Place learning overrides innate behaviors in Drosophila.

PubMed

Baggett, Vincent; Mishra, Aditi; Kehrer, Abigail L; Robinson, Abbey O; Shaw, Paul; Zars, Troy

2018-03-01

Animals in a natural environment confront many sensory cues. Some of these cues bias behavioral decisions independent of experience, and action selection can reveal a stimulus-response (S-R) connection. However, in a changing environment it would be a benefit for an animal to update behavioral action selection based on experience, and learning might modify even strong S-R relationships. How animals use learning to modify S-R relationships is a largely open question. Three sensory stimuli, air, light, and gravity sources were presented to individual Drosophila melanogaster in both naïve and place conditioning situations. Flies were tested for a potential modification of the S-R relationships of anemotaxis, phototaxis, and negative gravitaxis by a contingency that associated place with high temperature. With two stimuli, significant S-R relationships were abandoned when the cue was in conflict with the place learning contingency. The role of the dunce ( dnc ) cAMP-phosphodiesterase and the rutabaga ( rut ) adenylyl cyclase were examined in all conditions. Both dnc 1 and rut 2080 mutant flies failed to display significant S-R relationships with two attractive cues, and have characteristically lower conditioning scores under most conditions. Thus, learning can have profound effects on separate native S-R relationships in multiple contexts, and mutation of the dnc and rut genes reveal complex effects on behavior. © 2018 Baggett et al.; Published by Cold Spring Harbor Laboratory Press.

Hybrid computing using a neural network with dynamic external memory.

PubMed

Graves, Alex; Wayne, Greg; Reynolds, Malcolm; Harley, Tim; Danihelka, Ivo; Grabska-Barwińska, Agnieszka; Colmenarejo, Sergio Gómez; Grefenstette, Edward; Ramalho, Tiago; Agapiou, John; Badia, Adrià Puigdomènech; Hermann, Karl Moritz; Zwols, Yori; Ostrovski, Georg; Cain, Adam; King, Helen; Summerfield, Christopher; Blunsom, Phil; Kavukcuoglu, Koray; Hassabis, Demis

2016-10-27

Artificial neural networks are remarkably adept at sensory processing, sequence learning and reinforcement learning, but are limited in their ability to represent variables and data structures and to store data over long timescales, owing to the lack of an external memory. Here we introduce a machine learning model called a differentiable neural computer (DNC), which consists of a neural network that can read from and write to an external memory matrix, analogous to the random-access memory in a conventional computer. Like a conventional computer, it can use its memory to represent and manipulate complex data structures, but, like a neural network, it can learn to do so from data. When trained with supervised learning, we demonstrate that a DNC can successfully answer synthetic questions designed to emulate reasoning and inference problems in natural language. We show that it can learn tasks such as finding the shortest path between specified points and inferring the missing links in randomly generated graphs, and then generalize these tasks to specific graphs such as transport networks and family trees. When trained with reinforcement learning, a DNC can complete a moving blocks puzzle in which changing goals are specified by sequences of symbols. Taken together, our results demonstrate that DNCs have the capacity to solve complex, structured tasks that are inaccessible to neural networks without external read-write memory.

Why developmental niche construction is not selective niche construction: and why it matters

PubMed Central

2017-01-01

In the last decade, niche construction has been heralded as the neglected process in evolution. But niche construction is just one way in which the organism's interaction with and construction of the environment can have potential evolutionary significance. The constructed environment does not just select for, it also produces new variation. Nearly 3 decades ago, and in parallel with Odling-Smee's article ‘Niche-constructing phenotypes', West and King introduced the ‘ontogenetic niche’ to give the phenomena of exogenetic inheritance a formal name. Since then, a range of fields in the life sciences and medicine has amassed evidence that parents influence their offspring by means other than DNA (parental effects), and proposed mechanisms for how heritable variation can be environmentally induced and developmentally regulated. The concept of ‘developmental niche construction’ (DNC) elucidates how a diverse range of mechanisms contributes to the transgenerational transfer of developmental resources. My most central of claims is that whereas the selective niche of niche construction theory is primarily used to explain the active role of the organism in its selective environment, DNC is meant to indicate the active role of the organism in its developmental environment. The paper highlights the differences between the construction of the selective and the developmental niche, and explores the overall significance of DNC for evolutionary theory. PMID:28839923

Climate impact on the tree growth, vigor and productivity in Siberia

NASA Astrophysics Data System (ADS)

Kharuk, V.; Im, S.; Petrov, I.; Dvinskaya, M.

2017-12-01

Changing climate has an impact on the Siberian taiga forests. We analyzed GPP and NPP trends, growth index, and stands mortality within the Central Siberia (48°- 75°N/80°-115°E). Considered forests included larch-dominant (Larix sibirica, L. dahurica) and "dark needle conifer" (DNC: Abies sibirica, Pinus sibirica, Picea obovata) stands. GPP and NPP trends calculated based on the Terra/MODIS products. Growth index calculations based on dendrochronology data. Water stress analysis based on the gravimetric and microwave satellite data and MERRA-2 database. Analyzed variables included precipitation, air temperature, VPD, drought index SPEI, and root zone wetness. We found positive GPP trends within majority (>90%) of larch-dominant and DNC ranges, whereas NPP trends are positive on the <40% territory. Negative NPP trends correlated with growth index within key-sites. Siberian pine and fir growth index increase since late 1970th, turning to depression since late 1980th. Within permafrost zone larch growth correlated with sum of positive (t>+10C°) temperatures and vegetation period length. During recent years larch experience water stress in the beginning of vegetation period. Tree decline and mortality observed within DNC stands, and that phenomenon regularly coincided with zones of negative NPP trends. Mortality correlated with VPD, SPEI, and root zone moisture content. Bark beetles (including aggressive species Polygraphus proximus, similar to Dendroctonus ponderosae in American forests) attacked water-stressed trees. Geographically, mortality began on the margins of the DNC range (e.g., within the forest-steppe ecotone) and on terrain features with maximal water stress risk (narrow-shaped hilltops, convex steep south facing slopes, shallow well-drained soils). Currently, Siberian pine and fir decline observed within southern range of these species. In addition, air temperature and aridity increase promotes Siberian silkmoth (Dendrolimus sibiricus) outbreak that occurred about one degree northward of formerly range. Observing and predicting aridity increase will lead to the replacement of Siberian pine and fir within southern range of these species with more tolerant species (e.g., Pinus sylvestris, Larix spp.).

Verbal Learning and Memory in Cannabis and Alcohol Users: An Event-Related Potential Investigation

PubMed Central

Smith, Janette L.; De Blasio, Frances M.; Iredale, Jaimi M.; Matthews, Allison J.; Bruno, Raimondo; Dwyer, Michelle; Batt, Tessa; Fox, Allison M.; Solowij, Nadia; Mattick, Richard P.

2017-01-01

Aims: Long-term heavy use of cannabis and alcohol are known to be associated with memory impairments. In this study, we used event-related potentials to examine verbal learning and memory processing in a commonly used behavioral task. Method: We conducted two studies: first, a small pilot study of adolescent males, comprising 13 Drug-Naive Controls (DNC), 12 heavy drinkers (HD) and 8 cannabis users (CU). Second, a larger study of young adults, comprising 45 DNC (20 female), 39 HD (16 female), and 20 CU (9 female). In both studies, participants completed a modified verbal learning task (the Rey Auditory Verbal Learning Test, RAVLT) while brain electrical activity was recorded. ERPs were calculated for words which were subsequently remembered vs. those which were not remembered, and for presentations of learnt words, previously seen words, and new words in a subsequent recognition test. Pre-planned principal components analyses (PCA) were used to quantify the ERP components in these recall and recognition phases separately for each study. Results: Memory performance overall was slightly lower than published norms using the standardized RAVLT delivery, but was generally similar and showed the expected changes over trials. Few differences in performance were observed between groups; a notable exception was markedly poorer delayed recall in HD relative to DNC (Study 2). PCA identified components expected from prior research using other memory tasks. At encoding, there were no between-group differences in the usual P2 recall effect (larger for recalled than not-recalled words). However, alcohol-related differences were observed in a larger P540 (indexing recollection) in HD than DNC, and cannabis-related differences were observed in a smaller N340 (indexing familiarity) and a lack of previously seen > new words effect for P540 in Study 2. Conclusions: This study is the first examination of ERPs in the RAVLT in healthy control participants, as well as substance-using individuals, and represents an important advance in methodology. The results indicate alterations in recognition memory processing, which even if not manifesting in overt behavioral impairment, underline the potential for brain dysfunction with early exposure to alcohol and cannabis. PMID:29276495

Neuroanatomic and behavioral correlates of urinary dysfunction induced by vaginal distension in rats.

PubMed

Palacios, J L; Juárez, M; Morán, C; Xelhuantzi, N; Damaser, M S; Cruz, Y

2016-05-01

The aim of the present study was to use a model of simulated human childbirth in rats to determine the damage to genitourinary structures and behavioral signs of urinary dysfunction induced by vaginal distension (VD) in female rats. In experiment 1, the length of the genitourinary tract and the nerves associated with it were measured immediately after simulated human delivery induced by VD or sham (SH) procedures. Electroneurograms of the dorsal nerve of the clitoris (DNC) were also recorded. In experiment 2, histological characteristics of the bladder and major pelvic ganglion of VD and SH rats were evaluated. In experiment 3, urinary parameters were determined in conscious animals during 6 h of dark and 6 h of light before and 3 days after VD or SH procedures. VD significantly increased distal vagina width (P < 0.001) and the length of the motor branch of the sacral plexus (P < 0.05), DNC (P < 0.05), and vesical nerves (P < 0.01) and decreased DNC frequency and amplitude of firing. VD occluded the pelvic urethra, inducing urinary retention, hematomas in the bladder, and thinness of the epithelial (P < 0.05) and detrusor (P < 0.01) layers of the bladder. Major pelvic ganglion parameters were not modified after VD. Rats dripped urine in unusual places to void, without the stereotyped behavior of micturition after VD. The neuroanatomic injuries after VD occur alongside behavioral signs of urinary incontinence as determined by a new behavioral tool for assessing micturition in conscious animals.

LTTP profile variability.

DOT National Transportation Integrated Search

2001-09-01

The Long Term Pavement Performance (LTPP) program has been collecting profile and : International Roughness Index (IRI) information from more than 2,062 test sections since 1989 : using K.J. Law 690DNC optical sensor Profilometers. Analysis of the IR...

Dendrimer Nanocarriers for Transport Modulation Across Models of the Pulmonary Epithelium

PubMed Central

2015-01-01

The purpose of this study was to determine the effect of PEGylation on the interaction of poly(amidoamine) (PAMAM) dendrimer nanocarriers (DNCs) with in vitro and in vivo models of the pulmonary epithelium. Generation-3 PAMAM dendrimers with varying surface densities of PEG 1000 Da were synthesized and characterized. The results revealed that the apical to basolateral transport of DNCs across polarized Calu-3 monolayers increases with an increase in PEG surface density. DNC having the greatest number of PEG groups (n = 25) on their surface traversed at a rate 10-fold greater than its non-PEGylated counterpart, in spite of their larger size. This behavior was attributed to a significant reduction in charge density upon PEGylation. We also observed that PEGylation can be used to modulate cellular internalization. The total uptake of PEG-free DNC into polarized Calu-3 monolayers was 12% (w/w) vs 2% (w/w) for that with 25 PEGs. Polarization is also shown to be of great relevance in studying this in vitro model of the lung epithelium. The rate of absorption of DNCs administered to mice lungs increased dramatically when conjugated with 25 PEG groups, thus supporting the in vitro results. The exposure obtained for the DNC with 25PEG was determined to be very high, with peak plasma concentrations reaching 5 μg·mL–1 within 3 h. The combined in vitro and in vivo results shown here demonstrate that PEGylation can be potentially used to modulate the internalization and transport of DNCs across the pulmonary epithelium. Modified dendrimers thereby may serve as a valuable platform that can be tailored to target the lung tissue for treating local diseases, or the circulation, using the lung as pathway to the bloodstream, for systemic delivery. PMID:25455560

Dendrimer nanocarriers for transport modulation across models of the pulmonary epithelium.

PubMed

Bharatwaj, Balaji; Mohammad, Abdul Khader; Dimovski, Radovan; Cassio, Fernando L; Bazito, Reinaldo C; Conti, Denise; Fu, Qiang; Reineke, Joshua; da Rocha, Sandro R P

2015-03-02

The purpose of this study was to determine the effect of PEGylation on the interaction of poly(amidoamine) (PAMAM) dendrimer nanocarriers (DNCs) with in vitro and in vivo models of the pulmonary epithelium. Generation-3 PAMAM dendrimers with varying surface densities of PEG 1000 Da were synthesized and characterized. The results revealed that the apical to basolateral transport of DNCs across polarized Calu-3 monolayers increases with an increase in PEG surface density. DNC having the greatest number of PEG groups (n = 25) on their surface traversed at a rate 10-fold greater than its non-PEGylated counterpart, in spite of their larger size. This behavior was attributed to a significant reduction in charge density upon PEGylation. We also observed that PEGylation can be used to modulate cellular internalization. The total uptake of PEG-free DNC into polarized Calu-3 monolayers was 12% (w/w) vs 2% (w/w) for that with 25 PEGs. Polarization is also shown to be of great relevance in studying this in vitro model of the lung epithelium. The rate of absorption of DNCs administered to mice lungs increased dramatically when conjugated with 25 PEG groups, thus supporting the in vitro results. The exposure obtained for the DNC with 25PEG was determined to be very high, with peak plasma concentrations reaching 5 μg·mL(-1) within 3 h. The combined in vitro and in vivo results shown here demonstrate that PEGylation can be potentially used to modulate the internalization and transport of DNCs across the pulmonary epithelium. Modified dendrimers thereby may serve as a valuable platform that can be tailored to target the lung tissue for treating local diseases, or the circulation, using the lung as pathway to the bloodstream, for systemic delivery.

ClueNet: Clustering a temporal network based on topological similarity rather than denseness.

