal characteristics are the consequence of a slightly different environmental setting, and not due to a contamination with drill cuttings. Our data underline the large potential of benthic foraminifera as bio-indicators of anthropogenic enrichment in open marine settings, such as caused by the disposal of oily drill cuttings. The foraminiferal faunas react essentially by a density increase of a number of tolerant and/or opportunistic taxa, and a progressive disappearance of more sensitive taxa in the most impacted area. Rather surprisingly, large-sized taxa appear to be more sensitive than small-sized foraminiferal taxa.

Demography of a breeding population of whimbrel (Numenius phaeopus) near Churchill, Manitoba, Canada

NASA Astrophysics Data System (ADS)

Perz, Johanna

I used a GIS raster layer of an area in the Churchill, Manitoba region to investigate the effect of breeding habitat on demography and density of Whimbrel from 2010 through 2013. Program MARK was used to quantify adult and daily nest survival. Apparent annual survival of 0.73 +/- 0.06 SE (95% CI = 0.60-0.83) did not significantly differ between sexes or habitats and was lower than expected based on longevity records and estimates for other large-bodied shorebirds. Nest success, corrected for exposure days, was highly variable, ranging from a low of 3% (95% CI = 0-12%) in 2011 to a high of 71% (95% CI = 54-83%) in 2013. The highest rate of nest survival occurred in the spring with the warmest mean temperature. I developed a generalized linear model (GLM) with a negative-binomial distribution from random plots that were surveyed for abundance to extrapolate a local breeding population size of 410 +/- 230 SE and density of 3.2 birds per square km +/- 1.8 SE. The result of my study suggests that other aspects of habitat not captured by the land cover categories may be more important to population dynamics.

Importance of Nutrients and Nutrient Metabolism on Human Health

PubMed Central

Chen, Yiheng; Michalak, Marek; Agellon, Luis B.

2018-01-01

Nutrition transition, which includes a change from consumption of traditional to modern diets that feature high-energy density and low nutrient diversity, is associated with acquired metabolic syndromes. The human diet is comprised of diverse components which include both nutrients, supplying the raw materials that drive multiple metabolic processes in every cell of the body, and non-nutrients. These components and their metabolites can also regulate gene expression and cellular function via a variety of mechanisms. Some of these components are beneficial while others have toxic effects. Studies have found that persistent disturbance of nutrient metabolism and/or energy homeostasis, caused by either nutrient deficiency or excess, induces cellular stress leading to metabolic dysregulation and tissue damage, and eventually to development of acquired metabolic syndromes. It is now evident that metabolism is influenced by extrinsic factors (e.g., food, xenobiotics, environment), intrinsic factors (e.g., sex, age, gene variations) as well as host/microbiota interaction, that together modify the risk for developing various acquired metabolic diseases. It is also becoming apparent that intake of diets with low-energy density but high in nutrient diversity may be the key to promoting and maintaining optimal health.

Ultraviolet observations of the gas phase abundances in the diffuse clouds toward Zeta Ophiuchi at 3.5 kilometers per second resolution

NASA Technical Reports Server (NTRS)

Savage, Blair D.; Cardelli, Jason A.; Sofia, Ulysses J.

1992-01-01

Goddard High Resolution Spectrograph echelle mode measurements at 3.5 km/s resolution are presented for interstellar absorption produced by C II, O I, Mg I, Mg II, Al III, P II, Cr II, Mn II, Fe II, Ni II, Cu II, Zn II, Ga II, Ge II, and Kr I. The absorption line measurements are converted into representations of apparent column density per unit velocity in order to study the multicomponent nature of the absorption. The high spectral resolution of the measurements allows a comparative study of gas phase abundances for many species in the absorbing clouds near -27 and -15 km/s with a typical precision of about 0.05 dex. The matter absorbing near -27 km/s is situated in the local interstellar medium and has log N(H I) of about 19.74. This absorption provides information about the modest 'base' depletion associated with the lower density interstellar medium. The depletion results suggest that accretion processes are operating interstellar clouds that exhibit similar depletion efficiencies for some elements but much higher depletion efficiencies for others.

Effect of gamma ray and high-energy oxygen ion radiation on electrical and optical properties of MCT epitaxial layers

NASA Astrophysics Data System (ADS)

Sitharaman, S.; Kanjilal, D.; Arora, S. K.; Ganguly, S. K.; Nagpal, Anjana; Gautam, Madhukar; Raman, R.; Kumar, Shiv; Prakash, V. R.; Gupta, S. C.

1999-11-01

Hg1-xCdxTe epitaxial layers grown from Te-rich solution have been exposed to Gamma ray radiation up to 650 Grey using Co60 and high energy oxygen radiation at 100Mev. The electrical resistivity, carrier density and Hall mobility values at 77K and IR transmission at 300K have been measured in n,p and compensated epilayers both before and after irradiation. These properties are very much affected by these radiations. In the uncompensated p-type epitaxial layers both types of radiation produced an increase in extrinsic carrier density and a corresponding decrease in Hall mobility. It is observed that both types of radiation have significant effect on the compensated layers and the degree of compensation is greatly reduced by the oxygen irradiation. The 100 Mev oxygen irradiation produced an apparent shift in the bandgap towards shorter wavelength and the absorption below the energy gap is reduced as shown by FTIR measurements, whereas Gamma ray radiation up to the dose 650 Grey did not have any effect on optical properties. These results show the ability of oxygen radiation to passivate the activity of residual impurities or defects.

Observation and modeling of deflagration-to-detonation (DDT) transition in low-density HMX

NASA Astrophysics Data System (ADS)

Tringe, Joseph; Vandersall, Kevin; Reaugh, Jack; Levie, Harold; Henson, Bryan; Smilowitz, Laura; Parker, Gary

2015-06-01

We employ simultaneous flash x-ray radiography and streak imaging, together with a multi-phase finite element model, to understand deflagration-to-detonation transition (DDT) phenomena in low-density (~ 1.2 gm/cm3) powder of the explosive cyclotetramethylene-tetranitramine (HMX). HMX powder was lightly hand-tamped in a 12.7 mm diameter column, relatively lightly-confined in an optically-transparent polycarbonate cylinder with wall thickness 25.4 mm. We observe apparent compaction of the powder in advance of the detonation transition, both by x-ray contrast and by the motion of small steel spheres pre-emplaced throughout the length of explosive. High-speed imaging along the explosive cylinder length provides a temporally continuous record of the transition that is correlated with the high-resolution x-ray image record. Preliminary simulation of these experiments with the HERMES model implemented in the ALE3D code enables improved understanding of the explosive particle burning, compaction and detonation phenomena which are implied by the observed reaction rate and transition location within the cylinder. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Undersize solute element effects on defect structure development in copper under electron irradiation

NASA Astrophysics Data System (ADS)

Satoh, Y.; Yoshiie, T.; Arai, S.

2018-03-01

We conducted systematic experiments of defect structure development in Cu base binary alloys under 1000 kV electron irradiation at temperatures higher than 300 K, using in situ observations with high voltage electron microscopy. This report describes the effects of undersize elements: Co (-3.78%), Ni (-8.45%) and Be (-26.45%). The volume size factors are given in parentheses. The amounts of the respective elements were 2, 0.3, 0.05 at.%, or less. In Cu-Ni and Cu-Co and in the reference Cu, temperature dependence of the number density of interstitial-type dislocation loops had a down peak (i.e. loops hardly formed) at approximately 373 K, attributed to unexpected impurity atoms. Above the down-peak temperature, the addition of Co or Ni increased the loop number density through continuous nucleation of loops, extended the loop formation to higher temperatures, and decreased the apparent activation energy of loop growth rate. The addition of Be for 0.3 at.% or more delayed loop formation after formation of stacking fault tetrahedra (SFTs) around 300 K. The apparent mobility of self-interstitial atoms is expected to be smaller than that of vacancies because of strong binding with Be. Loop formation at temperatures higher than 373 K was enhanced by Be for 0.3 or 2 at.%, although it was suppressed greatly for 0.05 at.% or less. All undersize atoms increased the stability of SFTs under irradiation. Mechanisms of those effects were discussed and were briefly compared with earlier results found for oversize elements in Cu.

Early Science with the Large Millimeter Telescope: discovery of the 12CO(1-0) emission line in the ring galaxy VIIZw466

NASA Astrophysics Data System (ADS)

Wong, O. Ivy; Vega, O.; Sánchez-Argüelles, D.; Narayanan, G.; Wall, W. F.; Zwaan, M. A.; Rosa González, D.; Zeballos, M.; Bekki, K.; Mayya, Y. D.; Montaña, A.; Chung, A.

2017-04-01

We report an early science discovery of the 12CO(1-0) emission line in the collisional ring galaxy VII Zw466, using the Redshift Search Receiver instrument on the Large Millimeter Telescope Alfonso Serrano. The apparent molecular-to-atomic gas ratio either places the interstellar medium (ISM) of VII Zw466 in the H I-dominated regime or implies a large quantity of CO-dark molecular gas, given its high star formation rate. The molecular gas densities and star formation rate densities of VII Zw466 are consistent with the standard Kennicutt-Schmidt star formation law even though we find this galaxy to be H2-deficient. The choice of CO-to-H2 conversion factors cannot explain the apparent H2 deficiency in its entirety. Hence, we find that the collisional ring galaxy, VII Zw466, is either largely deficient in both H2 and H I or contains a large mass of CO-dark gas. A low molecular gas fraction could be due to the enhancement of feedback processes from previous episodes of star formation as a result of the star-forming ISM being confined to the ring. We conclude that collisional ring galaxy formation is an extreme form of galaxy interaction that triggers a strong galactic-wide burst of star formation that may provide immediate negative feedback towards subsequent episodes of star formation - resulting in a short-lived star formation history or, at least, the appearance of a molecular gas deficit.

Survival, growth, and movement of subadult humpback chub, Gila cypha, in the Little Colorado River, Arizona

USGS Publications Warehouse

Dzul, Maria C.; Yackulic, Charles B.; Stone, Dennis M.; Van Haverbeke, David R.

2016-01-01

Ecologists estimate vital rates, such as growth and survival, to better understand population dynamics and identify sensitive life history parameters for species or populations of concern. Here, we assess spatiotemporal variation in growth, movement, density, and survival of subadult humpback chub living in the Little Colorado River, Grand Canyon, AZ from 2001–2002 and 2009–2013. We divided the Little Colorado River into three reaches and used a multistate mark-recapture model to determine rates of movement and differences in survival and density between sites for different cohorts. Additionally, site-specific and year-specific effects on growth were evaluated using a linear model. Results indicate that summer growth was higher for upstream sites compared with downstream sites. In contrast, there was not a consistent spatial pattern across years in winter growth; however, river-wide winter growth was negatively related to the duration of floods from 1 October to 15 May. Apparent survival was estimated to be lower at the most downstream site compared with the upstream sites; however, this could be because in part of increased emigration into the Colorado River at downstream sites. Furthermore, the 2010 cohort (i.e. fish that are age 1 in 2010) exhibited high apparent survival relative to other years. Movement between reaches varied with year, and some years exhibited preferential upstream displacement. Improving understanding of spatiotemporal effects on age 1 humpback chub survival can help inform current management efforts to translocate humpback chub into new locations and give us a better understanding of the factors that may limit this tributary's carrying capacity for humpback chub.

The Influence of Urbanization Modes on the Spatial Circulation of Flaviviruses within Ouagadougou (Burkina Faso).

PubMed

Fournet, Florence; Rican, Stéphane; Vaillant, Zoé; Roudot, Anna; Meunier-Nikiema, Aude; Kassié, Daouda; Dabiré, Roch K; Salem, Gérard

2016-12-10

Dengue is an emerging infectious disease of global significance. Although this virus has been reported for a long time, its significance within the burden of diseases in West Africa is not obvious, especially in Burkina Faso. Our objective was to evaluate flavivirus presence in Ouagadougou (Burkina Faso) and the link between anti-flavivirus antibody seroprevalence and urbanization modes. A population-based cross-sectional survey was conducted and 3015 children were enrolled from Ouagadougou districts with different types and degrees of urbanization (with/without equipment and high/low building density). Flavivirus (FLAV) IgM MAC-ELISA and FLAV indirect IgG ELISA were performed. Associations between FLAV IgG presence (sign of past infection) and various independent variables were assessed using the chi-square test and a multivariate logistic regression analysis. The apparent prevalence of past flavivirus infections among the enrolled children was 22.7% (95% CI: 22.4-26.7) ( n = 685). Eleven children (0.4%; 95% CI: 0.61-2.14) were positive for FLAV IgM, indicating active transmission. Factors associated with flavivirus infection were identified among the enrolled children (age, sex), householders (educational level, asset index) and in the environment (building density, water access, waste management and house appearance); however, they showed great variability according to the city districts. The water access modality did not significantly influence FLAV IgG positivity. Conversely, apparently good practices of waste management had unexpected consequences (increased risk related to municipal dumpsters). Given the scale of ongoing urbanization and the spread of arboviral diseases, close collaboration between health and city stakeholders is needed.

A "caliper" type of controlled-source, frequency-domain, electromagnetic sounding method

NASA Astrophysics Data System (ADS)

Zhang, W.; Lin, J.; Zhou, F.; Liu, C.; Chen, J.; Xue, K.; Liu, L.; Wu, Y.

2011-12-01

We developed a special measurement manner for controlled-source, frequency-domain, electromagnetic sounding method that can improve resolution and efficiency, called as "caliper". This manner is base on our array electromagnetic system DPS-I, which consists of 53 channels and can cover 2500 m survey line at one arrangement. There are several steps to apply this method. First, a rough measurement is carried out, using large dynamic range but sparse frequencies. The ratio of adjacent frequency is set to be 2 or 4. The frequency points cover the entire frequency band that is required according to the geological environment, and are almost equidistantly distributed at logarithmic axis. Receivers array are arranged in one or more survey lines to measure the amplitude and phase of electromagnetic field components simultaneously. After all frequency points for rough measurement are measured, data in each sub-receiver are transmitted to the controller and the apparent resistivity and phase are calculated in field quickly. Then the pseudo section diagrams of apparent resistivity and phase are drew. By the pseudo section we can roughly lock the abnormal zone and determine the frequency band required for detail investigation of abnormal zone. Next, the measurement using high density of frequencies in this frequency band is carried out, which we called "detailed measurement". The ratio of adjacent frequency in this time is m which lies between 1 and 2. The exact value of m will depend on how detailed that the user expected. After "detailed measurement" is finished, the pseudo section diagrams of apparent resistivity and phase are drew in the same way with the first step. We can see more detailed information about the abnormal zone and decide whether further measurement is necessary. If it is necessary, we can repeat the second step using smaller m until the resolution meet the requirements to distinguish the target. By simulation, we know that high density of frequencies really help us to improve resolution. But we also need to say that the improvement is limited and it will do no help to add frequencies if the frequency is already dense enough. This method not only improves efficiency, but also improves the ability to distinguish the abnormal body. This measurement mode consisting of rough measurement and detailed measurement is similar to the caliper measurement of length, so called "caliper" type. It is accurate and fast. It not only can be applied to frequency-domain sounding, such as controlled source audio -frequency magnetotelluric (CSAMT), but also can be extended to the spectral induced polarization method. By using this measurement manner, high resolution and high-efficiency can be expected.

Kiloparsec Jet Properties of Hybrid, Low-, and High-Synchrotron-Peaked Blazars

NASA Astrophysics Data System (ADS)

Stanley, Ethan C.

Blazars are a rare class of active galactic nucleus (AGN) with relativistic jets closely aligned with the line of sight. Many aspects of the environments and kiloparsec-scale jet structure are not fully understood. Hybrid and high synchrotron peaked (HSP) blazars are two types of blazar that provide unique opportunities to study these jets. Hybrid blazars appear to have jets of differing morphology on each side of their core, suggesting that external factors shape their jet morphology. Three hybrid sources were investigated in radio, optical, and X-ray wavelengths: 8C 1849+670, PKS 2216-038, and PKS 1045-188. For all three, X-ray emission was detected only from the approaching jet. All three had jet radio flux densities and emission mechanisms similar to higher-power FR II sources, but two had approaching jets similar to lower-power FR I sources. None of the three showed definitive signs of asymmetry in their external environments. These results agree with previous multiwavelength studies of hybrid sources that show a dominance of FR I approaching jets and FR II emission mechanisms. With the addition of these three hybrid sources, 13 have been studied in total. Eleven have FR I approaching jets, and eight of those have FR II emission mechanisms. These trends may be due to small number statistics, or they may indicate other factors are creating hybrid-like appearances. High synchrotron peaked blazars are defined by the frequency of the peak of their jet synchrotron emission. Some have shown extreme variability which would imply incredibly-powerful and well-aligned jets, but VLBA observations have measured only modest jet speeds. A radio survey was performed to measure the extended radio luminosity of a large sample of HSP sources. These sources were compared to the complete radio flux density limited MOJAVE 1.5 Jy sample. Flat spectrum radio quasars (FSRQs) showed significant overlap with low synchrotron peaked (LSP) BL Lacs in multiple parameters, which may suggest that many FSRQs are "masquerading'' as LSP BL Lacs. HSP BL Lacs showed slightly lower extended radio luminosities and significantly lower maximum apparent jet speeds, suggesting that they are intrinsically weaker sources. There was a good correlation between maximum apparent jet speed and extended radio luminosity, which supports using the extended radio luminosity as a measure of intrinsic jet power. There was a lack of TeV-detected sources with higher extended radio luminosities, which suggests TeV emission may favor low power jets or high synchrotron peak frequencies. The apparent low power of HSP sources and TeV-detected sources questions any model of TeV emission and variability that depends on the jet (or a part of it) being intrinsically powerful.

The Effect of the Wall Contact and Post-Growth, Cool-Down on Defects in CdTe Crystals Grown By 'Contactless' PVT

NASA Technical Reports Server (NTRS)

Palosz, W.; Grasza, K.; Dudley, M.; Raghothamachar, B.; Cai, L.; Dunrose, K.; Halliday, D.; Boyall, N. M.; Rose, M. Franklin (Technical Monitor)

2001-01-01

To take a maximum advantage of materials processing in microgravity for understanding the effects of gravity, gravity-independent effects should be minimized. In crystal growth, the quality of the grown crystals may depend, among other factors, on their interaction with the walls of the processing container during and after growth, and on the rate of the crystal cool-down at the end of the process. To investigate the above phenomena, a series of CdTe crystal growth processes was carried out. The crystals were grown by physical vapor transport without contact with the side walls of the silica glass ampoules. To eliminate the effect of the seed quality, and to reduce the number of nuclei and related crystal grains, the Low Supersaturation Nucleation technique was applied. The source temperature was 930 C, the undercooling was a few degrees. The crystals, having the diameter of 25 mm, grew at the rate of a few mm per day. The post-growth cool-down to the room temperature was conducted at different rates, and lasted from a few minutes to four days. The crystals were characterized using chemical etching, low temperature luminescence, and Synchrotron White Beam X-ray Topography techniques. The dislocation (etch pit) density was measured and its distribution was analyzed by comparison with Poisson curves and with the Normalized Radial Distribution Correlation Function. In the regions where the crystal is in contact with silica, the materials show a considerable strain field which extends for a few mm or more from the silica-crystal interface. In the reference crystal grown with contact with the ampoule walls, and when the crystals are cooled at the highest rates, the etch pit/dislocation density is in the high 10(exp 5) per square centimeter region. Typical EPD values for lower cool-down rates are in the lower 10(exp 4) per square centimeter region. In some areas the actual dislocation density was about 10(exp 3) per square centimeter or even less. No apparent effect of the cool-down rate on polygonization was observed. Low temperature PL spectra show, that the dominant peak is (D(sup 0), h) and (A(sup 0), e) for samples with low and high dislocation densities, respectively. For low EPD crystals a peak at 1.45 eV with 21 meV phonon replicas was observed and attributed to donor-acceptor pair to neutral copper-acceptor transition. In high EPD crystals this PL structure was not observed, apparently due to the masking effect of the strong contribution from the dislocation band.

Charge dynamics of MgO single crystals subjected to KeV electron irradiation

NASA Astrophysics Data System (ADS)

Boughariou, A.; Blaise, G.; Braga, D.; Kallel, A.

2004-04-01

A scanning electron microscope has been equipped to study the fundamental aspects of charge trapping in insulating materials, by measuring the secondary electron emission (SEE) yield σ with a high precision (a few percent), as a function of energy, electron current density, and dose. The intrinsic secondary electron emission yield σ0 of uncharged MgO single crystals annealed at 1000 °C, 2 h, has been studied at four energies 1.1, 5, 15, and 30 keV on three different crystal orientations (100), (110), and (111). At low energies (1.1 and 5 keV) σ0 depends on the crystalline orientation wheras at high energies (30 keV) no differentiation occurs. It is shown that the value of the second crossover energy E2, for which the intrinsic SEE yield σ0=1, is extremely delicate to measure with precision. It is about 15 keV±500 eV for the (100) orientation, 13.5 keV±500 eV for the (110), and 18.5 keV±500 eV for the (111) one. At low current density J⩽105 pA/cm2, the variation of σ with the injected dose makes possible the observation of a self-regulated regime characterized by a steady value of the SEE yield σst=1. At low energies 1.1 and 5 keV, there is no current density effects in MgO, but at high energies ≈30 keV, apparent current density effects come from a bad collect of secondary electrons, due to very high negative surface potential. At 30 keV energy, an intense erratic electron exoemission was observed on the MgO (110) orientation annealed at 1500 °C. This phenomenon is the result of a disruptive process similar to flashover, which takes place at the surface of the material.

Apolipoprotein C-III Levels and Incident Coronary Artery Disease Risk: The EPIC-Norfolk Prospective Population Study.

PubMed

van Capelleveen, Julian C; Bernelot Moens, Sophie J; Yang, Xiaohong; Kastelein, John J P; Wareham, Nicholas J; Zwinderman, Aeilko H; Stroes, Erik S G; Witztum, Joseph L; Hovingh, G Kees; Khaw, Kay-Tee; Boekholdt, S Matthijs; Tsimikas, Sotirios

2017-06-01

Apolipoprotein C-III (apoC-III) is a key regulator of triglyceride metabolism. Elevated triglyceride-rich lipoproteins and apoC-III levels are causally linked to coronary artery disease (CAD) risk. The mechanism(s) through which apoC-III increases CAD risk remains largely unknown. The aim was to confirm the association between apoC-III plasma levels and CAD risk and to explore which lipoprotein subfractions contribute to this relationship between apoC-III and CAD risk. Plasma apoC-III levels were measured in baseline samples from a nested case-control study in the European Prospective Investigation of Cancer (EPIC)-Norfolk study. The study comprised 2711 apparently healthy study participants, of whom 832 subsequently developed CAD. We studied the association of baseline apoC-III levels with incident CAD risk, lipoprotein subfractions measured by nuclear magnetic resonance spectroscopy and inflammatory biomarkers. ApoC-III levels were significantly associated with CAD risk (odds ratio, 1.91; 95% confidence interval, 1.48-2.48 for highest compared with lowest quintile), retaining significance after adjustment for traditional CAD risk factors (odds ratio, 1.47; 95% confidence interval, 1.11-1.94). ApoC-III levels were positively correlated with triglyceride levels, ( r =0.39), particle numbers of very-low-density lipoprotein ( r =0.25), intermediate-density lipoprotein ( r =0.23), small dense low-density lipoprotein ( r =0.26), and high-sensitivity C-reactive protein ( r =0.15), whereas an inverse correlation was observed with large low-density lipoprotein particle number ( r =-0.11), P <0.001 for each. Mediation analysis indicated that the association between apoC-III and CAD risk could be explained by triglyceride elevation (triglyceride, very-low-density lipoprotein, and intermediate-density lipoprotein particles), small low-density lipoprotein particle size, and high-sensitivity C-reactive protein. ApoC-III levels are significantly associated with incident CAD risk. Elevated levels of remnant lipoproteins, small dense low-density lipoprotein, and low-grade inflammation may explain this association. © 2017 American Heart Association, Inc.

A straightforward method for measuring the range of apparent density of microplastics.

PubMed

Li, Lingyun; Li, Mengmeng; Deng, Hua; Cai, Li; Cai, Huiwen; Yan, Beizhan; Hu, Jun; Shi, Huahong

2018-10-15

Density of microplastics has been regarded as the primary property that affect the distribution and bioavailability of microplastics in the water column. For measuring the density of microplastis, we developed a simple and rapid method based on density gradient solutions. In this study, we tested four solvents to make the density gradient solutions, i.e., ethanol (0.8 g/cm 3 ), ultrapure water (1.0 g/cm 3 ), saturated NaI (1.8 g/cm 3 ) and ZnCl 2 (1.8 g/cm 3 ). Density of microplastics was measured via observing the float or sink status in the density gradient solutions. We found that density gradient solutions made from ZnCl 2 had a larger uncertainty in measuring density than that from NaI, most likely due to a higher surface tension of ZnCl 2 solution. Solutions made from ethanol, ultrapure water, and NaI showed consistent density results with listed densities of commercial products, indicating that these density gradient solutions were suitable for measuring microplastics with a density range of 0.8-1.8 g/cm 3 . Copyright © 2018 Elsevier B.V. All rights reserved.

Design and Application of a High-Temperature Linear Ion Trap Reactor

NASA Astrophysics Data System (ADS)

Jiang, Li-Xue; Liu, Qing-Yu; Li, Xiao-Na; He, Sheng-Gui

2018-01-01

A high-temperature linear ion trap reactor with hexapole design was homemade to study ion-molecule reactions at variable temperatures. The highest temperature for the trapped ions is up to 773 K, which is much higher than those in available reports. The reaction between V2O6 - cluster anions and CO at different temperatures was investigated to evaluate the performance of this reactor. The apparent activation energy was determined to be 0.10 ± 0.02 eV, which is consistent with the barrier of 0.12 eV calculated by density functional theory. This indicates that the current experimental apparatus is prospective to study ion-molecule reactions at variable temperatures, and more kinetic details can be obtained to have a better understanding of chemical reactions that have overall barriers. [Figure not available: see fulltext.

Three-dimensional carbon- and binder-free nickel nanowire arrays as a high-performance and low-cost anode for direct hydrogen peroxide fuel cell

NASA Astrophysics Data System (ADS)

Ye, Ke; Guo, Fen; Gao, Yinyi; Zhang, Dongming; Cheng, Kui; Zhang, Wenping; Wang, Guiling; Cao, Dianxue

2015-12-01

A novel three-dimensional carbon- and binder-free nickel nanowire arrays (Ni NAs) electrode is successfully fabricated by a facile galvanostatic electrodeposition method using polycarbonate membrane as the template. The Ni NAs electrode achieves a oxidation current density (divided by the electroactive surface areas of Ni) of 25.1 mA cm-2 in 4 mol L-1 KOH and 0.9 mol L-1 H2O2 at 0.2 V (vs. Ag/AgCl) accompanied with a desirable stability, which is significantly higher than the catalytic activity of H2O2 electro-oxidation achieved previously with precious metals as catalysts. The impressive electrocatalytic performance is largely attributed to the superior 3D open structure and high electronic conductivity, which ensures the high utilization of Ni surfaces and makes the electrode have higher electrochemical activity. The apparent activation energy of H2O2 electro-oxidation on the Ni NAs catalyst is 13.59 kJ mol-1. A direct peroxide-peroxide fuel cell using the Ni NAs as anode exhibits a peak power density of 48.7 mW cm-2 at 20 °C. The electrode displays a great promise as the anode of direct peroxide-peroxide fuel cell due to its low cost, high activity and stability.

Study on the RF inductively coupled plasma spheroidization of refractory W and W-Ta alloy powders

NASA Astrophysics Data System (ADS)

Chenfan, YU; Xin, ZHOU; Dianzheng, WANG; Neuyen VAN, LINH; Wei, LIU

2018-01-01

Spherical powders with good flowability and high stacking density are mandatory for powder bed additive manufacturing. Nevertheless, the preparation of spherical refractory tungsten and tungsten alloy powders is a formidable task. In this paper, spherical refractory metal powders processed by high-energy stir ball milling and RF inductively coupled plasma were investigated. By utilizing the technical route, pure spherical tungsten powders were prepared successfully, the flowability increased from 10.7 s/50 g to 5.5 s/50 g and apparent density increased from 6.916 g cm-3 to 11.041 g cm-3. Alloying element tantalum can reduce the tendency to micro-crack during tungsten laser melting and rapid solidification process. Spherical W-6Ta (%wt) powders were prepared in this way, homogeneous dispersion of tantalum in a tungsten matrix occurred but a small amount of flake-like shape particles appeared after high-energy stir ball milling. The flake-like shape particles can hardly be spheroidized in subsequent RF inductively coupled plasma process, might result from the unique suspended state of flaky particles under complex electric and magnetic fields as well as plasma-particle heat exchange was different under various turbulence models. As a result, the flake-like shape particles cannot pass through the high-temperature area of thermal plasma torch and cannot be spheroidized properly.

A simplified regional-scale electromagnetic induction - Salinity calibration model using ANOCOVA modeling techniques

USDA-ARS?s Scientific Manuscript database

Directed soil sampling based on geospatial measurements of apparent soil electrical conductivity (ECa) is a potential means of characterizing the spatial variability of any soil property that influences ECa including soil salinity, water content, texture, bulk density, organic matter, and cation exc...

The Global Internet Pandemic

ERIC Educational Resources Information Center

Carter, Deborah Joy

2009-01-01

The global rise of Internet-based education is discussed in relation to models drawn from social studies and epidemiology. Experiential and data density models are highlighted, also the capacity for technological change, and phenomena observed in the spread of disease. The lesson of these illustrations is that even apparently permanent phenomena…

Small numbers are sensed directly, high numbers constructed from size and density.

PubMed

Zimmermann, Eckart

2018-04-01

Two theories compete to explain how we estimate the numerosity of visual object sets. The first suggests that the apparent numerosity is derived from an analysis of more low-level features like size and density of the set. The second theory suggests that numbers are sensed directly. Consistent with the latter claim is the existence of neurons in parietal cortex which are specialized for processing the numerosity of elements in the visual scene. However, recent evidence suggests that only low numbers can be sensed directly whereas the perception of high numbers is supported by the analysis of low-level features. Processing of low and high numbers, being located at different levels of the neural hierarchy should involve different receptive field sizes. Here, I tested this idea with visual adaptation. I measured the spatial spread of number adaptation for low and high numerosities. A focused adaptation spread of high numerosities suggested the involvement of early neural levels where receptive fields are comparably small and the broad spread for low numerosities was consistent with processing of number neurons which have larger receptive fields. These results provide evidence for the claim that different mechanism exist generating the perception of visual numerosity. Whereas low numbers are sensed directly as a primary visual attribute, the estimation of high numbers however likely depends on the area size over which the objects are spread. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of dynamics in complex lyophilized formulations: II. Analysis of density variations in terms of glass dynamics and comparisons with global mobility, fast dynamics, and Positron Annihilation Lifetime Spectroscopy (PALS)

PubMed Central

Chieng, Norman; Cicerone, Marcus T.; Zhong, Qin; Liu, Ming; Pikal, Michael J.

