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Sample records for durissus terrificus neutralize

  1. The inhibitory effect of Camellia sinensis extracts against the neuromuscular blockade of Crotalus durissus terrificus venom

    PubMed Central

    de Jesus Reis Rosa, Luana; Silva, Gleidy Ana Araujo; Filho, Jorge Amaral; Silva, Magali Glauzer; Groppo, Francisco Carlos; Oshima-Franco, Yoko

    2010-01-01

    In geographically isolated populations where intensive medical care or serum therapy is not easily accessible snake envenomation is a major cause for concern. The aim of the present study was to test Camellia sinensis extracts, theaflavin and epigallocatechin (two of the main C. sinensis components) against the irreversible neuromuscular blockade induced by Crotalus durissus terrificus venom in mouse phrenic-nerve diaphragm preparations. A quantitative histological study was also performed. The venom (20µg/ml) completely decreased twitch tension after 70min and 5µg/ml venom abolished 50% of twitch amplitude after 60min. C. sinensis extract induced intense facilitatory effect in the preparation activity at 0.2mg/ml and slightly facilitatory effect at 0.05mg/ml. Both 0.05mg/ml C. sinensis extract and 0.05mg/ml commercial theaflavin maintained partial muscular activity in presence of 5µg/ml venom. The histological data confirms that Cs is able to protect the muscle from the myotoxic activity of the venom. Commercial epigallocatechin gallate did not show pre-synaptic nor post-synaptic activities. C. sinensis extract was able to protect the mouse phrenic-nerve diaphragm against the irreversible neuromuscular blockade induced by C. durissus terrificus venom. PMID:21544176

  2. The Evolutionary Implications of Hemipenial Morphology of Rattlesnake Crotalus durissus terrificus (Laurent, 1768) (Serpentes: Viperidae: Crotalinae)

    PubMed Central

    Porto, Marcovan; de Oliveira, Marco Antonio; Pissinatti, Lorenzo; Rodrigues, Renata Lopes; Rojas-Moscoso, Julio Alejandro; Cogo, José Carlos; Metze, Konradin; Antunes, Edson; Nahoum, César; Mónica, Fabíola Z.; De Nucci, Gilberto

    2013-01-01

    Most amniotes vertebrates have an intromittent organ to deliver semen. The reptile Sphenodon and most birds lost the ancestral penis and developed a cloaca-cloaca mating. Known as hemipenises, the copulatory organ of Squamata shows unique features between the amniotes intromittent organ. They are the only paired intromittent organs across amniotes and are fully inverted and encapsulated in the tail when not in use. The histology and ultrastructure of the hemipenes of Crotalus durissus rattlesnake is described as the evolutionary implications of the main features discussed. The organization of hemipenis of Crotalus durissus terrificus in two concentric corpora cavernosa is similar to other Squamata but differ markedly from the organization of the penis found in crocodilians, testudinata, birds and mammals. Based on the available data, the penis of the ancestral amniotes was made of connective tissue and the incorporation of smooth muscle in the framework of the sinusoids occurred independently in mammals and Crotalus durissus. The propulsor action of the muscle retractor penis basalis was confirmed and therefore the named should be changed to musculus hemipenis propulsor.The retractor penis magnus found in Squamata has no homology to the retractor penis of mammals, although both are responsible for the retraction of the copulatory organ. PMID:23840551

  3. The intrahippocampal infusion of crotamine from Crotalus durissus terrificus venom enhances memory persistence in rats.

    PubMed

    Vargas, Liane S; Lara, Marcus V S; Gonçalves, Rithiele; Mandredini, Vanusa; Ponce-Soto, Luis Alberto; Marangoni, Sergio; Dal Belo, Cháriston A; Mello-Carpes, Pâmela B

    2014-07-01

    Previous research has shown that crotamine, a toxin isolated from the venom of Crotalus durissus terrificus, induces the release of acetylcholine and dopamine in the central nervous system of rats. Particularly, these neurotransmitters are important modulators of memory processes. Therefore, in this study we investigated the effects of crotamine infusion on persistence of memory in rats. We verified that the intrahippocampal infusion of crotamine (1 μg/μl; 1 μl/side) improved the persistence of object recognition and aversive memory. By other side, the intrahippocampal infusion of the toxin did not alter locomotor and exploratory activities, anxiety or pain threshold. These results demonstrate a future prospect of using crotamine as potential pharmacological tool to treat diseases involving memory impairment, although it is still necessary more researches to better elucidate the crotamine effects on hippocampus and memory. PMID:24813333

  4. Blood oxygen affinity increases during digestion in the South American rattlesnake, Crotalus durissus terrificus.

    PubMed

    Bovo, Rafael P; Fuga, Adriana; Micheli-Campbell, Mariana A; Carvalho, José E; Andrade, Denis V