PubMed

Crawford, Joseph; Milenković, Tijana

2018-01-01

Network clustering is a very popular topic in the network science field. Its goal is to divide (partition) the network into groups (clusters or communities) of "topologically related" nodes, where the resulting topology-based clusters are expected to "correlate" well with node label information, i.e., metadata, such as cellular functions of genes/proteins in biological networks, or age or gender of people in social networks. Even for static data, the problem of network clustering is complex. For dynamic data, the problem is even more complex, due to an additional dimension of the data-their temporal (evolving) nature. Since the problem is computationally intractable, heuristic approaches need to be sought. Existing approaches for dynamic network clustering (DNC) have drawbacks. First, they assume that nodes should be in the same cluster if they are densely interconnected within the network. We hypothesize that in some applications, it might be of interest to cluster nodes that are topologically similar to each other instead of or in addition to requiring the nodes to be densely interconnected. Second, they ignore temporal information in their early steps, and when they do consider this information later on, they do so implicitly. We hypothesize that capturing temporal information earlier in the clustering process and doing so explicitly will improve results. We test these two hypotheses via our new approach called ClueNet. We evaluate ClueNet against six existing DNC methods on both social networks capturing evolving interactions between individuals (such as interactions between students in a high school) and biological networks capturing interactions between biomolecules in the cell at different ages. We find that ClueNet is superior in over 83% of all evaluation tests. As more real-world dynamic data are becoming available, DNC and thus ClueNet will only continue to gain importance.

Conifer Decline and Mortality in Siberia

NASA Astrophysics Data System (ADS)

Kharuk, V.; Im, S.; Ranson, K.

2015-12-01

"Dark needle conifer" (DNC: Abies sibirica, Pinus sibirica and Picea obovata) decline and mortality increase were documented in Russia during recent decades. Here we analyzed causes and scale of Siberian pine and fir mortality in Altai-Sayan and Baikal Lake Regions and West Siberian Plane based on in situdata and remote sensing (QuickBird, Landsat, GRACE). Geographically, mortality began on the margins of the DNC range (i.e., within the forest-steppe and conifer-broadleaf ecotones) and on terrain features with maximal water stress risk (narrow-shaped hilltops, convex steep south facing slopes, shallow well-drained soils). Within ridges, mortality occurred mainly along mountain passes, where stands faced drying winds. Regularly mortality was observed to decrease with elevation increase with the exception of Baikal Lake Mountains, where it was minimal near the lake shore and increased with elevation (up to about 1000 m a.s.l.). Siberian pine and fir mortality followed a drying trend with consecutive droughts since the 1980s. Dendrochronology analysis showed that mortality was correlated with vapor pressure deficit increase, drought index, soil moisture decrease and occurrence of late frosts. In Baikal region Siberian pine mortality correlated with Baikal watershed meteorological variables. An impact of previous year climate conditions on the current growth was found (r2 = 0.6). Thus, water-stressed trees became sensitive to bark beetles and fungi impact (including Polygraphus proximus and Heterobasidion annosum). At present, an increase in mortality is observed within the majority of DNC range. Results obtained also showed a primary role of water stress in that phenomenon with a secondary role of bark beetles and fungi attacks. In future climate with increased drought severity and frequency Siberian pine and fir will partly disappear from its current range, and will be substituted by drought-tolerant species (e.g., Pinus silvestris, Larix sibirica).

Sleep restores behavioral plasticity to Drosophila mutants

PubMed Central

Dissel, Stephane; Angadi, Veena; Kirszenblat, Leonie; Suzuki, Yasuko; Donlea, Jeff; Klose, Markus; Koch, Zachary; English, Denis; Winsky-Sommerer, Raphaelle; van Swinderen, Bruno; Shaw, Paul J.

2015-01-01

SUMMARY Given the role that sleep plays in modulating plasticity, we hypothesized that increasing sleep would restore memory to canonical memory mutants without specifically rescuing the causal molecular-lesion. Sleep was increased using three independent strategies: activating the dorsal Fan Shaped Body (FB), increasing the expression of Fatty acid binding protein (dFabp) or by administering the GABA-A agonist 4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridine-3-ol (THIP). Short-term memory (STM) or Long-term memory (LTM) was evaluated in rutabaga (rut) and dunce (dnc) mutants using Aversive Phototaxic Suppression (APS) and courtship conditioning. Each of the three independent strategies increased sleep and restored memory to rut and dnc mutants. Importantly, inducing sleep also reverses memory defects in a Drosophila model of Alzheimer’s disease. Together these data demonstrate that sleep plays a more fundamental role in modulating behavioral plasticity than previously appreciated and suggests that increasing sleep may benefit patients with certain neurological disorders. PMID:25913403

INCONSISTENCIES BETWEEN CYTOKINE PROFILES, ANTIBODY RESPONSES, AND RESPIRATORY HYPERRESPONSIVENESS FOLLOWING DERMAL EXPOSURE TO ISOCYANATES

EPA Science Inventory

Cytokine profiling of local lymph node responses has been proposed as a simple test to identify chemicals, such as low molecular weight diisocyanates, that pose a significant risk of occupational asthma. Previously, we reported cytokine mRNA profiles for dinitrochlorobenzene (DNC...

Back-calculation of layer parameters for LTPP test sections, volume II : layered elastic analysis for flexible and rigid pavements.

DOT National Transportation Integrated Search

2000-09-01

The Long Term Pavement Performance (LTPP) program has been collecting profile and : International Roughness Index (IRI) information from more than 2,062 test sections since 1989 : using K.J. Law 690DNC optical sensor Profilometers. Analysis of the IR...

78 FR 77708 - Notice of Continuation of Visitor Services

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-24

... been extended to the maximum allowable under 36 CFR 51.23. Under the provisions of current concession... Entertainment Recreation Area. Services, Inc. GLCA003-69 ARAMARK Sports and Glen Canyon National Entertainment Recreation Area. Services, Inc. GRCA003-97 D.N.C. Parks and Grand Canyon Resorts at Grand National Park...

Dendrosomal curcumin inhibits metastatic potential of human SW480 colon cancer cells through Down-regulation of Claudin1, Zeb1 and Hef1-1 gene expression.

PubMed

Dehghan Esmatabadi, Mohammad Javad; Farhangi, Baharak; Safari, Zahra; Kazerooni, Hanif; Shirzad, Hadi; Zolghadr, Fatemeh; Sadeghizadeh, Majid

2015-01-01

Colon cancer is one of the leading causes of cancer-associated death worldwide. The prognosis for advanced colorectal cancers remains dismal, mainly due to the propensity for metastatic progression. Accordingly, there is a need for effective anti-metastasis therapeutic agents. Since a great body of research has indicated anticancer effects for curcumin, we investigated the effects of dendrosomal curcumin (DNC) on cellular migration and adhesion of human SW480 cells and possible molecular mechanisms involved. Different methods were applied in this study including MTT, Scratch and adhesion assays as well as real-time PCR and transwell chamber assays. Based on the results obtained, DNC inhibits metastasis by decreasing Hef 1, Zeb 1 and Claudin 1 mRNA levels and can reduce SW480 cell proliferation with IC50values of 15.9, 11.6 and 7.64 μM at 24, 48 and 72 h post-treatment. Thus it might be considered as a safe formulation for therapeutic purpose in colorectal cancer cases.

Coordinated regulation of accessory genetic elements produces cyclic di-nucleotides for V. cholerae virulence.

PubMed

Davies, Bryan W; Bogard, Ryan W; Young, Travis S; Mekalanos, John J

2012-04-13

The function of the Vibrio 7(th) pandemic island-1 (VSP-1) in cholera pathogenesis has remained obscure. Utilizing chromatin immunoprecipitation sequencing and RNA sequencing to map the regulon of the master virulence regulator ToxT, we identify a TCP island-encoded small RNA that reduces the expression of a previously unrecognized VSP-1-encoded transcription factor termed VspR. VspR modulates the expression of several VSP-1 genes including one that encodes a novel class of di-nucleotide cyclase (DncV), which preferentially synthesizes a previously undescribed hybrid cyclic AMP-GMP molecule. We show that DncV is required for efficient intestinal colonization and downregulates V. cholerae chemotaxis, a phenotype previously associated with hyperinfectivity. This pathway couples the actions of previously disparate genomic islands, defines VSP-1 as a pathogenicity island in V. cholerae, and implicates its occurrence in 7(th) pandemic strains as a benefit for host adaptation through the production of a regulatory cyclic di-nucleotide. Copyright © 2012 Elsevier Inc. All rights reserved.

New insights into restless genital syndrome: static mechanical hyperesthesia and neuropathy of the nervus dorsalis clitoridis.

PubMed

Waldinger, Marcel D; Venema, Pieter L; van Gils, Ad P G; Schweitzer, Dave H

2009-10-01

Systematic study of dysesthetic and paresthetic regions contributing to persistent genital arousal in women with restless genital syndrome (ReGS) is needed for its clinical management. To investigate distinct localizations of ReGS. Twenty-three women, fulfilling all five criteria of persistent genital arousal disorder were included into the study. In-depth interviews, routine and hormonal investigations, electroencephalographs, and magnetic resonance imaging (MRI) of brain and pelvis were performed in all women. The localizations of genital sensations were investigated by physical examination of the ramus inferior of the pubic bone (RIPB) and by sensory testing of the skin of the genital area with a cotton swab (genital tactile mapping test or GTM test). Sensitivity of RIPB, GTM test. Of 23 women included in the study, 18(78%), 16(69%), and 12(52%) reported restless legs syndrome, overactive bladder syndrome, and urethra hypersensitivity. Intolerance of tight clothes and underwear (allodynia or hyperpathia) was reported by 19 (83%) women. All women were diagnosed with ReGS. Sitting aggravated ReGS in 20(87%) women. In all women, MRI showed pelvic varices of different degree in the vagina (91%), labia minora and/or majora (35%), and uterus (30%). Finger touch investigation of the dorsal nerve of the clitoris (DNC) along the RIPB provoked ReGS in all women. Sensory testing showed unilateral and bilateral static mechanical Hyperesthesia on various trigger points in the dermatome of the pudendal nerve, particularly in the part innervated by DNC, including pelvic bone. In three women, sensory testing induced an uninhibited orgasm during physical examination. ReGS is highly associated with pelvic varices and with sensory neuropathy of the pudendal nerve and DNC, whose symptoms are suggestive for small fiber neuropathy (SFN). Physical examination for static mechanical Hyperesthesia is a diagnostic test for ReGS and is recommended for all individuals with complaints of persistent restless genital arousal in absence of sexual desire.

ClueNet: Clustering a temporal network based on topological similarity rather than denseness

PubMed Central

Milenković, Tijana

2018-01-01

Network clustering is a very popular topic in the network science field. Its goal is to divide (partition) the network into groups (clusters or communities) of “topologically related” nodes, where the resulting topology-based clusters are expected to “correlate” well with node label information, i.e., metadata, such as cellular functions of genes/proteins in biological networks, or age or gender of people in social networks. Even for static data, the problem of network clustering is complex. For dynamic data, the problem is even more complex, due to an additional dimension of the data—their temporal (evolving) nature. Since the problem is computationally intractable, heuristic approaches need to be sought. Existing approaches for dynamic network clustering (DNC) have drawbacks. First, they assume that nodes should be in the same cluster if they are densely interconnected within the network. We hypothesize that in some applications, it might be of interest to cluster nodes that are topologically similar to each other instead of or in addition to requiring the nodes to be densely interconnected. Second, they ignore temporal information in their early steps, and when they do consider this information later on, they do so implicitly. We hypothesize that capturing temporal information earlier in the clustering process and doing so explicitly will improve results. We test these two hypotheses via our new approach called ClueNet. We evaluate ClueNet against six existing DNC methods on both social networks capturing evolving interactions between individuals (such as interactions between students in a high school) and biological networks capturing interactions between biomolecules in the cell at different ages. We find that ClueNet is superior in over 83% of all evaluation tests. As more real-world dynamic data are becoming available, DNC and thus ClueNet will only continue to gain importance. PMID:29738568

Resonant Acoustic Determination of Complex Elastic Moduli

DTIC Science & Technology

1991-03-01

Classification uncssified/.unimled - sae as report [] DnC ui, Unclassified 22a Name of Responsible Individual 22b Telephone (Include Area code) 22c Office Symbol...4090 DISP " Run: "Block2$ 4100 WAIT 1 4110 DISP "Mode: "Blocic3$ 4120 WAIT 1 4130 DISP" Date: "Block4$ 4140 WAIT 1 4150 DISP "Mass: "Mass;"grams

The Chicago 8 Trial, 40 Years Later: A Case Study in Teaching "U.S. v. Dellinger" (1969)

ERIC Educational Resources Information Center

Barr, Jeanne Polk

2009-01-01

Growing up in an era when protest at national political conventions is carefully contained in "free-speech zones" (often physically removed from the site of the official conventions), students today may have a difficult time conceptualizing the tumultuous scene that was the 1968 Democratic National Convention (DNC) in Chicago. Fueled by…

Theoretical microwave spectral constants for C2N, C2N/+/, and C3H

NASA Technical Reports Server (NTRS)

Green, S.

1980-01-01

Theoretical microwave spectral constants have been computed for C2N, C3H, and C2N(+). For C2N these are compared with values obtained from optical data. Calculated hyperfine constants are also presented for HNC, DNC, and HCNH(+). The possibility of observing these species in dense interstellar clouds is discussed.

Effect of CYP3A perpetrators on ibrutinib exposure in healthy participants.

PubMed

de Jong, Jan; Skee, Donna; Murphy, Joe; Sukbuntherng, Juthamas; Hellemans, Peter; Smit, Johan; de Vries, Ronald; Jiao, Juhui James; Snoeys, Jan; Mannaert, Erik

2015-08-01

Ibrutinib (PCI-32765), a potent covalent inhibitor of Bruton's tyrosine kinase, has shown efficacy against a variety of B-cell malignancies. Given the prominent role of CYP3A in ibrutinib metabolism, effect of coadministration of CYP3A perpetrators with ibrutinib was evaluated in healthy adults. Ibrutinib (120 mg [Study 1, fasted], 560 mg [studies 2 (fasted), and 3 (nonfasted)]) was given alone and with ketoconazole [Study 1; 400 mg q.d.], rifampin [Study 2; 600 mg q.d.], and grapefruit juice [GFJ, Study 3]. Lower doses of ibrutinib were used together with CYP3A inhibitors [Study 1: 40 mg; Study 3: 140 mg], as safety precaution. Under fasted condition, ketoconazole increased ibrutinib dose-normalized (DN) exposure [DN-AUClast: 24-fold; DN-C max: 29-fold], rifampin decreased ibrutinib exposure [C max: 13-fold; AUClast: 10-fold]. Under nonfasted condition, GFJ caused a moderate increase [DN-C max: 3.5-fold; DN-AUC: 2.2-fold], most likely through inhibition of intestinal CYP3A. Half-life was not affected by CYP perpetrators indicating the interaction was mainly on first-pass extraction. All treatments were well-tolerated.