2013-01-01

Amorphous HES/disaccharide (trehalose or sucrose) formulations, with and without added polyols (glycerol and sorbitol) and disaccharide formulations of human growth hormone (hGH), were prepared by freeze drying and characterized with particular interest in methodology for using high precision density measurements to evaluate free volume changes and a focus on comparisons between “free volume” changes obtained from analysis of density data, fast dynamics (local mobility), and PALS characterization of “free volume” hole size. Density measurements were performed using a helium gas pycnometer, and fast dynamics was characterized using incoherent neutron scattering spectrometer. Addition of sucrose and trehalose to hGH decreases free volume in the system with sucrose marginally more effective than trehalose, consistent with superior pharmaceutical stability of sucrose hGH formulations well below Tg relative to trehalose. We find that density data may be analyzed in terms of free volume changes by evaluation of volume changes on mixing and calculation of apparent specific volumes from the densities. Addition of sucrose to HES decreases free volume, but the effect of trehalose is not detectable above experimental error. Addition of sorbitol or glycerol to HES/trehalose base formulations appears to significantly decrease free volume, consistent with the positive impact of such additions on pharmaceutical stability (i.e., degradation) in the glassy state. Free volume changes, evaluated from density data, fast dynamics amplitude of local motion, and PALS hole size data generally are in qualitative agreement for the HES/disaccharide systems studied. All predict decreasing molecular mobility as disaccharides are added to HES. Global mobility as measured by enthalpy relaxation times, increases as disaccharides, particularly sucrose, are added to HES. PMID:23623797

Social-Ecological Patterns of Soil Heavy Metals Based on a Self-Organizing Map (SOM): A Case Study in Beijing, China

PubMed Central

Wang, Binwu; Li, Hong; Sun, Danfeng

2014-01-01

The regional management of trace elements in soils requires understanding the interaction between the natural system and human socio-economic activities. In this study, a social-ecological patterns of heavy metals (SEPHM) approach was proposed to identify the heavy metal concentration patterns and processes in different ecoregions of Beijing (China) based on a self-organizing map (SOM). Potential ecological risk index (RI) values of Cr, Ni, Zn, Hg, Cu, As, Cd and Pb were calculated for 1,018 surface soil samples. These data were averaged in accordance with 253 communities and/or towns, and compared with demographic, agriculture structure, geomorphology, climate, land use/cover, and soil-forming parent material to discover the SEPHM. Multivariate statistical techniques were further applied to interpret the control factors of each SEPHM. SOM application clustered the 253 towns into nine groups on the map size of 12 × 7 plane (quantization error 1.809; topographic error, 0.0079). The distribution characteristics and Spearman rank correlation coefficients of RIs were strongly associated with the population density, vegetation index, industrial and mining land percent and road density. The RIs were relatively high in which towns in a highly urbanized area with large human population density exist, while low RIs occurred in mountainous and high vegetation cover areas. The resulting dataset identifies the SEPHM of Beijing and links the apparent results of RIs to driving factors, thus serving as an excellent data source to inform policy makers for legislative and land management actions. PMID:24690947

A High-Density Genetic Map with Array-Based Markers Facilitates Structural and Quantitative Trait Locus Analyses of the Common Wheat Genome

PubMed Central

Iehisa, Julio Cesar Masaru; Ohno, Ryoko; Kimura, Tatsuro; Enoki, Hiroyuki; Nishimura, Satoru; Okamoto, Yuki; Nasuda, Shuhei; Takumi, Shigeo

2014-01-01

The large genome and allohexaploidy of common wheat have complicated construction of a high-density genetic map. Although improvements in the throughput of next-generation sequencing (NGS) technologies have made it possible to obtain a large amount of genotyping data for an entire mapping population by direct sequencing, including hexaploid wheat, a significant number of missing data points are often apparent due to the low coverage of sequencing. In the present study, a microarray-based polymorphism detection system was developed using NGS data obtained from complexity-reduced genomic DNA of two common wheat cultivars, Chinese Spring (CS) and Mironovskaya 808. After design and selection of polymorphic probes, 13,056 new markers were added to the linkage map of a recombinant inbred mapping population between CS and Mironovskaya 808. On average, 2.49 missing data points per marker were observed in the 201 recombinant inbred lines, with a maximum of 42. Around 40% of the new markers were derived from genic regions and 11% from repetitive regions. The low number of retroelements indicated that the new polymorphic markers were mainly derived from the less repetitive region of the wheat genome. Around 25% of the mapped sequences were useful for alignment with the physical map of barley. Quantitative trait locus (QTL) analyses of 14 agronomically important traits related to flowering, spikes, and seeds demonstrated that the new high-density map showed improved QTL detection, resolution, and accuracy over the original simple sequence repeat map. PMID:24972598

A high-density genetic map with array-based markers facilitates structural and quantitative trait locus analyses of the common wheat genome.

PubMed

Iehisa, Julio Cesar Masaru; Ohno, Ryoko; Kimura, Tatsuro; Enoki, Hiroyuki; Nishimura, Satoru; Okamoto, Yuki; Nasuda, Shuhei; Takumi, Shigeo

2014-10-01

The large genome and allohexaploidy of common wheat have complicated construction of a high-density genetic map. Although improvements in the throughput of next-generation sequencing (NGS) technologies have made it possible to obtain a large amount of genotyping data for an entire mapping population by direct sequencing, including hexaploid wheat, a significant number of missing data points are often apparent due to the low coverage of sequencing. In the present study, a microarray-based polymorphism detection system was developed using NGS data obtained from complexity-reduced genomic DNA of two common wheat cultivars, Chinese Spring (CS) and Mironovskaya 808. After design and selection of polymorphic probes, 13,056 new markers were added to the linkage map of a recombinant inbred mapping population between CS and Mironovskaya 808. On average, 2.49 missing data points per marker were observed in the 201 recombinant inbred lines, with a maximum of 42. Around 40% of the new markers were derived from genic regions and 11% from repetitive regions. The low number of retroelements indicated that the new polymorphic markers were mainly derived from the less repetitive region of the wheat genome. Around 25% of the mapped sequences were useful for alignment with the physical map of barley. Quantitative trait locus (QTL) analyses of 14 agronomically important traits related to flowering, spikes, and seeds demonstrated that the new high-density map showed improved QTL detection, resolution, and accuracy over the original simple sequence repeat map. © The Author 2014. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

Influence of chitosan structure on the formation and stability of DNA-chitosan polyelectrolyte complexes.

PubMed

Strand, Sabina P; Danielsen, Signe; Christensen, Bjørn E; Vårum, Kjell M

2005-01-01

The interactions between DNA and chitosans varying in fractional content of acetylated units (FA), degree of polymerization (DP), and degree of ionization were investigated by several techniques, including an ethidium bromide (EtBr) fluorescence assay, gel retardation, atomic force microscopy, and dynamic and electrophoretic light scattering. The charge density of the chitosan and the number of charges per chain were found to be the dominating factors for the structure and stability of DNA-chitosan complexes. All high molecular weight chitosans condensed DNA into physically stable polyplexes; however, the properties of the complexes were strongly dependent on FA, and thereby the charge density of chitosan. By employing fully charged oligomers of constant charge density, it was shown that the complexation of DNA and stability of the polyplexes is governed by the number of cationic residues per chain. A minimum of 6-9 positive charges appeared necessary to provide interaction strength comparable to that of polycations. In contrast, further increase in the number of charges above 9 did not increase the apparent binding affinity as judged from the EtBr displacement assay. The chitosan oligomers exhibited a pH-dependent interaction with DNA, reflecting the number of ionized amino groups. The complexation of DNA and the stability of oligomer-based polyplexes became reduced above pH 7.4. Such pH-dependent dissociation of polyplexes around the physiological pH is highly relevant in gene delivery applications and might be one of the reasons for the high transfection activity of oligomer-based polyplexes observed.

Effect of Temper Condition on Stress Relaxation Behavior of an Aluminum Copper Lithium Alloy

NASA Astrophysics Data System (ADS)

Mishra, Sumeet; Beura, Vikrant Kumar; Singh, Amit; Yadava, Manasij; Nayan, Niraj

2018-07-01

Deformation behavior of an Al-Cu-Li alloy in different temper conditions (solutionized and T8) is investigated using stress relaxation tests. Fundamental parameters such as the apparent and physical activation volume, strain rate sensitivity, effective stress, and exhaustion rate of mobile dislocation density are determined from single and multiple relaxation tests. It was found that dislocation-dislocation interaction controls the kinetics of plastic deformation in the solutionized sample, whereas dislocation-precipitate interaction is the overriding factor in the presence of T1 precipitates. The apparent activation volume was found to be significantly lower in the presence of T1 precipitates compared with solutionized samples. Strain rate sensitivity and effective stress were found to be higher in the presence of T1 precipitates. In addition, multiple relaxation tests showed that irrespective of microstructural features (solutes, semi-coherent precipitates), the mobile dislocation density reduces during the relaxation period. Further evidence regarding reduction in mobile dislocation density is obtained from uniaxial tensile tests carried out after stress relaxation tests, where both solutionized and T8 samples show an increase in strength. Additional discussion on relaxation strain is included to provide a complete overview regarding the time-dependent deformation behavior of the Al-Cu-Li alloy in different temper conditions.

Analysis of impacts of urban land use and land cover on air quality in the Las Vegas region using remote sensing information and ground observations

USGS Publications Warehouse

Xian, G.

2007-01-01

Urban development in the Las Vegas Valley of Nevada (USA) has expanded rapidly over the past 50 years. The air quality in the valley has suffered owing to increases from anthropogenic emissions of carbon monoxide, ozone and criteria pollutants of particular matter. Air quality observations show that pollutant concentrations have apparent heterogeneous characteristics in the urban area. Quantified urban land use and land cover information derived from satellite remote sensing data indicate an apparent local influence of urban development density on air pollutant distributions. Multi‐year observational data collected by a network of local air monitoring stations specify that ozone maximums develop in the May and June timeframe, whereas minimum concentrations generally occur from November to February. The fine particulate matter maximum occurs in July. Ozone concentrations are highest on the west and northwest sides of the valley. Night‐time ozone reduction contributes to the heterogeneous features of the spatial distribution for average ozone levels in the Las Vegas metropolitan area. Decreased ozone levels associated with increased urban development density suggest that the highest ozone and lowest nitrogen oxides concentrations are associated with medium to low density urban development in Las Vegas.

Effect of Temper Condition on Stress Relaxation Behavior of an Aluminum Copper Lithium Alloy

NASA Astrophysics Data System (ADS)

Mishra, Sumeet; Beura, Vikrant Kumar; Singh, Amit; Yadava, Manasij; Nayan, Niraj

2018-04-01

Deformation behavior of an Al-Cu-Li alloy in different temper conditions (solutionized and T8) is investigated using stress relaxation tests. Fundamental parameters such as the apparent and physical activation volume, strain rate sensitivity, effective stress, and exhaustion rate of mobile dislocation density are determined from single and multiple relaxation tests. It was found that dislocation-dislocation interaction controls the kinetics of plastic deformation in the solutionized sample, whereas dislocation-precipitate interaction is the overriding factor in the presence of T1 precipitates. The apparent activation volume was found to be significantly lower in the presence of T1 precipitates compared with solutionized samples. Strain rate sensitivity and effective stress were found to be higher in the presence of T1 precipitates. In addition, multiple relaxation tests showed that irrespective of microstructural features (solutes, semi-coherent precipitates), the mobile dislocation density reduces during the relaxation period. Further evidence regarding reduction in mobile dislocation density is obtained from uniaxial tensile tests carried out after stress relaxation tests, where both solutionized and T8 samples show an increase in strength. Additional discussion on relaxation strain is included to provide a complete overview regarding the time-dependent deformation behavior of the Al-Cu-Li alloy in different temper conditions.

Enhancing the energy density of safer Li-ion batteries by combining high-voltage lithium cobalt fluorophosphate cathodes and nanostructured titania anodes

PubMed Central

Ortiz, Gregorio F.; López, María C.; Li, Yixiao; McDonald, Matthew J.; Cabello, Marta; Tirado, José L.; Yang, Yong

2016-01-01

Recently, Li-ion batteries have been heavily scrutinized because of the apparent incompatibility between safety and high energy density. This work report a high voltage full battery made with TiO2/Li3PO4/Li2CoPO4F. The Li2CoPO4F cathode and TiO2 anode materials are synthesized by a sol–gel and anodization methods, respectively. X-ray diffraction (XRD) analysis confirmed that Li2CoPO4F is well-crystallized in orthorhombic crystal structure with Pnma space group. The Li3PO4-coated anode was successfully deposited as shown by the (011) lattice fringes of anatase TiO2 and (200) of γ-Li3PO4, as detected by HRTEM. The charge profile of Li2CoPO4F versus lithium shows a plateau at 5.0 V, revealing its importance as potentially high-voltage cathode and could perfectly fit with the plateau of anatase anode (1.8–1.9 V). The full cell made with TiO2/Li3PO4/Li2CoPO4F delivered an initial reversible capacity of 150 mA h g−1 at C rate with good cyclic performance at an average potential of 3.1–3.2 V. Thus, the full cell provides an energy density of 472 W h kg−1. This full battery behaves better than TiO2/Li2CoPO4F. The introduction of Li3PO4 as buffer layer is expected to help the cyclability of the electrodes as it allows a rapid Li-ion transport. PMID:26879916

A dynamic flare with anomalously dense flare loops

NASA Technical Reports Server (NTRS)

Svestka, Z.; Fontenla, J. M.; Machado, M. E.; Martin, S. F.; Neidig, D. F.

1986-01-01

The dynamic flare of November 6, 1980 developed a rich system of growing loops which could be followed in H-alpha for 1.5 hours. Throughout the flare, these loops, near the limb, were seen in emission against the disk. Theoretical computations of b-values for a hydrogen atom reveal that this requires electron densities in the loops to be close to 10 to the 12th per cu cm. From measured widths of higher Balmer lines the density at the tops of the loops was found to be 4 x 10 to the 12th per cu cm if no nonthermal motions were present. It is now general knowledge that flare loops are initially observed in X-rays and become visible in H-alpha only after cooling. For such a high density a loop would cool through radiation from 10 to the 7th K to 10 to the 4th K within a few minutes so that the dense H-alpha loops should have heights very close to the heights of the X-ray loops. This, however, contradicts the observations obtained by the HXIS and FCS instruments on board SMM which show the X-ray loops at much higher altitudes than the loops in H-alpha. Therefore, the density must have been significantly smaller when the loops were formed and the flare loops were apparently both shrinking and becoming denser while cooling.

Infection by a black spot-causing species of Uvulifer and associated opercular alterations in fishes from a high-desert stream in Wyoming

USGS Publications Warehouse

Quist, M.C.; Bower, M.R.; Hubert, W.A.

2007-01-01

Black spot is a common disease syndrome of freshwater fishes. This study provides information on the rank of density of the black spot agent and opercular bone alterations associated with at least one digenean, Uvulifer sp., infecting native and non-native catostomids and cyprinids of the Upper Colorado River Basin. We evaluated the density rank of pigmented metacercariae and associated alterations in the operculum of the bluehead sucker Catostomus discobolus, flannelmouth sucker C. latipinnis, white sucker C. commersoni, catostomid hybrids, roundtail chub Gila robusta, and creek chub Semotilus atromaculatus, sampled from Muddy Creek, Wyoming, USA in 2003 or 2004. All fish species contained individuals that exhibited gross signs of the black spot agent. Bluehead and flannelmouth suckers had 100% prevalence of infection. Although the other suckers and chubs contained encysted metacercariae in at least one individual, the presence of pigmented metacercariae was not apparent (i.e. based on gross observations) in many individuals. Catostomids had higher densities of metacercariae than cyprinids, as shown by frequency distributions of density ranks. Opercular holes (i.e. holes that completely penetrated the opercle and were in direct association with the pigment associated metacercariae) and pockets (depressions on the external surface of the opercle associated with metacercariae) were abundant among catostomids but rare among cyprinids. ?? Inter-Research 2007.

Infection by a black spot-causing species of Uvulifer and associated opercular alterations in fishes from a high-desert stream in Wyoming.

PubMed

Quist, Michael C; Bower, Michael R; Hubert, Wayne A

2007-12-13

Black spot is a common disease syndrome of freshwater fishes. This study provides information on the rank of density of the black spot agent and opercular bone alterations associated with at least one digenean, Uvulifer sp., infecting native and non-native catostomids and cyprinids of the Upper Colorado River Basin. We evaluated the density rank of pigmented metacercariae and associated alterations in the operculum of the bluehead sucker Catostomus discobolus, flannelmouth sucker C. latipinnis, white sucker C. commersoni, catostomid hybrids, roundtail chub Gila robusta, and creek chub Semotilus atromaculatus, sampled from Muddy Creek, Wyoming, USA in 2003 or 2004. All fish species contained individuals that exhibited gross signs of the black spot agent. Bluehead and flannelmouth suckers had 100% prevalence of infection. Although the other suckers and chubs contained encysted metacercariae in at least one individual, the presence of pigmented metacercariae was not apparent (i.e. based on gross observations) in many individuals. Catostomids had higher densities of metacercariae than cyprinids, as shown by frequency distributions of density ranks. Opercular holes (i.e. holes that completely penetrated the opercle and were in direct association with the pigment associated metacercariae) and pockets (depressions on the external surface of the opercle associated with metacercariae) were abundant among catostomids but rare among cyprinids.

Tidal disruption of Periodic Comet Shoemaker-Levy 9 and a constraint on its mean density

NASA Technical Reports Server (NTRS)

Boss, Alan P.

1994-01-01

The apparent tidal disruption of Periodic Comet Shoemaker-Levy 9 (1993e) during a close encounter within approximately 1.62 planetary radii of Jupiter can be used along with theoretical models of tidal disruption to place an upper bound on the density of the predisruption body. Depending on the theoretical model used, these upper bounds range from rho(sub c) less than 0.702 +/- 0.080 g/cu cm for a simple analytical model calibrated by numerical smoothed particle hydrodynamics (SPH) simulations to rho(sub c) less than 1.50 +/- 0.17 g/cu cm for a detailed semianalytical model. The quoted uncertainties stem from an assumed uncertainty in the perijove radius. However, the uncertainty introduced by the different theoretical models is the major source of error; this uncertainty could be eliminated by future SPH simulations specialized to cometary disruptions, including the effects of initially prolate, spinning comets. If the SPH-based upper bound turns out to be most appropriate, it would be consistent with the predisruption body being a comet with a relatively low density and porous structure, as has been asserted previously based on observations of cometary outgassing. Regardless of which upper bound is preferable, the models all agree that the predisruption body could not have been a relatively high-density body, such as an asteroid with rho approximately = 2 g/cu cm.

Self-assembled patches in PtSi/n-Si (111) diodes

NASA Astrophysics Data System (ADS)

Afandiyeva, I. M.; Altιndal, Ş.; Abdullayeva, L. K.; Bayramova, A. İ.

2018-05-01

Using the effect of the temperature on the capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of PtSi/n-Si (111) Schottky diodes the profile of apparent doping concentration (N Dapp), the potential difference between the Fermi energy level and the bottom of the conduction band (V n), apparent barrier height (Φ Bapp), series resistance (R s) and the interface state density N ss have been investigated. From the temperature dependence of (C–V) it was found that these parameters are non-uniformly changed with increasing temperature in a wide temperature range of 79–360 K. The voltage and temperature dependences of apparent carrier distribution we attributed to the existence of self-assembled patches similar the quantum wells, which formed due to the process of PtSi formation on semiconductor and the presence of hexagonal voids of Si (111).

Stochastic thermodynamics of fluctuating density fields: Non-equilibrium free energy differences under coarse-graining

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

Leonard, T.; Lander, B.; Seifert, U.

2013-11-28

We discuss the stochastic thermodynamics of systems that are described by a time-dependent density field, for example, simple liquids and colloidal suspensions. For a time-dependent change of external parameters, we show that the Jarzynski relation connecting work with the change of free energy holds if the time evolution of the density follows the Kawasaki-Dean equation. Specifically, we study the work distributions for the compression and expansion of a two-dimensional colloidal model suspension implementing a practical coarse-graining scheme of the microscopic particle positions. We demonstrate that even if coarse-grained dynamics and density functional do not match, the fluctuation relations for themore » work still hold albeit for a different, apparent, change of free energy.« less

Accounting for Cosmic Variance in Studies of Gravitationally Lensed High-redshift Galaxies in the Hubble Frontier Field Clusters

NASA Astrophysics Data System (ADS)

Robertson, Brant E.; Ellis, Richard S.; Dunlop, James S.; McLure, Ross J.; Stark, Dan P.; McLeod, Derek

2014-12-01

Strong gravitational lensing provides a powerful means for studying faint galaxies in the distant universe. By magnifying the apparent brightness of background sources, massive clusters enable the detection of galaxies fainter than the usual sensitivity limit for blank fields. However, this gain in effective sensitivity comes at the cost of a reduced survey volume and, in this Letter, we demonstrate that there is an associated increase in the cosmic variance uncertainty. As an example, we show that the cosmic variance uncertainty of the high-redshift population viewed through the Hubble Space Telescope Frontier Field cluster Abell 2744 increases from ~35% at redshift z ~ 7 to >~ 65% at z ~ 10. Previous studies of high-redshift galaxies identified in the Frontier Fields have underestimated the cosmic variance uncertainty that will affect the ultimate constraints on both the faint-end slope of the high-redshift luminosity function and the cosmic star formation rate density, key goals of the Frontier Field program.

Bounding filter - A simple solution to lack of exact a priori statistics.

NASA Technical Reports Server (NTRS)

Nahi, N. E.; Weiss, I. M.

1972-01-01

Wiener and Kalman-Bucy estimation problems assume that models describing the signal and noise stochastic processes are exactly known. When this modeling information, i.e., the signal and noise spectral densities for Wiener filter and the signal and noise dynamic system and disturbing noise representations for Kalman-Bucy filtering, is inexactly known, then the filter's performance is suboptimal and may even exhibit apparent divergence. In this paper a system is designed whereby the actual estimation error covariance is bounded by the covariance calculated by the estimator. Therefore, the estimator obtains a bound on the actual error covariance which is not available, and also prevents its apparent divergence.

Effect of Surface-active Additives on Physical Properties of Slurries of Vapor-process Magnesium

NASA Technical Reports Server (NTRS)

Pinns, Murray L

1955-01-01

The presence of 3 to 5 percent surface-active additive gave the lowest Brookfield apparent viscosity, plastic viscosity, and yield value that were obtained for slurry fuels containing approximately 50 percent vapor-process magnesium in JP-1 fuel. The slurries settled little and were easily remixed. A polyoxyethylene dodecyl alcohol was the most effective of 13 additives tested in reducing the Brookfield apparent viscosity and the yield value of the slurry. The seven most effective additives all had a hydroxyl group plus an ester or polyoxethylene group in the molecule. The densities of some of the slurries were measured.

Dione's Magnetospheric Interaction

NASA Astrophysics Data System (ADS)

Kurth, W. S.; Hospodarsky, G. B.; Schippers, P.; Moncuquet, M.; Lecacheux, A.; Crary, F. J.; Khurana, K. K.; Mitchell, D. G.

2015-12-01

Cassini has executed four close flybys of Dione during its mission at Saturn with one additional flyby planned as of this writing. The Radio and Plasma Wave Science (RPWS) instrument observed the plasma wave spectrum during each of the four encounters and plans to make additional observations during the 17 August 2015 flyby. These observations are joined by those from the Cassini Plasma Spectrometer (CAPS), Magnetospheric Imaging Instrument (MIMI), and the Magnetometer instrument (MAG), although neither CAPS nor MAG data were available for the fourth flyby. The first and fourth flybys were near polar passes while the second and third were near wake passes. The second flyby occurred during a time of hot plasma injections which are not thought to be specifically related to Dione. The Dione plasma wave environment is characterized by an intensification of the upper hybrid band and whistler mode chorus. The upper hybrid band shows frequency fluctuations with a period of order 1 minute that suggest density variations of up to 10%. These density variations are anti-correlated with the magnetic field magnitude, suggesting a mirror mode wave. Other than these periodic density fluctuations there appears to be no local plasma source which would be observed as a local enhancement in the density although variations in the electron distribution are apparent. Wake passages show a deep density depletion consistent with a plasma cavity downstream of the moon. Energetic particles show portions of the distribution apparently absorbed by the moon leading to anisotropies that likely drive both the intensification of the upper hybrid band as well as the whistler mode emissions. We investigate the role of electron anisotropies and enhanced hot electron fluxes in the intensification of the upper hybrid band and whistler mode emissions.

Growth dynamic of Naegleria fowleri in a microbial freshwater biofilm.

PubMed

Goudot, Sébastien; Herbelin, Pascaline; Mathieu, Laurence; Soreau, Sylvie; Banas, Sandrine; Jorand, Frédéric

2012-09-01

The presence of pathogenic free-living amoebae (FLA) such as Naegleria fowleri in freshwater environments is a potential public health risk. Although its occurrence in various water sources has been well reported, its presence and associated factors in biofilm remain unknown. In this study, the density of N. fowleri in biofilms spontaneously growing on glass slides fed by raw freshwater were followed at 32 °C and 42 °C for 45 days. The biofilms were collected with their substrata and characterized for their structure, numbered for their bacterial density, thermophilic free-living amoebae, and pathogenic N. fowleri. The cell density of N. fowleri within the biofilms was significantly affected both by the temperature and the nutrient level (bacteria/amoeba ratio). At 32 °C, the density remained constantly low (1-10 N. fowleri/cm(2)) indicating that the amoebae were in a survival state, whereas at 42 °C the density reached 30-900 N. fowleri/cm(2) indicating an active growth phase. The nutrient level, as well, strongly affected the apparent specific growth rate (μ) of N. fowleri in the range of 0.03-0.23 h(-1). At 42 °C a hyperbolic relationship was found between μ and the bacteria/amoeba ratio. A ratio of 10(6) to 10(7) bacteria/amoeba was needed to approach the apparent μ(max) value (0.23 h(-1)). Data analysis also showed that a threshold for the nutrient level of close to 10(4) bacteria/amoeba is needed to detect the growth of N. fowleri in freshwater biofilm. This study emphasizes the important role of the temperature and bacteria as prey to promote not only the growth of N. fowleri, but also its survival. Copyright © 2012 Elsevier Ltd. All rights reserved.

Evidence of Fanning in the Ophiuchus Stream

NASA Astrophysics Data System (ADS)

Sesar, Branimir; Price-Whelan, Adrian M.; Cohen, Judith G.; Rix, Hans-Walter; Pearson, Sarah; Johnston, Kathryn V.; Bernard, Edouard J.; Ferguson, Annette M. N.; Martin, Nicolas F.; Slater, Colin T.; Chambers, Kenneth C.; Flewelling, Heather; Wainscoat, Richard J.; Waters, Christopher

2016-01-01

The Ophiuchus stellar stream presents a dynamical puzzle: its old stellar populations (˜12 Gyr) cannot be reconciled with (1) its orbit in a simple model for the Milky Way potential and (2) its short angular extent, both of which imply that the observed stream formed within the last \\lt 1 {{Gyr}}. Recent theoretical work has shown that streams on chaotic orbits may abruptly fan out near their apparent ends; stars in these fans are dispersed in both position and velocity and may be difficult to associate with the stream. Here we present the first evidence of such stream-fanning in the Ophiuchus stream, traced by four blue horizontal branch stars beyond the apparent end of the stream. These stars stand out from the background by their high velocities ({v}{{los}}\\gt 230 km s-1) against ˜40 other stars: their velocities are comparable to those of the stream, but would be exceptional if they were unrelated halo stars. Their positions and velocities are, however, inconsistent with simple extrapolation of the observed cold, high-density portion of the stream. These observations suggest that stream-fanning may be a real, observable effect and, therefore, that Ophiuchus may be on a chaotic orbit. They also show that the Ophiuchus stream is more extended and hence dynamically older than previously thought, easing the stellar population versus dynamical age tension.

The triglycerides and glucose index is associated with cardiovascular risk factors in normal-weight children and adolescents.

PubMed

Simental-Mendía, Luis E; Hernández-Ronquillo, Gabriela; Gómez-Díaz, Rita; Rodríguez-Morán, Martha; Guerrero-Romero, Fernando

2017-12-01

BackgroundGiven the usefulness of the product of triglycerides and glucose (TyG) to recognize individuals at high risk for developing cardiovascular events, the aim of this study was to determine whether the TyG index is associated with the presence of cardiovascular risk factors in apparently healthy normal-weight children and adolescents.MethodsApparently healthy children and adolescents with normal weight, aged 6-15 years, were enrolled in a population-based cross-sectional study. The children were allocated into groups with and without cardiovascular risk factors. Cardiovascular risk factors were considered as the occurrence of at least one of the following: elevated blood pressure, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C), or hyperglycemia.ResultsA total of 2,117 children and adolescents were enrolled in the study; of them, 1,078 (50.9%) participants exhibited cardiovascular risk. The adjusted logistic regression analysis showed that elevated TyG index was significantly associated with hypertriglyceridemia (odds ratio (OR)=96.45, 95% confidence interval (CI): 48.44-192.04), low HDL-C (OR=2.07, 95% CI: 1.46-2.92), and hyperglycemia (OR=3.11, 95% CI: 2.05-4.72), but not with elevated blood pressure (OR=1.39, 95% CI: 0.89-2.16).ConclusionThe elevated TyG index is associated with the presence of cardiovascular risk factors in healthy normal-weight children and adolescents.

Non-Newtonian gravity or gravity anomalies?

NASA Technical Reports Server (NTRS)

Rubincam, David P.; Chao, B. Fong; Schatten, Kenneth H.; Sager, William W.