    2015-08-01

    Digesting snakes experience massive increases in metabolism that can last for many days and are accompanied by adjustments in the oxygen transport cascade. Accordingly, we examined the oxygen-binding properties of the blood in the South American rattlesnake (Crotalus durissus terrificus) during fasting and 24 and 48h after the snakes have ingested a rodent meal corresponding to 15% (±2%) of its own body mass. In general, oxygen-hemoglobin (Hb-O2) affinity was significantly increased 24h post-feeding, and then returned toward fasting values within 48h post-feeding. Content of organic phosphates ([NTP] and [NTP]/[Hb]), hemoglobin cooperativity (Hill's n), and Bohr Effect (ΔlogP50/ΔpH) were not affected by feeding. The postprandial increase in Hb-O2 affinity in the South American rattlesnake can be almost entirely ascribed by the moderate alkaline tide that follows meal ingestion. In general, digesting snakes were able to regulate blood metabolites at quite constant levels (e.g., plasma osmolality, lactate, glucose, and total protein levels). The level of circulating lipids, however, was considerably increased, which may be related to their mobilization, since lipids are known to be incorporated by the enterocytes after snakes have fed. In conclusion, our results indicate that the exceptional metabolic increment exhibited by C. d. terrificus during meal digestion is entirely supported by the aerobic pathways and that among the attending cardiorespiratory adjustments, pulmonary Hb-O2 loading is likely improved due to the increment in blood O2 affinity. PMID:25446935

  5. Massive Muscular Infection by a Sarcocystis Species in a South American Rattlesnake (Crotalus durissus terrificus).

    PubMed

    Roberts, J F; Wellehan, J F X; Weisman, J L; Rush, M; Childress, A L; Lindsay, David S

    2015-06-01

    Massive numbers of sarcocysts of a previously undescribed species of Sarcocystis were observed in the skeletal muscles throughout the body of an adult, female South American rattlesnake (Crotalus durissus terrificus). Examination of tissue sections by light microscopy demonstrated that sarcocysts were present in 20 to 40% of muscle fibers from 5 sampled locations. Sarcocysts were not present in cardiac muscle, smooth muscle, or other organs. Sarcocysts were 0.05-0.15 mm wide, had variable length depending on the viewed orientation and size of the muscle fiber, and had a sarcocyst wall less than 1-μm thick. Sarcocysts were subdivided by septa and had central degeneration in older sarcocysts. Host induced secondary encapsulation or an inflammatory response was not present. By transmission electron microscopy (TEM), the sarcocyst wall was Type I, with a parasitophorous membrane of approximately 100 nanometers in width arranged in an undulating pattern and intermittently folded inward in a branching pattern. The sarcocysts contained metrocytes in different stages of development and mature bradyzoites. The nucleic acid sequence from a section of the 18S small subunit rRNA gene was most closely related to S. mucosa that uses marsupials as intermediate hosts and has an unknown definitive host. This is apparently the third report of muscular Sarcocystis infection in snakes and is the first to describe the ultrastructure of the sarcocysts and use sequencing methods to aid in identification. PMID:25658773

  6. Opiate and acetylcholine-independent analgesic actions of crotoxin isolated from crotalus durissus terrificus venom.

    PubMed

    Zhang, Hui-Ling; Han, Rong; Chen, Zhi-Xing; Chen, Bo-Wen; Gu, Zhen-Lun; Reid, Paul F; Raymond, Laurence N; Qin, Zheng-Hong

    2006-08-01

    The venom of Crotalus durissus terrificus is reported to have analgesic activity and the administration of Crotoxin (Cro) to cancer patients is reported to reduce the consumption of analgesics. This study investigated the analgesia induced by Cro and the effects of atropine and naloxone on the antinociceptive activity of Cro in mice and rats. The results showed that Cro at 66.5, 44.3 and 29.5microg/kg (ip) exhibited a dose-dependent analgesic action in mice using the hotplate and acetic acid writhing tests. Cro at 44.3microg/kg (ip) had significant analgesic action in the rat tail-flick test. In the mouse acetic acid-writhing test, intracerebral ventricular administration of Cro 0.3microg/kg produced marked analgesic effects. Microinjection of Cro (0.15microg/kg) into the periaqueductal gray area also elicited a robust analgesic action in rat hotplate test. Atropine at 0.5mg/kg (im) or 10mg/kg (ip) or naloxone at 3mg/kg (ip) failed to block the analgesic effects of Cro. These results suggest that Cro has analgesic effects mediated by an action on the central nervous system. The muscarinic and opioid receptors are not involved in the antinociceptive effects of Cro. PMID:16857228