Celebrating National Women's History Month

NASA Image and Video Library

2013-03-14

Lori Garver, NASA Deputy Administrator gave opening remarks at an event at NASA Headquarters celebrating National Women's History Month, Thursday, March 14, 2013 in Washington. This year's keynote speaker was Donna Brazile, adjunct professor at Georgetown University, syndicated newspaper columnist and vice chair of voter registration and participation at the Democratic National Committee (DNC). The theme of this year's program was "Women Inspiring Innovation Through Imagination." Photo Credit: (NASA/Carla Cioffi)

Celebrating National Women's History Month

NASA Image and Video Library

2013-03-14

NASA Administrator Charles Bolden gave the introduction to the keynote speaker at an event celebrating National Women's History Month at NASA Headquarters, Thursday, March 14, 2013 in Washington. This year's keynote speaker was Donna Brazile, adjunct professor at Georgetown University, syndicated newspaper columnist and vice chair of voter registration and participation at the Democratic National Committee (DNC). The theme of this year's program was "Women Inspiring Innovation Through Imagination." Photo Credit: (NASA/Carla Cioffi)

Cross-Service Investigation of Geographical Information Systems

DTIC Science & Technology

2004-03-01

Figure 8 illustrates the combined layers. Information for the layers is stored in a database format. The two types of storage are vector and...raster models. In a vector model, the image and information are stored as geometric objects such as points, lines, or polygons. In a raster model...DNCs are a vector -based digital database with selected maritime significant physical features from hydrographic charts. Layers within the DNC are data

Pre Conference Hazardous Materials Workshop, West/East Coast Safety Conference, held 3-4 October/31 October - 1 November 1981,

DTIC Science & Technology

1981-01-01

itation and ulceration of skin Blacher,. picklers (nicals). refiners (metals). tinners. c,".:mical manufactur- ing Hydrofluoric X Severe burning of skin...strong solutions are used) DNc,.g, felt hat industry Nitric X Severe skin burns and ulcers Nitric acid worker%, electroplaters. met- al refincr, acid...Fertilije, makers, gr:cultural workers. Calcium cyanamide alkali salt makers Calcium oxide, carbon- X Dermatitis,. burns , or ulcers Lime %orkers

dnc-1/dynactin 1 Knockdown Disrupts Transport of Autophagosomes and Induces Motor Neuron Degeneration

PubMed Central

Ikenaka, Kensuke; Kawai, Kaori; Katsuno, Masahisa; Huang, Zhe; Jiang, Yue-Mei; Iguchi, Yohei; Kobayashi, Kyogo; Kimata, Tsubasa; Waza, Masahiro; Tanaka, Fumiaki; Mori, Ikue; Sobue, Gen

2013-01-01

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. We previously showed that the expression of dynactin 1, an axon motor protein regulating retrograde transport, is markedly reduced in spinal motor neurons of sporadic ALS patients, although the mechanisms by which decreased dynactin 1 levels cause neurodegeneration have yet to be elucidated. The accumulation of autophagosomes in degenerated motor neurons is another key pathological feature of sporadic ALS. Since autophagosomes are cargo of dynein/dynactin complexes and play a crucial role in the turnover of several organelles and proteins, we hypothesized that the quantitative loss of dynactin 1 disrupts the transport of autophagosomes and induces the degeneration of motor neuron. In the present study, we generated a Caenorhabditis elegans model in which the expression of DNC-1, the homolog of dynactin 1, is specifically knocked down in motor neurons. This model exhibited severe motor defects together with axonal and neuronal degeneration. We also observed impaired movement and increased number of autophagosomes in the degenerated neurons. Furthermore, the combination of rapamycin, an activator of autophagy, and trichostatin which facilitates axonal transport dramatically ameliorated the motor phenotype and axonal degeneration of this model. Thus, our results suggest that decreased expression of dynactin 1 induces motor neuron degeneration and that the transport of autophagosomes is a novel and substantial therapeutic target for motor neuron degeneration. PMID:23408943

Astrochemical Properties of Planck Cold Clumps

NASA Astrophysics Data System (ADS)

Tatematsu, Ken'ichi; Liu, Tie; Ohashi, Satoshi; Sanhueza, Patricio; Nguyen Lu'o'ng, Quang; Hirota, Tomoya; Liu, Sheng-Yuan; Hirano, Naomi; Choi, Minho; Kang, Miju; Thompson, Mark A.; Fuller, Gary; Wu, Yuefang; Li, Di; Di Francesco, James; Kim, Kee-Tae; Wang, Ke; Ristorcelli, Isabelle; Juvela, Mika; Shinnaga, Hiroko; Cunningham, Maria; Saito, Masao; Lee, Jeong-Eun; Tóth, L. Viktor; He, Jinhua; Sakai, Takeshi; Kim, Jungha; JCMT Large Program "SCOPE" Collaboration; TRAO Key Science Program "TOP" Collaboration

2017-02-01

We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N2H+ distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC3N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N2H+ emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, HN13C, N2D+, and cyclic-C3H2 toward nine clumps. The detection rate of N2D+ is 50%. Furthermore, we observed the NH3 emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (≲20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N2H+ core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N2D+. These two clumps are most likely on the verge of star formation. We introduce the chemical evolution factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps.

Electrical features of new DNC, CNC system viewed

NASA Astrophysics Data System (ADS)

Fritzsch, W.; Kochan, D.; Schaller, J.; Zander, H. J.

1985-03-01

Control structures capable of solving the problems of a flexible minial-labor manufacturing process are analyzed. The present state of development of equipment technology is described, and possible ways of modeling control processes are surveyed. Concepts which are frequently differently interpreted in various specialized disciplines are systematized, with a view toward creating the prerequisites for interdisciplinary cooperation. Problems and information flow during the preparatory and performance phases of manufacturing are examined with respect to coupling CAD/CAM functions. Mathematical modeling for direct numerical control is explored.

Three descending interneurons reporting deviation from course in the locust. I. Anatomy.

PubMed

Griss, C; Rowell, C H

1986-06-01

Three descending brain interneurons (DNI, DNM, DNC) are described from Locusta migratoria. All are paired, dorsally situated neurons, with soma in the protocerebrum, input dendrites in the proto- and deuterocerebrum, and a single axon running to the metathoracic ganglion and sometimes further. In DNI the soma and all cerebral arborizations lie ipsilateral to the axon. Discrete regions of arborization lie in the ipsilateral and medial ocellar tracts, the midprotocerebrum and the deuterocerebrum. In the other ganglia the axon branches only ipsilaterally, principally laterally in the flight motor neuropil but also towards the midline. DNC is similarly organized to DNI, but the cell crosses the midline in the brain. Soma, the single projection into a lateral ocellar tract, and the midprotocerebral arborization all lie contralateral to the axon. The deuterocerebral arborization is, however, ipsilateral to the axon. The pattern of projections in the remaining ganglia resembles that of DNI. The soma and all cerebral arborizations of DNM lie ipsilateral to the axon. The arborization is only weakly subdivided into protocerebral, deuterocerebral and medial ocellar tract regions. In the remaining ganglia the arborization extends bilaterally to similar areas of both left and right flight motor neuropil. A table of synonymy is given, equating the various names used for these neurons by previous authors. The morphology correlates well with the known input and output connections. They respond physiologically to deviations from the normal flight posture mediated by ocelli, eyes and wind hairs and connect to the thoracic flight apparatus.

Astrochemical Properties of Planck Cold Clumps

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

Tatematsu, Ken’ichi; Sanhueza, Patricio; Nguyễn Lu’o’ng, Quang

We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N{sub 2}H{sup +} distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC{sub 3}N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N{sub 2}H{sup +} emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, HN{sup 13}C, N{sub 2}D{sup +}, and cyclic-C{sub 3}H{sub 2}more » toward nine clumps. The detection rate of N{sub 2}D{sup +} is 50%. Furthermore, we observed the NH{sub 3} emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (≲20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N{sub 2}H{sup +} core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N{sub 2}D{sup +}. These two clumps are most likely on the verge of star formation. We introduce the chemical evolution factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps.« less

Fir Decline and Mortality in the Southern Siberian Mountains

NASA Technical Reports Server (NTRS)

Kharuk, Viacheslav I.; Im, Sergei T.; Petrov, Ilya A.; Dvinskaya, Mariya, L.; Fedotova, Elena V.; Ranson, Kenneth J.

2016-01-01

Increased dieback and mortality of dark needle conifer (DNC) stands (composed of fir (Abies sibirica),Siberian pine (Pinus sibirica) and spruce (Picea obovata))were documented in Russia during recent decades. Here we analyzed spatial and temporal patterns of fir decline and mortality in the southern Siberian Mountains based on satellite, in situ and dendrochronological data. The studied stands are located within the boundary between DNC taiga to the north and forest-steppe to the south. Fir decline and mortality were observed to originate where topographic features contributed to maximal water-stress risk, i.e., steep (1825),convex, south-facing slopes with a shallow well-drained root zone. Fir regeneration survived droughts and increased stem radial growth, while upper canopy trees died. Tree ring width(TRW) growth negatively correlated with vapor pressure deficit (VPD), drought index and occurrence of late frosts, and positively with soil water content. Previous year growth conditions (i.e., drought index, VPD, soil water anomalies)have a high impact on current TRW (r 0.600.74). Fir mortality was induced by increased water stress and severe droughts (as a primary factor) in synergy with bark-beetles and fungi attacks (as secondary factors). Dendrochronology data indicated that fir mortality is a periodic process. In a future climate with increased aridity and drought frequency, fir (and Siberian pine) may disappear from portions of its current range (primarily within the boundary with the forest steppe)and is likely to be replaced by drought-tolerant species such as Pinus sylvestris and Larix sibirica.

cAMP signaling mediates behavioral flexibility and consolidation of social status in Drosophila aggression.

PubMed

Chouhan, Nitin Singh; Mohan, Krithika; Ghose, Aurnab

2017-12-01

Social rituals, such as male-male aggression in Drosophila , are often stereotyped and the component behavioral patterns modular. The likelihood of transition from one behavioral pattern to another is malleable by experience and confers flexibility to the behavioral repertoire. Experience-dependent modification of innate aggressive behavior in flies alters fighting strategies during fights and establishes dominant-subordinate relationships. Dominance hierarchies resulting from agonistic encounters are consolidated to longer-lasting, social-status-dependent behavioral modifications, resulting in a robust loser effect. We showed that cAMP dynamics regulated by the calcium-calmodulin-dependent adenylyl cyclase, Rut, and the cAMP phosphodiesterase, Dnc, but not the Amn gene product, in specific neuronal groups of the mushroom body and central complex, mediate behavioral plasticity necessary to establish dominant-subordinate relationships. rut and dnc mutant flies were unable to alter fighting strategies and establish dominance relationships during agonistic interactions. This real-time flexibility during a fight was independent of changes in aggression levels. Longer-term consolidation of social status in the form of a loser effect, however, required additional Amn -dependent inputs to cAMP signaling and involved a circuit-level association between the α/β and γ neurons of the mushroom body. Our findings implicate cAMP signaling in mediating the plasticity of behavioral patterns in aggressive behavior and in the generation of a temporally stable memory trace that manifests as a loser effect. © 2017. Published by The Company of Biologists Ltd.

Vertical Distribution of Soil Denitrifying Communities in a Wet Sclerophyll Forest under Long-Term Repeated Burning.

PubMed

Liu, Xian; Chen, Chengrong; Wang, Weijin; Hughes, Jane M; Lewis, Tom; Hou, Enqing; Shen, Jupei

2015-11-01

Soil biogeochemical cycles are largely mediated by microorganisms, while fire significantly modifies biogeochemical cycles mainly via altering microbial community and substrate availability. Majority of studies on fire effects have focused on the surface soil; therefore, our understanding of the vertical distribution of microbial communities and the impacts of fire on nitrogen (N) dynamics in the soil profile is limited. Here, we examined the changes of soil denitrification capacity (DNC) and denitrifying communities with depth under different burning regimes, and their interaction with environmental gradients along the soil profile. Results showed that soil depth had a more pronounced impact than the burning treatment on the bacterial community size. The abundance of 16S rRNA and denitrification genes (narG, nirK, and nirS) declined exponentially with soil depth. Surprisingly, the nosZ-harboring denitrifiers were enriched in the deeper soil layers, which was likely to indicate that the nosZ-harboring denitrifiers could better adapt to the stress conditions (i.e., oxygen deficiency, nutrient limitation, etc.) than other denitrifiers. Soil nutrients, including dissolved organic carbon (DOC), total soluble N (TSN), ammonium (NH(4)(+)), and nitrate (NO(3)(-)), declined significantly with soil depth, which probably contributed to the vertical distribution of denitrifying communities. Soil DNC decreased significantly with soil depth, which was negligible in the depths below 20 cm. These findings have provided new insights into niche separation of the N-cycling functional guilds along the soil profile, under a varied fire disturbance regime.

Integration of energy analytics and smart energy microgrid into mobile medicine operations for the 2012 Democratic National Convention.