1988-01-01

Geophysical measurements of G differ from laboratory values, indicating that gravity may be non-Newtonian. A spherical harmonic formulation is presented for the variation of (Newtonian) gravity inside the Earth. Using the GEM-10B Earth Gravitational Field Model, it is shown that long-wavelength gravity anomalies, if not corrected, may masquerade as non-Newtonian gravity by providing significant influences on experimental observation of delta g/delta r and G. An apparent contradiction in other studies is also resolved: i.e., local densities appear in equations when average densities of layers seem to be called for.

Sodium modified molybdenum sulfide via molten salt electrolysis as an anode material for high performance sodium-ion batteries.

PubMed

Wang, Shuai; Tu, Jiguo; Yuan, Yan; Ma, Rui; Jiao, Shuqiang

2016-01-28

The paper reports a facile and cost effective method for fabricating sodium molybdenum sulfide nanoparticles through using MoS2 sheets as the precursor by sodium-modification. The electrochemical performances of sodium molybdenum sulfide nanoparticles are studied as anode materials for sodium-ion batteries. The galvanostatic charge-discharge measurements have been performed in a voltage range of 0.01-2.6 V vs. Na(+)/Na under different current densities, using the as-prepared sodium molybdenum sulfide nanoparticles as a working electrode. Typically, the initial discharge and charge capacities of sodium molybdenum sulfide nanoparticles are 475 and 380 mA h g(-1), respectively, at a current density of 20 mA g(-1). The sodium molybdenum sulfide nanoparticles exhibit high capacity with a reversible discharge capacity of about 190 mA h g(-1) after 100 cycles. It should be emphasized that the discharge reaction consists of two steps which correspond to voltage plateaus of 0.93 V and 0.85 V vs. Na(+)/Na in the first discharge curve of the Na/MoS2 battery, respectively. But there is only one apparent voltage plateau in the Na/Na-Mo-S battery, and it reduces to below 0.5 V vs. Na(+)/Na, which can enhance the power density. All of the findings demonstrate that sodium molybdenum sulfide nanoparticles have steady cycling performance and environmental and cost friendliness as next generation secondary batteries.

Indications of flow near maximum compression in layered deuterium-tritium implosions at the National Ignition Facility

DOE PAGES

Gatu Johnson, M.; Knauer, J. P.; Cerjan, C. J.; ...

2016-08-15

Here, an accurate understanding of burn dynamics in implosions of cryogenically layered deuterium (D) and tritium (T) filled capsules, obtained partly through precision diagnosis of these experiments, is essential for assessing the impediments to achieving ignition at the National Ignition Facility. We present measurements of neutrons from such implosions. The apparent ion temperatures T ion are inferred from the variance of the primary neutron spectrum. Consistently higher DT than DD T ion are observed and the difference is seen to increase with increasing apparent DT T ion. The line-of-sight rms variations of both DD and DT T ion are small,more » ~150eV, indicating an isotropic source. The DD neutron yields are consistently high relative to the DT neutron yields given the observed T ion. Spatial and temporal variations of the DT temperature and density, DD-DT differential attenuation in the surrounding DT fuel, and fluid motion variations contribute to a DT Tion greater than the DD T ion, but are in a one-dimensional model insufficient to explain the data. We hypothesize that in a three-dimensional interpretation, these effects combined could explain the results.« less

Indications of flow near maximum compression in layered deuterium-tritium implosions at the National Ignition Facility

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

Gatu Johnson, M.; Knauer, J. P.; Cerjan, C. J.

Here, an accurate understanding of burn dynamics in implosions of cryogenically layered deuterium (D) and tritium (T) filled capsules, obtained partly through precision diagnosis of these experiments, is essential for assessing the impediments to achieving ignition at the National Ignition Facility. We present measurements of neutrons from such implosions. The apparent ion temperatures T ion are inferred from the variance of the primary neutron spectrum. Consistently higher DT than DD T ion are observed and the difference is seen to increase with increasing apparent DT T ion. The line-of-sight rms variations of both DD and DT T ion are small,more » ~150eV, indicating an isotropic source. The DD neutron yields are consistently high relative to the DT neutron yields given the observed T ion. Spatial and temporal variations of the DT temperature and density, DD-DT differential attenuation in the surrounding DT fuel, and fluid motion variations contribute to a DT Tion greater than the DD T ion, but are in a one-dimensional model insufficient to explain the data. We hypothesize that in a three-dimensional interpretation, these effects combined could explain the results.« less

Deep imaging of high redshift QSO fields below the Lyman limit. II - Number counts and colors of field galaxies

NASA Technical Reports Server (NTRS)

Steidel, Charles C.; Hamilton, Donald

1993-01-01

We present an analysis of the number counts and colors of faint galaxies to about 26.5 mag in the fields of two high Galactic latitude, very-high-redshift QSOs. We concentrate on the general properties of the field galaxies at faint magnitudes. In particular, we readdress the faint galaxy number counts and colors as a function of apparent magnitude and we reexamine the possible contribution of very-high-redshift galaxies to the faint samples. We find that the number counts to R = 26 are well fitted by the relation log N(m) = 0.31R + C. The G-band counts for the same galaxies are consistent with the same slope fainter than G about 23.5, but exhibit a much steeper slope at brighter magnitudes. At R = 25.5, the differential number counts have reached about 1.2 x 10 exp 5/sq deg; the same surface density of galaxies is reached at G = 26.5. We confirm the existence of a gradual 'blueing' trend of the field galaxies toward fainter apparent magnitude; however, the blueing trend appears to extend only as faint as G about 24, fainter than which both the (G-R) and (U sub n-G) colors appear to level off. The mean colors of faint galaxies are considerably redder than flat spectrum. There are essentially no objects to R = 26 which have spectral energy distributions which are bluer than flat spectrum. The potential contribution of very-high-redshift galaxies may have been underestimated in previous analyses; the current data are consistent with the same population of relatively luminous galaxies at z about 3 as exist at z about 0.7.

A correlation between hard gamma-ray sources and cosmic voids along the line of sight

DOE PAGES

Furniss, A.; Sutter, P. M.; Primack, J. R.; ...

2014-11-25

We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4σ level. There is a less suggestive correlation for the Fermi hard source population (1.7σ). A correlation between 10-500 GeV fluxmore » and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4σ and 2.6σ, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity τ(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.« less

Demographic and growth responses of a guerrilla and a phalanx perennial grass in competitive mixtures

USGS Publications Warehouse

Humphrey, L. David; Pyke, David A.

1998-01-01

The advantages of guerrilla and phalanx growth for the guerrilla Elymus lanceolatus ssp. lanceolatus and phalanx E. l. ssp. wawawaiensis were evaluated over 2 years in two taxon mixtures with a range of densities of each subspecies and under two levels of watering. Ramet numbers and biomass of the guerrilla subspecies were higher than those of the phalanx grass in the first year but in the second year declined greatly, while the phalanx grass showed no change in biomass and an increase in ramet numbers. High neighbour densities affected the phalanx subspecies more strongly than the guerrilla subspecies in the first year, but in the second year there were few differences between subspecies. Biomass of the guerrilla grass remained greater than that of the phalanx grass but ramet numbers were similar in the second year. For both subspecies in both years, probability of flowering decreased at higher neighbour densities, indicating adaptation for competitive ability. In the first year, biomass was more strongly reduced by densities than flowering was, but in the second year, when crowding was apparently greater, flowering was more severely affected. Genet survival was high and similar for both subspecies. The presumed advantage of guerrilla subspecies in exploiting open space was supported. The guerrilla grass exploited resources more quickly in the first year by faster growth and greater ramet production, but its biomass, ramet numbers and rhizome growth, and thus its advantage, were reduced in the second year. The phalanx subspecies had slower growth, produced more ramets in later years, and delayed flowering until later years. Although less able to exploit open resources, it appeared adapted to more stressful conditions, and may be able to exploit temporal resource pulses more effectively.

A cost effective cultivation medium for biocalcification of Bacillus pasteurii KCTC 3558 and its effect on cement cubes properties.

PubMed

Yoosathaporn, S; Tiangburanatham, P; Bovonsombut, S; Chaipanich, A; Pathom-Aree, W

2016-01-01

Application of carbonate precipitation induced by Bacillus pasteurii for improving some properties of cement has been reported. However, it is not yet successful in commercial scale due to the high cost of cultivation medium. This is the first report on the application of effluent from chicken manure bio-gas plant, a high protein content agricultural waste, as an alternative growth medium for carbonate precipitation by B. pasteurii KCTC3558. Urease activity of B. pasteurii KCTC3558 cultured in chicken manure effluent medium and other three standard media were examined using phenate method. The highest urease production was achieved in chicken manure effluent medium (16.756Umg(-1) protein). Cost per liter of chicken manure effluent medium is up to 88.2% lower than other standard media. The most effective cultivation media was selected for carbonate precipitation study in cement cubes. Water absorption, voids, apparent density and compressive strength of cement cubes were measured according to the ASTM standard. The correlation between the increasing density and compressive strength of bacterial added cement cube was evident. The density of bacterial cement cube is 5.1% higher than control while the compressive strength of cement mixed with bacterial cells in chicken manure effluent medium increases up to 30.2% compared with control. SEM and XRD analysis also found the crystalline phase of calcium carbonate within bacterial cement which confirmed that the increasing density and compressive strength were resulted from bacterial carbonate precipitation. This study indicated that the effluent from chicken manure bio-gas plant could be used as an alternative cost effective culture medium for cultivation and biocalcification of B. pasteurii KCTC3558 in cement. Copyright © 2016. Published by Elsevier GmbH.

Microwave emissions from police radar.

PubMed

Fink, J M; Wagner, J P; Congleton, J J; Rock, J C

1999-01-01

This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation research institute provided 54 radar units for evaluation; 17 different models, encompassing 4 frequency bands and 3 antenna configurations, were included. Four of the 986 measurements taken exceeded the 5 mW/cm2 limit accepted by the International Radiation Protection Association and the National Council on Radiation Protection and Measurement, though none exceeded the American Conference of Governmental Industrial Hygienists, American National Standards Institute, Institute of Electrical and Electronic Engineers, or Occupational Safety and Health Administration standard of 10 mW/cm2. The four high measurements were maximum power density readings taken directly in front of the radar. Of the 812 measurements taken at the officers' seated ocular and testicular positions, none exceeded 0.04 mW/cm2; the highest of these (0.034 mW/cm2) was less than 1% of the most conservative current safety standards. High exposures in the limited region directly in front of the radar aperture are easily avoided with proper training. Results of this study indicate that police officer exposure to microwave radiation is apparently minimal. However, because of uncertainty in the medical and scientific communities concerning nonionizing radiation, it is recommended that law enforcement agencies implement a policy of prudent avoidance, including purchasing units with the lowest published maximum power densities, purchasing dash/rear deck-mounted units with antennae mounted outside the patrol vehicle, and training police officers to use the "stand-by" mode when not actually using radar.

X-ray tomography as a non-destructive tool for evaluating the preservation of primary isotope signatures and mineralogy of Mesozoic fossils

NASA Astrophysics Data System (ADS)

Santillan, J. D.; Boyce, J. W.; Eagle, R.; Martin, T.; Tuetken, T.; Eiler, J.

2010-12-01

The stable isotope compositions of carbonate and phosphate components in fossil teeth and bone are widely used to infer information on paleoclimate and the physiology of extinct organisms. Recently the potential for measuring the body temperatures of extinct vertebrates from analyses of 13C-18O bond ordering in fossil teeth has been demonstrated (Eagle et al. 2010). The interpretation of these isotopic signatures relies on an assessment of the resistance of fossil bioapatite to alteration, as diffusion within, and partial recrystallization, or replacement of the original bioapatite will lead to measured compositions that represent mixtures between primary and secondary phases and/or otherwise inaccurate apparent temperatures. X-ray computed tomography (CT) allows 3-D density maps of teeth to be made at micron-scale resolution. Such density maps have the potential to record textural evidence for alteration, recrystallization, or replacement of enamel. Because it is non-destructive, CT can be used prior to stable isotope analysis to identify potentially problematic samples without consuming or damaging scientifically significant specimens. As a test, we have applied CT to tooth fragments containing both dentin and enamel from Late Jurassic sauropods and a Late Cretaceous theropod that yielded a range of clumped isotope temperatures from anomalously high ˜60oC to physiologically plausible ≤40oC. This range of temperatures suggests partial, high-temperature modification of some specimens, but possible preservation of primary signals in others. Three-dimensional CT volumes generated using General Electric Phoenix|x-ray CT instruments were compared with visible light and back-scattered electron images of the same samples. The tube-detector combination used for the CT study consisted of a 180 kV nanofocus transmission tube coupled with a 127 micron pixel pitch detector ( ˜3-12μ m voxel edges), allowing us to clearly map out alteration zones in high contrast, while reducing edge effects and beam hardening artifacts. CT images of these teeth show a range of replacement textures. One tooth -- thought to be the least altered -- shows only localized positive density anomalies near fractures, while a second -- thought to be highly altered -- contains high-density replacement mineralization. A third tooth -- one suspected of possible partial alteration -- shows a network of rectilinear density anomalies in the enamel similar to 2-D transmitted light and back-scattered electron images. This may represent recrystallization or replacement of the primary bioapatite. Unlike 2-D imaging techniques, 3-D volumes can be used to quickly and easily make quantitative measurements of the volumes of altered and unaltered materials: For example, in the enamel of sample 3, we observe a ratio of high density to low density material of ˜ 3:2.

Influence of the current density on the electrochemical treatment of concentrated 1-butyl-3-methylimidazolium chloride solutions on diamond electrodes.

PubMed

Marcionilio, Suzana M L de Oliveira; Alves, Gisele M; E Silva, Rachel B Góes; Marques, Pablo J Lima; Maia, Poliana D; Neto, Brenno A D; Linares, José J

2016-10-01

This paper focuses on the influence of the current density treatment of a concentrated 1-butyl-3-methylimidazolium chloride (BMImCl) solution on an electrochemical reactor with a boron-doped diamond (BDD) anode. The decrease in the total organic carbon (TOC) and the BMImCl concentration demonstrate the capability of BDD in oxidizing ionic liquids (ILs) and further mineralizing (to CO2 and NO3 (-)) more rapidly at higher current densities in spite of the reduced current efficiency of the process. Moreover, the presence of Cl(-) led to the formation of oxychlorinated anions (mostly ClO3 (-) and ClO4 (-)) and, in combination with the ammonia generated in the cathode from the nitrate reduction, chloramines, more intensely at higher current density. Finally, the analysis of the intermediates formed revealed no apparent influence of the current density on the BMImCl degradation mechanism. The current density presents therefore a complex influence on the IL treatment process that is discussed throughout this paper.

Changes in interstellar atomic abundances from the galactic plane to the halo

NASA Technical Reports Server (NTRS)

Jenkins, E. B.

1982-01-01

A few, specially selected interstellar absorption lines were measured in the high resolution, far ultraviolet spectra of 200 O and B type stars observed by the International Ultraviolet Explorer (IUE). For lines of sight extending beyond about 500 pc from the galactic plane, the abundance of singly ionized iron atoms increases relative to singly ionized sulfur. However, the relative abundances of singly ionized sulfur, silicon and aluminum do not seem to change appreciably. An explanation for the apparent increase of iron is the partial sputtering of material off the surfaces of dust grains by interstellar shocks. Another possibility might be that the ejecta from type I supernovae enrich the low density medium in the halo with iron.

Formation and coarsening of near-surface Ga nanoparticles on SiN{sub x}

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

Canniff, J. C.; Jeon, S.; Huang, S.

2015-06-15

We have investigated the formation and coarsening of near-surface Ga nanoparticles (NPs) in SiN{sub x} using Ga{sup +} focused-ion-beam-irradiation of SiN{sub x}, followed by rapid thermal annealing. For surfaces with minimal curvature, diffusive growth is apparent, leading to nearly close packed arrays with NP diameters as small as 3 nm and densities as high as ∼4 × 10{sup 12} cm{sup −2}. The diffusive flux increases with annealing temperature, leading to NP coarsening by Ostwald ripening. For surfaces with increased curvature, diffusion towards the valleys also increases during annealing, leading to Ga NP coalescence and a bi-modal distribution of NP sizes.

Size-density scaling in protists and the links between consumer-resource interaction parameters.

PubMed

DeLong, John P; Vasseur, David A

2012-11-01

Recent work indicates that the interaction between body-size-dependent demographic processes can generate macroecological patterns such as the scaling of population density with body size. In this study, we evaluate this possibility for grazing protists and also test whether demographic parameters in these models are correlated after controlling for body size. We compiled data on the body-size dependence of consumer-resource interactions and population density for heterotrophic protists grazing algae in laboratory studies. We then used nested dynamic models to predict both the height and slope of the scaling relationship between population density and body size for these protists. We also controlled for consumer size and assessed links between model parameters. Finally, we used the models and the parameter estimates to assess the individual- and population-level dependence of resource use on body-size and prey-size selection. The predicted size-density scaling for all models matched closely to the observed scaling, and the simplest model was sufficient to predict the pattern. Variation around the mean size-density scaling relationship may be generated by variation in prey productivity and area of capture, but residuals are relatively insensitive to variation in prey size selection. After controlling for body size, many consumer-resource interaction parameters were correlated, and a positive correlation between residual prey size selection and conversion efficiency neutralizes the apparent fitness advantage of taking large prey. Our results indicate that widespread community-level patterns can be explained with simple population models that apply consistently across a range of sizes. They also indicate that the parameter space governing the dynamics and the steady states in these systems is structured such that some parts of the parameter space are unlikely to represent real systems. Finally, predator-prey size ratios represent a kind of conundrum, because they are widely observed but apparently have little influence on population size and fitness, at least at this level of organization. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Quantitative Correlation between Infectivity and Gp120 Density on HIV-1 Virions Revealed by Optical Trapping Virometry*

PubMed Central

DeSantis, Michael C.; Kim, Jin H.; Song, Hanna; Klasse, Per Johan

2016-01-01

The envelope glycoprotein (Env) gp120/gp41 is required for HIV-1 infection of host cells. Although in general it has been perceived that more Env gives rise to higher infectivity, the precise quantitative dependence of HIV-1 virion infectivity on Env density has remained unknown. Here we have developed a method to examine this dependence. This method involves 1) production of a set of single-cycle HIV-1 virions with varied density of Env on their surface, 2) site-specific labeling of Env-specific antibody Fab with a fluorophore at high efficiency, and 3) optical trapping virometry to measure the number of gp120 molecules on individual HIV-1 virions. The resulting gp120 density per virion is then correlated with the infectivity of the virions measured in cell culture. In the presence of DEAE-dextran, the polycation known to enhance HIV-1 infectivity in cell culture, virion infectivity follows gp120 density as a sigmoidal dependence and reaches an apparent plateau. This quantitative dependence can be described by a Hill equation, with a Hill coefficient of 2.4 ± 0.6. In contrast, in the absence of DEAE-dextran, virion infectivity increases monotonically with gp120 density and no saturation is observed under the experimental conditions. These results provide the first quantitative evidence that Env trimers cooperate on the virion surface to mediate productive infection by HIV-1. Moreover, as a result of the low number of Env trimers on individual virions, the number of additional Env trimers per virion that is required for the optimal infectivity will depend on the inclusion of facilitating agents during infection. PMID:27129237

Statistical and Spatial Analysis of Bathymetric Data for the St. Clair River, 1971-2007

USGS Publications Warehouse

Bennion, David

2009-01-01

To address questions concerning ongoing geomorphic processes in the St. Clair River, selected bathymetric datasets spanning 36 years were analyzed. Comparisons of recent high-resolution datasets covering the upper river indicate a highly variable, active environment. Although statistical and spatial comparisons of the datasets show that some changes to the channel size and shape have taken place during the study period, uncertainty associated with various survey methods and interpolation processes limit the statistically certain results. The methods used to spatially compare the datasets are sensitive to small variations in position and depth that are within the range of uncertainty associated with the datasets. Characteristics of the data, such as the density of measured points and the range of values surveyed, can also influence the results of spatial comparison. With due consideration of these limitations, apparently active and ongoing areas of elevation change in the river are mapped and discussed.

Increased Disease Calls for a Cost-Benefits Review of Marine Reserves

PubMed Central

Wootton, Emma C.; Woolmer, Andrew P.; Vogan, Claire L.; Pope, Edward C.; Hamilton, Kristina M.; Rowley, Andrew F.

2012-01-01

Marine reserves (or No-Take Zones) are implemented to protect species and habitats, with the aim of restoring a balanced ecosystem. Although the benefits of marine reserves are commonly monitored, there is a lack of insight into the potential detriments of such highly protected waters. High population densities attained within reserves may induce negative impacts such as unfavourable trophic cascades and disease outbreaks. Hence, we investigated the health of lobster populations in the UK’s Marine Conservation Zone (MCZ) at Lundy Island. Comparisons were made between the fished, Refuge Zone (RZ) and the un-fished, No-Take Zone (NTZ; marine reserve). We show ostensibly positive effects such as increased lobster abundance and size within the NTZ; however, we also demonstrate apparent negative effects such as increased injury and shell disease. Our findings suggest that robust cost-benefit analyses of marine reserves could improve marine reserve efficacy and subsequent management strategies. PMID:23240047

The structure of the interstellar medium at the 25 AU scale

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

Diamond, P.J.; Goss, W.M.; Romney, J.D.

1989-12-01

A three-station VLBI Galactic H I absorption experiment has been carried out with baselines up to 600 km. The large collecting area of the European VLBI Network consisting of the Lovell Telescope (Mark Ia), the 100 m telescope at Effelsberg, and the Westerbork Synthesis Radio Telescope was necessary to achieve adequate sensitivity for these high angular resolution (0.05 arcsec) and high-velocity resolution (0.5 km/s) observations. The extragalactic sources 3C 138, 3C 147, and 3C 380 were observed. Changes in the local H I apparent absorption were observed in all three sources as a function of resolution. The changes are mostmore » striking in the direction of 3C 138. The implied linear diameters are in the range 25 AU with typical H I densities of 10,000-100,000/cu cm. 19 refs.« less

Clinical and parasitological studies on malaria in Liberian adults living under intense malaria transmission.

PubMed

Petersen, E; Hogh, B; Marbiah, N T; Dolopaie, E; Gottschau, A; Hanson, A P; Bjorkman, A

1991-12-01

Occurrence of fevers and chills, headaches and body and joint pains, and body temperature and malaria parasitaemias were recorded monthly for a year for 121 Liberian adults. There was no apparent correlation between any of the symptoms and the presence or density of blood parasites; it was therefore not possible to define a case of clinical malaria in the study population, which was probably highly immune to infection. Only a few people with patent blood infections had elevated blood temperatures and these were below 37.5 degrees C. Malaria prevalence and levels of parasitaemia declined with age and indicated that immunity continues to develop well into adult age. The data did not support the view that adults experience symptoms at lower parasitaemias than children. Pregnant and non-pregnant women had similar levels of symptoms, but high levels of parasitaemia were found more frequently in the pregnant group.

Effect of Curing Period on Properties of Steel and Polypropylene Fibre Reinforced Ultra-High Performance Concrete

NASA Astrophysics Data System (ADS)

Smarzewski, Piotr

2017-10-01

This study has investigated the effect of curing period on the mechanical properties of straight polypropylene and hooked-end steel fibre reinforced ultra-high performance concrete (UHPC). Various physical properties are evaluated, i.e. absorbability, apparent density and open porosity. Compressive strength, tensile splitting strength, flexural strength and modulus of elasticity were determined at 28, 56 and 730 days. Comparative strength development of fibre reinforced mixes at 0.5%, 1%, 1.5% and 2% by volume fractions in relation to the mix without fibres was observed. Good correlations between the compressive strength and the modulus of elasticity are established. Steel and polypropylene fibres significantly increased the compressive strength, tensile splitting strength, flexural strength and modulus of elasticity of UHPC after two years curing period when fibre content volume was at least 1%. It seems that steel fibre reinforced UHPC has better properties than the polypropylene fibre reinforced UHPC.

JUPITER to Earth: A statin helps people with normal LDL-C and high hs-CRP, but what does it mean?

PubMed Central

SHISHEHBOR, MEHDI H.; HAZEN, STANLEY L.

2010-01-01

The JUPITER trial (Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin) (N Engl J Med 2008; 359:2195–2207) compared rosuvastatin (Crestor) 20 mg daily vs placebo in apparently healthy people who had levels of low-density lipoprotein cholesterol (LDL-C) lower than 130 mg/dL but elevated levels (≥ 2 mg/L) of high-sensitivity C-reactive protein (hs-CRP). Rosuvastatin treatment lowered LDL-C levels by 50% and hs-CRP levels by 37%, accompanied by a 44% relative risk reduction in the composite end point of unstable angina, revascularization, and confirmed death from cardiovascular causes. In absolute terms, 95 people had to be treated over 2 years to prevent one event. There was, however, a higher incidence of diabetes in the rosuvastatin group. PMID:19122109

A chromogranin A ELISA absent of an apparent high-dose hook effect observed in other chromogranin A ELISAs.

PubMed

Erickson, J Alan; Grenache, David G

2016-01-15

Routine testing for chromogranin A (CgA) using an established commercial ELISA revealed an apparent high-dose hook effect in approximately 15% of specimens. Investigations found the same effect in two additional ELISAs. We hypothesized that a CgA derived peptide(s) at high concentrations was responsible but experiments were inconclusive. Here we describe the analytical performance characteristics of the Chromoa™ CgA ELISA that did not display the apparent high-dose hook effect. Performance characteristics of the Chromoa ELISA were assessed. The reference interval was established utilizing healthy volunteers. Specimens producing the apparent high-dose hook effect in other assays were evaluated using the Chromoa ELISA. The limit of detection was 8ng/ml. Linearity was acceptable (slope=1.04, intercept=18.1 and r(2)=0.997). CVs were ≤4.6 and ≤9.3% for repeatability and within-laboratory imprecision, respectively. CgA was stable at ambient and refrigerated temperatures for a minimum of two and 14days, respectively. An upper reference interval limit of 95ng/ml was established. Specimens demonstrating the apparent high-dose hook effect in other ELISAs did not exhibit the phenomenon using the Chromoa ELISA. The Chromoa ELISA demonstrates acceptable performance for quantifying serum CgA. The apparent high-dose hook effect exhibited in other ELISAs was absent using the Chromoa assay. Copyright © 2015 Elsevier B.V. All rights reserved.

The carbohydrate-fat problem: can we construct a healthy diet based on dietary guidelines?

PubMed

Drewnowski, Adam

2015-05-01

The inclusion of nutrition economics in dietary guidance would help ensure that the Dietary Guidelines for Americans benefit equally all segments of the US population. The present review outlines some novel metrics of food affordability that assess nutrient density of foods and beverages in relation to cost. Socioeconomic disparities in diet quality in the United States are readily apparent. In general, groups of lower socioeconomic status consume cheaper, lower-quality diets and suffer from higher rates of noncommunicable diseases. Nutrient profiling models, initially developed to assess the nutrient density of foods, can be turned into econometric models that assess both calories and nutrients per reference amount and per unit cost. These novel metrics have been used to identify individual foods that were affordable, palatable, culturally acceptable, and nutrient rich. Not all nutrient-rich foods were expensive. In dietary surveys, both local and national, some high-quality diets were associated with relatively low cost. Those population subgroups that successfully adopted dietary guidelines at an unexpectedly low monetary cost were identified as "positive deviants." Constructing a healthy diet based on dietary guidelines can be done, provided that nutrient density of foods, their affordability, as well as taste and social norms are all taken into account. © 2015 American Society for Nutrition.

Cationic flocculants carrying hydrophobic functionalities: applications for solid/liquid separation.

PubMed

Schwarz, S; Jaeger, W; Paulke, B-R; Bratskaya, S; Smolka, N; Bohrisch, J

2007-07-26

The flocculation behaviors of three series of polycations with narrow molecular weight distributions carrying hydrophobic substituents on their backbones [poly(N-vinylbenzyl-N,N,N-trimethylammonium chloride), poly(N-vinylbenzyl-N,N-dimethyl-N-butylammonium chloride), and poly(N-vinylbenzylpyridinium chloride)] were investigated in dispersions of monodisperse polystyrene latexes and kaolin. Apparently, the charge density of the polycations decreases with increasing substituent hydrophobicity and increasing molecular weight of the polyelectrolytes. The necessary amount of flocculant for phase separation in dispersions with high substrate surface charge densities increases with increasing hydrophobicity of the polyelectrolyte. Nevertheless, the introduction of hydrophobic functionalities is beneficial, resulting in a substantial broadening of the range between the minimum and maximum amounts of flocculant necessary for efficient flocculation (flocculation window). An increase in ionic strength supports this effect. When the substrate has a low charge density, the hydrophobic interactions play a much more significant role in the flocculation process. Here, the minimum efficient doses remained the same for all three polyelectrolytes investigated, but the width of the flocculation window increased as the polycation hydrophobicity and the molecular weight increased. The necessary amount of flocculant increased with an increase in particle size at constant solid content of the dispersion, as well as with a decreasing number of particles at a constant particle size.

A mechanism for tectonic deformation on Venus

NASA Technical Reports Server (NTRS)

Phillips, Roger J.

1986-01-01

In the absence of identifiable physiographic features directly associated with plate tectonics, alternate mechanisms are sought for the intense tectonic deformation observed in radar images of Venus. One possible mechanism is direct coupling into an elastic lithosphere of the stresses associated with convective flow in the interior. Spectral Green's function solutions have been obtained for stresses in an elastic lithosphere overlying a Newtonian interior with an exponential depth dependence of viscosity, and a specified surface-density distribution driving the flow. At long wavelengths and for a rigid elastic/fluid boundary condition, horizontal normal stresses in the elastic lid are controlled by the vertical shear stress gradient and are directly proportional to the depth of the density disturbance in the underlying fluid. The depth and strength of density anomalies in the Venusian interior inferred by analyses of long wavelength gravity data suggest that stresses in excess of 100 MPa would be generated in a 10 km thick elastic lid unless a low viscosity channel occurring beneath the lid or a positive viscosity gradient uncouples the flow stresses. The great apparent depth of compensation of topographic features argues against this, however, thus supporting the importance of the coupling mechanism. If there is no elastic lid, stresses will also be very high near the surface, providing also that the viscosity gradient is negative.

Coat condition of ringtailed lemurs, Lemur catta at Berenty Reserve, Madagascar: I. Differences by age, sex, density and tourism, 1996-2006.