  7. Inflammatory mediators release in urine from mice injected with Crotalus durissus terrificus venom.

    PubMed

    Hernández Cruz, A; Barbosa Navarro, L; Mendonça, R Z; Petricevich, V L

    2011-01-01

    In this study, we investigated in groups of female BALB/c mice injected with Crotalus durissus terrificus venom (Cdt) the renal function based on creatinine clearance, percentage of fractional excretion cytokines and histological examination of renal tissue. Cdt caused renal alterations that induced proteinuria during the initial hours post-venom and reduced creatinine clearance 15 min. up to 2 hours post-venom administration. In urine from mice injected with Cdt induced a decrease in IL-4 levels. More pronounced increments of IL-5, IL-6 and IFN-γ were observed after 15 and 30 min, respectively. The highest levels of TNF and IL-10 were observed at 1 and 4 hs, respectively. The ratios of pro- and anti-inflammatory cytokines in animals injected with Cdt, which may be manifested in the inflammatory status during the envenoming. In groups of animals treated with Cdt were observed a decreasing in creatinine clearance and its effect on glomerular filtration rate was accompanied by decreased fractional excretion of cytokines and morphologic disturbances. This loss of change selectively in envenomation could thus explain why the relatively excretion of cytokines is reduced while of total proteins increases. In conclusion the fractional excretion of cytokines is significantly reduced in mice injected with Cdt, despite proteinuria. PMID:22174490

  8. Inflammatory Mediators Release in Urine from Mice Injected with Crotalus durissus terrificus Venom

    PubMed Central

    Hernández Cruz, A.; Barbosa Navarro, L.; Mendonça, R. Z.; Petricevich, V. L.

    2011-01-01

    In this study, we investigated in groups of female BALB/c mice injected with Crotalus durissus terrificus venom (Cdt) the renal function based on creatinine clearance, percentage of fractional excretion cytokines and histological examination of renal tissue. Cdt caused renal alterations that induced proteinuria during the initial hours post-venom and reduced creatinine clearance 15 min. up to 2 hours post-venom administration. In urine from mice injected with Cdt induced a decrease in IL-4 levels. More pronounced increments of IL-5, IL-6 and IFN-γ were observed after 15 and 30 min, respectively. The highest levels of TNF and IL-10 were observed at 1 and 4 hs, respectively. The ratios of pro- and anti-inflammatory cytokines in animals injected with Cdt, which may be manifested in the inflammatory status during the envenoming. In groups of animals treated with Cdt were observed a decreasing in creatinine clearance and its effect on glomerular filtration rate was accompanied by decreased fractional excretion of cytokines and morphologic disturbances. This loss of change selectively in envenomation could thus explain why the relatively excretion of cytokines is reduced while of total proteins increases. In conclusion the fractional excretion of cytokines is significantly reduced in mice injected with Cdt, despite proteinuria. PMID:22174490

  9. Intrahippocampal Infusion of Crotamine Isolated from Crotalus durissus terrificus Alters Plasma and Brain Biochemical Parameters †

    PubMed Central

    Gonçalves, Rithiele; Vargas, Liane S.; Lara, Marcus V. S.; Güllich, Angélica; Mandredini, Vanusa; Ponce-Soto, Luis; Marangoni, Sergio; Dal Belo, Cháriston A.; Mello-Carpes, Pâmela B.

    2014-01-01

    Crotamine is one of the main constituents of the venom of the South American rattlesnake Crotalus durissus terrificus. Here we sought to investigate the inflammatory and toxicological effects induced by the intrahippocampal administration of crotamine isolated from Crotalus whole venom. Adult rats received an intrahippocampal infusion of crotamine or vehicle and were euthanized 24 h or 21 days after infusion. Plasma and brain tissue were collected for biochemical analysis. Complete blood count, creatinine, urea, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), creatine-kinase (CK), creatine kinase-muscle B (CK-MB) and oxidative parameters (assessed by DNA damage and micronucleus frequency in leukocytes, lipid peroxidation and protein carbonyls in plasma and brain) were quantified. Unpaired and paired t-tests were used for comparisons between saline and crotamine groups, and within groups (24 h vs. 21 days), respectively. After 24 h crotamine infusion promoted an increase of urea, GOT, GPT, CK, and platelets values (p ≤ 0.01), while red blood cells, hematocrit and leukocytes values decreased (p ≤ 0.01). Additionally, 21 days after infusion crotamine group showed increased creatinine, leukocytes, TBARS (plasma and brain), carbonyl (plasma and brain) and micronucleus compared to the saline-group (p ≤ 0.01). Our findings show that crotamine infusion alter hematological parameters and cardiac markers, as well as oxidative parameters, not only in the brain, but also in the blood, indicating a systemic pro-inflammatory and toxicological activity. A further scientific attempt in terms of preserving the beneficial activity over toxicity is required. PMID:25380458

  10. Intrahippocampal infusion of crotamine isolated from Crotalus durissus terrificus alters plasma and brain biochemical parameters.