PubMed

McCahill, Peter W; Noste, Erin E; Rossman, A J; Callaway, David W

2014-12-01

Disasters create major strain on energy infrastructure in affected communities. Advances in microgrid technology offer the potential to improve "off-grid" mobile disaster medical response capabilities beyond traditional diesel generation. The Carolinas Medical Center's mobile emergency medical unit (MED-1) Green Project (M1G) is a multi-phase project designed to demonstrate the benefits of integrating distributive generation (DG), high-efficiency batteries, and "smart" energy utilization in support of major out-of-hospital medical response operations. Carolinas MED-1 is a mobile medical facility composed of a fleet of vehicles and trailers that provides comprehensive medical care capacities to support disaster response and special-event operations. The M1G project partnered with local energy companies to deploy energy analytics and an energy microgrid in support of mobile clinical operations for the 2012 Democratic National Convention (DNC) in Charlotte, North Carolina (USA). Energy use data recorded throughout the DNC were analyzed to create energy utilization models that integrate advanced battery technology, solar photovoltaic (PV), and energy conservation measures (ECM) to improve future disaster response operations. The generators that supply power for MED-1 have a minimum loading ratio (MLR) of 30 kVA. This means that loads below 30 kW lead to diesel fuel consumption at the same rate as a 30 kW load. Data gathered from the two DNC training and support deployments showed the maximum load of MED-1 to be around 20 kW. This discrepancy in MLR versus actual load leads to significant energy waste. The lack of an energy storage system reduces generator efficiency and limits integration of alternative energy generation strategies. A storage system would also allow for alternative generation sources, such as PV, to be incorporated. Modeling with a 450 kWh battery bank and 13.5 kW PV array showed a 2-fold increase in potential deployment times using the same amount of fuel versus the current conventional system. The M1G Project demonstrated that the incorporation of a microgrid energy management system and a modern battery system maximize the MED-1 generators' output. Using a 450 kWh battery bank and 13.5 kW PV array, deployment operations time could be more than doubled before refueling. This marks a dramatic increase in patient care capabilities and has significant public health implications. The results highlight the value of smart-microgrid technology in developing energy independent mobile medical capabilities and expanding cost-effective, high-quality medical response.

A Delayed Neutron Counting System for the Analysis of Special Nuclear Materials

NASA Astrophysics Data System (ADS)

Sellers, Madison Theresa

Nuclear forensic analysis is a modem science that uses numerous analytical techniques to identify and attribute nuclear materials in the event of a nuclear explosion, radiological terrorist attack or the interception of illicit nuclear material smuggling. The Canadian Department of National Defence has participated in recent international exercises that have highlighted the Nation's requirement to develop nuclear forensics expertise, protocol and capabilities, specifically pertaining to the analysis of special nuclear materials (SNM). A delayed neutron counting (DNC) system has been designed and established at the Royal Military College of Canada (RMC) to enhance the Government's SNM analysis capabilities. This analytical technique complements those already at RMC by providing a rapid and non-destructive method for the analysis of the fissile isotopes of both uranium (U) and plutonium (Pu). The SLOWPOKE-2 reactor at RMC produces a predominately thermal neutron flux. These neutrons induce fission in the SNM isotopes 233U, 235U and 239Pu releasing prompt fast neutrons, energy and radioactive fission fragments. Some of these fission fragments undergo beta - decay and subsequently emit neutrons, which can be recorded by an array of sensitive 3He detectors. The significant time period between the fission process and the release of these neutrons results in their identification as 'delayed neutrons'. The recorded neutron spectrum varies with time and the count rate curve is unique to each fissile isotope. In-house software, developed by this project, can analyze this delayed neutron curve and provides the fissile mass in the sample. Extensive characterization of the DNC system has been performed with natural U samples with 235 U content ranging from 2--7 microg. The system efficiency and dead time behaviour determined by the natural uranium sample analyses were validated by depleted uranium samples with similar quantities of 235 U resulting in a typical relative error of 3.6%. The system has accurately determined 235U content over three orders of magnitude with 235U amounts as low as 10 ng. The results have also been proven to be independent of small variations in total analyte volume and geometry, indicating that it is an ideal technique for the analysis of samples containing SNM in a variety of different matrices. The Analytical Sciences Group at RMC plans to continue DNC system development to include 233U and 239pu analysis and mixtures of SNM isotopes. Keywords: delayed neutron counting, special nuclear materials, nuclear forensics.

Bill spurs efforts to improve forecasting of inland flooding from tropical storms

NASA Astrophysics Data System (ADS)

Showstack, Randy

Newly-enacted U.S. legislation to reduce the threat of inland flooding from tropical storms could provide a "laser beam" focus to dealing with this natural hazard, according to Rep. Bob Etheridge (D-N.C.), the chief sponsor of the bill.The Tropical Cyclone Inland Forecasting Improvement and Warning System Development Act, (PL. 107-253), signed into law on 29 October, authorizes the National Oceanic and Atmospheric Administration's U.S. Weather Research Program (USWRP) to improve the capability to accurately forecast inland flooding from tropical storms through research and modeling.

Celebrating National Women's History Month

NASA Image and Video Library

2013-03-14

Donna Brazile, adjunct professor at Georgetown University, syndicated newspaper columnist and vice chair of voter registration and participation at the Democratic National Committee (DNC), gives the keynote speech at a program celebrating National Women's History Month at NASA Headquarters, Thursday, March 14, 2013 in Washington. The theme of this year's program was "Women Inspiring Innovation Through Imagination." The program was sponsored by the HQ Equal Opportunity and Diversity Management Division at NASA Headquarters and commemorates the 100th Anniversary of the Women's Suffrage March on Washington. Photo Credit: (NASA/Carla Cioffi)

Binding of basic amphipathic peptides to neutral phospholipid membranes: a thermodynamic study applied to dansyl-labeled melittin and substance P analogues.

PubMed

Pérez-Payá, E; Porcar, I; Gómez, C M; Pedrós, J; Campos, A; Abad, C

1997-08-01

A thermodynamic approach is proposed to quantitatively analyze the binding isotherms of peptides to model membranes as a function of one adjustable parameter, the actual peptide charge in solution z(p)+. The main features of this approach are a theoretical expression for the partition coefficient calculated from the molar free energies of the peptide in the aqueous and lipid phases, an equation proposed by S. Stankowski [(1991) Biophysical Journal, Vol. 60, p. 341] to evaluate the activity coefficient of the peptide in the lipid phase, and the Debye-Hückel equation that quantifies the activity coefficient of the peptide in the aqueous phase. To assess the validity of this approach we have studied, by means of steady-state fluorescence spectroscopy, the interaction of basic amphipathic peptides such as melittin and its dansylcadaverine analogue (DNC-melittin), as well as a new fluorescent analogue of substance P, SP (DNC-SP) with neutral phospholipid membranes. A consistent quantitative analysis of each binding curve was achieved. The z(p)+ values obtained were always found to be lower than the physical charge of the peptide. These z(p)+ values can be rationalized by considering that the peptide charged groups are strongly associated with counterions in buffer solution at a given ionic strength. The partition coefficients theoretically derived using the z(p)+ values were in agreement with those deduced from the Gouy-Chapman formalism. Ultimately, from the z(p)+ values the molar free energies for the free and lipid-bound states of the peptides have been calculated.

Fir Decline and Mortality in the Southern Siberian Mountains

NASA Technical Reports Server (NTRS)

Kharuk, Viacheslav I.; Im, Sergei T.; Petrov, Ilya A.; Dvinskaya, Mariya, L.; Fedotova, Elena V.; Ranson, Kenneth J.

2016-01-01

Increased dieback and mortality of dark needle conifer (DNC) stands (composed of fir (Abies sibirica),Siberian pine (Pinus sibirica) and spruce (Picea obovata)) were documented in Russia during recent decades. Here we analyzed spatial and temporal patterns of fir decline and mortality in the southern Siberian Mountains based on satellite, in situ and dendrochronological data. The studied stands are located within the boundary between DNC taiga to the north and forest-steppe to the south. Fir decline and mortality were observed to originate where topographic features contributed to maximal water-stress risk, i.e., steep (18 deg to 25 deg), convex, south-facing slopes with a shallow well-drained root zone. Fir regeneration survived droughts and increased stem radial growth, while upper canopy trees died. Tree ring width (TRW) growth negatively correlated with vapor pressure deficit (VPD), drought index and occurrence of late frosts, and positively with soil water content. Previous year growth conditions (i.e., drought index, VPD, soil water anomalies) have a high impact on current TRW (r = 0.60 to 0.74). Fir mortality was induced by increased water stress and severe droughts (as a primary factor) in synergy with bark-beetles and fungi attacks (as secondary factors). Dendrochronology data indicated that fir mortality is a periodic process. In a future climate with increased aridity and drought frequency, fir (and Siberian pine) may disappear from portions of its current range (primarily within the boundary with the forest- steppe) and is likely to be replaced by drought-tolerant species such as Pinus sylvestris and Larix sibirica.

KSC-04PD-1557

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sen. John F. Kerry, D-Mass., greets Kennedy Space Center employees during a tour of the Orbiter Processing Facility (OPF). The orbiter Discovery is being prepared for flight in the OPF on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04pd1557

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - Sen. John F. Kerry, D-Mass., greets Kennedy Space Center employees during a tour of the Orbiter Processing Facility (OPF). The orbiter Discovery is being prepared for flight in the OPF on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

A modeling study of the effects of aerosols on clouds and precipitation over East Asia

NASA Astrophysics Data System (ADS)

Liu, Xiaodong; Xie, Xiaoning; Yin, Zhi-Yong; Liu, Changhai; Gettelman, Andrew

2011-12-01

The National Center for Atmospheric Research Community Atmosphere Model (version 3.5) coupled with the Morrison-Gettelman two-moment cloud microphysics scheme is employed to simulate the aerosol effects on clouds and precipitation in two numerical experiments, one representing present-day conditions (year 2000) and the other the pre-industrial conditions (year 1750) over East Asia by considering both direct and indirect aerosol effects. To isolate the aerosol effects, we used the same set of boundary conditions and only altered the aerosol emissions in both experiments. The simulated results show that the cloud microphysical properties are markedly affected by the increase in aerosols, especially for the column cloud droplet number concentration (DNC), liquid water path (LWP), and the cloud droplet effective radius (DER). With increased aerosols, DNC and LWP have been increased by 137% and 28%, respectively, while DER is reduced by 20%. Precipitation rates in East Asia and East China are reduced by 5.8% and 13%, respectively, by both the aerosol's second indirect effect and the radiative forcing that enhanced atmospheric stability associated with the aerosol direct and first indirect effects. The significant reduction in summer precipitation in East Asia is also consistent with the weakening of the East Asian summer monsoon, resulting from the decreasing thermodynamic contrast between the Asian landmass and the surrounding oceans induced by the aerosol's radiative effects. The increase in aerosols reduces the surface net shortwave radiative flux over the East Asia landmass, which leads to the reduction of the land surface temperature. With minimal changes in the sea surface temperature, hence, the weakening of the East Asian summer monsoon further enhances the reduction of summer precipitation over East Asia.

Water exit pathways and proton pumping mechanism in B-type cytochrome c oxidase from molecular dynamics simulations.

PubMed

Yang, Longhua; Skjevik, Åge A; Han Du, Wen-Ge; Noodleman, Louis; Walker, Ross C; Götz, Andreas W

2016-09-01

Cytochrome c oxidase (CcO) is a vital enzyme that catalyzes the reduction of molecular oxygen to water and pumps protons across mitochondrial and bacterial membranes. While proton uptake channels as well as water exit channels have been identified for A-type CcOs, the means by which water and protons exit B-type CcOs remain unclear. In this work, we investigate potential mechanisms for proton transport above the dinuclear center (DNC) in ba3-type CcO of Thermus thermophilus. Using long-time scale, all-atom molecular dynamics (MD) simulations for several relevant protonation states, we identify a potential mechanism for proton transport that involves propionate A of the active site heme a3 and residues Asp372, His376 and Glu126(II), with residue His376 acting as the proton-loading site. The proposed proton transport process involves a rotation of residue His376 and is in line with experimental findings. We also demonstrate how the strength of the salt bridge between residues Arg225 and Asp287 depends on the protonation state and that this salt bridge is unlikely to act as a simple electrostatic gate that prevents proton backflow. We identify two water exit pathways that connect the water pool above the DNC to the outer P-side of the membrane, which can potentially also act as proton exit transport pathways. Importantly, these water exit pathways can be blocked by narrowing the entrance channel between residues Gln151(II) and Arg449/Arg450 or by obstructing the entrance through a conformational change of residue Tyr136, respectively, both of which seem to be affected by protonation of residue His376. Copyright © 2016 Elsevier B.V. All rights reserved.

A system for the measurement of delayed neutrons and gammas from special nuclear materials

DOE PAGES

Andrews, M. T.; Corcoran, E. C.; Goorley, J. T.; ...

2014-11-27

The delayed neutron counting (DNC) system at the Royal Military College of Canada has been upgraded to accommodate concurrent delayed neutron and gamma measurements. This delayed neutron and gamma counting (DNGC) system uses a SLOWPOKE-2 reactor to irradiate fissile materials before their transfer to a counting arrangement consisting of six ³He and one HPGe detector. The application of this system is demonstrated in an example where delayed neutron and gamma emissions are used in complement to examine ²³³U content and determine fissile mass with an average relative error and accuracy of -2.2 and 1.5 %, respectively.

KSC-04PD-1560

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sen. John F. Kerry (center), D-Mass., discusses Space Shuttle processing with NASA Vehicle Manager Stephanie Stilson during a tour of the Orbiter Processing Facility (OPF). They are standing under the orbiter Discovery, which is being prepared for flight on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04pd1560

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - Sen. John F. Kerry (center), D-Mass., discusses Space Shuttle processing with NASA Vehicle Manager Stephanie Stilson during a tour of the Orbiter Processing Facility (OPF). They are standing under the orbiter Discovery, which is being prepared for flight on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

Indian Ocean Validation,

DTIC Science & Technology

1987-09-01

S9 fd 30 2 D0i 0m10 20 802 AR. Oy ad n A o io in 3 0 3 7 ..n . . . w o w., , ... .. . . . . d ata m gaterng eie ws amdfe Lito sT-1 Omeg nav~igtion AE...signals propagated from each of N stations over paths of 2-10 length dl, d2, ... as shown in Figure 2.1. Station 2 Station N Station 1 D dl SUBJECT Figure...t2* = (d1* - d2*)/c + ( El - 62) t2* - t3* = (d2* - d3*)/c + ( E2 - E3) t*N 1 - t*N - ( d *N 1 - dN*)/c + ( N-1 EN) (6) 47he results obtained in

Simulations of planet migration driven by planetesimal scattering

NASA Astrophysics Data System (ADS)

Kirsh, David R.; Duncan, Martin; Brasser, Ramon; Levison, Harold F.