PubMed

Jolly, Alison

2009-03-01

An index of coat condition can be a non-invasive tool for tracking health and stress at population level. Coat condition in ringtailed lemurs, Lemur catta, was recorded during September-November birth seasons of 1996, 1997, 1999, and 2001-2006 at Berenty Reserve, Madagascar. Condition was scored on a scale from 0: full, fluffy coat with guard hairs present, to 5: half or more of body hairless. Adult males did not differ overall from adult females. Coats were worse in adults than in 2-year-old subadults; 1-year-old juveniles were intermediate. Mothers and adult males lost coat condition as the season progressed: non-mother females maintained condition. Years 1999-2002 scored better coats than either 1996-1997 or 2003-2006. Lemurs in high population density areas had worse coats than in natural forest, but tourist presence had less effect than density. Monitoring coat condition in an apparently healthy population reveals differences between population segments, and in a forest fragment with limited immigration or emigration it can track progressive changes, correcting impressions of progressive improvement or degradation over time. Above all it gives a baseline for response to climate changes or eventual pathology. (c) 2008 Wiley-Liss, Inc.

Plant Response to Soils, Site Preparation, and Initial Pine Planting Density

Treesearch

Henry A. Pearson; Gale L. Wolters; Ronald E. Thill; Alton Martin; V. Clark Baldwin

1995-01-01

This study described the effects of soils, site preparation, and initial pine regeneration spacings on tree growth and the associated understory woody and herbaceous plant succession. Although Sawyer soils appeared more productive than Ruston soils before the harvest and regeneration treatments, woody and herbaceous plant differences were not apparent between the...

40 CFR 796.1950 - Vapor pressure.

Code of Federal Regulations, 2011 CFR

2011-07-01

... to a wide variety of chemical types and structures, EPA has sponsored research and development work... Chemistry, 3:664-670 (1969). (3) Spencer, W.F. and Cliath, M.M. “Vapor Density and Apparent Vapor Pressure of Lindane,” Journal of Agricultural and Food Chemistry, 18:529-530 (1970). [50 FR 39252, Sept. 27...

40 CFR 796.1950 - Vapor pressure.

Code of Federal Regulations, 2012 CFR

2012-07-01

... to a wide variety of chemical types and structures, EPA has sponsored research and development work... Chemistry, 3:664-670 (1969). (3) Spencer, W.F. and Cliath, M.M. “Vapor Density and Apparent Vapor Pressure of Lindane,” Journal of Agricultural and Food Chemistry, 18:529-530 (1970). [50 FR 39252, Sept. 27...

40 CFR 796.1950 - Vapor pressure.

Code of Federal Regulations, 2013 CFR

2013-07-01

... to a wide variety of chemical types and structures, EPA has sponsored research and development work... Chemistry, 3:664-670 (1969). (3) Spencer, W.F. and Cliath, M.M. “Vapor Density and Apparent Vapor Pressure of Lindane,” Journal of Agricultural and Food Chemistry, 18:529-530 (1970). [50 FR 39252, Sept. 27...

40 CFR 796.1950 - Vapor pressure.

Code of Federal Regulations, 2014 CFR

2014-07-01

... to a wide variety of chemical types and structures, EPA has sponsored research and development work... Chemistry, 3:664-670 (1969). (3) Spencer, W.F. and Cliath, M.M. “Vapor Density and Apparent Vapor Pressure of Lindane,” Journal of Agricultural and Food Chemistry, 18:529-530 (1970). [50 FR 39252, Sept. 27...

Effects of self-aggregation on the hydration of an amphiphilic antidepressant drug in different aqueous media

NASA Astrophysics Data System (ADS)

Taboada, Pablo; Gutiérrez-Pichel, Manuel; Mosquera, Víctor

2004-03-01

Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic antidepressant drug clomipramine hydrochloride have been determined from density and ultrasound velocity measurements in the temperature range 288.15-313.15 K in buffered aqueous solution of pH 3.0 and 5.5. Critical concentrations of aggregation of this drug were obtained from inflections on the plots of the sound velocity against drug concentration. Apparent molal adiabatic compressibilities of the aggregates formed by the drug, calculated by combining the ultrasound velocity and density data, were typical of those for a stacked aggregate. From the temperature dependence of the critical concentration and using the mass action model combined with the Phillips definition of the critical concentration the thermodynamic standard quantities: free Gibbs energy, enthalpy and entropy of aggregate formation were calculated. The critical concentration and energy involved in the aggregation process of this drug have been also evaluated experimentally using isothermal titration calorimetry at 298.15 K. The solvent-drug interactions have been discussed from compressibility and calorimetry data.

Electrical resistivity of ultrafine-grained copper with nanoscale growth twins

NASA Astrophysics Data System (ADS)

Chen, X. H.; Lu, L.; Lu, K.

2007-10-01

We have investigated electrical resistivities of high-purity ultrafine-grained Cu containing different concentrations of nanoscale growth twins, but having identical grain size. The samples were synthesized by pulsed electrodeposition, wherein the density of twins was varied systematically by adjusting the processing parameters. The electrical resistivity of the Cu specimen with a twin spacing of 15nm at room temperature (RT) is 1.75μΩcm (the conductivity is about 97% IACS), which is comparable to that of coarse-grained (CG) pure Cu specimen. A reduction in twin density for the same grain size (with twin lamellar spacings of 35 and 90nm, respectively) results in an increment in electrical resistivity from 1.75to2.12μΩcm. However, the temperature coefficient of resistivity at RT for these Cu specimens is insensitive to the twin spacing and shows a consistent value of ˜3.78×10-3/K, which is slightly smaller than that of CG Cu (3.98×10-3/K). The increased electrical resistivities of the Cu samples were ascribed dominantly to the intrinsic grain boundary (GB) scattering, while the GB defects and GB energy would decrease with increasing twin density. Transmission electron microscope observations revealed the GB configuration difference from the Cu samples with various twin densities. Plastic deformation would induce an apparent increase in the resistivity. The higher of the twin density, the higher increment of RT resistivity was detected in the Cu specimens subjected to 40% rolling strain. Both the deviated twin boundaries and strained GBs may give rise to an increase in the resistivity.

Multi-thermal observations of newly formed loops in a dynamic flare

NASA Technical Reports Server (NTRS)

Svestka, Zdenek F.; Fontenla, Juan M.; Machado, Marcos E.; Martin, Sara F.; Neidig, Donald F.

1987-01-01

The dynamic flare of November 6, 1980 (max at about 15:26 UT) developed a rich system of growing loops which could be followed in H-alpha for 1.5 hr. Throughout the flare, these loops, near the limb, were seen in emission against the disk. Theoretical computations of deviations from LTE populations for a hydrogen atom reveal that this requires electron densities in the loops close to, or in excess of 10 to the 12th/cu cm. From measured widths of higher Balmer lines the density at the tops of the loops was found to be 4 x 10 to the 12th/cu cm if no nonthermal motions were present, or 5 x 10 to the 11th/cu cm for a turbulent velocity of about 12 km/s. It is now general knowledge that flare loops are initially observed in X-rays and become visible in H-alpha only after cooling. For such a high density, a loop would cool through radiation from 10 to the 7th to 10 to the 4th K within a few minutes so that the dense H-alpha loops should have heights very close to the heights of the X-ray loops. This, however, contradicts the observations obtained by the HXIS and FCS instruments on board SMM which show the X-ray loops at much higher altitudes than the loops in H-alpha. Therefore, it is suggested that the density must have been significantly lower when the loops were formed, and that the flare loops were apparently both shrinking and increasing in density while cooling.

Population density and refractive error among Chinese children.

PubMed

Zhang, Mingzhi; Li, Liping; Chen, Lizhen; Lee, Jack; Wu, Jiasi; Yang, Amy; Chen, Connie; Xu, Daocheng; Lam, Dennis S C; Sharma, Abhishek; Griffiths, Sian; Gao, Yang; Congdon, Nathan

2010-10-01

China is urbanizing rapidly, and the prevalence of myopia is high. This study was conducted to identify the reasons for observed differences in the prevalence of myopia among urban versus rural Chinese children. All children with uncorrected acuity of 6/12 or worse and a 50% random sample of children with vision better than 6/12 at all secondary schools in mixed rural-urban Liangying Township, Guangdong, underwent cycloplegic refraction, and provided data on age, gender, parental education, weekly near work and time outdoors, and urban development level of respondents' neighborhoods (12-item questionnaire). Population density of 32 villages and urban zones in Liangying was calculated from census figures (mean population density, 217 persons/km(2); range, 94-957; mean for Guangdong, 486). Among 5844 eligible children, 4612 (78.9%) had parental consent and completed examinations; 2957 were refracted per protocol, and 2480 (83.9%) of these had questionnaire data. Those with completed examinations were more likely to be girls (P < 0.001), and questionnaire respondents were more myopic (P = 0.02), but otherwise did not differ significantly from nonrespondents. In multivariate models, older age (P < 0.001), more near work (P = 0.02), and higher population density (P = 0.003), but not development index, parental education, or time outdoors were significantly associated with more myopic refractive error. Higher population density appears to be associated with myopia risk, independent of academic activity, time spent outdoors, familial educational level, or economic development, factors that have been thought to explain higher myopia prevalence among urban children. Mechanisms for this apparent association should be sought.

A Presynaptic Function of Shank Protein in Drosophila.

PubMed

Wu, Song; Gan, Guangming; Zhang, Zhiping; Sun, Jie; Wang, Qifu; Gao, Zhongbao; Li, Meixiang; Jin, Shan; Huang, Juan; Thomas, Ulrich; Jiang, Yong-Hui; Li, Yan; Tian, Rui; Zhang, Yong Q

2017-11-29

Human genetic studies support that loss-of-function mutations in the SH 3 domain and ank yrin repeat containing family proteins (SHANK1-3), the large synaptic scaffolding proteins enriched at the postsynaptic density of excitatory synapses, are causative for autism spectrum disorder and other neuropsychiatric disorders in humans. To better understand the in vivo functions of Shank and facilitate dissection of neuropathology associated with SHANK mutations in human, we generated multiple mutations in the Shank gene, the only member of the SHANK family in Drosophila melanogaster Both male and female Shank null mutants were fully viable and fertile with no apparent morphological or developmental defects. Expression analysis revealed apparent enrichment of Shank in the neuropils of the CNS. Specifically, Shank coexpressed with another PSD scaffold protein, Homer, in the calyx of mushroom bodies in the brain. Consistent with high expression in mushroom body calyces, Shank mutants show an abnormal calyx structure and reduced olfactory acuity. These morphological and functional phenotypes were fully rescued by pan-neuronal reexpression of Shank, and only partially rescued by presynaptic but no rescue by postsynaptic reexpression of Shank. Our findings thus establish a previously unappreciated presynaptic function of Shank. SIGNIFICANCE STATEMENT Mutations in SHANK family genes are causative for idiopathic autism spectrum disorder. To understand the neural function of Shank, a large scaffolding protein enriched at the postsynaptic densities, we examined the role of Drosophila Shank in synapse development at the peripheral neuromuscular junctions and the central mushroom body calyx. Our results demonstrate that, in addition to its conventional postsynaptic function, Shank also acts presynaptically in synapse development in the brain. This study offers novel insights into the synaptic role of Shank. Copyright © 2017 the authors 0270-6474/17/3711592-13$15.00/0.

Mechanical behavior of regular open-cell porous biomaterials made of diamond lattice unit cells.

PubMed

Ahmadi, S M; Campoli, G; Amin Yavari, S; Sajadi, B; Wauthle, R; Schrooten, J; Weinans, H; Zadpoor, A A

2014-06-01

Cellular structures with highly controlled micro-architectures are promising materials for orthopedic applications that require bone-substituting biomaterials or implants. The availability of additive manufacturing techniques has enabled manufacturing of biomaterials made of one or multiple types of unit cells. The diamond lattice unit cell is one of the relatively new types of unit cells that are used in manufacturing of regular porous biomaterials. As opposed to many other types of unit cells, there is currently no analytical solution that could be used for prediction of the mechanical properties of cellular structures made of the diamond lattice unit cells. In this paper, we present new analytical solutions and closed-form relationships for predicting the elastic modulus, Poisson׳s ratio, critical buckling load, and yield (plateau) stress of cellular structures made of the diamond lattice unit cell. The mechanical properties predicted using the analytical solutions are compared with those obtained using finite element models. A number of solid and porous titanium (Ti6Al4V) specimens were manufactured using selective laser melting. A series of experiments were then performed to determine the mechanical properties of the matrix material and cellular structures. The experimentally measured mechanical properties were compared with those obtained using analytical solutions and finite element (FE) models. It has been shown that, for small apparent density values, the mechanical properties obtained using analytical and numerical solutions are in agreement with each other and with experimental observations. The properties estimated using an analytical solution based on the Euler-Bernoulli theory markedly deviated from experimental results for large apparent density values. The mechanical properties estimated using FE models and another analytical solution based on the Timoshenko beam theory better matched the experimental observations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Correlated patterns in hydrothermal plume distribution and apparent magmatic budget along 2500 km of the Southeast Indian Ridge

USGS Publications Warehouse

Baker, Edward; Christophe Hémond,; Anne Briais,; Marcia Maia,; Scheirer, Daniel S.; Sharon L. Walker,; Tingting Wang,; Yongshun John Chen,

2014-01-01

Multiple geological processes affect the distribution of hydrothermal venting along a mid-ocean ridge. Deciphering the role of a specific process is often frustrated by simultaneous changes in other influences. Here we take advantage of the almost constant spreading rate (65–71 mm/yr) along 2500 km of the Southeast Indian Ridge (SEIR) between 77°E and 99°E to examine the spatial density of hydrothermal venting relative to regional and segment-scale changes in the apparent magmatic budget. We use 227 vertical profiles of light backscatter and (on 41 profiles) oxidation-reduction potential along 27 first and second-order ridge segments on and adjacent to the Amsterdam-St. Paul (ASP) Plateau to map ph, the fraction of casts detecting a plume. At the regional scale, venting on the five segments crossing the magma-thickened hot spot plateau is almost entirely suppressed (ph = 0.02). Conversely, the combined ph (0.34) from all other segments follows the global trend of ph versus spreading rate. Off the ASP Plateau, multisegment trends in ph track trends in the regional axial depth, high where regional depth increases and low where it decreases. At the individual segment scale, a robust correlation between ph and cross-axis inflation for first-order segments shows that different magmatic budgets among first-order segments are expressed as different levels of hydrothermal spatial density. This correlation is absent among second-order segments. Eighty-five percent of the plumes occur in eight clusters totaling ∼350 km. We hypothesize that these clusters are a minimum estimate of the length of axial melt lenses underlying this section of the SEIR.

The Influence of Urbanization Modes on the Spatial Circulation of Flaviviruses within Ouagadougou (Burkina Faso)

PubMed Central

Fournet, Florence; Rican, Stéphane; Vaillant, Zoé; Roudot, Anna; Meunier-Nikiema, Aude; Kassié, Daouda; Dabiré, Roch K.; Salem, Gérard

2016-01-01

Dengue is an emerging infectious disease of global significance. Although this virus has been reported for a long time, its significance within the burden of diseases in West Africa is not obvious, especially in Burkina Faso. Our objective was to evaluate flavivirus presence in Ouagadougou (Burkina Faso) and the link between anti-flavivirus antibody seroprevalence and urbanization modes. A population-based cross-sectional survey was conducted and 3015 children were enrolled from Ouagadougou districts with different types and degrees of urbanization (with/without equipment and high/low building density). Flavivirus (FLAV) IgM MAC-ELISA and FLAV indirect IgG ELISA were performed. Associations between FLAV IgG presence (sign of past infection) and various independent variables were assessed using the chi-square test and a multivariate logistic regression analysis. The apparent prevalence of past flavivirus infections among the enrolled children was 22.7% (95% CI: 22.4–26.7) (n = 685). Eleven children (0.4%; 95% CI: 0.61–2.14) were positive for FLAV IgM, indicating active transmission. Factors associated with flavivirus infection were identified among the enrolled children (age, sex), householders (educational level, asset index) and in the environment (building density, water access, waste management and house appearance); however, they showed great variability according to the city districts. The water access modality did not significantly influence FLAV IgG positivity. Conversely, apparently good practices of waste management had unexpected consequences (increased risk related to municipal dumpsters). Given the scale of ongoing urbanization and the spread of arboviral diseases, close collaboration between health and city stakeholders is needed. PMID:27973402

Correlated patterns in hydrothermal plume distribution and apparent magmatic budget along 2500 km of the Southeast Indian Ridge

NASA Astrophysics Data System (ADS)

Baker, Edward T.; Hémond, Christophe; Briais, Anne; Maia, Marcia; Scheirer, Daniel S.; Walker, Sharon L.; Wang, Tingting; Chen, Yongshun John

2014-08-01

Multiple geological processes affect the distribution of hydrothermal venting along a mid-ocean ridge. Deciphering the role of a specific process is often frustrated by simultaneous changes in other influences. Here we take advantage of the almost constant spreading rate (65-71 mm/yr) along 2500 km of the Southeast Indian Ridge (SEIR) between 77°E and 99°E to examine the spatial density of hydrothermal venting relative to regional and segment-scale changes in the apparent magmatic budget. We use 227 vertical profiles of light backscatter and (on 41 profiles) oxidation-reduction potential along 27 first and second-order ridge segments on and adjacent to the Amsterdam-St. Paul (ASP) Plateau to map ph, the fraction of casts detecting a plume. At the regional scale, venting on the five segments crossing the magma-thickened hot spot plateau is almost entirely suppressed (ph = 0.02). Conversely, the combined ph (0.34) from all other segments follows the global trend of ph versus spreading rate. Off the ASP Plateau, multisegment trends in ph track trends in the regional axial depth, high where regional depth increases and low where it decreases. At the individual segment scale, a robust correlation between ph and cross-axis inflation for first-order segments shows that different magmatic budgets among first-order segments are expressed as different levels of hydrothermal spatial density. This correlation is absent among second-order segments. Eighty-five percent of the plumes occur in eight clusters totaling ˜350 km. We hypothesize that these clusters are a minimum estimate of the length of axial melt lenses underlying this section of the SEIR.

Arterial function of carotid and brachial arteries in postmenopausal vegetarians.

PubMed

Su, Ta-Chen; Torng, Pao-Ling; Jeng, Jiann-Shing; Chen, Ming-Fong; Liau, Chiau-Suong

2011-01-01

Vegetarianism is associated with a lower risk of cardiovascular disease. However, studies of arterial function in vegetarians are limited. This study investigated arterial function in vegetarianism by comparing 49 healthy postmenopausal vegetarians with 41 age-matched omnivores. The arterial function of the common carotid artery was assessed by carotid duplex, while the pulse dynamics method was used to measure brachial artery distensibility (BAD), compliance (BAC), and resistance (BAR). Fasting blood levels of glucose, lipids, lipoprotein (a), high-sensitivity C-reactive protein, homocysteine, and vitamin B12 were also measured. Vegetarians had significantly lower serum cholesterol, high-density and low-density lipoprotein, and glucose compared with omnivores. They also had lower vitamin B12 but higher homocysteine levels. Serum levels of lipoprotein (a) and high-sensitivity C-reactive protein were no different between the two groups. There were no significant differences in carotid beta stiffness index, BAC, and BAD between the two groups even after adjustment for associated covariates. However, BAR was significantly lower in vegetarians than in omnivores. Multiple linear regression analysis revealed that age and pulse pressure were two important determinants of carotid beta stiffness index and BAD. Vegetarianism is not associated with better arterial elasticity. Apparently healthy postmenopausal vegetarians are not significantly better in terms of carotid beta stiffness index, BAC, and BAD, but have significantly decreased BAR than omnivores. Prevention of vitamin B12 deficiency might be beneficial for cardiovascular health in vegetarians.

Differentiating aquatic plant communities in a eutrophic river using hyperspectral and multispectral remote sensing

USGS Publications Warehouse

Tian, Y.Q.; Yu, Q.; Zimmerman, M.J.; Flint, S.; Waldron, M.C.

2010-01-01

This study evaluates the efficacy of remote sensing technology to monitor species composition, areal extent and density of aquatic plants (macrophytes and filamentous algae) in impoundments where their presence may violate water-quality standards. Multispectral satellite (IKONOS) images and more than 500 in situ hyperspectral samples were acquired to map aquatic plant distributions. By analyzing field measurements, we created a library of hyperspectral signatures for a variety of aquatic plant species, associations and densities. We also used three vegetation indices. Normalized Difference Vegetation Index (NDVI), near-infrared (NIR)-Green Angle Index (NGAI) and normalized water absorption depth (DH), at wavelengths 554, 680, 820 and 977 nm to differentiate among aquatic plant species composition, areal density and thickness in cases where hyperspectral analysis yielded potentially ambiguous interpretations. We compared the NDVI derived from IKONOS imagery with the in situ, hyperspectral-derived NDVI. The IKONOS-based images were also compared to data obtained through routine visual observations. Our results confirmed that aquatic species composition alters spectral signatures and affects the accuracy of remote sensing of aquatic plant density. The results also demonstrated that the NGAI has apparent advantages in estimating density over the NDVI and the DH. In the feature space of the three indices, 3D scatter plot analysis revealed that hyperspectral data can differentiate several aquatic plant associations. High-resolution multispectral imagery provided useful information to distinguish among biophysical aquatic plant characteristics. Classification analysis indicated that using satellite imagery to assess Lemna coverage yielded an overall agreement of 79% with visual observations and >90% agreement for the densest aquatic plant coverages. Interpretation of biophysical parameters derived from high-resolution satellite or airborne imagery should prove to be a valuable approach for assessing the effectiveness of management practices for controlling aquatic plant growth in inland waters, as well as for routine monitoring of aquatic plants in lakes and suitable lentic environments. ?? 2010 Blackwell Publishing Ltd.

Field evaluation of open and closed-path CO2 flux systems over asphalt surface

NASA Astrophysics Data System (ADS)

Bogoev, I.; Santos, E.

2016-12-01

Eddy covariance (EC) is a widely used method for quantifying surface fluxes of heat, water vapor and carbon dioxide between ecosystems and the atmosphere. A typical EC system consists of an ultrasonic anemometer measuring the 3D wind vector and a fast-response infrared gas analyzer for sensing the water vapor and CO2 density in the air. When using an open-path analyzer that detects the constituent's density in situ a correction for concurrent air temperature and humidity fluctuations must be applied, Webb et al. (1980). In environments with small magnitudes of CO2 flux (<5µmol m-2 s-1) and in the presence of high sensible heat flux, like wintertime over boreal forest, open-path flux measurements have been challenging since the magnitude of the density corrections are as large as the uncorrected CO2 flux itself. A new technology merging the sensing paths of the gas analyzer and the sonic anemometer has been recently developed. This new integrated instrument allows a direct measurement of CO2 mixing ratio in the open air and has the potential to improve the quality of the temperature related density corrections by synchronously measuring the sensible heat flux in the optical path of the gas analyzer. We evaluate the performance and the accuracy of this new sensor over a large parking lot with an asphalt surface where the CO2 fluxes are considered low and the interfering sensible heat fluxes are above 200 Wm-2. A co-located closed-path EC system is used as a reference measurement to examine any systematic biases and apparent CO2 uptake observed with open-path sensors under high sensible heat flux regimes. Half-hour mean and variance of CO2 and water vapor concentrations are evaluated. The relative spectral responses, covariances and corrected turbulent fluxes using a common sonic anemometer are analyzed. The influence of sensor separation and frequency response attenuation on the density corrections is discussed.

Effect of surfactants on apparent oxygen consumption of photosystem I isolated from Arthrospira platensis.

PubMed

Yu, Daoyong; Huang, Guihong; Xu, Fengxi; Ge, Baosheng; Liu, Shuang; Xu, Hai; Huang, Fang

2014-11-01

Surfactants play a significant role in solubilization of photosystem I (PSI) in vitro. Triton X-100 (TX), n-Dodecyl-β-D-maltoside (DDM), and sodium dodecyl sulfate (SDS) were employed to solubilize PSI particles in MES buffer to compare the effect of surfactant and its dosage on the apparent oxygen consumption rate of PSI. Through a combined assessment of sucrose density gradient centrifugation, Native PAGE and 77 K fluorescence with the apparent oxygen consumption, the nature of the enhancement of the apparent oxygen consumption activity of PSI by surfactants has been analyzed. Aggregated PSI particles can be dispersed by surfactant molecules into micelles, and the apparent oxygen consumption rate is higher for surfactant-solubilized PSI than for integral PSI particles. For DDM, PSI particles are solubilized mostly as the integral trimeric form. For TX, PSI particles are solubilized as incomplete trimeric and some monomeric forms. For the much harsher surfactant, SDS, PSI particles are completely solubilized as monomeric and its subunit forms. The enhancement of the oxygen consumption rate cannot be explained only by the effects of surfactant on the equilibrium between monomeric and trimeric forms of solubililized PSI. Care must be taken when the electron transfer activity of PSI is evaluated by methods based on oxygen consumption because the apparent oxygen consumption rate is influenced by uncoupled chlorophyll (Chl) from PSI, i.e., the larger the amount of uncoupled Chl, the higher the rate of apparent oxygen consumption. 77 K fluorescence spectra can be used to ensure that there is no uncoupled Chl present in the system. In order to eliminate the effect of trace uncoupled Chl, an efficient physical quencher of (1)O2, such as 1 mM NaN3, may be added into the mixture.

Solvation behaviour of L-leucine in aqueous ionic liquid at different temperatures: Volumetric approach

NASA Astrophysics Data System (ADS)

Sharma, Samriti; Sandarve, Sharma, Amit K.; Sharma, Meena

2018-05-01

For the investigation of interactions of L-leucine in aqueous solutions of an ionic liquid (1-butyl-3-methylimidazolium tetra fluoroborate [Bmim][BF4]) at atmospheric pressure over a temperature range of (293.15K to 313.16K), we use the volumetric approach. By using the density data we have calculated the apparent molar volume, VΦ, limiting apparent molar volume, V0Φ, the slope, Sv, partial molar volume of transfer, V0Φ,tr. The values of these acoustical parameters have been used for the interpretation of different interactions like hydrophilic-hydrophilic, hydrophilic-hydrophobic, ion hydrophilic, solute-solvent and solute-solute interactions in the amino acid and ionic liquid solutions.

3D Imaging of Density Gradients Using Plenoptic BOS

NASA Astrophysics Data System (ADS)

Klemkowsky, Jenna; Clifford, Chris; Fahringer, Timothy; Thurow, Brian

2016-11-01

The combination of background oriented schlieren (BOS) and a plenoptic camera, termed Plenoptic BOS, is explored through two proof-of-concept experiments. The motivation of this work is to provide a 3D technique capable of observing density disturbances. BOS uses the relationship between density and refractive index gradients to observe an apparent shift in a patterned background through image comparison. Conventional BOS systems acquire a single line-of-sight measurement, and require complex configurations to obtain 3D measurements, which are not always conducive to experimental facilities. Plenoptic BOS exploits the plenoptic camera's ability to generate multiple perspective views and refocused images from a single raw plenoptic image during post processing. Using such capabilities, with regards to BOS, provides multiple line-of-sight measurements of density disturbances, which can be collectively used to generate refocused BOS images. Such refocused images allow the position of density disturbances to be qualitatively and quantitatively determined. The image that provides the sharpest density gradient signature corresponds to a specific depth. These results offer motivation to advance Plenoptic BOS with an ultimate goal of reconstructing a 3D density field.

The dependence of stellar properties on initial cloud density

NASA Astrophysics Data System (ADS)

Jones, Michael O.; Bate, Matthew R.

2018-05-01

We investigate the dependence of stellar properties on the initial mean density of the molecular cloud in which stellar clusters form using radiation hydrodynamical simulations that resolve the opacity limit for fragmentation. We have simulated the formation of three star clusters from the gravitational collapse of molecular clouds whose densities vary by a factor of a hundred. As with previous calculations including radiative feedback, we find that the dependence of the characteristic stellar mass, Mc, on the initial mean density of the cloud, ρ, is weaker than the dependence of the thermal Jeans mass. However, unlike previous calculations, which found no statistically significant variation in the median mass with density, we find a weak dependence approximately of the form Mc∝ρ-1/5. The distributions of properties of multiple systems do not vary significantly between the calculations. We compare our results to the result of observational surveys of star-forming regions, and suggest that the similarities between the properties of our lowest density calculation and the nearby Taurus-Auriga region indicate that the apparent excess of solar-type stars observed may be due to the region's low density.

Heartwood and sapwood in eucalyptus trees: non-conventional approach to wood quality.

PubMed

Cherelli, Sabrina G; Sartori, Maria Márcia P; Próspero, André G; Ballarin, Adriano W

2018-01-01

This study evaluated the quality of heartwood and sapwood from mature trees of three species of Eucalyptus, by means of the qualification of their proportion, determination of basic and apparent density using non-destructive attenuation of gamma radiation technique and calculation of the density uniformity index. Six trees of each species (Eucalyptus grandis - 18 years old, Eucalyptus tereticornis - 35 years old and Corymbia citriodora - 28 years old) were used in the experimental program. The heartwood and sapwood were delimited by macroscopic analysis and the calculation of areas and percentage of heartwood and sapwood were performed using digital image. The uniformity index was calculated following methodology which numerically quantifies the dispersion of punctual density values of the wood around the mean density along the radius. The percentage of the heartwood was higher than the sapwood in all species studied. The density results showed no statistical difference between heartwood and sapwood. Differently from the density results, in all species studied there was statistical differences between uniformity indexes for heartwood and sapwood regions, making justifiable the inclusion of the density uniformity index as a quality parameter for Eucalyptus wood.

Age at menarche, age at menopause and duration of fertility as risk factors for osteoporosis.

PubMed

Sioka, C; Fotopoulos, A; Georgiou, A; Xourgia, X; Papadopoulos, A; Kalef-Ezra, J A

2010-02-01

To investigate the relationship of osteopenia and osteoporosis in apparently healthy postmenopausal patients with age at menarche, age at menopause and duration of fertility. One hundred and twenty-four apparently healthy Greek postmenopausal women underwent spinal and hip X-ray absorptiometry scans. Among them, 47 were classified as normal (control group), 52 as osteopenic, and 25 as having osteoporosis. These groups were compared according to their age at menarche (three subgroups of 10-12, 13 and 14-16 years old), at menopause (three subgroups of 40-45, 46-50 and > or = 51 years old) and duration of fertility (four subgroups of < or = 30, 31-35, 36-40 and 41-45 years). The groups were not found to differ statistically according to age and age at menarche. However, decreased bone mineral density was found in patients with duration of fertility not exceeding 30 years (p = 0.034) and age at menopause less than 45 years (p = 0.034). No association was found between bone mineral density in Greek postmenopausal women and either number of live births or lactation. In postmenopausal females, the cumulative exposure to endogenous estrogens, measured as years of menstruation, seems to be a significant protective factor against the development of postmenopausal osteoporosis. Age at menopause between 40 and 45 years, but not age at menarche, correlated with low bone mineral density in postmenopausal females.