    PubMed

    Gonçalves, Rithiele; Vargas, Liane S; Lara, Marcus V S; Güllich, Angélica; Mandredini, Vanusa; Ponce-Soto, Luis; Marangoni, Sergio; Dal Belo, Cháriston A; Mello-Carpes, Pâmela B

    2014-11-01

    Crotamine is one of the main constituents of the venom of the South American rattlesnake Crotalus durissus terrificus. Here we sought to investigate the inflammatory and toxicological effects induced by the intrahippocampal administration of crotamine isolated from Crotalus whole venom. Adult rats received an intrahippocampal infusion of crotamine or vehicle and were euthanized 24 h or 21 days after infusion. Plasma and brain tissue were collected for biochemical analysis. Complete blood count, creatinine, urea, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), creatine-kinase (CK), creatine kinase-muscle B (CK-MB) and oxidative parameters (assessed by DNA damage and micronucleus frequency in leukocytes, lipid peroxidation and protein carbonyls in plasma and brain) were quantified. Unpaired and paired t-tests were used for comparisons between saline and crotamine groups, and within groups (24 h vs. 21 days), respectively. After 24 h crotamine infusion promoted an increase of urea, GOT, GPT, CK, and platelets values (p ≤ 0.01), while red blood cells, hematocrit and leukocytes values decreased (p ≤ 0.01). Additionally, 21 days after infusion crotamine group showed increased creatinine, leukocytes, TBARS (plasma and brain), carbonyl (plasma and brain) and micronucleus compared to the saline-group (p ≤ 0.01). Our findings show that crotamine infusion alter hematological parameters and cardiac markers, as well as oxidative parameters, not only in the brain, but also in the blood, indicating a systemic pro-inflammatory and toxicological activity. A further scientific attempt in terms of preserving the beneficial activity over toxicity is required. PMID:25380458

  11. Preliminary X-ray crystallographic studies of a tetrameric phospholipase A{sub 2} formed by two isoforms of crotoxin B from Crotalus durissus terrificus venom

    SciTech Connect

    Marchi-Salvador, D. P.; Corrêa, L. C.; Salvador, G. H. M.; Magro, A. J.; Oliveira, C. Z.; Iulek, J.; Soares, A. M.; Fontes, M. R. M.

    2007-12-01

    Crotoxin B is a basic phospholipase A{sub 2} found in the venom of C. durissus terrificus and is one of the subunits that constitute crotoxin. Here, the crystallization, X-ray diffraction data collection and molecular-replacement solution of a novel tetrameric complex formed by two dimers of crotoxin B isoforms are presented. Crotoxin B is a basic phospholipase A{sub 2} found in the venom of Crotalus durissus terrificus and is one of the subunits that constitute crotoxin. This heterodimeric toxin, which is the main component of C. d. terrificus venom, is completed by an acidic, nontoxic and non-enzymatic component (crotoxin A) and is involved in important envenomation effects, such as neurological disorders, myotoxicity and renal failure. Although crotoxin was first crystallized in 1938, no crystal structure is currently available for crotoxin, crotoxin A or crotoxin B. In this work, the crystallization, X-ray diffraction data collection to 2.28 Å resolution and molecular-replacement solution of a novel tetrameric complex formed by two dimers of crotoxin B isoforms (CB1 and CB2) is presented.

  12. Crotoxin from Crotalus durissus terrificus Is Able to Down-Modulate the Acute Intestinal Inflammation in Mice

    PubMed Central

    Almeida, Caroline de Souza; Andrade-Oliveira, Vinicius; Câmara, Niels Olsen Saraiva; Jacysyn, Jacqueline F.; Faquim-Mauro, Eliana L.

    2015-01-01

    Inflammatory bowel diseases (IBD) is the result of dysregulation of mucosal innate and adaptive immune responses. Factors such as genetic, microbial and environmental are involved in the development of these disorders. Accordingly, animal models that mimic human diseases are tools for the understanding the immunological processes of the IBD as well as to evaluate new therapeutic strategies. Crotoxin (CTX) is the main component of Crotalus durissus terrificus snake venom and has an immunomodulatory effect. Thus, we aimed to evaluate the modulatory effect of CTX in a murine model of colitis induced by 2,4,6- trinitrobenzene sulfonic acid (TNBS). The CTX was administered intraperitoneally 18 hours after the TNBS intrarectal instillation in BALB/c mice. The CTX administration resulted in decreased weight loss, disease activity index (DAI), macroscopic tissue damage, histopathological score and myeloperoxidase (MPO) activity analyzed after 4 days of acute TNBS colitis. Furthermore, the levels of TNF-α, IL-1β and IL-6 were lower in colon tissue homogenates of TNBS-mice that received the CTX when compared with untreated TNBS mice. The analysis of distinct cell populations obtained from the intestinal lamina propria showed that CTX reduced the number of group 3 innate lymphoid cells (ILC3) and Th17 population; CTX decreased IL-17 secretion but did not alter the frequency of CD4+Tbet+ T cells induced by TNBS instillation in mice. In contrast, increased CD4+FoxP3+ cell population as well as secretion of TGF-β, prostaglandin E2 (PGE2) and lipoxin A4 (LXA4) was observed in TNBS-colitis mice treated with CTX compared with untreated TNBS-colitis mice. In conclusion, the CTX is able to modulate the intestinal acute inflammatory response induced by TNBS, resulting in the improvement of clinical status of the mice. This effect of CTX is complex and involves the suppression of the pro-inflammatory environment elicited by intrarectal instillation of TNBS due to the induction of a