2009-01-01

Evidence has mounted for some time that planet migration is an important part of the formation of planetary systems, both in the Solar System [Malhotra, R., 1993. Nature 365, 819-821] and in extrasolar systems [Mayor, M., Queloz, D., 1995. Nature 378, 355-359; Lin, D.N.C., Bodenheimer, P., Richardson, D.C., 1996. Nature 380, 606-607]. One mechanism that produces migration (the change in a planet's semi-major axis a over time) is the scattering of comet- and asteroid-size bodies called planetesimals [Fernandez, J.A., Ip, W.-H., 1984. Icarus 58, 109-120]. Significant angular momentum exchange can occur between the planets and the planetesimals during local scattering, enough to cause a rapid, self-sustained migration of the planet [Ida, S., Bryden, G., Lin, D.N.C., Tanaka, H., 2000. Astrophys. J. 534, 428-445]. This migration has been studied for the particular case of the four outer planets of the Solar System (as in Gomes et al. [Gomes, R.S., Morbidelli, A., Levison, H.F., 2004. Icarus 170, 492-507]), but is not well understood in general. We have used the Miranda [McNeil, D., Duncan, M., Levison, H.F., 2005. Astron. J. 130, 2884-2899] computer simulation code to perform a broad parameter-space survey of the physical variables that determine the migration of a single planet in a planetesimal disk. Migration is found to be predominantly inwards, and the migration rate is found to be independent of planet mass for low-mass planets in relatively high-mass disks. Indeed, a simple scaling relation from Ida et al. [Ida, S., Bryden, G., Lin, D.N.C., Tanaka, H., 2000. Astrophys. J. 534, 428-445] matches well with the dependencies of the migration rate: |{da}/{dt}|=aT{4πΣa/M; with T the orbital period of the planet and Σ the surface density of the planetesimal disk. When the planet's mass exceeds that of the planetesimals within a few Hill radii (the unit of the planet's gravitational reach), the migration rate decreases strongly with planet mass. Other trends are identified with the root-mean-squared eccentricity of the planetesimal disk, the mass of the particles dragged by the planet in the corotation region, and the index of the surface density power law. The trends are discussed in the context of an analysis of the scattering process itself, which was performed using a large simulation of massless planetesimals. The scattering process alters semi-major axes, eccentricities and timescales of interaction for the planetesimals. In particular, a bias in scattering timescales on either side of the planet's orbit leads to a very strong tendency for the planet to migrate inwards, towards the star, instead of outwards. The detection of this tendency relies on a level of resolution that may not have been achieved in past studies. The results of this work show that planet migration driven by planetesimal scattering should be a widespread phenomenon, especially for low-mass planets such as still-forming protoplanets.

KSC-04PD-1556

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. From left, Sen. John F. Kerry, D- Mass., Sen. Bob Graham, D-Fla., and former astronaut and Sen. John H. Glenn, D-Ohio, receive a briefing from Kennedy Space Center Director James W. Kennedy before a tour of the Orbiter Processing Facility (OPF). In the OPF, the orbiter Discovery is being prepared for flight on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04PD-1558

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sen. Bill Nelson (second from left), D-Fla., former astronaut and Sen. John H. Glenn, D-Ohio, and Sen. John F. Kerry, D-Mass., receive a briefing from NASA Vehicle Manager Stephanie Stilson during a tour of the Orbiter Processing Facility (OPF). They are standing under the orbiter Discovery, which is being prepared for flight on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04PD-1564

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sen. John F. Kerry, D-Mass., visits the flight deck of Space Shuttle Discovery during a tour of the Orbiter Processing Facility (OPF). The bunny suit he is wearing is clean room attire required for anyone coming in close proximity to Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

Analysis of low levels of rare earths by radiochemical neutron activation analysis

USGS Publications Warehouse

Wandless, G.A.; Morgan, J.W.

1985-01-01

A procedure for the radiochemical neutron-activation analysis for the rare earth elements (REE) involves the separation of the REE as a group by rapid ion-exchange methods and determination of yields by reactivation or by energy dispersive X-ray fluorescence (EDXRF) spectrometry. The U. S. Geological Survey (USGS) standard rocks, BCR-1 and AGV-1, were analyzed to determine the precision and accuracy of the method. We found that the precision was ??5-10% on the basis of replicate analysis and that, in general the accuracy was within ??5% of accepted values for most REE. Data for USGS standard rocks BIR-1 (Icelandic basalt) and DNC-1 (North Carolina diabase) are also presented. ?? 1985 Akade??miai Kiado??.

KSC-04pd1558

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - Sen. Bill Nelson (second from left), D-Fla., former astronaut and Sen. John H. Glenn, D-Ohio, and Sen. John F. Kerry, D-Mass., receive a briefing from NASA Vehicle Manager Stephanie Stilson during a tour of the Orbiter Processing Facility (OPF). They are standing under the orbiter Discovery, which is being prepared for flight on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04pd1556

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - From left, Sen. John F. Kerry, D-Mass., Sen. Bob Graham, D-Fla., and former astronaut and Sen. John H. Glenn, D-Ohio, receive a briefing from Kennedy Space Center Director James W. Kennedy before a tour of the Orbiter Processing Facility (OPF). In the OPF, the orbiter Discovery is being prepared for flight on the next Space Shuttle mission. The tour follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04pd1564

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - Sen. John F. Kerry, D-Mass., visits the flight deck of Space Shuttle Discovery during a tour of the Orbiter Processing Facility (OPF). The “bunny suit” he is wearing is clean room attire required for anyone coming in close proximity to Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

Congressional Black Caucus meets with NASA

NASA Image and Video Library

2010-01-13

NASA Administrator Charles Bolden, space shuttle crew STS-129 and members of the Congressional Black Caucus pose for a group photo at the Capitol Building, Wednesday, Jan. 13, 2010, in Washington. Back row from left to right: U.S. Rep Donna Edwards (D-MD), U.S. Rep Diane Watson (D-CA), NASA Administrator Charles Bolden, astronauts Leland Melvin, Mike Foreman, Robert Satcher, Barry Wilmore, Randy Breznik, and U.S. Rep Mel Watt (D-NC). Front row from left to right: U.S. Rep Robert Scott (D-VA), U.S. Rep. Corrine Brown (D-Fla), U.S. Rep. Barbara Lee (D-CA), U.S. Rep. Donna Christensen (D-VI) and U.S. Rep. Donald Payne (D-NJ). The crew of STS-129 presented the CBC with a montage commemorating their mission. Photo Credit: (NASA/Paul E. Alers)

KSC-04PD-1563

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sen. Bill Nelson (right), D-Fla., explains the layout of the glass cockpit to Sen. John F. Kerry, D-Mass., on the flight deck of orbiter Discovery during a tour of the Orbiter Processing Facility (OPF). The bunny suits they are wearing are clean room attire required for anyone coming in close proximity to Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04PD-1562

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sen. John F. Kerry (left), D-Mass., and Sen. Bill Nelson, D-Fla., dressed in clean room attire, visit the flight deck of Space Shuttle Discovery during a tour of the Orbiter Processing Facility (OPF). The bunny suits are required dress for anyone coming in close proximity to Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

Johnston Island Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.

DTIC Science & Technology

1985-01-01

BARD 1 7oi,.’. sland NAS NAS Jul 45 22 ,v 46 N 16 44 % 6 j 2 2 Sar -’ Same 23 Nov46 3u Lee47 Same Sam, am’ 243 So: - m . .Sa ,G4.. 444 Same 5.1- 4 Sam...Mar62 06Nov 62 S aime Sam, Same .. W1 07l N0,62- -Dpc62 SzL- . aea 12 Sam Same Jan 63 Feb 63 Salr,, a Sam, . m Same MarŚ Dnc rg14 Sao Same Jan 65 Jun...USAFETAC 0 O-IO5(OL Al. AMFf$0MOREi.S 0 AU OssoRl K T, . 0. WEATHER CONDITIONS ., - ’- ;’ , ’ ’ : ’ , - ’ I . - " 2 STATION . . . . . STATION NAME YRARS M NT

KSC-04pd1562

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - Sen. John F. Kerry (left), D-Mass., and Sen. Bill Nelson, D-Fla., dressed in clean room attire, visit the flight deck of Space Shuttle Discovery during a tour of the Orbiter Processing Facility (OPF). The “bunny suits” are required dress for anyone coming in close proximity to Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

Why might regional vaccinology networks fail? The case of the Dutch-Nordic Consortium.

PubMed

Hendriks, Jan; Blume, Stuart

2016-07-07

We analyzed an attempt to develop and clinically test a pneumococcal conjugate vaccine for the developing world, undertaken by public health institutions from the Netherlands, Sweden, Denmark, Norway and Finland: the Dutch Nordic Consortium (DNC), between 1990 and 2000. Our review shows that the premature termination of the project was due less to technological and scientific challenges and more to managerial challenges and institutional policies. Various impeding events, financial and managerial challenges gradually soured the initially enthusiastic collaborative spirit until near the end the consortium struggled to complete the minimum objectives of the project. By the end of 1998, a tetravalent prototype vaccine had been made that proved safe and immunogenic in Phase 1 trials in adults and toddlers in Finland. The planned next step, to test the vaccine in Asia in infants, did not meet approval by the local authorities in Vietnam nor later in the Philippines and the project eventually stopped.The Dutch DNC member, the National Institute of Public Health and the Environment (RIVM) learned important lessons, which subsequently were applied in a following vaccine technology transfer project, resulting in the availability at affordable prices for the developing world of a conjugate vaccine against Haemophilus influenzae type b. We conclude that vaccine development in the public domain with technology transfer as its ultimate aim requires major front-end funding, committed leadership at the highest institutional level sustained for many years and a competent recipient-manufacturer, which needs to be involved at a very early stage of the development.At the national level, RIVM's policy to consolidate its national manufacturing task through securing a key global health position in support of a network of public vaccine manufacturers proved insufficiently supported by the relevant ministries of the Dutch government. Difficulties to keep up with high costs, high-risk innovative vaccine development and production in a public sector setting led to the gradual loss of production tasks and to the 2009 Government decision to privatize the vaccine production tasks of the Institute.

KSC-04PD-1561

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sen. Bob Graham (back), D-Fla., former astronaut and Sen. John H. Glenn (front left), D-Ohio, Sen. John F. Kerry, D-Mass., and Sen. Bill Nelson, D-Fla., don clean room attire during a tour of the Orbiter Processing Facility (OPF). The bunny suits are required dress for anyone coming in close proximity to the orbiter Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes Americas commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04pd1563

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - Sen. Bill Nelson (right), D-Fla., explains the layout of the glass cockpit to Sen. John F. Kerry, D-Mass., on the flight deck of orbiter Discovery during a tour of the Orbiter Processing Facility (OPF). The “bunny suits” they are wearing are clean room attire required for anyone coming in close proximity to Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

KSC-04pd1561

NASA Image and Video Library

2004-07-26

KENNEDY SPACE CENTER, FLA. - Sen. Bob Graham (back), D-Fla., former astronaut and Sen. John H. Glenn (front left), D-Ohio, Sen. John F. Kerry, D-Mass., and Sen. Bill Nelson, D-Fla., don clean room attire during a tour of the Orbiter Processing Facility (OPF). The “bunny suits” are required dress for anyone coming in close proximity to the orbiter Discovery, currently being prepared for flight on the next Space Shuttle mission. The tour of the OPF follows a public meeting Kerry held at the Dr. Kurt H. Debus Conference Facility at the Kennedy Space Center Visitor Complex. He said he chose to speak at KSC because it symbolizes America’s commitment to science, innovation and technology. He and Sen. John Edwards, D-N.C., are on a speaking tour prior to their appearance at the Democratic National Convention in Boston.

Confessions of a robot lobotomist

NASA Technical Reports Server (NTRS)

Gottshall, R. Marc

1994-01-01

Since its inception, numerically controlled (NC) machining methods have been used throughout the aerospace industry to mill, drill, and turn complex shapes by sequentially stepping through motion programs. However, the recent demand for more precision, faster feeds, exotic sensors, and branching execution have existing computer numerical control (CNC) and distributed numerical control (DNC) systems running at maximum controller capacity. Typical disadvantages of current CNC's include fixed memory capacities, limited communication ports, and the use of multiple control languages. The need to tailor CNC's to meet specific applications, whether it be expanded memory, additional communications, or integrated vision, often requires replacing the original controller supplied with the commercial machine tool with a more powerful and capable system. This paper briefly describes the process and equipment requirements for new controllers and their evolutionary implementation in an aerospace environment. The process of controller retrofit with currently available machines is examined, along with several case studies and their computational and architectural implications.

Vibrational Frequencies and Spectroscopic Constants for 1(sup 3)A' HNC and 1(sup 3)A' HOC+ from High-Accuracy Quartic Force Fields

NASA Technical Reports Server (NTRS)

Fortenberry, Ryan C.; Crawford, T. Daniel; Lee, Timothy J.

2014-01-01

The spectroscopic constants and vibrational frequencies for the 1(sup 3)A' states of HNC, DNC, HOC+, and DOC+ are computed and discussed in this work. The reliable CcCR quartic force field based on high-level coupled cluster ab initio quantum chemical computations is exclusively utilized to provide the anharmonic potential. Then, second order vibrational perturbation theory and vibrational configuration interaction methods are employed to treat the nuclear Schroedinger equation. Second-order perturbation theory is also employed to provide spectroscopic data for all molecules examined. The relationship between these molecules and the corresponding 1(sup 3)A' HCN and HCO+ isomers is further developed here. These data are applicable to laboratory studies involving formation of HNC and HOC+ as well as astronomical observations of chemically active astrophysical environments.