Carbon - Bulk Density Relationships for Highly Weathered Soils of the Americas

NASA Astrophysics Data System (ADS)

Nave, L. E.

2014-12-01

Soils are dynamic natural bodies composed of mineral and organic materials. As a result of this mixed composition, essential properties of soils such as their apparent density, organic and mineral contents are typically correlated. Negative relationships between bulk density (Db) and organic matter concentration provide well-known examples across a broad range of soils, and such quantitative relationships among soil properties are useful for a variety of applications. First, gap-filling or data interpolation often are necessary to develop large soil carbon (C) datasets; furthermore, limitations of access to analytical instruments may preclude C determinations for every soil sample. In such cases, equations to derive soil C concentrations from basic measures of soil mass, volume, and density offer significant potential for purposes of soil C stock estimation. To facilitate estimation of soil C stocks on highly weathered soils of the Americas, I used observations from the International Soil Carbon Network (ISCN) database to develop carbon - bulk density prediction equations for Oxisols and Ultisols. Within a small sample set of georeferenced Oxisols (n=89), 29% of the variation in A horizon C concentrations can be predicted from Db. Including the A-horizon sand content improves predictive capacity to 35%. B horizon C concentrations (n=285) were best predicted by Db and clay content, but were more variable than A-horizons (only 10% of variation explained by linear regression). Among Ultisols, a larger sample set allowed investigation of specific horizons of interest. For example, C concentrations of plowed A (Ap) horizons are predictable based on Db, sand and silt contents (n=804, r2=0.38); gleyed argillic (Btg) horizon concentrations are predictable from Db, sand and clay contents (n=190, r2=0.23). Because soil C stock estimates are more sensitive to variation in soil mass and volume determinations than to variation in C concentration, prediction equations such as these may be used on carefully collected samples to constrain soil C stocks. The geo-referenced ISCN database allows users the opportunity to derive similar predictive relationships among measured soil parameters; continued input of new datasets from highly weathered soils of the Americas will improve the precision of these prediction equations.

Can schooling regulate marine populations and ecosystems?

NASA Astrophysics Data System (ADS)

Maury, Olivier

2017-08-01

Schools, shoals and swarms are pervasive in the oceans. They have to provide very strong advantages to have been selected and generalized in the course of evolution. Auto-organized groups are usually assumed to provide facilitated encounters of reproduction partners, improved protection against predation, better foraging efficiency, and hydrodynamic gains. However, present theories regarding their evolutionary advantages do not provide an unambiguous explanation to their universality. In particular, the mechanisms commonly proposed to explain grouping provide little support to the formation of very large groups that are common in the sea (e.g. Rieucau et al., 2014). From literature review, data analysis and using a simple mathematical model, I show that large auto-organized groups appear at high population density while only small groups or dispersed individuals remain at low population density. Following, an analysis of tuna tagging data and simple theoretical developments show that large groups are likely to expose individuals to a dramatic decrease of individual foraging success and simultaneous increase of predatory and disease mortality, while small groups avoid those adverse feedbacks and provide maximum foraging success and protection against predation, as it is usually assumed. This would create an emergent density-dependent regulation of marine populations, preventing them from outbursts at high density, and protecting them at low density. This would be a major contribution to their resilience and a crucial process of ecosystems dynamics. A two-step evolutionary process acting at the individual level is proposed to explain how this apparently suicidal behaviour could have been selected and generalized. It explains how grouping would have permitted the emergence of extremely high fecundity life histories, despite their notorious propensity to destabilize populations. The potential implications of the ;grouping feedback; on population resilience, ecosystem stability and the persistence of marine biodiversity are discussed. The risk of harvesting marine species with fishing gears that enable catching dispersed individuals (such as longline, gillnet, trawl or using fishing aggregative devices for instance) is underlined. Finally, tropical tunas are used to exemplify the potential importance of schooling in shaping complex life histories and species interaction.

Magnetic and gravity gradiometry framework for Mesoproterozoic iron oxide-apatite and iron oxide-copper-gold deposits, southeast Missouri, USA

USGS Publications Warehouse

McCafferty, Anne E.; Phillips, Jeffrey; Driscoll, Rhonda L.

2016-01-01

High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three-dimensional models, an extensive statistical summary of density and apparent magnetic susceptibility measurements is presented that includes data on several hundred samples taken from the deposits, altered wall rocks, and unaltered country rocks.

Time Periods of Unusual Density Behavior Observed by GRACE and CHAMP

NASA Astrophysics Data System (ADS)

McLaughlin, C. A.; Fattig, E.; Mysore Krishna, D.; Locke, T.; Mehta, P. M.

2011-12-01

Time periods of low cross correlation between precision orbit ephemeris (POE) derived density and accelerometer density for CHAMP and GRACE are examined. In particular, the cross correlation for GRACE dropped from typical values near 0.9 to much lower values and then returned to typical over the time period of late October to late December of 2005. This time period includes a maneuver where GRACE-A and GRACE-B swapped positions. However, the drop in cross correlation begins and reaches its low point before the maneuvers begin. In addition, the densities were found using GRACE-A, but GRACE-B did most of the maneuvering. The time period is characterized by high frequency variations in accelerometer density of the same magnitude as the daylight to eclipse variations over the course of an orbit. However, the daylight to eclipse variations are particularly small during this time period because the orbit plane is near the terminator. Additionally, the difference between the accelerometer and POE derived densities are not unusually large during this time period. This implies the variations are not unusual, just more significant when the orbit plane is near terminator. Cyclical variations in correlation of the POE derived densities with accelerometer derived densities are seen for both GRACE and CHAMP, but the magnitude of the variations are much larger for GRACE, possibly because of the higher altitude of GRACE. The cycles seem to be phased so that low correlations occur with low beta angle when the orbit plane is near the terminator. The low correlation is possibly caused by the lower amplitude of the daylight to eclipse signal making higher frequency variations relatively more important. However, another possible explanation is terminator waves in density that propagate to the thermosphere from lower in the atmosphere. These waves have been observed in CHAMP accelerometer data and global circulation model simulations. Further investigation is needed to see if the variations correspond to terminator waves or if they represent typical high frequency signal from another source that is more apparent when the orbit plane is near the terminator. 1. C. A. McLaughlin, E. Fattig, D. Mysore Krishna, and P. M. Mehta, "Time Periods of Anomalous Density for GRACE and CHAMP," AAS/AIAA Astrodynamics Specialists Conference, AAS 11-613, Girdwood, AK, August 2011. 2. C. A. McLaughlin, A. Hiatt, and T. Lechtenberg, "Calibrating Precision Orbit Derived Total Density," Journal of Spacecraft and Rockets, Vol. 48, No. 1, January-February 2011, pp. 166-174.

Diffusion-weighted magnetic resonance imaging of uterine cervical cancer.

PubMed

Liu, Ying; Bai, Renju; Sun, Haoran; Liu, Haidong; Wang, Dehua

2009-01-01

To determine the feasibility of diffusion-weighted magnetic resonance (MR) imaging (DWI) of uterine cervical cancer and to investigate whether the apparent diffusion coefficient (ADC) values of cervical cancer differ from those of normal cervix and whether they could indicate the histologic type and the pathologic grade of tumor. Forty-two female patients with histopathologically proven uterine cervical cancer and 15 female patients with uterine leiomyomas underwent preoperative MR examinations using a 1.5-T clinical scanner (GE 1.5T Twin-Speed Infinity with Excite II scanner; GE Healthcare, Waukesha, Wis). Scanning sequences included T2-weighted fast spin-echo imaging, T2-weighted fast spin-echo with fat suppression imaging, T1-weighted spin-echo imaging, and DWI with diffusion factors of 0 and 1000 s/mm2. Parameters evaluated consisted of ADC values of uterine cervical cancer and normal cervix. Histologic specimens were stained with hematoxylin and eosin. The cellular densities of 32 uterine cervical cancers were calculated, which were regarded as the ratio of the total area of tumor cell nuclei divided by the area of sample image. Apparent diffusion coefficient value was statistically different (P = 0.000) between normal and cancerous tissue in the uterine cervix; the former one was (mean [SD], 1.50 [0.16]) x 10(-3) mm2/s, and the latter one was (0.88 [0.15]) x 10(-3) mm2/s. Apparent diffusion coefficient value of squamous carcinoma was statistically lower than that of adenocarcinoma (P = 0.040). The ADC value of uterine cervical cancer correlated negatively with cellular density (r = -0.711, P = 0.000) and the grading of tumor (r = -0.778, P = 0.000). Diffusion-weighted MR imaging has a potential ability to differentiate between normal and cancerous tissue in the uterine cervix, and it can indicate the histologic type of uterine cervical cancer as well. The ADC value of uterine cervical cancer represents tumor cellular density, thus providing a new method for evaluating the pathologic grading of tumor.

Application of remote sensing analysis and MT method for identification geothermal prospect zone in Mt. Endut

NASA Astrophysics Data System (ADS)

Akbar, A. M.; Permadi, A. N.; Wildan, D.; Sobirin, R.; Supriyanto

2017-07-01

Mount Endut is located at Banten Province, 40 km southward Rangkasbitung City, with geographic UTM position between 9261000-9274000 N and 639000-652000 E. Preliminary survey at Mt. Endut was geological and geochemical survey in 2006, resistivity survey and MT survey in 2007 with 27 measurement point. All survey conducted by Pusat Sumber Daya Geologi (PSDG). According to result of premilinary survey, Mt. Endut is dominated by quartenary volcanic rock produced by Mt. Endut, which breakthrough tertiary sediment layer. NE to SW normal fault produced surface manifestation, namely Cikawah (CKW) hot spring and Handeleum (HDL) hot spring. According to SiO2 and NaK geothermometer, subsurface temperature of Mt Endut is ranging from 162 to 180 °C. Apparent resistivity maps show that thermal manifestation areas coincide with pronounced high anomaly due to resistive intrusion bodies contrast to conductive sedimentary basements. In order to delineate permeability zone, fracture fault density (FFD) analysis from remote sensing image is carry out. FFD analysis from lansdat 7 image shows the area on westward flank of Mt. Endut have high fracture fault density (162-276 m/km2), higher than it's surrounding area and can be assume that area is weak zone and have high permeability. That's structure density anomaly coincide with low resistivity from Magnetotelluric data. Resistivity structure from Magnetotelluric data shows western flank have low permeability layer (14-27 Ohmm) with average thickness 250 m. Below this layer there is layer with higher resistivity (37-100 Ohmm) with ±1000 m depth and interpreted as shallow reservoir. Massive resistif intrusive bodies act controlled the surface manifestation, and act as boundary and bounded the geothermal system in western part of Mt. Endut.

Gamma-ray observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

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

Ackermann, M.; Ajello, M.; Allafort, A.

We report on the gamma-ray observations of giant molecular clouds Orion A and B with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The gamma-ray emission in the energy band between ~100 MeV and ~100 GeV is predicted to trace the gas mass distribution in the clouds through nuclear interactions between the Galactic cosmic rays (CRs) and interstellar gas. The gamma-ray production cross-section for the nuclear interaction is known to ~10% precision which makes the LAT a powerful tool to measure the gas mass column density distribution of molecular clouds for a known CR intensity. Wemore » present here such distributions for Orion A and B, and correlate them with those of the velocity-integrated CO intensity (W CO) at a 1° × 1° pixel level. The correlation is found to be linear over a W CO range of ~10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The W CO-to-mass conversion factor, X CO, is found to be ~2.3 × 10 20 cm -2(K km s –1) –1 for the high-longitude part of Orion A (l > 212°), ~1.7 times higher than ~1.3 × 10 20 found for the rest of Orion A and B. We interpret the apparent high X CO in the high-longitude region of Orion A in the light of recent works proposing a nonlinear relation between H2 and CO densities in the diffuse molecular gas. W CO decreases faster than the H 2 column density in the region making the gas "darker" to W CO.« less

Gamma-Ray Observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.;

Choice of no-slip curved boundary condition for lattice Boltzmann simulations of high-Reynolds-number flows.

PubMed

Sanjeevi, Sathish K P; Zarghami, Ahad; Padding, Johan T

2018-04-01

Various curved no-slip boundary conditions available in literature improve the accuracy of lattice Boltzmann simulations compared to the traditional staircase approximation of curved geometries. Usually, the required unknown distribution functions emerging from the solid nodes are computed based on the known distribution functions using interpolation or extrapolation schemes. On using such curved boundary schemes, there will be mass loss or gain at each time step during the simulations, especially apparent at high Reynolds numbers, which is called mass leakage. Such an issue becomes severe in periodic flows, where the mass leakage accumulation would affect the computed flow fields over time. In this paper, we examine mass leakage of the most well-known curved boundary treatments for high-Reynolds-number flows. Apart from the existing schemes, we also test different forced mass conservation schemes and a constant density scheme. The capability of each scheme is investigated and, finally, recommendations for choosing a proper boundary condition scheme are given for stable and accurate simulations.

Choice of no-slip curved boundary condition for lattice Boltzmann simulations of high-Reynolds-number flows

NASA Astrophysics Data System (ADS)

Sanjeevi, Sathish K. P.; Zarghami, Ahad; Padding, Johan T.

2018-04-01

Various curved no-slip boundary conditions available in literature improve the accuracy of lattice Boltzmann simulations compared to the traditional staircase approximation of curved geometries. Usually, the required unknown distribution functions emerging from the solid nodes are computed based on the known distribution functions using interpolation or extrapolation schemes. On using such curved boundary schemes, there will be mass loss or gain at each time step during the simulations, especially apparent at high Reynolds numbers, which is called mass leakage. Such an issue becomes severe in periodic flows, where the mass leakage accumulation would affect the computed flow fields over time. In this paper, we examine mass leakage of the most well-known curved boundary treatments for high-Reynolds-number flows. Apart from the existing schemes, we also test different forced mass conservation schemes and a constant density scheme. The capability of each scheme is investigated and, finally, recommendations for choosing a proper boundary condition scheme are given for stable and accurate simulations.

Multiwalled Carbon Nanotube/nanofiber Arrays as Conductive and Dry Adhesive Interface Materials

NASA Technical Reports Server (NTRS)

Tong, Tao; Zhao, Yang; Delzeit, Lance; Majumdar, Arun; Kashani, Ali

2004-01-01

We demonstrate the possibility of making conductive and dry adhesive interfaces between multiwalled carbon nanotube (MWNT) and nanofiber (MWNF) arrays grown by chemical vapor deposition with transition-metal as catalyst on highly Boron doped silicon substrates. The maximum observed adhesion force between MWNT and MWNF surfaces is 3.5 mN for an apparent contact area of 2 mm by 4 mm. The minimum contact resistance measured at the same time is approx.20 Omega. Contact resistances of MWNT-MWNT and MWNT-gold interfaces were also measured as pressure forces around several mN were applied at the interface. The resulting minimum contact resistances are on the same order but with considerable variation from sample to sample. For MWNT-MWNT contacts, a minimum contact resistance of approx.1 Omega is observed for a contact area of 2 mm by 1 mm. The relatively high contact resistances, considering the area density of the nanotubes, might be explained by the high cross-tube resistances at the contact interfaces.

Density Distributions of Cyclotrimethylenetrinitramines (RDX)

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

Hoffman, D M

2002-03-19

As part of the US Army Foreign Comparative Testing (FCT) program the density distributions of six samples of class 1 RDX were measured using the density gradient technique. This technique was used in an attempt to distinguish between RDX crystallized by a French manufacturer (designated insensitive or IRDX) from RDX manufactured at Holston Army Ammunition Plant (HAAP), the current source of RDX for Department of Defense (DoD). Two samples from different lots of French IRDX had an average density of 1.7958 {+-} 0.0008 g/cc. The theoretical density of a perfect RDX crystal is 1.806 g/cc. This yields 99.43% of themore » theoretical maximum density (TMD). For two HAAP RDX lots the average density was 1.786 {+-} 0.002 g/cc, only 98.89% TMD. Several other techniques were used for preliminary characterization of one lot of French IRDX and two lot of HAAP RDX. Light scattering, SEM and polarized optical microscopy (POM) showed that SNPE and Holston RDX had the appropriate particle size distribution for Class 1 RDX. High performance liquid chromatography showed quantities of HMX in HAAP RDX. French IRDX also showed a 1.1 C higher melting point compared to HAAP RDX in the differential scanning calorimetry (DSC) consistent with no melting point depression due to the HMX contaminant. A second part of the program involved characterization of Holston RDX recrystallized using the French process. After reprocessing the average density of the Holston RDX was increased to 1.7907 g/cc. Apparently HMX in RDX can act as a nucleating agent in the French RDX recrystallization process. The French IRDX contained no HMX, which is assumed to account for its higher density and narrower density distribution. Reprocessing of RDX from Holston improved the average density compared to the original Holston RDX, but the resulting HIRDX was not as dense as the original French IRDX. Recrystallized Holston IRDX crystals were much larger (3-500 {micro}m or more) then either the original class 1 HAAP RDX or French IRDX.« less

Usefulness of the LDL-C/apoB ratio in the overall evaluation of atherogenicity of lipid profile.

PubMed

Kaneva, Anastasiya M; Potolitsyna, Natalya N; Bojko, Evgeny R

2017-02-01

The ratio of low-density lipoprotein cholesterol to apolipoprotein-B (LDL-C/apoB) conventionally represents an alternative index of LDL particle size. This study was undertaken to determine the importance of LDL-C/apoB ratio in the overall evaluation of atherogenicity of lipid profile. The plasma levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (apo) A-I, apoB and apoE were measured in 186 apparently healthy men using enzymatic and immunoturbidimetric methods. The subjects with low values of the LDL-C/apoB ratio, indicating a predominance of small dense LDL (sd-LDL) particles in plasma, were characterized by higher TG levels and lower apoE levels. Low levels of apoE are most likely a cause of reduced clearance of TG-rich lipoproteins, which promotes the formation of sd-LDL. Determination of the LDL-C/apoB ratio can be used for monitoring qualitative changes in lipid profile, in addition to traditional lipid variables indicating quantitative changes.

Sorption of lead onto two gram-negative marine bacteria in seawater

USGS Publications Warehouse

Harvey, Ronald W.; Leckie, James O.

1985-01-01

Laboratory adsorption experiments performed at environmentally significant lead (Pb) and cell concentrations indicate that the marine bacteria examined have significant binding capacities for Pb. However, the behavior governing Pb sorption onto gram-negative bacteria in seawater may be quite complex. The sorption kinetics appear to involve two distinct phases, i.e., a rapid removal of Pb from solution within the first few minutes, followed by a slow but nearly constant removal over many hours. Also, the average binding coefficient, calculated for Pb sorption onto bacteria and a measure of binding intensity, increases with decreasing sorption density (amounts of bacteria-associated Pb per unit bacterial surface) at low cell concentrations (105 cells ml−1), but decreases with decreasing sorption density at higher cell concentrations (107 cells ml−1). The latter effect is apparently due to the production of significant amounts of extra-cellular organics at high cell concentrations that compete directly with bacterial surfaces for available lead. Lead toxicity and active uptake by marine bacteria did not appear significant at the Pb concentrations used.

Equalization of energy density in boiling water reactors (as exemplified by WB-50). Development and testing of WB -50 computational model on the basis of MCU-RR code

NASA Astrophysics Data System (ADS)

Chertkov, Yu B.; Disyuk, V. V.; Pimenov, E. Yu; Aksenova, N. V.

2017-01-01

Within the framework of research in possibility and prospects of power density equalization in boiling water reactors (as exemplified by WB-50) a work was undertaken to improve prior computational model of the WB-50 reactor implemented in MCU-RR software. Analysis of prior works showed that critical state calculations have deviation of calculated reactivity exceeding ±0.3 % (ΔKef/Kef) for minimum concentrations of boric acid in the reactor water and reaching 2 % for maximum concentration values. Axial coefficient of nonuniform burnup distribution reaches high values in the WB-50 reactor. Thus, the computational model needed refinement to take into account burnup inhomogeneity along the fuel assembly height. At this stage, computational results with mean square deviation of less than 0.7 % (ΔKef/Kef) and dispersion of design values of ±1 % (ΔK/K) shall be deemed acceptable. Further lowering of these parameters apparently requires root cause analysis of such large values and paying more attention to experimental measurement techniques.

Investigation of a complete sample of flat spectrum radio sources from the S5 survey

NASA Astrophysics Data System (ADS)

Eckart, A.; Witzel, A.; Biermann, P.; Johnston, K. J.; Simon, R.; Schalinski, C.; Kuhr, H.

1986-11-01

An analysis of 13 extragalactic sources of the S5 survey with flux densities greater than or equal to 1 Jy at 4990 MHz, mapped with milliarcsecond resolution at 1.6 and 5 GHz by means of VLBI, is presented. All sources appear to display multiple components dominated in flux density at 6 cm by a core component which is self-absorbed at 18 cm. Comparison of the measured to predicted X-ray flux density of the core radio components suggests that all sources should display bulk relativistic motion with small angles to the line of sight, and four sources show rapid changes in their radio structures which can be interpreted as apparent superliminal motion.

Physicochemical properties and ion-solvent interactions in aqueous sodium, ammonium, and lead acetate solution

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Mendkudle, M. S.

2014-09-01

Densities (ρ), viscosities (η) and refractive indices ( n D) of aqueous sodium acetate (SA), ammonium acetate (AA), and lead acetate (LA) solutions have been measured for different concentrations of salts at 302.15 K. Apparent molar volumes (φv) for studied solutions were calculated from density data, and fitted to Masson's relation and partial molar volume (φ{v/o}) was determined. Viscosity data were fitted to Jones-Dole equation and viscosity A- and B-coefficients were determined. Refractive index and density data were fitted to Lorentz and Lorenz equation and specific refraction ( R D) were calculated. Behavior of various physicochemical properties indicated presence of strong ion-solvent interactions in present systems and the acetate salts structure maker in water.

Effect of composition on physical properties of food powders

NASA Astrophysics Data System (ADS)

Szulc, Karolina; Lenart, Andrzej

2016-04-01

The paper presents an influence of raw material composition and technological process applied on selected physical properties of food powders. Powdered multi-component nutrients were subjected to the process of mixing, agglomeration, coating, and drying. Wetting liquids ie water and a 15% water lactose solution, were used in agglomeration and coating. The analyzed food powders were characterized by differentiated physical properties, including especially: particle size, bulk density, wettability, and dispersibility. The raw material composition of the studied nutrients exerted a statistically significant influence on their physical properties. Agglomeration as well as coating of food powders caused a significant increase in particle size, decreased bulk density, increased apparent density and porosity, and deterioration in flowability in comparison with non-agglomerated nutrients.

Thermal and active fluctuations of a compressible bilayer vesicle

NASA Astrophysics Data System (ADS)

Sachin Krishnan, T. V.; Yasuda, Kento; Okamoto, Ryuichi; Komura, Shigeyuki

2018-05-01

We discuss thermal and active fluctuations of a compressible bilayer vesicle by using the results of hydrodynamic theory for vesicles. Coupled Langevin equations for the membrane deformation and the density fields are employed to calculate the power spectral density matrix of membrane fluctuations. Thermal contribution is obtained by means of the fluctuation dissipation theorem, whereas active contribution is calculated from exponentially decaying time correlation functions of active random forces. We obtain the total power spectral density as a sum of thermal and active contributions. An apparent response function is further calculated in order to compare with the recent microrheology experiment on red blood cells. An enhanced response is predicted in the low-frequency regime for non-thermal active fluctuations.

Investigation of Techniques for Inventorying Forested Regions. Volume 1: Reflectance Modeling and Empirical Multispectral Analysis of Forest Canopy Components

NASA Technical Reports Server (NTRS)

Nalepka, R. F. (Principal Investigator); Sadowski, F. G.; Malila, W. A.

1977-01-01

The author has identified the following significant results. Effects of vegetation density on overall canopy reflectance differed dramatically, depending on spectral band, base material, and vegetation type. For example, reflectance changes caused by variations in vegetation density were hardly apparant for a simulated burned surface in LANDSAT band 5, while large changes occurred in band 7. When increasing densities of tree overstory were placed over understories, intermediate to dense overstories effectively masked the understories and dominated the spectral signatures. Dramatic changes in reflectance occurred for canopies placed on a number of varying topographic positions. Such changes were seen to result in the spectral overlap of some nonforested with densely forested situations.

A method for mapping apparent stress and energy radiation applied to the 1994 Northridge earthquake fault zone-revisited

USGS Publications Warehouse

McGarr, A.; Fletcher, Joe B.

2001-01-01

McGarr and Fletcher (2000) introduced a technique for estimating apparent stress and seismic energy radiation associated with small patches of a larger fault plane and then applied this method to the slip model of the Northridge earthquake (Wald et al., 1996). These results must be revised because we did not take account of the difference between the seismic energy near the fault and that in the farfield. The fraction f(VR) of the near-field energy that propagates into the far-field is a monotonic function that ranges from 0.11 to 0.40 as rupture velocity VR increases from 0.6?? to 0.95??, where ?? is the shear wave speed. The revised equation for apparent stress for subfault ij is taij = f(VR) ????/ 2 Dij??? D(t)ij2dt, where ?? is density, D(t)ij is the time-dependent slip, and Dij is the final slip. The corresponding seismic energy is Eaij = ADijtaij, where A is the subfault area. Our corrected distributions of apparent stress and radiated energy over the Northridge earthquake fault zone are about 35% of those published before.

Exploring Solute-Solvent Interactions of -Amino Acids in Aqueous [] Arrangements by Volumetric, Viscometric, Refractometric, and Acoustic Approach

NASA Astrophysics Data System (ADS)

Roy, Mahendra Nath; Roy, Milan Chandra; Basak, Saptarshi

2014-05-01

Qualitative and quantitative analysis of molecular interaction prevailing in glycine, l-alanine, l-valine, and aqueous solution of ionic liquid (IL) [1-ethylpyridinium tetrafluoroborate (] have been investigated by thermophysical properties. The apparent molar volume (), viscosity -coefficient, molal refraction (), and adiabatic compressibility ( of glycine, l-alanine, and l-valine have been studied in 0.001 mol , 0.003 mol , and 0.005 mol aqueous 1-ethylpyridinium tetrafluoroborate [] solutions at 298.15 K from the values of densities , viscosities (), refractive index (, and speed of sound , respectively. The extent of interaction, i.e., the solute-solvent interaction is expressed in terms of the limiting apparent molar volume (, viscosity -coefficient, and limiting apparent molar adiabatic compressibility (. The limiting apparent molar volumes (, experimental slopes ( derived from the Masson equation, and viscosity - and -coefficients using the Jones-Dole equation have been interpreted in terms of ion-ion and ion-solvent interactions, respectively. Molal refractions ( have been calculated with the help of the Lorentz-Lorenz equation. The role of the solvent (aqueous IL solution) and the contribution of solute-solute and solute-solvent interactions to the solution complexes have also been analyzed through the derived properties.

Borehole Stability in High-Temperature Formations

NASA Astrophysics Data System (ADS)

Yan, Chuanliang; Deng, Jingen; Yu, Baohua; Li, Wenliang; Chen, Zijian; Hu, Lianbo; Li, Yang

2014-11-01

In oil and gas drilling or geothermal well drilling, the temperature difference between the drilling fluid and formation will lead to an apparent temperature change around the borehole, which will influence the stress state around the borehole and tend to cause borehole instability in high geothermal gradient formations. The thermal effect is usually not considered as a factor in most of the conventional borehole stability models. In this research, in order to solve the borehole instability in high-temperature formations, a calculation model of the temperature field around the borehole during drilling is established. The effects of drilling fluid circulation, drilling fluid density, and mud displacement on the temperature field are analyzed. Besides these effects, the effect of temperature change on the stress around the borehole is analyzed based on thermoelasticity theory. In addition, the relationships between temperature and strength of four types of rocks are respectively established based on experimental results, and thermal expansion coefficients are also tested. On this basis, a borehole stability model is established considering thermal effects and the effect of temperature change on borehole stability is also analyzed. The results show that the fracture pressure and collapse pressure will both increase as the temperature of borehole rises, and vice versa. The fracture pressure is more sensitive to temperature. Temperature has different effects on collapse pressures due to different lithological characters; however, the variation of fracture pressure is unrelated to lithology. The research results can provide a reference for the design of drilling fluid density in high-temperature wells.

Mild Oxidation Promotes and Advanced Oxidation Impairs Remodeling of Human High-Density Lipoprotein in vitro

PubMed Central

Gao, Xuan; Jayaraman, Shobini; Gursky, Olga

2008-01-01

SUMMARY High-density lipoproteins (HDL) prevent atherosclerosis by removing cholesterol from macrophages and by exerting anti-oxidant and anti-inflammatory effects. Oxidation is thought to impair HDL functions, yet certain oxidative modifications may be advantageous; thus, mild oxidation reportedly enhances cell cholesterol uptake by HDL whereas extensive oxidation impairs it. To elucidate the underlying energetic and structural basis, we analyzed the effects of copper and hypochlorite (that preferentially oxidize lipids and proteins, respectively) on thermal stability of plasma spherical HDL. Circular dichroism, light scattering, calorimetry, gel electrophoresis and electron microscopy showed that mild oxidation destabilizes HDL and accelerates protein dissociation and lipoprotein fusion, while extensive oxidation inhibits these reactions; this inhibition correlates with massive protein cross-linking and lipolysis. We propose that mild oxidation lowers kinetic barriers for HDL remodeling due to diminished apolipoprotein affinity for lipids resulting from oxidation of methionine and aromatic residues in apolipoproteins A-I and A-II followed by protein cross-linking into dimers and/or trimers. In contrast, advanced oxidation inhibits protein dissociation and HDL fusion due to lipid re-distribution from core to surface upon lipolysis and to massive protein cross-linking. Our results help reconcile the apparent controversy in the studies of oxidized HDL and suggest that mild oxidation may benefit HDL functions. PMID:18190928

Sequence and transcriptional analysis of the genes responsible for curdlan biosynthesis in Agrobacterium sp. ATCC 31749 under simulated dissolved oxygen gradients conditions.