  13. Crotoxin from Crotalus durissus terrificus snake venom induces the release of glutamate from cerebrocortical synaptosomes via N and P/Q calcium channels.

    PubMed

    Lomeo, Rosangela da Silva; Gonçalves, Ana Paula de Faria; da Silva, Carolina Nunes; de Paula, André Tunes; Costa Santos, Danielle Oliveira; Fortes-Dias, Consuelo Latorre; Gomes, Dawidson Assis; de Lima, Maria Elena

    2014-07-01

    Crotoxin (Crtx), the main toxin in the venom of Crotalus durissus terrificus snake, is a heterodimer with a basic subunit, CB, and an acidic subunit, CA. CB is a phospholipase A2 that depends on CA to specifically bind to the cell membrane. This toxin acts in the central nervous system (CNS) causing chronic seizure effects and other cytotoxic effects. Here, we report its action on glutamate release in rat cerebral cortex synaptosomes. Aiming at a better understanding of the mechanism of action of Crtx, calcium channel blockers were used and internalization studies were performed in cerebellar granule neurons. Our results show that Crtx induces calcium-dependent glutamate release via N and P/Q calcium channels. In addition, the CB subunit of Crtx is shown to be internalized. This internalization does not depend on the presence of CA subunit neither on the PLA2 activity of CB. A correlation between CB internalization and glutamate release remains to be established. PMID:24751366

  14. New immunization protocol to produce crotalic antivenom combining Crotalus durissus terrificus venom and its PLA2.

    PubMed

    Fusco, Luciano Sebastián; Rodríguez, Juan Pablo; Teibler, Pamela; Maruñak, Silvana; Acosta, Ofelia; Leiva, Laura

    2015-01-01

    Antivenoms are usually obtained by animal immunization with successive inoculations of increasing sublethal amounts of venom, which may impair the animal health. The high lethality of venom requires prolonged immunization plans with small amounts of venom. Thus, we propose an alternative plan that includes a pre-immunization of the animal with phospholipase A2, the main crotoxin component, which is responsible for the whole venom lethality. For comparison, three different immunization schemes were designed: high dose protocol (HDP; 0.5-27 mg of venom), low dose protocol (LDP; 0.1-7 mg of venom) and Mix protocol (MP; preimmunization 0.1-1.2 mg of crotalic PLA2, and then 4.5-8 mg of venom). Antibody titers were determined by ELISA, in blood plasma obtained from the marginal vein of the ear. The neutralizing ability of the different sera obtained by all protocols (HDS, LDS and MS) was tested against the most important pharmacological activities of whole venom: PLA2 activity, myotoxicity, thrombin like activity and lethality. MS showed the best neutralizing efficacy and at the same time, it was obtained by an immunization protocol that takes account of animal health care, since it requires low quantities of venoms in comparison to traditional protocols. PMID:25453603

  15. Effect of Chlorogenic Acid (5-Caffeoylquinic Acid) Isolated from Baccharis oxyodonta on the Structure and Pharmacological Activities of Secretory Phospholipase A2 from Crotalus durissus terrificus

    PubMed Central

    Toyama, Daniela O.; Ferreira, Marcelo J. P.; Romoff, Paulete; Fávero, Oriana A.; Gaeta, Henrique H.; Toyama, Marcos H.