Thermo-optical properties of Alexandrite laser crystal

NASA Astrophysics Data System (ADS)

Loiko, Pavel; Ghanbari, Shirin; Matrosov, Vladimir; Yumashev, Konstantin; Major, Arkady

2018-02-01

Alexandrite is a well-known material for broadly tunable and power-scalable near-IR lasers. We measured the thermal coefficients of the optical path (TCOP) and thermo-optic coefficients (TOCs) of Alexandrite at 632.8 nm for three principal light polarizations, E || a, E || b and E || c. All TOCs are positive and show a notable polarization-anisotropy, dna/dT = 5.5, dnb/dT = 7.0 and dnc/dT = 14.9×10-6 K-1. We also characterized thermal lensing in a continuous-wave Alexandrite laser which used a Brewster-oriented c-cut 0.16 at.% Cr3+ doped BeAl2O4 crystal pumped at 532 nm and emitted at 750.9 nm (E || b). The measured thermal lens was positive and astigmatic. The sensitivity factors of the thermal lens (Mx,y = dDx,y/dPabs) were found to be Mx = 1.74 and My = 2.38 [m-1/W].

Essential role of TRPC6 channels in G2/M phase transition and development of human glioma.

PubMed

Ding, Xia; He, Zhuohao; Zhou, Kechun; Cheng, Ju; Yao, Hailan; Lu, Dongliang; Cai, Rong; Jin, Yening; Dong, Bin; Xu, Yinghui; Wang, Yizheng

2010-07-21

Patients with glioblastoma multiforme, the most aggressive form of glioma, have a median survival of approximately 12 months. Calcium (Ca(2+)) signaling plays an important role in cell proliferation, and some members of the Ca(2+)-permeable transient receptor potential canonical (TRPC) family of channel proteins have demonstrated a role in the proliferation of many types of cancer cells. In this study, we investigated the role of TRPC6 in cell cycle progression and in the development of human glioma. TRPC6 protein and mRNA expression were assessed in glioma (n = 33) and normal (n = 17) brain tissues from patients and in human glioma cell lines U251, U87, and T98G. Activation of TRPC6 channels was tested by platelet-derived growth factor-induced Ca(2+) imaging. The effect of inhibiting TRPC6 activity or expression using the dominant-negative mutant TRPC6 (DNC6) or RNA interference, respectively, was tested on cell growth, cell cycle progression, radiosensitization of glioma cells, and development of xenografted human gliomas in a mouse model. The green fluorescent protein (GFP) and wild-type TRPC6 (WTC6) were used as controls. Survival of mice bearing xenografted tumors in the GFP, DNC6, and WTC6 groups (n = 13, 15, and 13, respectively) was compared using Kaplan-Meier analysis. All statistical tests were two-sided. Functional TRPC6 was overexpressed in human glioma cells. Inhibition of TRPC6 activity or expression attenuated the increase in intracellular Ca(2+) by platelet-derived growth factor, suppressed cell growth and clonogenic ability, induced cell cycle arrest at the G2/M phase, and enhanced the antiproliferative effect of ionizing radiation. Cyclin-dependent kinase 1 activation and cell division cycle 25 homolog C expression regulated the cell cycle arrest. Inhibition of TRPC6 activity also reduced tumor volume in a subcutaneous mouse model of xenografted human tumors (P = .014 vs GFP; P < .001 vs WTC6) and increased mean survival in mice in an intracranial model (P < .001 vs GFP or WTC6). In this preclinical model, TRPC6 channels were essential for glioma development via regulation of G2/M phase transition. This study suggests that TRPC6 might be a new target for therapeutic intervention of human glioma.

Climate-Driven Changes Within the Larch Forest of Northern Siberia

NASA Astrophysics Data System (ADS)

Kharuk, V.

2015-12-01

Thanks to the support of NASA's Carbon Cycle and Ecosystem Focus Area programs, joint NASA/ Siberian Branch of the Russian Academy of Sciences studies have been conducted throughout Siberia. The overall objective has been to obtain field and satellite measurements to examine carbon stocks and track changes in forests across this vast area. In this presentation, we discuss some of the finding from this 25+ year collaboration' i.e., observed climate-driven changes within larch communities in northern Siberia. Field measurements and satellite data, including Terra/MODIS, Landsat, GRACE and QuickBird were used for analysis of forest conditions. The following results will be discussed. (1). At the northern limit of larch (Larix gmelinii) range (i.e.,~72°N) tree mortality was observed during the cooling period from the 16th century to the beginning of the 19th century. Post- Little Ice Age (LIA) trees re-establishment followed warming temperatures by the middle of the19th century. The current tree line has recovered to the pre-LIA line location although tree heights and stand densities are comparatively lower. The mean rate of upward migration was found to be 0.35 m yr-1 (with a range of 0.21-0.58). (2) The migration of the "dark needle conifers" (DNC: Abies sibirica, Pinus sibirica, Picea obovata) into the southern margin zone of larch dominated forest was documented. Meanwhile, within the traditional DNC range decline and mortality of both Siberian pine and fir were observed and attributed, primarily, due to an increased drought. (3) Within Central Siberia larch growth is limited by early summer temperatures and available water from thawing permafrost. Larch tree ring width (TRW) correlated with early summer temperatures and water vapor pressure (r = 0.73 and r = 0.69, respectively), drought (SPEI; r = 0.68-0.82), snow accumulation (r = 0.61), previous year precipitation (r = 0.63) and soil water anomalies (r = 0.79). Larch TRW growth and Gross Primary Productivity increased during recent decades. (4) A study along the meridian of ~100° E between (64°… 71°+N) shows mean fire return intervals increased from about 80 years at 64°N, to ~200 years near the Arctic Circle, and ~300 years near the northern range limit of larch stands. Post LIA warming caused approximately a doubling of fire events.

Lessons Learned During Cryogenic Optical Testing of the Advanced Mirror System Demonstrators (AMSDs)

NASA Technical Reports Server (NTRS)

Hadaway, James; Reardon, Patrick; Geary, Joseph; Robinson, Brian; Stahl, Philip; Eng, Ron; Kegley, Jeff

2004-01-01

Optical testing in a cryogenic environment presents a host of challenges above and beyond those encountered during room temperature testing. The Advanced Mirror System Demonstrators (AMSDs) are 1.4 m diameter, ultra light-weight (<20 kg/mA2), off-axis parabolic segments. They are required to have 250 nm PV & 50 nm RMS surface figure error or less at 35 K. An optical testing system, consisting of an Instantaneous Phase Interferometer (PI), a diffractive null corrector (DNC), and an Absolute Distance Meter (ADM), was used to measure the surface figure & radius-of-curvature of these mirrors at the operational temperature within the X-Ray Calibration Facility (XRCF) at Marshall Space Flight Center (MSFC). The Ah4SD program was designed to improve the technology related to the design, fabrication, & testing of such mirrors in support of NASA s James Webb Space Telescope (JWST). This paper will describe the lessons learned during preparation & cryogenic testing of the AMSDs.

N-body simulations of viscous instability of planetary rings

NASA Astrophysics Data System (ADS)

Salo, Heikki; Schmidt, Jürgen

2010-04-01

We study viscous instability of planetary rings in terms of N-body simulations. We show that for rings composed of fairly elastic particles (e.g. as in Hatzes et al. [Hatzes, A., Bridges, F.G., Lin, D.N.C., 1988. Collisional properties of ice spheres at low impact velocities. Mon. Not. R. Astron. Soc. 231, 1091-1115]) the instability may lead to the spontaneous formation of dense ringlets in a background of lower density. In most parts of Saturn's rings the particle collisions are probably much more dissipative, as suggested by the presence of self-gravity wakes, and classic viscous instability should be suppressed. However, our results demonstrate that the mechanism of viscous instability itself is valid. The dynamical effects of size-dependent elasticity in a system with a size distribution have never been studied before. We show that this may in principle lead to a size-selective viscous instability, small particles concentrating on ringlets against the more uniform background of large particles.

Acoustic monitoring method and system in laser-induced optical breakdown (LIOB)

DOEpatents

O'Donnell, Matthew [Ann Arbor, MI; Ye, Jing Yong [Ann Arbor, MI; Norris, Theodore B [Dexter, MI; Baker, Jr., James R.; Balogh, Lajos P [Ann Arbor, MI; Milas, Susanne M [Ann Arbor, MI; Emelianov, Stanislav Y [Ann Arbor, MI; Hollman, Kyle W [Fenton, MI

2008-05-06

An acoustic monitoring method and system in laser-induced optical breakdown (LIOB) provides information which characterize material which is broken down, microbubbles in the material, and/or the microenvironment of the microbubbles. In one embodiment of the invention, femtosecond laser pulses are focused just inside the surface of a volume of aqueous solution which may include dendrimer nanocomposite (DNC) particles. A tightly focused, high frequency, single-element ultrasonic transducer is positioned such that its focus coincides axially and laterally with this laser focus. When optical breakdown occurs, a microbubble forms and a shock or pressure wave is emitted (i.e., acoustic emission). In addition to this acoustic signal, the microbubble may be actively probed with pulse-echo measurements from the same transducer. After the microbubble forms, received pulse-echo signals have an extra pulse, describing the microbubble location and providing a measure of axial microbubble size. Wavefield plots of successive recordings illustrate the generation, growth, and collapse of microbubbles due to optical breakdown. These same plots can also be used to quantify LIOB thresholds.

The Use of Ecological Niche Modeling to Infer Potential Risk Areas of Snakebite in the Mexican State of Veracruz

PubMed Central

Yañez-Arenas, Carlos; Peterson, A. Townsend; Mokondoko, Pierre; Rojas-Soto, Octavio; Martínez-Meyer, Enrique

2014-01-01

Background Many authors have claimed that snakebite risk is associated with human population density, human activities, and snake behavior. Here we analyzed whether environmental suitability of vipers can be used as an indicator of snakebite risk. We tested several hypotheses to explain snakebite incidence, through the construction of models incorporating both environmental suitability and socioeconomic variables in Veracruz, Mexico. Methodology/Principal Findings Ecological niche modeling (ENM) was used to estimate potential geographic and ecological distributions of nine viper species' in Veracruz. We calculated the distance to the species' niche centroid (DNC); this distance may be associated with a prediction of abundance. We found significant inverse relationships between snakebites and DNCs of common vipers (Crotalus simus and Bothrops asper), explaining respectively 15% and almost 35% of variation in snakebite incidence. Additionally, DNCs for these two vipers, in combination with marginalization of human populations, accounted for 76% of variation in incidence. Conclusions/Significance Our results suggest that niche modeling and niche-centroid distance approaches can be used to mapping distributions of environmental suitability for venomous snakes; combining this ecological information with socioeconomic factors may help with inferring potential risk areas for snakebites, since hospital data are often biased (especially when incidences are low). PMID:24963989

Reinforced Adversarial Neural Computer for de Novo Molecular Design.

PubMed

Putin, Evgeny; Asadulaev, Arip; Ivanenkov, Yan; Aladinskiy, Vladimir; Sanchez-Lengeling, Benjamin; Aspuru-Guzik, Alán; Zhavoronkov, Alex

2018-06-12

In silico modeling is a crucial milestone in modern drug design and development. Although computer-aided approaches in this field are well-studied, the application of deep learning methods in this research area is at the beginning. In this work, we present an original deep neural network (DNN) architecture named RANC (Reinforced Adversarial Neural Computer) for the de novo design of novel small-molecule organic structures based on the generative adversarial network (GAN) paradigm and reinforcement learning (RL). As a generator RANC uses a differentiable neural computer (DNC), a category of neural networks, with increased generation capabilities due to the addition of an explicit memory bank, which can mitigate common problems found in adversarial settings. The comparative results have shown that RANC trained on the SMILES string representation of the molecules outperforms its first DNN-based counterpart ORGANIC by several metrics relevant to drug discovery: the number of unique structures, passing medicinal chemistry filters (MCFs), Muegge criteria, and high QED scores. RANC is able to generate structures that match the distributions of the key chemical features/descriptors (e.g., MW, logP, TPSA) and lengths of the SMILES strings in the training data set. Therefore, RANC can be reasonably regarded as a promising starting point to develop novel molecules with activity against different biological targets or pathways. In addition, this approach allows scientists to save time and covers a broad chemical space populated with novel and diverse compounds.

iSS-PC: Identifying Splicing Sites via Physical-Chemical Properties Using Deep Sparse Auto-Encoder.

PubMed

Xu, Zhao-Chun; Wang, Peng; Qiu, Wang-Ren; Xiao, Xuan

2017-08-15

Gene splicing is one of the most significant biological processes in eukaryotic gene expression, such as RNA splicing, which can cause a pre-mRNA to produce one or more mature messenger RNAs containing the coded information with multiple biological functions. Thus, identifying splicing sites in DNA/RNA sequences is significant for both the bio-medical research and the discovery of new drugs. However, it is expensive and time consuming based only on experimental technique, so new computational methods are needed. To identify the splice donor sites and splice acceptor sites accurately and quickly, a deep sparse auto-encoder model with two hidden layers, called iSS-PC, was constructed based on minimum error law, in which we incorporated twelve physical-chemical properties of the dinucleotides within DNA into PseDNC to formulate given sequence samples via a battery of cross-covariance and auto-covariance transformations. In this paper, five-fold cross-validation test results based on the same benchmark data-sets indicated that the new predictor remarkably outperformed the existing prediction methods in this field. Furthermore, it is expected that many other related problems can be also studied by this approach. To implement classification accurately and quickly, an easy-to-use web-server for identifying slicing sites has been established for free access at: http://www.jci-bioinfo.cn/iSS-PC.

A multi-residue method for 17 anticoccidial drugs and ractopamine in animal tissues by liquid chromatography-tandem mass spectrometry and time-of-flight mass spectrometry.