PubMed

Zhang, Hong-Tao; Zhan, Xiao-Bei; Zheng, Zhi-Yong; Wu, Jian-Rong; Yu, Xiao-Bin; Jiang, Yun; Lin, Chi-Chung

2011-07-01

Expression at the mRNA level of ten selected genes in Agrobacterium sp. ATCC 31749 under various dissolved oxygen (DO) levels during curdlan fermentation related to electron transfer chain (ETC), tricarboxylic acid (TCA) cycle, peptidoglycan/lipopolysaccharide biosynthesis, and uridine diphosphate (UDP)-glucose biosynthesis were determined by qRT-PCR. Experiments were performed at DO levels of 30%, 50%, and 75%, as well as under low-oxygen conditions. The effect of high cell density on transcriptional response of the above genes under low oxygen was also studied. Besides cytochrome d (cyd A), the transcription levels of all the other genes were increased at higher DO and reached maximum at 50% DO. Under 75% DO, the transcriptional levels of all the genes were repressed. In addition, transcription levels of icd, sdh, cyo A, and fix N genes did not exhibit significant fluctuation with high cell density culture under low oxygen. These results suggested a mechanism for DO regulation of curdlan synthesis through regulation of transcriptional levels of ETCs, TCA, and UDP-glucose synthesis genes during curdlan fermentation. To our knowledge, this is the first report that DO concentration apparently regulates curdlan biosynthesis in Agrobacterium sp. ATCC 31749 providing essential lead for the optimization of the fermentation at the industrial scale.

Comminution of solids caused by kinetic energy of high shear strain rate, with implications for impact, shock, and shale fracturing.

PubMed

Bazant, Zdenek P; Caner, Ferhun C

2013-11-26

Although there exists a vast literature on the dynamic comminution or fragmentation of rocks, concrete, metals, and ceramics, none of the known models suffices for macroscopic dynamic finite element analysis. This paper outlines the basic idea of the macroscopic model. Unlike static fracture, in which the driving force is the release of strain energy, here the essential idea is that the driving force of comminution under high-rate compression is the release of the local kinetic energy of shear strain rate. The density of this energy at strain rates >1,000/s is found to exceed the maximum possible strain energy density by orders of magnitude, making the strain energy irrelevant. It is shown that particle size is proportional to the -2/3 power of the shear strain rate and the 2/3 power of the interface fracture energy or interface shear stress, and that the comminution process is macroscopically equivalent to an apparent shear viscosity that is proportional (at constant interface stress) to the -1/3 power of this rate. A dimensionless indicator of the comminution intensity is formulated. The theory was inspired by noting that the local kinetic energy of shear strain rate plays a role analogous to the local kinetic energy of eddies in turbulent flow.

Ti3C2 MXene co-catalyst on metal sulfide photo-absorbers for enhanced visible-light photocatalytic hydrogen production

PubMed Central

Ran, Jingrun; Gao, Guoping; Li, Fa-Tang; Ma, Tian-Yi; Du, Aijun; Qiao, Shi-Zhang

2017-01-01

Scalable and sustainable solar hydrogen production through photocatalytic water splitting requires highly active and stable earth-abundant co-catalysts to replace expensive and rare platinum. Here we employ density functional theory calculations to direct atomic-level exploration, design and fabrication of a MXene material, Ti3C2 nanoparticles, as a highly efficient co-catalyst. Ti3C2 nanoparticles are rationally integrated with cadmium sulfide via a hydrothermal strategy to induce a super high visible-light photocatalytic hydrogen production activity of 14,342 μmol h−1 g−1 and an apparent quantum efficiency of 40.1% at 420 nm. This high performance arises from the favourable Fermi level position, electrical conductivity and hydrogen evolution capacity of Ti3C2 nanoparticles. Furthermore, Ti3C2 nanoparticles also serve as an efficient co-catalyst on ZnS or ZnxCd1−xS. This work demonstrates the potential of earth-abundant MXene family materials to construct numerous high performance and low-cost photocatalysts/photoelectrodes. PMID:28045015

Bearing fatigue investigation 3

NASA Technical Reports Server (NTRS)

Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

1982-01-01

The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

Ti3C2 MXene co-catalyst on metal sulfide photo-absorbers for enhanced visible-light photocatalytic hydrogen production

NASA Astrophysics Data System (ADS)

Ran, Jingrun; Gao, Guoping; Li, Fa-Tang; Ma, Tian-Yi; Du, Aijun; Qiao, Shi-Zhang

2017-01-01

Scalable and sustainable solar hydrogen production through photocatalytic water splitting requires highly active and stable earth-abundant co-catalysts to replace expensive and rare platinum. Here we employ density functional theory calculations to direct atomic-level exploration, design and fabrication of a MXene material, Ti3C2 nanoparticles, as a highly efficient co-catalyst. Ti3C2 nanoparticles are rationally integrated with cadmium sulfide via a hydrothermal strategy to induce a super high visible-light photocatalytic hydrogen production activity of 14,342 μmol h-1 g-1 and an apparent quantum efficiency of 40.1% at 420 nm. This high performance arises from the favourable Fermi level position, electrical conductivity and hydrogen evolution capacity of Ti3C2 nanoparticles. Furthermore, Ti3C2 nanoparticles also serve as an efficient co-catalyst on ZnS or ZnxCd1-xS. This work demonstrates the potential of earth-abundant MXene family materials to construct numerous high performance and low-cost photocatalysts/photoelectrodes.

High-resolution mapping of motor vehicle carbon dioxide emissions

NASA Astrophysics Data System (ADS)

McDonald, Brian C.; McBride, Zoe C.; Martin, Elliot W.; Harley, Robert A.

2014-05-01

A fuel-based inventory for vehicle emissions is presented for carbon dioxide (CO2) and mapped at various spatial resolutions (10 km, 4 km, 1 km, and 500 m) using fuel sales and traffic count data. The mapping is done separately for gasoline-powered vehicles and heavy-duty diesel trucks. Emission estimates from this study are compared with the Emissions Database for Global Atmospheric Research (EDGAR) and VULCAN. All three inventories agree at the national level within 5%. EDGAR uses road density as a surrogate to apportion vehicle emissions, which leads to 20-80% overestimates of on-road CO2 emissions in the largest U.S. cities. High-resolution emission maps are presented for Los Angeles, New York City, San Francisco-San Jose, Houston, and Dallas-Fort Worth. Sharp emission gradients that exist near major highways are not apparent when emissions are mapped at 10 km resolution. High CO2 emission fluxes over highways become apparent at grid resolutions of 1 km and finer. Temporal variations in vehicle emissions are characterized using extensive day- and time-specific traffic count data and are described over diurnal, day of week, and seasonal time scales. Clear differences are observed when comparing light- and heavy-duty vehicle traffic patterns and comparing urban and rural areas. Decadal emission trends were analyzed from 2000 to 2007 when traffic volumes were increasing and a more recent period (2007-2010) when traffic volumes declined due to recession. We found large nonuniform changes in on-road CO2 emissions over a period of 5 years, highlighting the importance of timely updates to motor vehicle emission inventories.

Influence of stress, temperature, and strain on calcite twins constrained by deformation experiments

NASA Astrophysics Data System (ADS)

Rybacki, E.; Evans, B.; Janssen, C.; Wirth, R.; Dresen, G.

2013-08-01

A series of low-strain triaxial compression and high-strain torsion experiments were performed on marble and limestone samples to examine the influence of stress, temperature, and strain on the evolution of twin density, the percentage of grains with 1, 2, or 3 twin sets, and the twin width—all parameters that have been suggested as either paleopiezometers or paleothermometers. Cylindrical and dog-bone-shaped samples were deformed in the semibrittle regime between 20 °C and 350 °C, under confining pressures of 50-400 MPa, and at strain rates of 10- 4-10- 6 s- 1. The samples sustained shear stresses, τ, up to 280 MPa, failing when deformed to shear strains γ > 1. The mean width of calcite twins increased with both temperature and strain, and thus, measurement of twin width provides only a rough estimation of peak temperature, unless additional constraints on deformation are known. In Carrara marble, the twin density, NL (no of twins/mm), increased as the rock hardened with strain and was approximately related to the peak differential stress, σ (MPa), by the relation σ=19.5±9.8√{N}. Dislocation tangles occurred along twin boundaries, resulting in a complicated cell structure, which also evolved with stress. As previously established, the square root of dislocation density, observed after quench, also correlated with peak stress. Apparently, both twin density and dislocation cell structure are important state variables for describing the strength of these rocks.

What lies beneath: geophysical mapping of a concealed Precambrian intrusive complex along the Iowa–Minnesota border

USGS Publications Warehouse

Drenth, Benjamin J.; Anderson, Raymond R.; Schulz, Klaus J.; Feinberg, Joshua M.; Chandler, Val W.; Cannon, William F.

2015-01-01

Large-amplitude gravity and magnetic highs over northeast Iowa are interpreted to reflect a buried intrusive complex composed of mafic–ultramafic rocks, the northeast Iowa intrusive complex (NEIIC), intruding Yavapai province (1.8–1.72 Ga) rocks. The age of the complex is unproven, although it has been considered to be Keweenawan (∼1.1 Ga). Because only four boreholes reach the complex, which is covered by 200–700 m of Paleozoic sedimentary rocks, geophysical methods are critical to developing a better understanding of the nature and mineral resource potential of the NEIIC. Lithologic and cross-cutting relations interpreted from high-resolution aeromagnetic and airborne gravity gradient data are presented in the form of a preliminary geologic map of the basement Precambrian rocks. Numerous magnetic anomalies are coincident with airborne gravity gradient (AGG) highs, indicating widespread strongly magnetized and dense rocks of likely mafic–ultramafic composition. A Yavapai-age metagabbro unit is interpreted to be part of a layered intrusion with subvertical dip. Another presumed Yavapai unit has low density and weak magnetization, observations consistent with felsic plutons. Northeast-trending, linear magnetic lows are interpreted to reflect reversely magnetized diabase dikes and have properties consistent with Keweenawan rocks. The interpreted dikes are cut in places by normally magnetized mafic–ultramafic rocks, suggesting that the latter represent younger Keweenawan rocks. Distinctive horseshoe-shaped magnetic and AGG highs correspond with a known gabbro, and surround rocks with weaker magnetization and lower density. Here, informally called the Decorah complex, the source body has notable geophysical similarities to Keweenawan alkaline ring complexes, such as the Coldwell and Killala Lake complexes, and Mesoproterozoic anorogenic complexes, such as the Kiglapait, Hettasch, and Voisey’s Bay intrusions in Labrador. Results presented here suggest that much of the NEIIC is composed of such complexes, and broadly speaking, may be a discontinuous group of several intrusive bodies. Most units are cut by suspected northwest-trending faults imaged as magnetic lineaments, and one produces apparent sinistral fault separation of a dike in the eastern part of the survey area. The location, trend, and apparent sinistral sense of motion are consistent with the suspected faults being part of the Belle Plaine fault zone, a complex transform fault zone within the Midcontinent rift system that is here proposed to correspond with a major structural discontinuity.

Investigation of aquaporins and apparent diffusion coefficient from ultra-high b-values in a rat model of diabetic nephropathy.

PubMed

Wang, Yu; Zhang, Heng; Zhang, Ruzhi; Zhao, Zhoushe; Xu, Ziqian; Wang, Lei; Liu, Rongbo; Gao, Fabao

2017-01-01

To assess kidney damage in a rat model of type-2 diabetic nephropathy based on apparent diffusion coefficient (ADC) data obtained from ultra-high b-values and discuss its relationship to the expression of aquaporins (AQPs). This study was approved by the institutional Animal Care and Use Committee. Thirty male Sprague-Dawley rats were randomised into two groups: (1) untreated controls and (2) diabetes mellitus (DM). All rats underwent diffusion-weighted imaging (DWI) with 18 b-values (0-4500 s/mm 2 ). Maps of low ADC (ADC low ), standard ADC (ADC st ) and ultra-high ADC (ADC uh ) were calculated from low b-values (0-200 s/mm 2 ), standard b-values (300-1500 s/mm 2 ) and ultra-high b-values (1700-4500 s/mm 2 ), respectively. The expression of AQPs in the kidneys was studied using immunohistochemistry. Laboratory parameters of diabetic and kidney functions, ADC low , ADC st , ADC uh , and the optical density (OD) of AQP expression in the two groups were compared using an independent t test. Correlations between ADCs and the OD of AQP expression were evaluated by Pearson's correlation analysis. ADC uh were significantly higher in the cortex (CO), outer stripe of the outer medulla (OS) and inner stripe of the outer medulla (IS), and the OD values of AQ-2 were significantly higher in the OS, IS and inner medulla (IM) in DM animals compared with control animals. ADC uh and OD values of AQP-2 expression were positively correlated in the OS, IS and IM of the kidney. ADC uh may work as useful metrics for early detection of kidney damage in diabetic nephropathy and may be associated with AQP-2 expression.

Growth Performance, Mineral Digestibility, and Blood Characteristics of Ostriches Receiving Drinking Water Supplemented with Varying Levels of Chelated Trace Mineral Complex.

PubMed

Seyfori, Hossein; Ghasemi, Hossein Ali; Hajkhodadadi, Iman; Nazaran, Mohammad Hassan; Hafizi, Maryam

2018-05-01

The effects of water supplementation of chelated trace minerals (CTM, which is named Bonzaplex designed with chelate compounds technology) on growth performance, apparent total tract digestibility (ATTD) of minerals, and some blood metabolites, TM, and antioxidant enzyme values in African ostriches were investigated from 8 to 12 months of age. A total of 20 8-month-old ostriches (five birds in five replicate pens) was randomly allocated into one of the following four treatments: (1) control (basal diet + tap water), (2) low CTM (basal diet +100 mg/bird/day CTM powder in tap water), (3) medium CTM (basal diet +1 g/bird/day CTM powder in tap water), and (4) high CTM (basal diet +2 g/bird/day CTM powder in tap water). Compared with control, medium CTM improved (P < 0.05) daily weight gain and ATTD of phosphorous, zinc, and copper in 12-month-old ostriches. Furthermore, the feed conversion ratio was lower, and ATTD of magnesium was higher in the medium- and high-CTM groups than that in the control group (P < 0.05). At the end of the trial, ostriches receiving high-CTM treatment exhibited the lower (P < 0.05) serum triglyceride and very low-density lipoprotein cholesterol concentrations and higher copper levels compared to those of the control treatment. Supplementation of higher amounts of CTM (medium and high CTM) also increased the activity of serum superoxide dismutase (P < 0.05). No differences were detected for other blood parameters including glucose, total protein, albumin, cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, iron, magnesium, and glutathione peroxidase values. In conclusion, supplementation of CTM at the level of 1 g/bird/day to the drinking water can be recommended for improving growth performance, mineral absorption, and antioxidant status of ostriches fed diets containing the recommended levels of inorganic TM.

Apparent dietary intake in remote aboriginal communities.

PubMed

Lee, A J; O'Dea, K; Mathews, J D

1994-06-01

Apparent per capita food and nutrient intake in six remote Australian Aboriginal communities using the 'store-turnover' method is described. The method is based on the analysis of community-store food invoices. The face validity of the method supports the notion that, under the unique circumstances of remote Aboriginal communities, the turnover of foodstuffs from the community store is a useful measure of apparent dietary intake for the community as a whole. In all Aboriginal communities studied, the apparent intake of energy, sugars and fat was excessive, while the apparent intake of dietary fibre and several nutrients, including folic acid, was low. White sugar, flour, bread and meat provided in excess of 50 per cent of the apparent total energy intake. Of the apparent high fat intake, fatty meats contributed nearly 40 per cent in northern coastal communities and over 60 per cent in central desert communities. Sixty per cent of the apparent high intake of sugars was derived from sugar per se in both regions. Compared with national Australian apparent consumption data, intakes of sugar, white flour and sweetened carbonated beverages were much higher in Aboriginal communities, and intakes of wholemeal bread, fruit and vegetables were much lower. Results of the store-turnover method have important implications for community-based nutrition intervention programs.

New Views on Dark Matter from Emergent Gravity

NASA Astrophysics Data System (ADS)

Sun, Sichun; Zhang, Yun-Long

2018-01-01

We discuss a scenario that apparent dark matter comes from the induced gravity in the (3+1)- dimensional spacetime, which can be embedded into one higher dimensional flat spacetime. The stress tensor of dark energy and dark matter is identified with the Brown-York stress tensor on the hypersurface, and we find an interesting constraint relation between the dark matter and dark energy density parameter and baryonic density parameter. Our approach may show a new understanding for Verlinde's emergent gravity from higher dimensions. We also comment on some phenomenological implications, including gravitational wave solutions and MOND limit.

Solution behavior of metoclopramide in aqueous-alcoholic solutions at 30°C

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Sawale, R. T.; Tawde, P. D.; Kalyankar, T. M.

2016-07-01

Densities (ρ) and refractive indices ( n D) of solutions of antiemetic drug metoclopramide (4-amino-5-chloro- N-(2-(diethylamino)ethyl)-2-methoxybenzamide hydrochloride hydrate) in methanolwater and ethanol-water mixtures of different compositions were measured at 30°C. Apparent molar volume (φv) of the drug was calculated from density data and partial molar volumes (φ v 0 ) were determined from Massons relation. Concentration dependence of nD has been studied to determine refractive indices of solution at infinite dilution ( n D 0 ). Results have been interpreted in terms of solute-solvent interactions.

The Importance of Optical Pathlength Control for Plasma Absorption Measurements

NASA Technical Reports Server (NTRS)

Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, M.; Partridge, Harry (Technical Monitor)

2001-01-01

An inductively coupled GEC Cell with modified viewing ports has been used to measure in-situ absorption in CF4 plasmas via Fourier Transform Infrared Spectroscopy, and the results compared to those obtained in a standard viewport configuration. The viewing ports were modified so that the window boundary is inside, rather than outside, of the GEC cell. Because the absorption obtained is a spatially integrated absorption, measurements made represent an averaging of absorbing species inside and outside of the plasma. This modification is made to reduce this spatial averaging and thus allow a more accurate estimation of neutral species concentrations and temperatures within the plasmas. By reducing this pathlength, we find that the apparent CF4 consumption increases from 65% to 95% and the apparent vibrational temperature of CF4 rises by 50-75 K. The apparent fraction of etch product SiF4 decreases from 4% to 2%. The data suggests that these density changes may be due to significant temperature gradients between the plasma and chamber viewports.

Apparent competition drives community-wide parasitism rates and changes in host abundance across ecosystem boundaries

PubMed Central

Frost, Carol M.; Peralta, Guadalupe; Rand, Tatyana A.; Didham, Raphael K.; Varsani, Arvind; Tylianakis, Jason M.

2016-01-01

Species have strong indirect effects on others, and predicting these effects is a central challenge in ecology. Prey species sharing an enemy (predator or parasitoid) can be linked by apparent competition, but it is unknown whether this process is strong enough to be a community-wide structuring mechanism that could be used to predict future states of diverse food webs. Whether species abundances are spatially coupled by enemy movement across different habitats is also untested. Here, using a field experiment, we show that predicted apparent competitive effects between species, mediated via shared parasitoids, can significantly explain future parasitism rates and herbivore abundances. These predictions are successful even across edges between natural and managed forests, following experimental reduction of herbivore densities by aerial spraying of insecticide over 20 hectares. This result shows that trophic indirect effects propagate across networks and habitats in important, predictable ways, with implications for landscape planning, invasion biology and biological control. PMID:27577948

An Iterative Method for Problems with Multiscale Conductivity

PubMed Central

Kim, Hyea Hyun; Minhas, Atul S.; Woo, Eung Je

2012-01-01

A model with its conductivity varying highly across a very thin layer will be considered. It is related to a stable phantom model, which is invented to generate a certain apparent conductivity inside a region surrounded by a thin cylinder with holes. The thin cylinder is an insulator and both inside and outside the thin cylinderare filled with the same saline. The injected current can enter only through the holes adopted to the thin cylinder. The model has a high contrast of conductivity discontinuity across the thin cylinder and the thickness of the layer and the size of holes are very small compared to the domain of the model problem. Numerical methods for such a model require a very fine mesh near the thin layer to resolve the conductivity discontinuity. In this work, an efficient numerical method for such a model problem is proposed by employing a uniform mesh, which need not resolve the conductivity discontinuity. The discrete problem is then solved by an iterative method, where the solution is improved by solving a simple discrete problem with a uniform conductivity. At each iteration, the right-hand side is updated by integrating the previous iterate over the thin cylinder. This process results in a certain smoothing effect on microscopic structures and our discrete model can provide a more practical tool for simulating the apparent conductivity. The convergence of the iterative method is analyzed regarding the contrast in the conductivity and the relative thickness of the layer. In numerical experiments, solutions of our method are compared to reference solutions obtained from COMSOL, where very fine meshes are used to resolve the conductivity discontinuity in the model. Errors of the voltage in L2 norm follow O(h) asymptotically and the current density matches quitewell those from the reference solution for a sufficiently small mesh size h. The experimental results present a promising feature of our approach for simulating the apparent conductivity related to changes in microscopic cellular structures. PMID:23304238

Long-term study of longitudinal dependence in primary particle precipitation in the north Jovian aurora

NASA Technical Reports Server (NTRS)

Livengood, T. A.; Strobel, D. F.; Moos, H. W.

1990-01-01

The wavelength-dependent absorption apparent in IUE spectra of the north Jovian aurora is analyzed to determine the column density of hydrocarbons above the altitude of the FUV auroral emission. Both the magnetotail and torus auroral zone models are considered in estimating zenith angles, with very similar results obtained for both models. It is found that the hydrocarbon column density above the FUV emission displays a consistent dependence on magnetic longitude, with the peak density occurring approximately coincident with the peak in the observed auroral intensity. Two distinct scenarios for the longitude dependence of the column density are discussed. In one, the Jovian upper atmosphere is longitudinally homogeneous, and the variation in optical depth is due to a variation in penetration, and thus energy, of the primary particles. In the other, the energy of the primaries is longitudinally homogeneous, and it is aeronomic properties which change, probably due to auroral heating.

Uranium hydrogeochemical and stream sediment reconnaissance data from the area of the Shishmaref, Kotzebue, Selawik and Shungnak Quadrangles, northern Seward Peninsula and vicinity, Alaska

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

Warren, R.G.; Hill, D.E.; Sharp, R.R. Jr.

1978-05-01

During the summer of 1976, 1336 water and 1251 sediment samples were collected for Los Alamos Scientific Laboratory (LASL) from 1356 streams and small lakes or ponds within Shishmaref, Kotzebue, Selawik, and western portion of Shungnak NTMS quadrangles in western Alaska. Both a water and sediment sample were generally obtained from each location at a nominal location density of 1/23 km/sup 2/. Total uranium was measured in waters by fluorometry and in sediments and a few waters by delayed neutron counting at LASL. Uranium concentrations in waters have a mean of 0.31 ppB and a maximum of 9.23 ppB, andmore » sediments exhibit a mean of 3.44 ppM and a maximum of 37.7 ppM. A large number of high-uranium concentrations occur in both water and sediment samples collected in the Selawik Hills. At least two locations within the Selawik Hills appear favorable for further investigation of possible uranium mineralization. A cluster of high-uranium sediments, seen in the Waring Mountains, are probably derived from a lower Cretaceous conglomerate unit which is assocated with known airborne radiometric anomalies. Apparently less favorable areas for further investigation of possible uranium mineralization are also located in the Waring Mountains and Kiana Hills. Additional samples were collected within the Shungnak quadrange to increase the sampling density used elsewhere in the area to about one location per 11 km/sup 2/ (double-density). Contoured plots of uranium concentrations for both waters and sediments were prepared for all double-density sample locations, and then for the even-numbered and odd-numbered locations separately. These plots indicate that the HSSR sampling density of 1/23 km/sup 2/ used in lowland areas of Alaska provide essentially the same definition of relative areal uranium distributions in waters and sediments as seen when the density is doubled. These plots indicate that regional distribution patterns for uranium are well defined without selective sampling of geologic units.« less

Intraspecific density dependence and a guild of consumers coexisting on one resource.

PubMed

McPeek, Mark A

2012-12-01

The importance of negative intraspecific density dependence to promoting species coexistence in a community is well accepted. However, such mechanisms are typically omitted from more explicit models of community dynamics. Here I analyze a variation of the Rosenzweig-MacArthur consumer-resource model that includes negative intraspecific density dependence for consumers to explore its effect on the coexistence of multiple consumers feeding on a single resource. This analysis demonstrates that a guild of multiple consumers can easily coexist on a single resource if each limits its own abundance to some degree, and stronger intraspecific density dependence permits a wider variety of consumers to coexist. The mechanism permitting multiple consumers to coexist works in a fashion similar to apparent competition or to each consumer having its own specialized predator. These results argue for a more explicit emphasis on how negative intraspecific density dependence is generated and how these mechanisms combine with species interactions to shape overall community structure.

Vibroacoustics of the piano soundboard: Reduced models, mobility synthesis, and acoustical radiation regime

NASA Astrophysics Data System (ADS)

Boutillon, Xavier; Ege, Kerem

2013-09-01

In string musical instruments, the sound is radiated by the soundboard, subject to the strings excitation. This vibration of this rather complex structure is described here with models which need only a small number of parameters. Predictions of the models are compared with the results of experiments that have been presented in Ege et al. [Vibroacoustics of the piano soundboard: (non)linearity and modal properties in the low- and mid-frequency ranges, Journal of Sound and Vibration 332 (5) (2013) 1288-1305]. The apparent modal density of the soundboard of an upright piano in playing condition, as seen from various points of the structure, exhibits two well-separated regimes, below and above a frequency flim that is determined by the wood characteristics and by the distance between ribs. Above flim, most modes appear to be localised, presumably due to the irregularity of the spacing and height of the ribs. The low-frequency regime is predicted by a model which consists of coupled sub-structures: the two ribbed areas split by the main bridge and, in most cases, one or two so-called cut-off corners. In order to assess the dynamical properties of each of the subplates (considered here as homogeneous plates), we propose a derivation of the (low-frequency) modal density of an orthotropic homogeneous plate which accounts for the boundary conditions on an arbitrary geometry. Above flim, the soundboard, as seen from a given excitation point, is modelled as a set of three structural wave-guides, namely the three inter-rib spacings surrounding the excitation point. Based on these low- and high-frequency models, computations of the point-mobility and of the apparent modal densities seen at several excitation points match published measurements. The dispersion curve of the wave-guide model displays an acoustical radiation scheme which differs significantly from that of a thin homogeneous plate. It appears that piano dimensioning is such that the subsonic regime of acoustical radiation extends over a much wider frequency range than it would be for a homogeneous plate with the same low-frequency vibration. One problem in piano manufacturing is examined in relationship with the possible radiation schemes induced by the models.

Geophysical evidence for melt in the deep lunar interior and implications for lunar evolution (Invited)

NASA Astrophysics Data System (ADS)

Khan, A.; Connolly, J. A.; Pommier, A.

2013-12-01

Analysis of lunar seismic and lunar laser ranging data has yielded evidence that has been interpreted to indicate a molten zone in the lower-most mantle and/or the outer core of the Moon. Such a zone would provide strong constraints on models of the thermal evolution of the Moon. Here we invert lunar geophysical data in combination with phase-equilibrium modeling to derive information about the thermo-chemical and physical structure of the deep lunar interior. Specifically, we assess whether a molten layer is required by the geophysical data and, if so, its likely composition and physical properties (e.g., density and seismic wave speeds). The data considered are mean mass and moment of inertia, second-degree tidal Love number, and frequency-dependent electromagnetic sounding data. The main conclusion drawn from this study is that a region with high dissipation located deep within the Moon is indeed required to explain the geophysical data. If this dissipative region is located within the mantle, then the solidus is crossed at a depth of ~1200 km (>1600 deg C). The apparent absence of far-side deep moonquakes (DMQs) is supporting evidence for a highly dissipative layer. Inverted compositions for the partially molten layer (typically 100--200 km thick) are enriched in FeO and TiO2 relative to the surrounding mantle. While the melt phase in >95 % of inverted models is neutrally buoyant at pressures of ~4.5--4.6 GPa, the melt contains less TiO2 (>~4 wt %) than the Ti-rich (~16 wt % TiO2) melts that produced a set of high-density primitive lunar magmas (~3.4 g/ccm). Melt densities computed here range from 3.3 to 3.4 g/ccm bracketing the density of lunar magmas with moderate-to-high TiO2 contents. Our results are consistent with a model of lunar evolution in which the cumulate pile formed from crystallization of the magma ocean as it overturned, trapping heat-producing elements in the lower mantle.

Nonlinear MHD Waves in a Prominence Foot

NASA Astrophysics Data System (ADS)

Ofman, L.; Knizhnik, K.; Kucera, T.; Schmieder, B.

2015-11-01

We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propagating fluctuations. However, the optically thick nature of the emission lines inhibits a unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity (δI/I ˜ δn/n). The waves are evident as significant density fluctuations that vary with height and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with a typical period in the range of 5-11 minutes and wavelengths <2000 km. Recent Doppler shift observations show the transverse displacement of the propagating waves. The magnetic field was measured with the THEMIS instrument and was found to be 5-14 G. For the typical prominence density the corresponding fast magnetosonic speed is ˜20 km s-1, in qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.

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

Ofman, L.; Knizhnik, K.; Kucera, T.

We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propagating fluctuations. However, the optically thick nature of the emission lines inhibits a unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity (δI/I ∼ δn/n). The waves are evidentmore » as significant density fluctuations that vary with height and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with a typical period in the range of 5–11 minutes and wavelengths <2000 km. Recent Doppler shift observations show the transverse displacement of the propagating waves. The magnetic field was measured with the THEMIS instrument and was found to be 5–14 G. For the typical prominence density the corresponding fast magnetosonic speed is ∼20 km s{sup −1}, in qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.« less

High Energy Particle Acceleration and Turbulent Magnetic Field Amplification in Shell Type Supernova Remnants. Degree awarded by Minnesota Univ.

NASA Technical Reports Server (NTRS)

Keohane, Jonathan Wilmore

1998-01-01

Thesis submitted to the faculty of the Graduate School of the University of Minnesota in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Part I discusses the spatial correlation between the x-ray and radio morphologies of Cas A, and in the process address: the effect of inhomogeneous absorption on the apparent x-ray morphology, the interaction between the SNR and a molecular cloud, and the rapid move toward equipartition between the magnetic and gas energy densities. Discussions of the x-ray./radio correlation continues in Chapter 5, where we present a new, deep, ROSAT HRI image of Cas A. Chapter 7 presents ASCA spectra, with non-thermal spectral fits for 13 of the youngest SNRs in the Galaxy.