    2014-01-01

    The aim of this paper was to investigate the effect of chlorogenic acid (5-caffeoylquinic acid, 5CQA), isolated from Baccharis oxyodonta, on the structure and pharmacological effect of secretory phospholipase A2 (sPLA2) from Crotalus durissus terrificus. All in vitro and in vivo experiments were conducted using a purified sPLA2 compared under the same experimental conditions with sPLA2 : 5CQA. 5CQA induced several discrete modifications in the secondary structure and the hydrophobic characteristics of native sPLA2 that induced slight changes in the α-helical content, increase in the random coil structure, and decrease of fluorescence of native sPLA2. Moreover, 5CQA significantly decreased the enzymatic activity and the oedema and myonecrosis induced by native sPLA2. As the catalytic activity of sPLA2 plays an important role in several of its biological and pharmacological properties, antibacterial activity was used to confirm the decrease in its enzymatic activity by 5CQA, which induced massive bacterial cell destruction. We found that 5CQA specifically abolished the enzymatic activity of sPLA2 and induced discrete protein unfolding that mainly involved the pharmacological site of sPLA2. These results showed the potential application of 5CQA in the snake poisoning treatment and modulation of the pathological effect of inflammation induced by secretory PLA2. PMID:25258715

  16. Phospholipase A2 Isolated from the Venom of Crotalus durissus terrificus Inactivates Dengue virus and Other Enveloped Viruses by Disrupting the Viral Envelope

    PubMed Central

    Muller, Vanessa Danielle; Soares, Ricardo Oliveira; dos Santos-Junior, Nilton Nascimento; Trabuco, Amanda Cristina; Cintra, Adelia Cristina; Figueiredo, Luiz Tadeu; Caliri, Antonio; Sampaio, Suely Vilela; Aquino, Victor Hugo

    2014-01-01

    The Flaviviridae family includes several virus pathogens associated with human diseases worldwide. Within this family, Dengue virus is the most serious threat to public health, especially in tropical and sub-tropical regions of the world. Currently, there are no vaccines or specific antiviral drugs against Dengue virus or against most of the viruses of this family. Therefore, the development of vaccines and the discovery of therapeutic compounds against the medically most important flaviviruses remain a global public health priority. We previously showed that phospholipase A2 isolated from the venom of Crotalus durissus terrificus was able to inhibit Dengue virus and Yellow fever virus infection in Vero cells. Here, we present evidence that phospholipase A2 has a direct effect on Dengue virus particles, inducing a partial exposure of genomic RNA, which strongly suggests inhibition via the cleavage of glycerophospholipids at the virus lipid bilayer envelope. This cleavage might induce a disruption of the lipid bilayer that causes a destabilization of the E proteins on the virus surface, resulting in inactivation. We show by computational analysis that phospholipase A2 might gain access to the Dengue virus lipid bilayer through the pores found on each of the twenty 3-fold vertices of the E protein shell on the virus surface. In addition, phospholipase A2 is able to inactivate other enveloped viruses, highlighting its potential as a natural product lead for developing broad-spectrum antiviral drugs. PMID:25383618

  17. Evidence for a respiratory component, similar to mammalian respiratory sinus arrhythmia, in the heart rate variability signal from the rattlesnake, Crotalus durissus terrificus.

    PubMed

    Campbell, Hamish A; Leite, Cleo A C; Wang, Tobias; Skals, Marianne; Abe, Augusto S; Egginton, Stuart; Rantin, F Tadeu; Bishop, Charles M; Taylor, Edwin W

    2006-07-01

    Autonomic control of heart rate variability and the central location of vagal preganglionic neurones (VPN) were examined in the rattlesnake (Crotalus durissus terrificus), in order to determine whether respiratory sinus arrhythmia (RSA) occurred in a similar manner to that described for mammals. Resting ECG signals were recorded in undisturbed snakes using miniature datalogging devices, and the presence of oscillations in heart rate (fh) was assessed by power spectral analysis (PSA). This mathematical technique provides a graphical output that enables the estimation of cardiac autonomic control by measuring periodic changes in the heart beat interval. At fh above 19 min(-1) spectra were mainly characterised by low frequency components, reflecting mainly adrenergic tonus on the heart. By contrast, at fh below 19 min(-1) spectra typically contained high frequency components, demonstrated to be cholinergic in origin. Snakes with a fh >19 min(-1) may therefore have insufficient cholinergic tonus and/or too high an adrenergic tonus acting upon the heart for respiratory sinus arrhythmia (RSA) to develop. A parallel study monitored fh simultaneously with the intraperitoneal pressures associated with lung inflation. Snakes with a fh<19 min(-1) exhibited a high frequency (HF) peak in the power spectrum, which correlated with ventilation rate (fv). Adrenergic blockade by propranolol infusion increased the variability of the ventilation cycle, and the oscillatory component of the fh spectrum broadened accordingly. Infusion of atropine to effect cholinergic blockade abolished this HF component, confirming a role for vagal control of the heart in matching fh and fv in the rattlesnake. A neuroanatomical study of the brainstem revealed two locations for vagal preganglionic neurones (VPN). This is consistent with the suggestion that generation of ventilatory components in the heart rate variability (HRV) signal are dependent on spatially distinct loci for cardiac VPN. Therefore

  18. The analgesic activity of crotamine, a neurotoxin from Crotalus durissus terrificus (South American rattlesnake) venom: a biochemical and pharmacological study.