PubMed

Matus, Johanna L; Boison, Joe O

2016-05-01

A new and sensitive multi-residue liquid chromatography-tandem mass spectrometry (LC-MS/MS) and liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QToF-MS) method was developed and validated for the determination and confirmation of residues of 17 anticoccidials, plus free ractopamine in poultry muscle and liver, and bovine muscle, liver, and kidney tissues. The 17 anticoccidials are lasalocid, halofuginone, narasin, monensin, semduramicin, ethopabate, robenidine, buquinolate, toltrazuril as its sulfone metabolite, maduramicin, salinomycin, diclazuril, amprolium, decoquinate, dinitolmide, clopidol, and the nicarbazin metabolite DNC (N,N1-bis(4-nitrophenyl)urea). The analytes were extracted and cleaned up within a 3-hour period by simply extracting the analytes into a solvent mixture with salts followed by centrifugation, dilution, and filtration. The validated method was used in a pilot study for the analysis of 173 samples that included quail liver, bovine kidney, liver, muscle, and horse muscle. The predominant residues found in this study were monensin, ractopamine, and lasalocid. The results of this pilot study showed that this new method is applicable to real samples, and is fit for use in a regulatory testing programme. © 2016 Her Majesty the Queen in Right of Canada. Drug Testing and Analysis. © 2016 John Wiley & Sons, Ltd. © 2016 Her Majesty the Queen in Right of Canada. Drug Testing and Analysis. © 2016 John Wiley & Sons, Ltd.

Soft real-time alarm messages for ATLAS TDAQ

NASA Astrophysics Data System (ADS)

Darlea, G.; Al Shabibi, A.; Martin, B.; Lehmann Miotto, G.

2010-05-01

The ATLAS TDAQ network consists of three separate Ethernet-based networks (Data, Control and Management) with over 2000 end-nodes. The TDAQ system has to be aware of the meaningful network failures and events in order for it to take effective recovery actions. The first stage of the process is implemented with Spectrum, a commercial network management tool. Spectrum detects and registers all network events, then it publishes the information via a CORBA programming interface. A gateway program (called NSG—Network Service Gateway) connects to Spectrum through CORBA and exposes to its clients a Java RMI interface. This interface implements a callback mechanism that allows the clients to subscribe for monitoring "interesting" parts of the network. The last stage of the TDAQ network monitoring tool is implemented in a module named DNC (DAQ to Network Connection), which filters the events that are to be reported to the TDAQ system: it subscribes to the gateway only for the machines that are currently active in the system and it forwards only the alarms that are considered important for the current TDAQ data taking session. The network information is then synthesized and presented in a human-readable format. These messages can be further processed either by the shifter who is in charge, the network expert or the Online Expert System. This article aims to describe the different mechanisms of the chain that transports the network events to the front-end user, as well as the constraints and rules that govern the filtering and the final format of the alarm messages.

Comparative genomic analyses reveal a vast, novel network of nucleotide-centric systems in biological conflicts, immunity and signaling

PubMed Central

Burroughs, A. Maxwell; Zhang, Dapeng; Schäffer, Daniel E.; Iyer, Lakshminarayan M.; Aravind, L.

2015-01-01

Cyclic di- and linear oligo-nucleotide signals activate defenses against invasive nucleic acids in animal immunity; however, their evolutionary antecedents are poorly understood. Using comparative genomics, sequence and structure analysis, we uncovered a vast network of systems defined by conserved prokaryotic gene-neighborhoods, which encode enzymes generating such nucleotides or alternatively processing them to yield potential signaling molecules. The nucleotide-generating enzymes include several clades of the DNA-polymerase β-like superfamily (including Vibrio cholerae DncV), a minimal version of the CRISPR polymerase and DisA-like cyclic-di-AMP synthetases. Nucleotide-binding/processing domains include TIR domains and members of a superfamily prototyped by Smf/DprA proteins and base (cytokinin)-releasing LOG enzymes. They are combined in conserved gene-neighborhoods with genes for a plethora of protein superfamilies, which we predict to function as nucleotide-sensors and effectors targeting nucleic acids, proteins or membranes (pore-forming agents). These systems are sometimes combined with other biological conflict-systems such as restriction-modification and CRISPR/Cas. Interestingly, several are coupled in mutually exclusive neighborhoods with either a prokaryotic ubiquitin-system or a HORMA domain-PCH2-like AAA+ ATPase dyad. The latter are potential precursors of equivalent proteins in eukaryotic chromosome dynamics. Further, components from these nucleotide-centric systems have been utilized in several other systems including a novel diversity-generating system with a reverse transcriptase. We also found the Smf/DprA/LOG domain from these systems to be recruited as a predicted nucleotide-binding domain in eukaryotic TRPM channels. These findings point to evolutionary and mechanistic links, which bring together CRISPR/Cas, animal interferon-induced immunity, and several other systems that combine nucleic-acid-sensing and nucleotide-dependent signaling. PMID:26590262

ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Complex Organic and Deuterated Molecules

NASA Astrophysics Data System (ADS)

Sakai, Takeshi; Yanagida, Takahiro; Furuya, Kenji; Aikawa, Yuri; Sanhueza, Patricio; Sakai, Nami; Hirota, Tomoya; Jackson, James M.; Yamamoto, Satoshi

2018-04-01

We have observed complex organic molecules (COMs) and deuterated species toward a hot core/corino (HC) associated with the infrared dark cloud clump G34.43+00.24 MM3 with the Atacama Large Millimeter/submillimeter Array. We have detected six normal-COMs (CH3OH, CH3CHO, CH3CH2CN, CH3OCH3, HCOOCH3, and NH2CHO), one deuterated-COM (CH2DCN), and two deuterated fundamental molecules (D2CO and DNC) toward G34.43+00.24 MM3 HC. None of these lines, except for CH3OH, are detected toward the shocked regions in our data, which suggests that COMs do not originate in shocks. The abundance of the COMs relative to CH3OH in G34.43+00.24 MM3 HC is found to be similar to those in high-mass hot cores, rather than those in hot corinos in low-mass star-forming regions. This result suggests that the physical conditions of the warm-up phase of G34.43+00.24 MM3 HC are similar to those of high-mass sources. On the other hand, the D2CO abundance relative to CH3OH in G34.43+00.24 MM3 HC is higher than that of other hot cores, and seems to be comparable to that of hot corinos. The relatively high D2CO/CH3OH ratio of G34.43+00.24 MM3 HC implies a long cold starless phase of G34.43+00.24 MM3 HC.

Comprehensive Pb-Sr-Nd-Hf isotopic, trace element, and mineralogical characterization of mafic to ultramafic rock reference materials

NASA Astrophysics Data System (ADS)

Fourny, Anaïs.; Weis, Dominique; Scoates, James S.

2016-03-01

Controlling the accuracy and precision of geochemical analyses requires the use of characterized reference materials with matrices similar to those of the unknown samples being analyzed. We report a comprehensive Pb-Sr-Nd-Hf isotopic and trace element concentration data set, combined with quantitative phase analysis by XRD Rietveld refinement, for a wide range of mafic to ultramafic rock reference materials analyzed at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia. The samples include a pyroxenite (NIM-P), five basalts (BHVO-2, BIR-1a, JB-3, BE-N, GSR-3), a diabase (W-2), a dolerite (DNC-1), a norite (NIM-N), and an anorthosite (AN-G); results from a leucogabbro (Stillwater) are also reported. Individual isotopic ratios determined by MC-ICP-MS and TIMS, and multielement analyses by HR-ICP-MS are reported with 4-12 complete analytical duplicates for each sample. The basaltic reference materials have coherent Sr and Nd isotopic ratios with external precision below 50 ppm (2SD) and below 100 ppm for Hf isotopes (except BIR-1a). For Pb isotopic reproducibility, several of the basalts (JB-3, BHVO-2) require acid leaching prior to dissolution. The plutonic reference materials also have coherent Sr and Nd isotopic ratios (<50 ppm), however, obtaining good reproducibility for Pb and Hf isotopic ratios is more challenging for NIM-P, NIM-N, and AN-G due to a variety of factors, including postcrystallization Pb mobility and the presence of accessory zircon. Collectively, these results form a comprehensive new database that can be used by the geochemical community for evaluating the radiogenic isotope and trace element compositions of volcanic and plutonic mafic-ultramafic rocks.

Nitrogen and hydrogen fractionation in high-mass star-forming cores from observations of HCN and HNC

NASA Astrophysics Data System (ADS)

Colzi, L.; Fontani, F.; Caselli, P.; Ceccarelli, C.; Hily-Blant, P.; Bizzocchi, L.

2018-02-01

The ratio between the two stable isotopes of nitrogen, 14N and 15N, is well measured in the terrestrial atmosphere ( 272), and for the pre-solar nebula ( 441, deduced from the solar wind). Interestingly, some pristine solar system materials show enrichments in 15N with respect to the pre-solar nebula value. However, it is not yet clear if and how these enrichments are linked to the past chemical history because we have only a limited number of measurements in dense star-forming regions. In this respect, dense cores, which are believed to be the precursors of clusters and also contain intermediate- and high-mass stars, are important targets because the solar system was probably born within a rich stellar cluster, and such clusters are formed in high-mass star-forming regions. The number of observations in such high-mass dense cores has remained limited so far. In this work, we show the results of IRAM-30 m observations of the J = 1-0 rotational transition of the molecules HCN and HNC and their 15N-bearing counterparts towards 27 intermediate- and high-mass dense cores that are divided almost equally into three evolutionary categories: high-mass starless cores, high-mass protostellar objects, and ultra-compact HII regions. We have also observed the DNC(2-1) rotational transition in order to search for a relation between the isotopic ratios D/H and 14N/15N. We derive average 14N/15N ratios of 359 ± 16 in HCN and of 438 ± 21 in HNC, with a dispersion of about 150-200. We find no trend of the 14N/15N ratio with evolutionary stage. This result agrees with what has been found for N2H+ and its isotopologues in the same sources, although the 14N/15N ratios from N2H+ show a higher dispersion than in HCN/HNC, and on average, their uncertainties are larger as well. Moreover, we have found no correlation between D/H and 14N/15N in HNC. These findings indicate that (1) the chemical evolution does not seem to play a role in the fractionation of nitrogen, and that (2) the fractionation of hydrogen and nitrogen in these objects is not related. IRAM data used in the paper (FITS) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A129

VizieR Online Data Catalog: Panchromatic observations of PTF11qcj (Corsi+, 2014)

NASA Astrophysics Data System (ADS)

Corsi, A.; Ofek, E. O.; Gal-Yam, A.; Frail, D. A.; Kulkarni, S. R.; Fox, D. B.; Kasliwal, M. M.; Sullivan, M.; Horesh, A.; Carpenter, J.; Maguire, K.; Arcavi, I.; Cenko, S. B.; Cao, Y.; Mooley, K.; Pan, Y.-C.; Sesar, B.; Sternberg, A.; Xu, D.; Bersier, D.; James, P.; Bloom, J. S.; Nugent, P. E.

2016-02-01

On 2011 November 1, we discovered PTF11qcj in an R-band image from the 48 inch Samuel Oschin telescope at Palomar Observatory (P48), which is routinely used by the Palomar Transient Factory (PTF). Subsequent observations with the P48 were conducted with the Mould-R and Gunn-g filters. Photometry (Table2) was performed relative to the SDSS r-band and g-band magnitudes of stars in the field. Multi-color optical (gri) optical light curves were also obtained using the Palomar 60 inch telescope (P60) and the RATCAM optical imager on the robotic 2m Liverpool Telescope (LT) located at the Roque de Los Muchachos Observatory on La Palma. On 2011 November 15, we started a long-term monitoring campaign of PTF11qcj (along with calibrators J1327+4326 and 3C 286) with the Karl G. Jansky Very Large Array (VLA; http://public.nrao.edu/telescopes/vla) in its D, DnC, C, CnB, and A configurations, under our Target of Opportunity programs (VLA/11A-227, VLA/11B-034, VLA/11B-247, VLA/12B-195; PI: A. Corsi). The light curves of PTF11qcj at frequencies of 2.5GHz, 3.5GHz, 5GHz, 7.4GHz, 13.5GHz, 16GHz are reported in Table3. We also observed the field of PTF11qcj (together with the test calibrator J1203+480) using the Combined Array for Research in Millimeter-wave Astronomy (CARMA; http://www.mmarray.org/), at a frequency of 93GHz. The data collected on 2011 November 19 and 2011 November 26 (CARMA program no. c0857; PI: A. Horesh) both resulted in a detection of PTF11qcj (Table3). We have carried out an X-ray monitoring campaign of PTF11qcj with Chandra and Swift. All our Swift-XRT observations yielded non detections (see Table 4), while Chandra detected PTF11qcj in three epochs (DDT proposals nos. 501793, 501794, 501797; PI: A. Corsi). The results of our X-ray follow-up are reported in Table4. We observed the position of PTF11qcj with Spitzer on two epochs (on 2012 March 28.747 and 2012 June 25.643; Table5; DDT proposal no. 31731; PI: A. Corsi). On 2012 March 28 (Table5), we also observed the field of PTF11qcj in Ks-band with the Palomar 200 inch telescope (P200). (4 data files).

The applicability of the viscous α-parameterization of gravitational instability in circumstellar disks

NASA Astrophysics Data System (ADS)

Vorobyov, E. I.

2010-01-01

We study numerically the applicability of the effective-viscosity approach for simulating the effect of gravitational instability (GI) in disks of young stellar objects with different disk-to-star mass ratios ξ . We adopt two α-parameterizations for the effective viscosity based on Lin and Pringle [Lin, D.N.C., Pringle, J.E., 1990. ApJ 358, 515] and Kratter et al. [Kratter, K.M., Matzner, Ch.D., Krumholz, M.R., 2008. ApJ 681, 375] and compare the resultant disk structure, disk and stellar masses, and mass accretion rates with those obtained directly from numerical simulations of self-gravitating disks around low-mass (M∗ ∼ 1.0M⊙) protostars. We find that the effective viscosity can, in principle, simulate the effect of GI in stellar systems with ξ≲ 0.2- 0.3 , thus corroborating a similar conclusion by Lodato and Rice [Lodato, G., Rice, W.K.M., 2004. MNRAS 351, 630] that was based on a different α-parameterization. In particular, the Kratter et al.'s α-parameterization has proven superior to that of Lin and Pringle's, because the success of the latter depends crucially on the proper choice of the α-parameter. However, the α-parameterization generally fails in stellar systems with ξ≳ 0.3 , particularly in the Classes 0 and I phases of stellar evolution, yielding too small stellar masses and too large disk-to-star mass ratios. In addition, the time-averaged mass accretion rates onto the star are underestimated in the early disk evolution and greatly overestimated in the late evolution. The failure of the α-parameterization in the case of large ξ is caused by a growing strength of low-order spiral modes in massive disks. Only in the late Class II phase, when the magnitude of spiral modes diminishes and the mode-to-mode interaction ensues, may the effective viscosity be used to simulate the effect of GI in stellar systems with ξ≳ 0.3 . A simple modification of the effective viscosity that takes into account disk fragmentation can somewhat improve the performance of α-models in the case of large ξ and even approximately reproduce the mass accretion burst phenomenon, the latter being a signature of the early gravitationally unstable stage of stellar evolution [Vorobyov, E.I., Basu, S., 2006. ApJ 650, 956]. However, further numerical experiments are needed to explore this issue.