The anomalous 3.43 and 3.53 micron emission features toward HD 97048 and Elias 1 - C-C vibrational modes of polycyclic aromatic hydrocarbons?

NASA Technical Reports Server (NTRS)

Schutte, W. A.; Tielens, A. G. G. M.; Allamandola, L. J.; Wooden, D. H.; Cohen, M.

1990-01-01

The 5-8 micron spectra obtained toward the two protostellar sources, HD 97048 and Elias 1 exhibit strong anomalous emission features at 3.43 and 3.53 microns. Combining these results with earlier data established that the emission in the general IR features is extended on at least a 20-arcsec scale. In view of the high energy density in the emission zone, as well as the apparent correspondence of the anomalous 3.43 and 3.53 micron features with weak emission shoulders associated with the general family of IR emission bands, an explanation for these observations in terms of C-C overtones and combination tones of large or dehydrogenated polycyclic aromatic hydrocarbons is judged to be provisionally suitable.

Crypto-periodicity in Mansonella ozzardi.

PubMed

Pichon, G

1983-01-01

Studying nycthemeral microfilarial density in eight carriers of Mansonella ozzardi, Nathan et al. concluded that there is an absence of periodicity in M. ozzardi in Trinidad. Re-examination of the results obtained shows evidence of crypto-periodicity. Two of the eight patients showed highly significant periodicity but the biorhythms appear to be almost out of phase, the respective peaks being at 18.00 hours and 02.00 hours. The six other patients showed no obvious periodicity; the calculated acrophases (peak hours), instead of being randomly spaced, regrouped with the preceding ones: late afternoon in two subjects and in the second half of the night for the other four. It is concluded that the apparent non-periodicity is due to the co-existence of two periodic forms, but these are markedly out of phase.

High Energy Particle Acceleration and Turbulent Magnetic Field Amplification in Shell Type Supernova Remnants

NASA Astrophysics Data System (ADS)

Keohane, Jonathan Wilmore

1998-07-01

Thesis submitted to the faculty of the Graduate School of the University of Minnesota in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Part I discusses the spatial correlation between the x-ray and radio morphologies of Cas A, and in the process address: the effect of inhomogeneous absorption on the apparent x-ray morphology, the interaction between the SNR and a molecular cloud, and the rapid move toward equipartition between the magnetic and gas energy densities. Discussions of the x-ray./radio correlation continues in Chapter 5, where we present a new, deep, ROSAT HRI image of Cas A. Chapter 7 presents ASCA spectra, with non-thermal spectral fits for 13 of the youngest SNRs in the Galaxy.

Solar Mesosphere Explorer satellite measurements of el Chichon stratospheric aerosols. 1: Cloud morphology

NASA Technical Reports Server (NTRS)

Rusch, D. W.; Clancy, R. T.; Eparvier, F. G.; Thomas, G. E.; Thomas, R. J.

1994-01-01

Data from the Solar Mesosphere Explorer (SME) is used to track the time, latitude, and altitude (above 18 km) development of the aerosol cloud injected into the stratosphere by the eruption of el Chichon. This unique data set, using scattering data from the near-infrared (1.27 and 1.87 microns) and visible (440 nm) spectrometers on SME, covers the period from the initial injection in April 1982 through the end of 1986. Although the bulk of the mass is contained in the latitude band from 10 deg S to 30 deg N for the entire duration of the measurements, transport of material to high latitudes is apparent in the data in the post eruption period. The times aerosol density maxima vary greatly as a function of altitude and latitude.

The importance of risk-aversion as a measurable psychological parameter governing risk-taking behaviour

NASA Astrophysics Data System (ADS)

Thomas, P. J.

2013-09-01

A utility function with risk-aversion as its sole parameter is developed and used to examine the well-known psychological phenomenon, whereby risk averse people adopt behavioural strategies that are extreme and apparently highly risky. The pioneering work of the psychologist, John W. Atkinson, is revisited, and utility theory is used to extend his mathematical model. His explanation of the psychology involved is improved by regarding risk-aversion not as a discrete variable with three possible states: risk averse, risk neutral and risk confident, but as continuous and covering a large range. A probability distribution is derived, the "motivational density", to describe the process of selecting tasks of different degrees of difficulty. An assessment is then made of practicable methods for measuring risk-aversion.

Thermal Decomposition Synthesis of Graphene Nanosheets Anchored on Mn3O4 Nanoparticles as Anodes in Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Tang, Xihao; Ma, Xiao; Qiu, Danfeng; Bu, Gang; Xia, Yongjun; Zhao, Bin; Lin, Zixia; Shi, Yi

2018-01-01

Graphene nanosheets (GNS) anchored on Mn3O4 nanoparticles have been successfully synthesized through in situ thermal decomposition of Mn (NO3)2 without the use of any templates or surfactants. Mn3O4 particles were coordinately distributed on the GNS surface. This was achieved by forming 3D nanostructures to avoid detrimental graphene layer stacking, and was characterized using a scanning electron microscope. The Mn3O4/GNS nanocomposite delivers an initial capacity of 1450 mAh g-1 at a current density of 100 mA g-1. It also maintains a high reversible capacity of 930 mAh g-1 even after 60 charge-discharge cycles without showing any apparent decay.

Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes.

PubMed

Bennell, K L; Brukner, P D; Malcolm, S A

1996-09-01

It is apparent that bone density in male athletes can be reduced without a concomitant decrease in testosterone, suggesting that bone density and testosterone concentrations in the normal range are not closely related in male athletes. Further research is necessary to monitor concurrent changes in bone density and testosterone over a period of time in exercising males. In any case, the effect of exercise on the male reproductive system does not appear as extreme as that which can occur in female athletes, and any impact on bone density is not nearly as evident. These results imply that factors apart from testosterone concentrations must be responsible for the observed osteopenia in some male athletes. Many factors have the potential to adversely affect bone density, independently of alterations in reproductive function. These include low calcium intake, energy deficit, weight loss, psychological stress, and low body fat, all of which may be associated with intense endurance training. Future research investigating skeletal health in male athletes should include a thorough assessment of reproductive function in addition to these other factors.

Kinetic and stoichiometric constraints determine the pathway of H2O2 consumption by red blood cells.

PubMed

Orrico, Florencia; Möller, Matías N; Cassina, Adriana; Denicola, Ana; Thomson, Leonor

2018-05-09

Red blood cells (RBC) are considered as a circulating sink of H 2 O 2 , but a significant debate remains over the role of the different intraerythocyte peroxidases. Herein we examined the kinetic of decomposition of exogenous H 2 O 2 by human RBC at different cell densities, using fluorescent and oxymetric methods, contrasting the results against a mathematical model. Fluorescent measurements as well as oxygen production experiments showed that catalase was responsible for most of the decomposition of H 2 O 2 at cell densities suitable for both experimental settings (0.1-10 × 10 10 cell L -1 ), since sodium azide but not N-ethylmaleimide (NEM) inhibited H 2 O 2 consumption. Oxygen production decreased at high cell densities until none was detected above 1.1 × 10 12 cell L- 1 , being recovered after inhibition of the thiol dependent systems by NEM. This result underlined that the consumption of H 2 O 2 by catalase prevail at RBC densities regularly used for research, while the thiol dependent systems predominate when the cell density increases, approaching the normal number in blood (5 × 10 12 cell L- 1 ). The mathematical model successfully reproduced experimental results and at low cell number it showed a time sequence involving Prx as the first line of defense, followed by catalase, with a minor role by Gpx. The turning points were given by the total consumption of reduced Prx in first place and reduced GSH after that. However, Prx alone was able to account for the added H 2 O 2 (50µM) at physiological RBC density, calling attention to the importance of cell density in defining the pathway of H 2 O 2 consumption and offering an explanation to current apparently conflicting results in the literature. Copyright © 2018. Published by Elsevier Inc.

ACCOUNTING FOR COSMIC VARIANCE IN STUDIES OF GRAVITATIONALLY LENSED HIGH-REDSHIFT GALAXIES IN THE HUBBLE FRONTIER FIELD CLUSTERS

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

Robertson, Brant E.; Stark, Dan P.; Ellis, Richard S.

Strong gravitational lensing provides a powerful means for studying faint galaxies in the distant universe. By magnifying the apparent brightness of background sources, massive clusters enable the detection of galaxies fainter than the usual sensitivity limit for blank fields. However, this gain in effective sensitivity comes at the cost of a reduced survey volume and, in this Letter, we demonstrate that there is an associated increase in the cosmic variance uncertainty. As an example, we show that the cosmic variance uncertainty of the high-redshift population viewed through the Hubble Space Telescope Frontier Field cluster Abell 2744 increases from ∼35% atmore » redshift z ∼ 7 to ≳ 65% at z ∼ 10. Previous studies of high-redshift galaxies identified in the Frontier Fields have underestimated the cosmic variance uncertainty that will affect the ultimate constraints on both the faint-end slope of the high-redshift luminosity function and the cosmic star formation rate density, key goals of the Frontier Field program.« less

Calculation of amorphous silica solubilities at 25° to 300°C and apparent cation hydration numbers in aqueous salt solutions using the concept of effective density of water

USGS Publications Warehouse

Fournier, Robert O.; Williams, Marshall L.

1983-01-01

The solubility of amorphous silica in aqueous salt solutions at 25° to 300°C can be calculated using information on its solubility in pure water and a model in which the activity of water in the salt solution is defined to equal the effective density. pe, of “free” water in that solution. At temperatures of 100°C and above, pe closely equals the product of the density of the solution times the weight fraction of water in the solution. At 25°C, a correction parameter must be applied to pe that incorporates a term called the apparent cation hydration number, h. Because of the many assumptions and other uncertainties involved in determining values of h, by the model used here, the reported numbers are not necessarily real hydration numbers even though they do agree with some published values determined by activity and diffusion methods. Whether or not h is a real hydration number, it would appear to be useful in its inclusion within a more extensive activity coefficient term that describes the departure of silica solubilities in concentrated salt solutions from expected behavior according to the model presented here. Values of h can be calculated from measured amorphous silica solubilities in salt solutions at 25°C provided there is no complexing of dissolved silica with the dissolved salt, or if the degree of complexing is known. The previously postulated aqueous silica-sulfate complexing in aqueous Na2SO4 solutions is supported by results of the present effective density of water model

The role of hydrodynamic stress on the phenotypic characteristics of single and binary biofilms of Pseudomonas fluorescens.

PubMed

Simões, M; Pereira, M O; Vieira, M J

2007-01-01

This study investigates the phenotype of turbulent (Re = 5,200) and laminar (Re = 2,000) flow-generated Pseudomonas fluorescens biofilms. Three P. fluorescens strains, the type strain ATCC 13525 and two strains isolated from an industrial processing plant, D3-348 and D3-350, were used throughout this study. The isolated strains were used to form single and binary biofilms. The biofilm physiology (metabolic activity, cellular density, mass, extracellular polymeric substances, structural characteristics and outer membrane proteins [OMP] expression) was compared. The results indicate that, for every situation, turbulent flow-generated biofilms were more active (p < 0.05), had more mass per cm(2) (p < 0.05), a higher cellular density (p < 0.05), distinct morphology, similar matrix proteins (p > 0.1) and identical (isolated strains -single and binary biofilms) and higher (type strain) matrix polysaccharides contents (p < 0.05) than laminar flow-generated biofilms. Flow-generated biofilms formed by the type strain revealed a considerably higher cellular density and amount of matrix polysaccharides than single and binary biofilms formed by the isolated strains (p < 0.05). Similar OMP expression was detected for the several single strains and for the binary situation, not dependent on the hydrodynamic conditions. Binary biofilms revealed an equal coexistence of the isolated strains with apparent neutral interactions. In summary, the biofilms formed by the type strain represent, apparently, the worst situation in a context of control. The results obtained clearly illustrate the importance of considering strain variation and hydrodynamics in biofilm development, and complement previous studies which have focused on physical aspects of structural and density differences.

Dynamics of a recovering Arctic bird population: the importance of climate, density dependence, and site quality

USGS Publications Warehouse

Bruggeman, Jason E.; Swem, Ted; Andersen, David E.; Kennedy, Patricia L.; Nigro, Debora A.

2015-01-01

Intrinsic and extrinsic factors affect vital rates and population-level processes, and understanding these factors is paramount to devising successful management plans for wildlife species. For example, birds time migration in response, in part, to local and broadscale climate fluctuations to initiate breeding upon arrival to nesting territories, and prolonged inclement weather early in the breeding season can inhibit egg-laying and reduce productivity. Also, density-dependent regulation occurs in raptor populations, as territory size is related to resource availability. Arctic Peregrine Falcons (Falco peregrinus tundrius; hereafter Arctic peregrine) have a limited and northern breeding distribution, including the Colville River Special Area (CRSA) in the National Petroleum Reserve–Alaska, USA. We quantified influences of climate, topography, nest productivity, prey habitat, density dependence, and interspecific competition affecting Arctic peregrines in the CRSA by applying the Dail-Madsen model to estimate abundance and vital rates of adults on nesting cliffs from 1981 through 2002. Arctic peregrine abundance increased throughout the 1980s, which spanned the population's recovery from DDT-induced reproductive failure, until exhibiting a stationary trend in the 1990s. Apparent survival rate (i.e., emigration; death) was negatively correlated with the number of adult Arctic peregrines on the cliff the previous year, suggesting effects of density-dependent population regulation. Apparent survival and arrival rates (i.e., immigration; recruitment) were higher during years with earlier snowmelt and milder winters, and apparent survival was positively correlated with nesting season maximum daily temperature. Arrival rate was positively correlated with average Arctic peregrine productivity along a cliff segment from the previous year and initial abundance was positively correlated with cliff height. Higher cliffs with documented higher productivity (presumably indicative of higher-quality habitat), are a priority for continued protection from potential nearby development and disturbance to minimize population-level impacts. Climate change may affect Arctic peregrines in multiple ways, including through access to more snow-free nest sites and a lengthened breeding season that may increase likelihood of nest success. Our work provides insight into factors affecting a population during and after recovery, and demonstrates how the Dail-Madsen model can be used for any unmarked population with multiple years of abundance data collected through repeated surveys.

Apparent mineral retention is similar in control and hyperinsulinemic men after consumption of high amylose cornstarch.

PubMed

Behall, Kay M; Howe, Juliette C; Anderson, Richard A

2002-07-01

The effects on apparent mineral retention after long-term consumption of a high amylose diet containing 30 g resistant starch (RS) were investigated in 10 control and 14 hyperinsulinemic men. Subjects consumed products (bread, muffins, cookies, corn flakes and cheese puffs) made with standard (70% amylopectin, 30% amylose; AP) or high amylose (70% amylose, 30% amylopectin; AM) cornstarch for two 14-wk periods in a crossover pattern. Starch products replaced usual starches in the habitual diet for 10 wk followed by 4 wk of consuming the controlled diets. During wk 12, all urine, feces and duplicate foods were collected for 7 d. Urinary chromium losses after a glucose tolerance test or 24-h collections of the hyperinsulinemic and control subjects did not differ and were not altered by diet. Except for zinc, the two subject types did not differ significantly in apparent mineral balance. Apparent retentions of calcium and magnesium were not significantly affected by diet (AM vs. AP) or type-by-diet interaction. Apparent iron retention tended to be greater after AM than AP consumption (P < 0.09). Apparent copper retention was greater after consuming AP than after AM (P < 0.02), whereas apparent zinc retention was greater after consuming AM than after AP (P < 0.018). Zinc also showed a significant type-by-diet interaction (P < 0.034) with control subjects retaining less zinc after consuming AP than after AM. In summary, a high amylose cornstarch diet containing 30 g RS could be consumed long term without markedly affecting, and possibly enhancing, retention of some minerals.

Method and apparatus for removal of gaseous, liquid and particulate contaminants from molten metals

DOEpatents

Hobson, D.O.; Alexeff, I.; Sikka, V.K.

1987-08-10

Method and apparatus for removal of nonelectrically-conducting gaseous, liquid, and particulate contaminants from molten metal compositions by applying a force thereto. The force (commonly referred to as the Lorentz Force) exerted by simultaneous application of an electric field and a magnetic field on a molten conductor causes an increase, in the same direction as the force, in the apparent specific gravity thereof, but does not affect the nonconducting materials. This difference in apparent densities cause the nonconducting materials to ''float'' in the opposite direction from the Lorentz Force at a rapid rate. Means are further provided for removal of the contaminants and prevention of stirring due to rotational forces generated by the applied fields. 6 figs.

Method and apparatus for removal of gaseous, liquid and particulate contaminants from molten metals

DOEpatents

Hobson, David O.; Alexeff, Igor; Sikka, Vinod K.

1988-01-01

Method and apparatus for removal of nonelectrically-conducting gaseous, liquid, and particulate contaminants from molten metal compositions by applying a force thereto. The force (commonly referred to as the Lorentz Force) exerted by simultaneous application of an electric field and a magnetic field on a molten conductor causes an increase, in the same direction as the force, in the apparent specific gravity thereof, but does not affect the nonconducting materials. This difference in apparent densities cause the nonconducting materials to "float" in the opposite direction from the Lorentz Force at a rapid rate. Means are further provided for removal of the contaminants and prevention of stirring due to rotational forces generated by the applied fields.

The Yearly Variation in Fall-Winter Arctic Winter Vortex Descent

NASA Technical Reports Server (NTRS)

Schoeberl, Mark R.; Newman, Paul A.

1999-01-01

Using the change in HALOE methane profiles from early September to late March, we have estimated the minimum amount of diabatic descent within the polar which takes place during Arctic winter. The year to year variations are a result in the year to year variations in stratospheric wave activity which (1) modify the temperature of the vortex and thus the cooling rate; (2) reduce the apparent descent by mixing high amounts of methane into the vortex. The peak descent amounts from HALOE methane vary from l0km -14km near the arrival altitude of 25 km. Using a diabatic trajectory calculation, we compare forward and backward trajectories over the course of the winter using UKMO assimilated stratospheric data. The forward calculation agrees fairly well with the observed descent. The backward calculation appears to be unable to produce the observed amount of descent, but this is only an apparent effect due to the density decrease in parcels with altitude. Finally we show the results for unmixed descent experiments - where the parcels are fixed in latitude and longitude and allowed to descend based on the local cooling rate. Unmixed descent is found to always exceed mixed descent, because when normal parcel motion is included, the path average cooling is always less than the cooling at a fixed polar point.

Improving the assessment of predator functional responses by considering alternate prey and predator interactions.

PubMed

Chan, K; Boutin, S; Hossie, T J; Krebs, C J; O'Donoghue, M; Murray, D L

2017-07-01

To improve understanding of the complex and variable patterns of predator foraging behavior in natural systems, it is critical to determine how density-dependent predation and predator hunting success are mediated by alternate prey or predator interference. Despite considerable theory and debate seeking to place predator-prey interactions in a more realistic context, few empirical studies have quantified the role of alternate prey or intraspecific interactions on predator-prey dynamics. We assessed functional responses of two similarly sized, sympatric carnivores, lynx (Lynx canadensis) and coyotes (Canis latrans), foraging on common primary (snowshoe hares; Lepus americanus) and alternate (red squirrels; Tamiasciurus hudsonicus) prey in a natural system. Lynx exhibited a hyperbolic prey-dependent response to changes in hare density, which is characteristic of predators relying primarily on a single prey species. In contrast, the lynx-squirrel response was found to be linear ratio dependent, or inversely dependent on hare density. The coyote-hare and coyote-squirrel interactions also were linear and influenced by predator density. We explain these novel results by apparent use of spatial and temporal refuges by prey, and the likelihood that predators commonly experience interference and lack of satiation when foraging. Our study provides empirical support from a natural predator-prey system that (1) predation rate may not be limited at high prey densities when prey are small or rarely captured; (2) interference competition may influence the predator functional response; and (3) predator interference has a variable role across different prey types. Ultimately, distinct functional responses of predators to different prey types illustrates the complexity associated with predator-prey interactions in natural systems and highlights the need to investigate predator behavior and predation rate in relation to the broader ecological community. © 2017 by the Ecological Society of America.

Variation of the external quantum efficiency with temperature and current density in red, blue, and deep ultraviolet light-emitting diodes

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

Park, Jun Hyuk; Lee, Jong Won; Kim, Dong Yeong

The temperature-dependent external quantum efficiencies (EQEs) were investigated for a 620 nm AlGaInP red light-emitting diodes (LEDs), a 450 nm GaInN blue LED, and a 285 nm AlGaN deep-ultraviolet (DUV) LED. We observed distinct differences in the variation of the EQE with temperature and current density for the three types of LEDs. Whereas the EQE of the AlGaInP red LED increases as temperature decreases below room temperature, the EQEs of GaInN blue and AlGaN DUV LEDs decrease for the same change in temperature in a low-current density regime. The free carrier concentration, as determined from the dopant ionization energy, shows a strong material-system-specificmore » dependence, leading to different degrees of asymmetry in carrier concentration for the three types of LEDs. We attribute the EQE variation of the red, blue, and DUV LEDs to the different degrees of asymmetry in carrier concentration, which can be exacerbated at cryogenic temperatures. As for the EQE variation with temperature in a high-current density regime, the efficiency droop for the AlGaInP red and GaInN blue LEDs becomes more apparent as temperature decreases, due to the deterioration of the asymmetry in carrier concentration. However, the EQE of the AlGaN DUV LED initially decreases, then reaches an EQE minimum point, and then increases again due to the field-ionization of acceptors by the Poole-Frenkel effect. The results elucidate that carrier transport phenomena allow for the understanding of the droop phenomenon across different material systems, temperatures, and current densities.« less

Arrestin-rhodopsin binding stoichiometry in isolated rod outer segment membranes depends on the percentage of activated receptors.

PubMed

Sommer, Martha E; Hofmann, Klaus Peter; Heck, Martin

2011-03-04

In the rod cell of the retina, arrestin is responsible for blocking signaling of the G-protein-coupled receptor rhodopsin. The general visual signal transduction model implies that arrestin must be able to interact with a single light-activated, phosphorylated rhodopsin molecule (Rho*P), as would be generated at physiologically relevant low light levels. However, the elongated bi-lobed structure of arrestin suggests that it might be able to accommodate two rhodopsin molecules. In this study, we directly addressed the question of binding stoichiometry by quantifying arrestin binding to Rho*P in isolated rod outer segment membranes. We manipulated the "photoactivation density," i.e. the percentage of active receptors in the membrane, with the use of a light flash or by partially regenerating membranes containing phosphorylated opsin with 11-cis-retinal. Curiously, we found that the apparent arrestin-Rho*P binding stoichiometry was linearly dependent on the photoactivation density, with one-to-one binding at low photoactivation density and one-to-two binding at high photoactivation density. We also observed that, irrespective of the photoactivation density, a single arrestin molecule was able to stabilize the active metarhodopsin II conformation of only a single Rho*P. We hypothesize that, although arrestin requires at least a single Rho*P to bind the membrane, a single arrestin can actually interact with a pair of receptors. The ability of arrestin to interact with heterogeneous receptor pairs composed of two different photo-intermediate states would be well suited to the rod cell, which functions at low light intensity but is routinely exposed to several orders of magnitude more light.

Desert pastoralists' negative and positive effects on rare wildlife in the Gobi.

PubMed

Ekernas, L Stefan; Sarmento, Wesley M; Davie, Hannah S; Reading, Richard P; Murdoch, James; Wingard, Ganchimeg J; Amgalanbaatar, Sukh; Berger, Joel

2017-04-01

In arid regions of the developing world, pastoralists and livestock commonly inhabit protected areas, resulting in human-wildlife conflict. Conflict is inextricably linked to the ecological processes shaping relationships between pastoralists and native herbivores and carnivores. To elucidate relationships underpinning human-wildlife conflict, we synthesized 15 years of ecological and ethnographic data from Ikh Nart Nature Reserve in Mongolia's Gobi steppe. The density of argali (Ovis ammon), the world's largest wild sheep, at Ikh Nart was among the highest in Mongolia, yet livestock were >90% of ungulate biomass and dogs >90% of large-carnivore biomass. For argali, pastoral activities decreased food availability, increased mortality from dog predation, and potentially increased disease risk. Isotope analyses indicated that livestock accounted for >50% of the diet of the majority of gray wolves (Canis lupus) and up to 90% of diet in 25% of sampled wolves (n = 8). Livestock composed at least 96% of ungulate prey in the single wolf pack for which we collected species-specific prey data. Interviews with pastoralists indicated that wolves annually killed 1-4% of Ikh Nart's livestock, and pastoralists killed wolves in retribution. Pastoralists reduced wolf survival by killing them, but their livestock were an abundant food source for wolves. Consequently, wolf density appeared to be largely decoupled from argali density, and pastoralists had indirect effects on argali that could be negative if pastoralists increased wolf density (apparent competition) or positive if pastoralists decreased wolf predation (apparent facilitation). Ikh Nart's argali population was stable despite these threats, but livestock are increasingly dominant numerically and functionally relative to argali. To support both native wildlife and pastoral livelihoods, we suggest training dogs to not kill argali, community insurance against livestock losses to wolves, reintroducing key native prey species to hotspots of human-wolf conflict, and developing incentives for pastoralists to reduce livestock density. © 2016 Society for Conservation Biology.

Multi-epoch VLBA Imaging of 20 New TeV Blazars: Apparent Jet Speeds

NASA Astrophysics Data System (ADS)

Piner, B. Glenn; Edwards, Philip G.

2018-01-01

We present 88 multi-epoch Very Long Baseline Array (VLBA) images (most at an observing frequency of 8 GHz) of 20 TeV blazars, all of the high-frequency-peaked BL Lac (HBL) class, that have not been previously studied at multiple epochs on the parsec scale. From these 20 sources, we analyze the apparent speeds of 43 jet components that are all detected at four or more epochs. As has been found for other TeV HBLs, the apparent speeds of these components are relatively slow. About two-thirds of the components have an apparent speed that is consistent (within 2σ) with no motion, and some of these components may be stationary patterns whose apparent speed does not relate to the underlying bulk flow speed. In addition, a superluminal tail to the apparent speed distribution of the TeV HBLs is detected for the first time, with eight components in seven sources having a 2σ lower limit on the apparent speed exceeding 1c. We combine the data from these 20 sources with an additional 18 sources from the literature to analyze the complete apparent speed distribution of all 38 TeV HBLs that have been studied with very long baseline interferometry at multiple epochs. The highest 2σ apparent speed lower limit considering all sources is 3.6c. This suggests that bulk Lorentz factors of up to about 4, but probably not much higher, exist in the parsec-scale radio-emitting regions of these sources, consistent with estimates obtained in the radio by other means such as brightness temperatures. This can be reconciled with the high Lorentz factors estimated from the high-energy data if the jet has velocity structures consisting of different emission regions with different Lorentz factors. In particular, we analyze the current apparent speed data for the TeV HBLs in the context of a model with a fast central spine and a slower outer layer.

Disease and community structure: white-nose syndrome alters spatial and temporal niche partitioning in sympatric bat species

Treesearch

David S. Jachowski; Chris A. Dobony; Laci S. Coleman; William M. Ford; Eric R. Britzke; Jane L. Rodrigue; Brian. Leung

2014-01-01

Emerging infectious diseases present a major perturbation with apparent direct effects such as reduced population density, extirpation and/or extinction. Comparatively less is known about the potential indirect effects of disease that likely alter community structure and larger ecosystem function. Since 2006, white-nose syndrome (WNS) has resulted in the loss of over 6...

Management of riparian buffers: upslope thinning with downslope impacts

Treesearch

Kenneth J. Ruzicka; Klaus J. Puettmann; Deanna H. Olson

2014-01-01

We examined the potential of using upslope density management to influence growth and drought tolerance of trees in untreated downslope riparian forests. Increment cores from Douglas-fir trees in three mature stands in western Oregon, USA, were collected and measured. Trees responded to an apparent edge effect up to 15 m downslope of thinned areas but not downslope of...

Prescribed burning for oak savanna restoration in central Minnesota.

Treesearch

Alan S. White

1986-01-01

Low intensity, spring prescribed burns have been used since 1964 at the Cedar Creek Natural History Area in Minnesota in an attempt to restore the area to an oak savanna. Burned areas are now more savanna like (having greater grass and forb and lower shrub and lower tree representation) than unburned areas but still have higher overstory densities than apparently...

Brownian motion from Boltzmann's equation.

NASA Technical Reports Server (NTRS)

Montgomery, D.

1971-01-01

Two apparently disparate lines of inquiry in kinetic theory are shown to be equivalent: (1) Brownian motion as treated by the (stochastic) Langevin equation and Fokker-Planck equation; and (2) Boltzmann's equation. The method is to derive the kinetic equation for Brownian motion from the Boltzmann equation for a two-component neutral gas by a simultaneous expansion in the density and mass ratios.

Influence of crystal characteristics on the shock sensitivities of cyclotrimethylene trinitramine, cyclotetramethylene tetranitramine, and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetra-cyclo[5,5,0,03,1105,9]dodecane immersed in liquid

NASA Astrophysics Data System (ADS)

Li, Hongzhen; Xu, Rong; Kang, Bing; Li, Jinshan; Zhou, Xiaoqing; Zhang, Chaoyang; Nie, Fude

2013-05-01

The shock sensitivities of differently qualified cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine(HMX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetra-cyclo[5,5,0,03,1105,9]dodecane (CL-20) immersed in liquid were determined by the large-scale gap tests, for systemic discussion on the influences of crystal characteristics on them. As a result, it shows that (1) the immersion of crystals in liquid leads to an obvious sensitivity decrease; (2) for all three explosives, their shock sensitivities are lowered with increasing their crystal apparent densities or decreasing their particle sizes, and almost not affected by particle morphologies; (3) the crystal twins are readily formed for HMX and the most distinct factor influencing its shock sensitivities; (4) it is found that the crystal apparent density affects most obviously the shock sensitivities for RDX and CL-20; and (5) CL-20, HMX, and RDX are less and less sensitive to shock, suggesting chemical components are also a determining factor.

Pore cross-section area on predicting elastic properties of trabecular bovine bone for human implants.