    PubMed

    Mancin, A C; Soares, A M; Andrião-Escarso, S H; Faça, V M; Greene, L J; Zuccolotto, S; Pelá, I R; Giglio, J R

    1998-12-01

    Crotamine, a 4.88 kDa neurotoxic protein, has been purified to apparent homogeneity from Crotalus durissus venom by gel filtration on Sephadex G-75. When injected (i.p. or s.c.) in adult male Swiss mice (20-25 g), it induced a time-dose dependent analgesic effect which was inhibited by naloxone, thus suggesting an opioid action mechanism. When compared with morphine (4 mg/kg), crotamine, even in extremely low doses (133.4 microg/kg, i.p., about 0.4% of a LD50 is approximately 30-fold more potent than morphine (w/w) as an analgesic. On a molar basis it is more than 500-fold more potent than morphine. It is also much more potent than the lower molecular weight crude fractions of the same venom. The antinociceptive effects of crotamine and morphine were assayed by the hot plate test and by the acetic acid-induced writhing method. Therefore, both central and peripheral mechanisms should be involved. Histopathological analysis of the brain, liver, skeletal muscles, stomach, lungs, spleen, heart, kidneys and small intestine of the crotamine injected mice did not show any visible lesion in any of these organs by light microscopy. Since crotamine accounted for 22% (w/w) of the desiccated venom, it was identified as its major antinociceptive low molecular weight peptide component. PMID:9839677

  19. Isolation, characterization and screening of the in vitro cytotoxic activity of a novel L-amino acid oxidase (LAAOcdt) from Crotalus durissus terrificus venom on human cancer cell lines.

    PubMed

    Teixeira, Tuila Leveghim; Oliveira Silva, Viviane Aline; da Cunha, Daniel Batista; Polettini, Flávia Lino; Thomaz, Camila Daniele; Pianca, Ariana Aparecida; Zambom, Fabiana Letícia; da Silva Leitão Mazzi, Denise Pimenta; Reis, Rui Manuel; Mazzi, Maurício Ventura

    2016-09-01

    An L-amino acid oxidase (LAAOcdt) from Crotalus durissus terrificus venom was purified to homogeneity in a two-step procedure using molecular exclusion on Sephadex G-75, followed by Phenyl Sepharose FF chromatography. The molecular mass of the purified enzyme was 113 kDa, as determined by SDS-PAGE under reducing conditions. LAAOcdt showed amino acid homology to other L-amino acid oxidases isolated from different snake venoms. The comparative analysis of the internal peptide sequences of the NNPGILEYPVKPSEEGK fragments by LC-MS/MS spectrometry revealed 100% identity with C. durissus cumanensis LAAO. The purified protein catalyzed the oxidative deamination of L-amino acids, and the most specific substrates were L-Tyr and L-Phe. The enzyme presented optimum activity at pH 7.4 and at 44 °C. LAAOcdt also showed hemolytic activity (0.6-20 μg/μL) and induced both the formation plasma clots (5-100 μg/μL) and platelet aggregation (2.5 × 10(-3), 5.0 × 10(-3) and 10 × 10(-3) μg/mL), as well as bactericidal activity (2.5-10 μg/μL) against Staphylococcus aureus. Moreover, LAAOcdt exhibited cytotoxicity in distinct cancer cell lines, which presented a heterogeneous response profile. The mean IC50 value was 10.5 μg/mL. Glioma and pancreatic carcinoma cells were the most sensitive cell lines; they showed mean IC50 values of 7.2 μg/mL and 7.4 μg/mL, respectively. The exposure of the drug-sensitive cells to LAAOcdt for 24 h upregulated activated p-H2AX and efficiently decreased P42/P44 (ERK) activation in glioma cells (HCB151), which suggested an anti-proliferative effect. In addition, increased p21 expression was observed in SiHa cells, which showed a resistant phenotype. On the other hand, the flow cytometry and immunoblotting analyses showed that the enzyme did not induce cancer cell apoptosis. These results suggest that another cell death mechanism might contribute to the LAAOcdt-induced cytotoxicity. Taken together, this work may help to elucidate

  20. Secretory phospholipases A(2) isolated from Bothrops asper and from Crotalus durissus terrificus snake venoms induce distinct mechanisms for biosynthesis of prostaglandins E2 and D2 and expression of cyclooxygenases.