Asymptotic density and effective negligibility

NASA Astrophysics Data System (ADS)

Astor, Eric P.

In this thesis, we join the study of asymptotic computability, a project attempting to capture the idea that an algorithm might work correctly in all but a vanishing fraction of cases. In collaboration with Hirschfeldt and Jockusch, broadening the original investigation of Jockusch and Schupp, we introduce dense computation, the weakest notion of asymptotic computability (requiring only that the correct answer is produced on a set of density 1), and effective dense computation, where every computation halts with either the correct answer or (on a set of density 0) a symbol denoting uncertainty. A few results make more precise the relationship between these notions and work already done with Jockusch and Schupp's original definitions of coarse and generic computability. For all four types of asymptotic computation, including generic computation, we demonstrate that non-trivial upper cones have measure 0, building on recent work of Hirschfeldt, Jockusch, Kuyper, and Schupp in which they establish this for coarse computation. Their result transfers to yield a minimal pair for relative coarse computation; we generalize their method and extract a similar result for relative dense computation (and thus for its corresponding reducibility). However, all of these notions of near-computation treat a set as negligible iff it has asymptotic density 0. Noting that this definition is not computably invariant, this produces some failures of intuition and a break with standard expectations in computability theory. For instance, as shown by Hamkins and Miasnikov, the halting problem is (in some formulations) effectively densely computable, even in polynomial time---yet this result appears fragile, as indicated by Rybalov. In independent work, we respond to this by strengthening the approach of Jockusch and Schupp to avoid such phenomena; specifically, we introduce a new notion of intrinsic asymptotic density, invariant under computable permutation, with rich relations to both randomness and classical computability theory. For instance, we prove that the stochasticities corresponding to permutation randomness and injection randomness coincide, and identify said stochasticity as intrinsic density 1/2. We then define sets of intrinsic density 0 to be effectively negligible, and classify this as a new immunity property, determining its position in the standard hierarchy from immune to cohesive for both general and Delta02 sets. We further characterize the Turing degrees of effectively negligible sets as those which are either high (a' ≥T 0") or compute a DNC (diagonally non-computable) function. In fact, this result holds over RCA0, demonstrating the reverse-mathematical equivalence of the principles ID0 and DOM \\sext DNR. . Replacing Jockusch and Schupp's negligibility (density 0) by effective negligibility (intrinsic density 0), we then obtain new notions of intrinsically dense computation. Finally, we generalize Rice's Theorem to all forms of intrinsic dense computation, showing that no set that is 1-equivalent to a non-trivial index set is intrinsically densely computable; in particular, in contrast to ordinary dense computation, we see that the halting problem cannot be intrinsically densely computable.

Deuteration around the ultracompact HII region Monoceros R2

NASA Astrophysics Data System (ADS)

Treviño-Morales, S. P.; Pilleri, P.; Fuente, A.; Kramer, C.; Roueff, E.; González-García, M.; Cernicharo, J.; Gerin, M.; Goicoechea, J. R.; Pety, J.; Berné, O.; Ossenkopf, V.; Ginard, D.; García-Burillo, S.; Rizzo, J. R.; Viti, S.

2014-09-01

Context. The massive star-forming region Monoceros R2 (Mon R2) hosts the closest ultra-compact Hii region, where the photon-dominated region (PDR) between the ionized and molecular gas can be spatially resolved with current single-dish telescopes. Aims: We aim at studying the chemistry of deuterated molecules toward Mon R2 to determine the deuterium fractions around a high-UV irradiated PDR and investigate the chemistry of these species. Methods: We used the IRAM-30 m telescope to carry out an unbiased spectral survey toward two important positions (namely IF and MP2) in Mon R2 at 1, 2, and 3 mm. This spectral survey is the observational basis of our study of the deuteration in this massive star-forming region. Our high spectral resolution observations (~0.25-0.65 km s-1) allowed us to resolve the line profiles of the different species detected. Results: We found a rich chemistry of deuterated species at both positions of Mon R2, with detections of C2D, DCN, DNC, DCO+, D2CO, HDCO, NH2D, and N2D+ and their corresponding hydrogenated species and rarer isotopologs. The high spectral resolution of our observations allowed us to resolve three velocity components: the component at 10 km s-1 is detected at both positions and seems associated with the layer most exposed to the UV radiation from IRS 1; the component at 12 km s-1 is found toward the IF position and seems related to the foreground molecular gas; finally, a component at 8.5 km s-1 is only detected toward the MP2 position, most likely related to a low-UV irradiated PDR. We derived the column density of the deuterated species (together with their hydrogenated counterparts), and determined the deuterium fractions as Dfrac = [XD]/[XH]. The values of Dfrac are around 0.01 for all the observed species, except for HCO+ and N2H+, which have values 10 times lower. The values found in Mon R2 are similar to those measured in the Orion Bar, and are well explained with a pseudo-time-dependent gas-phase model in which deuteration occurs mainly via ion-molecule reactions with H2D+, CH2D+ and C2HD+. Finally, the [H13CN]/[HN13C] ratio is very high (~11) for the 10 km s-1 component, which also agree with our model predictions for an age of ~0.01 to a few 0.1 Myr. Conclusions: The deuterium chemistry is a good tool for studying the low-mass and high-mass star-forming regions. However, while low-mass star-forming regions seem well characterized with Dfrac(N2H+) or Dfrac(HCO+), a more complete chemical modeling is required to date massive star-forming regions. This is due to the higher gas temperature together with the rapid evolution of massive protostars. Appendices are available in electronic form at http://www.aanda.org

Abiotic production of nitrous oxide by lightning. Implications for a false positive identification of life on Earth-Like Planets around quiescent M Dwarfs

NASA Astrophysics Data System (ADS)

Navarro, Karina F.; Navarro-Gonzalez, Rafael; McKay, Christopher P.

Nitrous oxide (N _{2}O) is uniformly mixed in the troposphere with a concentration of about 310 ppb but disappears in the stratosphere (Prinn et al., 1990); N _{2}O is mostly emitted at a rate of 1x10 (13) g yr (-1) as a byproduct of microbial activity in soils and in the ocean by two processes: a) denitrification (reduction of nitrate and nitrite), and b) nitrification (oxidation of ammonia) (Maag and Vinther, 1996). The abiotic emission of N _{2}O in the contemporaneous Earth is small, mostly arising from lightning activity (2x10 (9) g yr (-1) , Hill et al., 1984) and by reduction of nitrite by Fe(II)-minerals in soils in Antarctica (Samarkin et al., 2010). Since N _{2}O has absorption bands in the mid-IR (7.8, 8.5, and 17 mumm) that makes it detectable by remote sensing (Topfer et al., 1997; Des Marais et al., 2002), it has been suggested as a potential biosignature in the search for life in extrasolar planets (Churchill and Kasting, 2000). However, the minimum required concentration for positive identification is 10,000 ppb with missions like Terrestrial Planet Finder and Darwin (Churchill and Kasting, 2000). Therefore, it is not a suitable biomarker for extrasolar Earth-like planets orbiting stars similar to the Sun. Because N _{2}O is protected in the troposphere from UV photolysis by the stratospheric ozone layer, its concentration would decrease with decreasing oxygen (O _{2}) concentrations, if the biological source strength remains constant (Kasting and Donahue, 1980). For a primitive Earth-like (Hadean) atmosphere dominated by CO _{2}, and no free O _{2}, the expected N _{2}O concentration would be about 3 ppb with the current microbial N _{2}O flux (Churchill and Kasting, 2000). The resulting N _{2}O spectral signature of this atmosphere would be undetectable unless the N _{2}O microbial flux would be 10 (4) greater than its present value (Churchill and Kasting, 2000). Since this flux is unlikely, it is impossible to use it as a biomarker in anoxic CO _{2} dominated primitive Earth-like atmospheres. However, during the rise in atmospheric O _{2} at the start of the Proterozoic, the ocean became stratified (anoxic at the bottom and oxygenic at the surface). During this period, the emissions of N _{2}O were probably higher than today associated with a stronger microbial activity in the early anoxic ocean layer (Grenfell et al., 2011). Under this scenario, the predicted N _{2}O concentration would be about 3920 ppb, considering 10% the current atmospheric O _{2} concentrations, 100 times higher the current microbial N _{2}O flux, and a fainter Sun (94.3%) (Grenfell et al., 2011). This concentration would be still undetectable (Grenfell et al., 2011). A completely different scenario could be expected in Earth-like planets orbiting M dwarfs, which are the most abundant stars in the galaxy, representing about 75% of the total stellar population. M stars exhibit a large range in activity levels from very low levels of chromospheric and coronal activity, the so-called “quiescent” to high levels, the so-called “active" states. Photochemical models predict that the N _{2}O concentration would only increase to about 1,000 ppb for the current Earth orbiting an active M star, but surprisingly up to about 1,000 ppm for the current Earth orbiting a quiescent M star (Segura et al., 2005). Therefore, N _{2}O becomes a promising biomarker. Under this scenario it is important to constrain the abiotic sources of N _{2}O under different atmospheric conditions to avoid a false positive identification of life. Here we report an experimental study of the effects of lightning discharges on the nitrogen fixation rate during the evolution of the Earth’s early atmosphere from 10 to 1 percent of carbon dioxide in molecular nitrogen. We extended our study from no methane up to 1,000 ppm CH _{4}, which would be applicable to the postbiotic Earth (Tian et al., 2011). Lightning was simulated in the laboratory by a plasma generated with a pulsed Nd-YAG laser (Navarro-González et al., 2001). Our results show that the energy yield of N _{2}O slightly increases from 3.6x10 (13) molecules J (-1) at 1% CO _{2} to 4.7x10 (13) molecules J (-1) at 10% CO _{2}, and is independent of the initial methane concentration. It is unclear how the lightning flashing rate would have varied on the early Earth, and how different would be it on an Earth-like planet orbiting a quiescent M star; however, assuming that it is similar to the present value of about 1x10 (18) J yr (-1) (Navarro-González et al., 2001), our results imply that the production rate of N _{2}O was about 2x10 (9) g yr (-1) , about 5,000 times less the current microbial flux. This abiotic flux of N _{2}O by lightning is about 200 times higher than that produced by corona discharges (Nna Mvondo et al., 2005). Extrapolating this flux in Segura et al.’s (2005) model, an assuming no effect for the lack of atmospheric oxygen, implies a N _{2}O concentration of 200 ppb. This value could be underestimated if lightning activity would be enhanced on Earth-like planets orbiting a quiescent M star. However, we conclude that lightning activity could not interfere with the remote detection of life using N _{2}O as a biosignature. References: Churchill, D. and Kasting, J.: 2000, Nitrous oxide in the early atmosphere: A marker for life? ESA SP 451. Des Marais, D.J., Harwit, M.O., Jucks, K.W., Kasting, J.F., Lin, D.N.C., Lunine, J.I,. Schneider, J., Seager, S., Traub, W.A., and Woolf, N.J.: 2002, Remote Sensing of Planetary Properties and Biosignatures on Extrasolar Terrestrial Planets, Astrobio. 2, 153-181. Grenfell, J.L., Gebauer, S., von Paris, P.,, Godolt, M, Hedelt, P., Patzer, A.B.C., Stracke, B., and Rauer, H.: 2011, Sensitivity of biomarkers to changes in chemical emissions in the Earth’s Proterozoic atmosphere, Icarus 211, 81-88. Hill, R.D., Rinker, R.G., and Coucouvinos, A.: 1984, Nitrous oxide production by lightning, J. Geophys. Res. 89, 1411-1421. Kasting, J.F. and Donahue, T.M.: 1980. The evolution of atmospheric ozone. J. Geophys. Res. 85, 3255-3263. Maag, M., and Vinther, F.P.: 1996, Nitrous oxide emission by nitrification and denitrification in different soil types and at different soil moisture contents and temperatures. Appl. Soil Ecol. 4, 5-14. Navarro-González, R., McMay, C.P. and Nna Mvondo, D.: 2001, A posible nitrogen crisis for Archaean life due to reduced nitrogen fixation by lightning. Nature 412, 61-64. Nna Mvondo, D., Navarro-González, R., Raulin, F., and Coll, P.: 2005, Nitrogen fixation by corona discharge on the early precambrian Earth. Origins Life Evol. Biosph. 35, 401-409. Prinn, R., Cunnold, D., Rasmussen, R., Simmonds, P., Alyea, F., Crawford, A., Fraser P., and Rosen R.: 1990, Atmospheric emissions and trends of nitrous oxide deduced from 10 years of ALE-GAGE data.J.Geophys. Res. 95, 18369-18385. Samarkin, V.A., Madigan, M.T., Bowles, M.W., Casciotti, K.L., Priscu, J.C., McKay, C.P., and Joye, S.B.: 2010, Abiotic nitrous oxide emission from the hypersaline Don Juan Pond in Antarctica. Nature Geosci. 3, 341-344. Segura, A., Kasting, J.F., Meadows, V., Cohen, M., Scalo, J., Crisp, D.,Butler, R.A.H.,and Tinetti, G.: 2005, Biosignatures from Earth-Like Planets Around M Dwarfs. Astrobiology 5, 706-725. Tian, F., Kasting, J.F. and Zahnle, K.: 2011, Revisiting HCN formation in Earth's early atmosphere. Earth Planet. Sci. Lett. 308, 417-423. Topfer T., Petrov, K.P., Mine Y., Jundt D., Curl, R.F. and F.K. Tittel: 1997, Room-temperature mid-infrared laser sensor for trace gas detection. Appl. Optics 36, 8042-8049.