PubMed

Maciel, Alfredo; Presbítero, Gerardo; Piña, Cristina; del Pilar Gutiérrez, María; Guzmán, José; Munguía, Nadia

2015-01-01

A clear understanding of the dependence of mechanical properties of bone remains a task not fully achieved. In order to estimate the mechanical properties in bones for implants, pore cross-section area, calcium content, and apparent density were measured in trabecular bone samples for human implants. Samples of fresh and defatted bone tissue, extracted from one year old bovines, were cut in longitudinal and transversal orientation of the trabeculae. Pore cross-section area was measured with an image analyzer. Compression tests were conducted into rectangular prisms. Elastic modulus presents a linear tendency as a function of pore cross-section area, calcium content and apparent density regardless of the trabecular orientation. The best variable to estimate elastic modulus of trabecular bone for implants was pore cross-section area, and affirmations to consider Nukbone process appropriated for marrow extraction in trabecular bone for implantation purposes are proposed, according to bone mechanical properties. Considering stress-strain curves, defatted bone is stiffer than fresh bone. Number of pores against pore cross-section area present an exponential decay, consistent for all the samples. These graphs also are useful to predict elastic properties of trabecular samples of young bovines for implants.

Effect of binder liquid type on spherical crystallization.

PubMed

Maghsoodi, Maryam; Hajipour, Ali

2014-11-01

Spherical crystallization is a process of formation of agglomerates of crystals held together by binder liquid. This research focused on understanding the effect of type of solvents used as binder liquid on the agglomeration of crystals. Carbamazepine and ethanol/water were used respectively as a model drug and crystallization system. Eight solvents as binder liquid including chloroform, dichloromethane, isopropyl acetate, ethyl acetate, n-hexane, dimethyl aniline, benzene and toluene were examined to better understand the relationship between the physical properties of the binder liquid and its ability to bring about the formation of the agglomerates. Moreover, the agglomerates obtained from effective solvents as binder liquid were evaluated in term of size, apparent particle density and compressive strength. In this study the clear trend was observed experimentally in the agglomerate formation as a function of physical properties of the binder liquid such as miscibility with crystallization system. Furthermore, the properties of obtained agglomerates such as size, apparent particle density and compressive strength were directly related to physical properties of effective binder liquids. RESULTS of this study offer a useful starting point for a conceptual framework to guide the selection of solvent systems for spherical crystallization.

Study on antidiabetic activity of wheat and barley starch using asymmetrical flow field-flow fractionation coupled with multiangle light scattering.

PubMed

Dou, Haiyang; Zhou, Bing; Jang, Hae-Dong; Lee, Seungho

2014-05-02

The ability of asymmetrical flow field-flow fractionation (AF4) coupled online with multiangle light scattering (MALS) and refractive index detector (RI) (AF4-MALS-RI) for monitoring of change in molecular conformation of wheat and barley starch during germination process was evaluated. AF4 provides separation of starch molecules based on their hydrodynamic sizes, and MALS yields the molar mass and molecular size (radius of gyration, Rg). In vitro and in vivo anti-hyperglycemic effect of germinated wheat and barley was studied. The relationship between antidiabetic activity and molecular conformation was, for the first time, investigated. The ratio of Rg to the hydrodynamic radius (Rh) and the apparent density were proven to be important parameters as they offer an insight into molecular conformation. Results showed that, when geminated, the apparent density and the antidiabetic activity of barley were significantly increased, suggesting germination makes the molecules more compact which could contribute to enhancement of their antidiabetic activity. The information obtained by AF4-MALS-RI is valuable for understanding of germination mechanism, and thus for developing functional foods. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of olive mill waste addition on the properties of porous fired clay bricks using Taguchi method.

PubMed

Sutcu, Mucahit; Ozturk, Savas; Yalamac, Emre; Gencel, Osman

2016-10-01

Production of porous clay bricks lightened by adding olive mill waste as a pore making additive was investigated. Factors influencing the brick manufacturing process were analyzed by an experimental design, Taguchi method, to find out the most favorable conditions for the production of bricks. The optimum process conditions for brick preparation were investigated by studying the effects of mixture ratios (0, 5 and 10 wt%) and firing temperatures (850, 950 and 1050 °C) on the physical, thermal and mechanical properties of the bricks. Apparent density, bulk density, apparent porosity, water absorption, compressive strength, thermal conductivity, microstructure and crystalline phase formations of the fired brick samples were measured. It was found that the use of 10% waste addition reduced the bulk density of the samples up to 1.45 g/cm(3). As the porosities increased from 30.8 to 47.0%, the compressive strengths decreased from 36.9 to 10.26 MPa at firing temperature of 950 °C. The thermal conductivities of samples fired at the same temperature showed a decrease of 31% from 0.638 to 0.436 W/mK, which is hopeful for heat insulation in the buildings. Increasing of the firing temperature also affected their mechanical and physical properties. This study showed that the olive mill waste could be used as a pore maker in brick production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Testing the role of patch openness as a causal mechanism for apparent area sensitivity in a grassland specialist.

PubMed

Keyel, Alexander C; Bauer, Carolyn M; Lattin, Christine R; Romero, L Michael; Reed, J Michael

2012-06-01

Area sensitivity, species being disproportionately present on larger habitat patches, has been identified in many taxa. We propose that some apparently area-sensitive species are actually responding to how open a habitat patch is, rather than to patch size. We tested this hypothesis for Bobolinks (Dolichonyx oryzivorus) by comparing density and occupancy to a novel openness index, patch area, and edge effects. Bobolink density and occupancy showed significant relationships with openness, but logistic models based on an openness occupancy threshold had greater explanatory power. Thresholds remained approximately consistent from June through August, and shifted to be more open in September. Variance partitioning supported the openness index as unique and relevant. We found no relationships between measures of body condition (body mass, body size, circulating corticosterone levels) and either openness or area. Our findings have implications for studies of area sensitivity, especially with regards to inconsistencies reported within species: specifically, (1) whether or not a study finds a species to be area sensitive may depend on whether small, open sites were sampled, and (2) area regressions were sensitive to observed densities at the largest sites, suggesting that variation in these fields could lead to inconsistent area sensitivity responses. Responses to openness may be a consequence of habitat selection mediated by predator effects. Finally, openness measures may have applications for predicting effects of habitat management or development, such as adding wind turbines, in open habitat.

Negative effects of Microcystis blooms on the crustacean plankton in an enclosure experiment in the subtropical China.

PubMed

Chen, Fei-zhou; Xie, Ping; Tang, Hui-juan; Liu, Hong

2005-01-01

Effects of Microcystis blooms on the crustacean plankton were studied using enclosure experiments during July-September, 2000. Eight enclosures were set in the hypereutrophic Donghu Lake. Different nutrient concentrations through additional nutrient and sediment in enclosures were expected to result in different abundance of Microcystis. From July to early August, the phytoplankton community was dominated by Chlorophyta, Cryptophyta, Bacillariophyta and Cyanophyta other than Microcystis aeruginosa. M. aeruginosa showed a rapid increase during early August in all enclosures and predominated. Crustacean plankton was dominated by the herbivorous Moina micrura, Diaphanosoma brachyurum and Ceriodaphnia cornuta, and the predaceous Mesocyclops sp. and Thermocyclops taihokuensis. During the pre-bloom period, the dynamics of M. micrura population appeared to be mainly affected by the predaceous cyclopoids. With the development of Microcystis blooms, such interaction between M. micrura and cyclopoids seemed weakened, especially when the Microcystis biomass was high. But there was no apparent influence on the interaction between Leptodora kindti and its zooplanktonic prey. The density of two cyclopoids decreased with the enhancement of Microcystis. The density decline of M. micrura was caused by both predation and inhibition by Microcystis. The low food availability of other edible phytoplankton during the blooms led to low densities of both C. cornuta and D. brachyurum by late August. It appears that dense Microcystis blooms exert strong negative effects on the herbivorous cladocerans and the predaceous cyclopoids.

Modeling X-ray Absorbers in AGNs with MHD-Driven Accretion-Disk Winds

NASA Astrophysics Data System (ADS)

Fukumura, Keigo; Kazanas, D.; Shrader, C. R.; Tombesi, F.; Contopoulos, J.; Behar, E.

2013-04-01

We have proposed a systematic view of the observed X-ray absorbers, namely warm absorbers (WAs) in soft X-ray and highly-ionized ultra-fast outflows (UFOs), in the context of magnetically-driven accretion-disk wind models. While potentially complicated by variability and thermal instability in these energetic outflows, in this simplistic model we have calculated 2D kinematic field as well as density and ionization structure of the wind with density profile of 1/r corresponding to a constant column distribution per decade of ionization parameter. In particular we show semi-analytically that the inner layer of the disk-wind manifests itself as the strongly-ionized fast outflows while the outer layer is identified as the moderately-ionized absorbers. The computed characteristics of these two apparently distinct absorbers are consistent with X-ray data (i.e. a factor of ~100 difference in column and ionization parameters as well as low wind velocity vs. near-relativistic flow). With the predicted contour curves for these wind parameters one can constrain allowed regions for the presence of WAs and UFOs.The model further implies that the UFO's gas pressure is comparable to that of the observed radio jet in 3C111 suggesting that the magnetized disk-wind with density profile of 1/r is a viable agent to help sustain such a self-collimated jet at small radii.

Morphological and physiological divergences within Quercus ilex support the existence of different ecotypes depending on climatic dryness

PubMed Central

Peguero-Pina, José Javier; Sancho-Knapik, Domingo; Barrón, Eduardo; Camarero, Julio Jesús; Vilagrosa, Alberto; Gil-Pelegrín, Eustaquio

2014-01-01

Background and Aims Several studies show apparently contradictory findings about the functional convergence within the Mediterranean woody flora. In this context, this study evaluates the variability of functional traits within holm oak (Quercus ilex) to elucidate whether provenances corresponding to different morphotypes represent different ecotypes locally adapted to the prevaling stress levels. Methods Several morphological and physiological traits were measured at leaf and shoot levels in 9-year-old seedlings of seven Q. ilex provenances including all recognized morphotypes. Plants were grown in a common garden for 9 years under the same environmental conditions to avoid possible biases due to site-specific characteristics. Key Results Leaf morphometry clearly separates holm oak provenances into ‘ilex’ (more elongated leaves with low vein density) and ‘rotundifolia’ (short and rounded leaves with high vein density) morphotypes. Moreover, these morphotypes represent two consistent and very contrasting functional types in response to dry climates, mainly in terms of leaf area, major vein density, leaf specific conductivity, resistance to drought-induced cavitation and turgor loss point. Conclusions The ‘ilex’ and ‘rotundifolia’ morphotypes correspond to different ecotypes as inferred from their contrasting functional traits. To the best of our knowledge, this is the first time that the combined use of morphological and physiological traits has provided support for the concept of these two holm oak morphotypes being regarded as two different species. PMID:24941998

Galaxy And Mass Assembly: evolution of the Hα luminosity function and star formation rate density up to z < 0.35

NASA Astrophysics Data System (ADS)

Gunawardhana, M. L. P.; Hopkins, A. M.; Bland-Hawthorn, J.; Brough, S.; Sharp, R.; Loveday, J.; Taylor, E.; Jones, D. H.; Lara-López, M. A.; Bauer, A. E.; Colless, M.; Owers, M.; Baldry, I. K.; López-Sánchez, A. R.; Foster, C.; Bamford, S.; Brown, M. J. I.; Driver, S. P.; Drinkwater, M. J.; Liske, J.; Meyer, M.; Norberg, P.; Robotham, A. S. G.; Ching, J. H. Y.; Cluver, M. E.; Croom, S.; Kelvin, L.; Prescott, M.; Steele, O.; Thomas, D.; Wang, L.

2013-08-01

Measurements of the low-z Hα luminosity function, Φ, have a large dispersion in the local number density of sources (˜0.5-1 Mpc-3 dex-1), and correspondingly in the star formation rate density (SFRD). The possible causes for these discrepancies include limited volume sampling, biases arising from survey sample selection, different methods of correcting for dust obscuration and active galactic nucleus contamination. The Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey (SDSS) provide deep spectroscopic observations over a wide sky area enabling detection of a large sample of star-forming galaxies spanning 0.001 < SFRHα (M⊙ yr- 1) < 100 with which to robustly measure the evolution of the SFRD in the low-z Universe. The large number of high-SFR galaxies present in our sample allow an improved measurement of the bright end of the luminosity function, indicating that the decrease in Φ at bright luminosities is best described by a Saunders functional form rather than the traditional Schechter function. This result is consistent with other published luminosity functions in the far-infrared and radio. For GAMA and SDSS, we find the r-band apparent magnitude limit, combined with the subsequent requirement for Hα detection leads to an incompleteness due to missing bright Hα sources with faint r-band magnitudes.

Correlation of TBE Incidence with Red Deer and Roe Deer Abundance in Slovenia

PubMed Central

Knap, Nataša; Avšič-Županc, Tatjana

2013-01-01

Tick-borne encephalitis (TBE) is a virus infection which sometimes causes human disease. The TBE virus is found in ticks and certain vertebrate tick hosts in restricted endemic localities termed TBE foci. The formation of natural foci is a combination of several factors: the vectors, a suitable and numerous enough number of hosts and in a habitat with suitable vegetation and climate. The present study investigated the influence of deer on the incidence of tick-borne encephalitis. We were able to obtain data from deer culls. Using this data, the abundance of deer was estimated and temporal and spatial analysis was performed. The abundance of deer has increased in the past decades, as well as the incidence of tick-borne encephalitis. Temporal analysis confirmed a correlation between red deer abundance and tick-borne encephalitis occurrence. Additionally, spatial analysis established, that in areas with high incidence of tick-borne encephalitis red deer density is higher, compared to areas with no or few human cases of tick-borne encephalitis. However, such correlation could not be confirmed between roe deer density and the incidence of tick-borne encephalitis. This is presumably due to roe deer density being above a certain threshold so that availability of tick reproduction hosts has no apparent effect on ticks' host finding and consequently may not be possible to correlate with incidence of human TBE. PMID:23776668

Ability of the plasma concentration ratio of triglyceride/high-density lipoprotein cholesterol to identify increased cardio-metabolic risk in an east Asian population.

PubMed

Sung, Ki-Chul; Reaven, Gerald; Kim, Sun

2014-07-01

The plasma concentration ratio of triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C) has identified increased cardio-metabolic risk and outcome in European populations. The goal of this study was to see if this ratio would also have clinical utility in identifying cardio-metabolic risk in an East Asian population. Measurements of various cardio-metabolic risk factors, including coronary calcium scores, were available on 12,166 apparently healthy Korean adults. Approximately 25% of men and women with the highest TG/HDL-C ratios were classified as being at high cardio-metabolic risk, and their risk factor profiles compared to the remainder of the population, as well as to individuals with the metabolic syndrome (MetS). High cardio-metabolic risk (upper 25%) was defined as a TG/HDL-C ratio ≥3.5 (men) or ≥2.0 (women), and all cardio-metabolic risk factors measured, including coronary calcium scores, were significantly more adverse when compared to individuals beneath these cut-points. Although cardio-metabolic risk profiles appeared reasonably comparable in subjects identified by either a high TG/HDL-C or a diagnosis of MetS, use of the TG/HDL-C increased the numbers at high risk. Evidence that determination of the plasma TG/HDL-C concentration ratio provides a simple way to identify individual at increased cardio-metabolic risk has been extended to an East Asian population. The ability of an elevated TG/HDL-C ratio to accomplish this goal is comparable to that achieved using the more complicated MetS criteria. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Pilot study to access the role of Ceratomyxa shasta infection in mortality of fall-run Chinook smolts migrating through the lower Klamath River in 2008

USGS Publications Warehouse

Foott, Scott; Stutzer, Greg; Fogerty, R.; Hansel, Hal; Juhnke, Steven; Beeman, John W.

2009-01-01

Apparent survival and migration rate of radio-tagged hatchery subyearling Chinook salmon released at Iron Gate Hatchery was monitored in the Klamath River to see if the timing of mortality coincided with observations of ceratomyxosis in re-captured coded wire tag cohorts. Despite rapid emigration, these relatively large (mean fork length 92 mm) smolts had a cumulative apparent survival to the estuary of 0.074 (SE 0.024) and standardized rates of survival per 100 km tended to decrease linearly with distance from the hatchery. The last fish detection occurred 26 days after release but median travel time between Iron Gate Hatchery (rkm 309) and the last receiver near the Klamath estuary (Blake’s Riffle rkm 13) was about 10 days. The majority of apparent mortality (8-10 d post-release) occurred before disease from Ceratomyxa shasta infection is expected after exposure to infectious waters. Despite numerous observations of ceratomyxosis in the Klamath R. during June, an obvious link between disease and apparent survival was not present in this study. Future studies should examine the acute (e.g., predator types and densities) and chronic (e.g., swimming performance impairment due to disease) mortality factors for juvenile Chinook salmon smolts in the Klamath River.

Prevalence of traditional and novel markers of cardiovascular disease risk in Scottish adolescents: socioeconomic effects.

PubMed

Buchan, Duncan S; Ollis, Stewart; Thomas, Non-Eleri; Simpson, Alan; Young, John D; Cooper, Stephen-Mark; Malina, Robert M; Cockcroft, John R; Baker, Julien S

2012-10-01

Information on the health status and physical activity of Scottish adolescents is limited. This study examines the prevalence of cardiovascular disease (CVD) risk in Scottish adolescents by socioeconomic status (SES). Participants were recruited from two high schools that differed in the SES of the students in attendance. The sample included 73 boys and 34 girls (16.4 ± 0.6 years). Variables included anthropometry, physical activity, physical fitness, blood pressure, diet, and 11 metabolic markers of CVD risk. Significant sex differences (P ≤ 0.01) were noted for stature, waist circumference, waist-hip ratio, physical activity, cardiorespiratory fitness, muscular power, sprint speed, and several CVD risk factors: high-density lipoprotein (HDL), low-density lipoprotein (LDL), interleukin-6 (IL-6), and C-reactive protein (CRP) levels. Boys from a lower SES had significantly higher levels of glucose and plasminogen activator inhibitor-1 (PAI-1) but lower levels of adiponectin compared with boys from a higher SES. Girls from a lower SES had significantly (P ≤ 0.01) higher glucose and PAI-1 levels but lower levels of insulin and adiponectin than girls from a higher SES. High fat diets, low physical activity levels, and elevated CRP and total cholesterol levels were the CVD risk factors most commonly identified as being at-risk levels in this cohort, regardless of sex or SES. SES differences were not consistently apparent, but several CVD risk factors were identified as elevated in this sample of adolescents, regardless of sex or SES.

Expression of the human apolipoprotein A-I gene in transgenic mice alters high density lipoprotein (HDL) particle size distribution and diminishes selective uptake of HDL cholesteryl esters

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

Chajekshaul, T.; Hayek, T.; Walsh, A.

1991-08-01

Transgenic mice carrying the human apolipoprotein (apo) A-I gene (HuAITg mice) were used to examine the effects of overexpression of the human gene on high density lipoprotein (HDL) particle size distribution and metabolism. On a chow diet, control mice had HDL cholesterol and apo A-I levels of 49 {plus minus} 2 and 137 {plus minus} 12 mg/dl of plasma, respectively. HuAITg mice had HDL cholesterol, human apo A-I, and mouse apo A-I levels of 88 {plus minus} 2, 255 {plus minus} 19, and 16 {plus minus} 2 mg/dl, respectively. Nondenaturing gradient gel electrophoresis revealed control mouse plasma HDL to bemore » primarily monodisperse with a particle diameter of 10.2 nm, whereas HuAITg mouse plasma HDL was polydisperse with particles of diameter 11.4, 10.2, and 8.7 nm, which correspond in size to human HDL1, HDL2, and HDL3, respectively. In vivo turnover studies of HDL labeled with (3H)cholesteryl linoleyl ether and 125I-apo A-I were performed. In control animals, the fractional catabolic rate (FCR) for HDL cholesteryl ester was significantly more than the apo A-I FCR. In the HuAITg mice, the HDL cholesteryl ester FCR was the same as the apo A-I FCR. There were no significant differences between control and HuAITg animals in the sites of tissue removal of HDL cholesteryl ester, with the liver extracting most of the injected radioactivity. Control and HuAITg animals had comparable liver and intestinal cholesterol synthesis and LDL FCR. In conclusion, HuAITg mice have principally human and not mouse apo A-I in their plasma. This apparently causes a change in HDL particle size distribution in the transgenic mice to one resembling the human pattern. The replacement of mouse by human apo A-I also apparently causes the loss of the selective uptake pathway of HDL cholesteryl esters present in control mice.« less

Effects of self-irradiation in plutonium alloys

DOE PAGES

Chung, B. W.; Lema, K. E.; Allen, P. G.

2015-09-16

In this paper, we present updated results of self-irradiation effects on 238Pu-enriched 239Pu alloys measured by immersion density, dilatometry, and tensile tests. We obtained the self-irradiation equivalent time of nearly 200 years, nearly 100 years longer than in our previous papers. At this extended aging, we find the rate of decrease in density has slowed significantly, stabilizing around 15.73 g/cc, without signs of void swelling. The volume expansion measured at 35°C also shows apparent saturation at less than 0.25%. Quasi-static tensile measurement still show gradual increase in the strength of plutonium alloys with age.

Low defect densities in molecular beam epitaxial GaAs achieved by isoelectronic In doping

NASA Technical Reports Server (NTRS)

Bhattacharya, P. K.; Dhar, S.; Berger, P.; Juang, F.-Y.

1986-01-01

A study has been made of the effects of adding small amounts of In (0.2-1.2 pct) to GaAs grown by molecular beam epitaxy. The density of four electron traps decreases in concentration by an order of magnitude, and the peak intensities of prominent emissions in the excitonic spectra are reduced with increase in In content. Based on the higher surface migration rate of In, compared to Ga, at the growth temperatures it is apparent that the traps and the excitonic transitions are related to point defects. This agrees with earlier observations by Briones and Collins (1982) and Skromme et al. (1985).

Narrowband noise study of sliding charge density waves in NbSe3 nanoribbons

NASA Astrophysics Data System (ADS)

Onishi, Seita; Jamei, Mehdi; Zettl, Alex

2017-02-01

Transport properties (dc electrical resistivity, threshold electric field, and narrow-band noise) are reported for nanoribbon specimens of NbSe3 with thicknesses as low as 18 nm. As the sample thickness decreases, the resistive anomalies characteristic of the charge density wave (CDW) state are suppressed and the threshold fields for nonlinear CDW conduction apparently diverge. Narrow-band noise measurements allow determination of the concentration of carriers condensed in the CDW state n c , reflective of the CDW order parameter Δ. Although the CDW transition temperatures are relatively independent of sample thickness, in the lower CDW state Δ decreases dramatically with decreasing sample thickness.

Morphological and Star Formation Evolution to z = 1

NASA Astrophysics Data System (ADS)

Hammer, F.

The decrease, since z = 1, of the rest-frame UV luminosity density is related to global changes in morphology, color and emission lines properties of galaxies. This is apparently followed by a similar decrease of the rest-frame IR luminosity density. I discuss the relative contribution from the different galaxy morphological types to the observed evolution. The main contributors are compact galaxies observed in large number at optical wavelengths, and the sparse population of extincted & powerful starbursts observed by ISO. This latter population is made of large and massive galaxies mostly found in interacting systems, some of which could be leading to the formation of massive ellipticals at z < 1.

Characterization of onset of parametric decay instability of lower hybrid waves

NASA Astrophysics Data System (ADS)

Baek, S. G.; Bonoli, P. T.; Parker, R. R.; Shiraiwa, S.; Wallace, G. M.; Porkolab, M.; Takase, Y.; Brunner, D.; Faust, I. C.; Hubbard, A. E.; LaBombard, B. L.; Lau, C.

2014-02-01

The goal of the lower hybrid current drive (LHCD) program on Alcator C-Mod is to develop and optimize ITER-relevant steady-state plasmas by controlling the current density profile. Using a 4×16 waveguide array, over 1 MW of LH power at 4.6 GHz has been successfully coupled to the plasmas. However, current drive efficiency precipitously drops as the line averaged density (n¯e) increases above 1020m-3. Previous numerical work shows that the observed loss of current drive efficiency in high density plasmas stems from the interactions of LH waves with edge/scrape-off layer (SOL) plasmas [Wallace et al., Physics of Plasmas 19, 062505 (2012)]. Recent observations of parametric decay instability (PDI) suggest that non-linear effects should be also taken into account to fully characterize the parasitic loss mechanisms [Baek et al., Plasma Phys. Control Fusion 55, 052001 (2013)]. In particular, magnetic configuration dependent ion cyclotron PDIs are observed using the probes near n¯e≈1.2×1020m-3. In upper single null plasmas, ion cyclotron PDI is excited near the low field side separatrix with no apparent indications of pump depletion. The observed ion cyclotron PDI becomes weaker in inner wall limited plasmas, which exhibit enhanced current drive effects. In lower single null plasmas, the dominant ion cyclotron PDI is excited near the high field side (HFS) separatrix. In this case, the onset of PDI is correlated with the decrease in pump power, indicating that pump wave power propagates to the HFS and is absorbed locally near the HFS separatrix. Comparing the observed spectra with the homogeneous growth rate calculation indicates that the observed ion cyclotron instability is excited near the plasma periphery. The incident pump power density is high enough to overcome the collisional homogeneous threshold. For C-Mod plasma parameters, the growth rate of ion sound quasi-modes is found to be typically smaller by an order of magnitude than that of ion cyclotron quasi-modes. When considering the convective threshold near the plasma edge, convective growth due to parallel coupling rather than perpendicular coupling is likely to be responsible for the observed strength of the sidebands. To demonstrate the improved LHCD efficiency in high density plasmas, an additional launcher has been designed. In conjunction with the existing launcher, this new launcher will allow access to an ITER-like high single pass absorption regime, replicating the JLH(r) expected in ITER. The predictions from the time domain discharge scenarios, in which the two launchers are used, will be also presented.

Advanced oxidation protein products and their relationship with cardiovascular risk factors in young apparently healthy people.

PubMed

Villalpando Sánchez, Diana Carolina; Alvarez Aguilar, Cleto; Gómez García, Anel

Advanced oxidation protein products (AOPPs) are used as a marker to estimate oxidative stress in plasma proteins. Oxidative stress is considered a factor of cardiovascular risk (CVRF) related to increased blood pressure, and dyslipidaemia. The aim of this study was to evaluate the association between plasma AOPPs and CVRF in apparently healthy young adults. A prospective cross-sectional study was conducted on 120 students of the Faculty of Chemical-Pharmacobiology of the UMSNH. Body mass index (BMI) and blood pressure were determined. A blood specimen was also collected to quantify AOPPs, glucose, total cholesterol, lipoproteins (high, low, and very low density), and triglycerides. Differences were observed in the groups with and without CVRF, with significant differences in BMI, waist, body fat (P<.05), and lipid profile (P<.0001). AOPPs were higher in the group of young people with three and four CVRF (F: 4.651; P=.002). A negatively correlation was found between AOPPs and LDL cholesterol (r=-0.364; P=.0001). It was observed that AOPPs concentrations are increased as CVRF increase in young adults. Thus, this could be considered an important risk factor, because their deposition in the atherosclerotic plaque favours the atherogenic process, and thus the development of cardiovascular disease. Quantification of AOPPs contributes to the indirect determination of oxidative status in the body. The study of metabolic and oxidative state of apparently healthy young adults is important in the prevention of cardiovascular disease in later life. More longitudinal studies are required to study its evolution. Copyright © 2017 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.

Prevalence of Dyslipidemia and Associated Factors in Obese Children and Adolescents.

PubMed

Elmaoğulları, Selin; Tepe, Derya; Uçaktürk, Seyit Ahmet; Karaca Kara, Fatma; Demirel, Fatma

2015-09-01

Childhood-onset obesity is associated with increased mortality and morbidity related to cardiovascular diseases (CVD) during adulthood. Dyslipidemia has a fundamental role in the pathogenesis of CVD. This study aimed to evaluate the prevalence of dyslipidemia and related factors among obese children and adolescents. Obese patients aged between 2 and 18 years were included in the study. Serum concentrations of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C), high-density lipoprotein (HDL-C), fasting glucose levels, insulin, thyroid-stimulating hormone (TSH), free thyroxine (fT4), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and liver ultrasound findings were evaluated retrospectively. Among 823 obese patients, 353 (42.9%) met the dyslipidemia criteria: 21.7% had hypertriglyceridemia, 19.7% had low levels of HDL-C, 18.6% had hypercholesterolemia, and 13.7% had high levels of LDL-C. Older age and/or high body mass index (BMI) were related to increased prevalence of dyslipidemia. Hepatosteatosis was more common among dyslipidemic patients. The frequency of insulin resistance (IR) and of higher levels of ALT and TSH were also detected in dyslipidemic patients. Patients with both dyslipidemia and grade 2-3 hepatosteatosis had higher levels of ALT, AST and TSH and lower levels of fT4. Prevalence of dyslipidemia is high in obese children, and hypertriglyceridemia is in the foreground. Higher levels of IR and more apparent abnormal liver function test results are observed in the context of dyslipidemia and hepatosteatosis coexistence. Metabolic and hormonal alterations related with thyroid functions may also be associated with dyslipidemia and hepatosteatosis in obese patients.

Effects of diets containing high or low amounts of stearic acid on plasma lipoprotein fractions and fecal fatty acid excretion of men.

PubMed

Dougherty, R M; Allman, M A; Iacono, J M

1995-05-01

Ten middle-aged males participated in a crossover study to determine the cholesterolemic effect of high amounts of stearic acid in a natural diet. They consumed a 20-d stabilization diet followed by two 40-d intervention diets containing either 1.5% of energy as stearic (18:0) acid and 7.3% of energy as palmitic (16:0) acid (low stearate: LS) or 2.4% of energy as 16:0 and 7.3% of energy as 18:0 (high stearate: HS). The experimental diets also contained approximately 10% of energy each as saturated and monounsaturated fatty acids and 7.2-8% of energy as polyunsaturated fatty acids. The primary source of 18:0 in the HS diet was sheanut oil (commercially referred to as shea butter) and palm oil and butter in the LS diet. Plasma total, low-density-lipoprotein, and high-density-lipoprotein cholesterol were significantly lower with the HS than with the LS diet. Total fecal fatty acid excretion was higher throughout the HS period. Apparent digestibility of the major dietary fatty acids showed that all of the selected fatty acids, except 18:0, were > or = 95% absorbed. These data demonstrate that feeding diets containing about two times the usual amount of stearic acid consumed in the United States, contributed to an increase in plasma lipoprotein concentrations at 40 d from an earlier decrease at 20 d. The time required to achieve stable cholesterol concentrations appears to vary depending on the kind of saturated fatty acids present in the diet.