    PubMed

    Moreira, Vanessa; Gutiérrez, José Maria; Soares, Andreimar Martins; Zamunér, Stella Regina; Purgatto, Eduardo; Teixeira, Catarina de Fátima Pereira

    2008-09-01

    The effects of myotoxin III (MT-III), a phospholipase A(2) (sPLA2) from Bothrops asper snake venom, and crotoxin B (CB), a neurotoxic and myotoxic sPLA2 from the venom of Crotalus durissus terrificus, on cyclooxygenases (COXs) expression and biosynthesis of prostaglandins (PGs) were evaluated, together with the mechanisms involved in these effects. Upon intraperitoneal injection in mice, both sPLA(2)s promoted the synthesis of PGD2 and PGE2, with a different time-course. MT-III, but not CB, induced COX-2 expression by peritoneal leukocytes without modification on COX-1 constitutive expression, whereas CB increased the constitutive activity of COX-1. MT-III increased the enzymatic activity of COX-1 and COX-2. Similar effects were observed when these sPLA(2)s were incubated with isolated macrophages, evidencing a direct effect on these inflammatory cells. Moreover, both toxins elicited the release of arachidonic acid from macrophages in vitro. Inhibition of cPLA2 by AACOCF3, but not of iPLA2 by PACOCF3 or BEL, significantly reduced PGD2, PGE2 and arachidonic acid (AA) release promoted by MT-III. These inhibitors did not affect MT-III-induced COX-2 expression. In contrast, cPLA2 inhibition did not modify the effects of CB, whereas iPLA2 inhibition reduced PGD2 and AA production induced by CB. These findings imply that distinct regulatory mechanisms leading to PGs' synthesis are triggered by these snake venom sPLA(2)s. Such differences are likely to explain the dissimilar patterns of inflammatory reaction elicited by these sPLA(2)s in vivo. PMID:18619987

  1. P9a(Cdt-PLA2) from Crotalus durissus terrificus as good immunogen to be employed in the production of crotalic anti-PLA2 IgG.

    PubMed

    Fusco, Luciano S; Rodríguez, Juan Pablo; Torres-Huaco, Frank; Huancahuire-Vega, Salomón; Teibler, Pamela; Acosta, Ofelia; Marangoni, Sergio; Ponce-Soto, Luis Alberto; Leiva, Laura C

    2015-10-01

    Four proteins with phospholipase A2 (PLA2) activity, designated P9a(Cdt-PLA2), P9b(Cdt-PLA2), P10a(Cdt-PLA2) and P10b(Cdt-PLA2) were purified from the venom of Crotalus durissus terrificus by two chromatographic steps: a gel filtration and reversed phase HPLC. The profile obtained clearly shows that three of them have a similar abundance. The molecular mass, 14193.8340Da for P9a(Cdt-PLA2), 14134.9102Da for P9b(Cdt-PLA2), 14242.6289Da for P10a(Cdt-PLA2) and 14183.8730Da for P10b(Cdt-PLA2), were initially evaluated by SDS-PAGE and confirmed by ESI-Q-TOF spectrometry, and all of them displayed a monomeric conformation. Also, partial amino acid sequence of each protein was obtained and their alignments with other crotalic PLA2 revealed a high degree of identity among them. Additionally, we studied some pharmacological activities like neurotoxicity, myotoxicity and lethality, which prompted us to pick two of them, P9a(Cdt-PLA2) and P10a(Cdt-PLA2) that resulted to be less toxic that the others, and further characterize them to be used as immunogen. We next injected these last proteins in mice to produce antitoxins against them and ELISA and dot blots reveled that both toxins do not show immunogenic differences, unlike those other pharmacologic activities tested. Furthermore, the antibodies produced cross-reacted with all the isoforms purified demonstrating the feasibility of using only one of them and ensuring the cross-reaction of all. The results obtained show that P9a(Cdt-PLA2) isoform has the lowest toxicity and also a good purification performance; thus this protein may be a promising candidate to be employed in the production of crotalic antitoxins. PMID:26129711

  2. Biochemical characterization of two crotamine isoforms isolated by a single step RP-HPLC from Crotalus durissus terrificus (South American rattlesnake) venom and their action on insulin secretion by pancreatic islets.

    PubMed

    Toyama, M H; Carneiro, E M; Marangoni, S; Barbosa, R L; Corso, G; Boschero, A C

    2000-03-01

    Crotamine, a neurotoxin present in the venom of the South American rattlesnake Crotalus durrisus terrificus exists as several polymorphic variants, as demonstrated by recombinant DNA technology (Smith and Schmidt, Toxicon 28 (1990) 575-585). We have isolated native crotamine by chromatography on Sephadex G75, and have purified two crotamine isoforms (F2 and F3) by a single step of RP-HPLC. Native crotamine and RP-HPLC fractions F2 and F3 produced skeletal muscle spasms and spastic paralysis in mice. At low glucose concentrations (2.8-5.6 mmol/l), none of the crotamines altered the insulin secretion by rat isolated islets. In the presence of 16.7 mmol glucose/l, F2 (5 microg/ml), but not F3, increased insulin secretion two-fold, whereas native crotamine (1.5, 5 and 16.5 microg/ml) potentiated the secretion dose-dependently. The increase in insulin secretion induced by F2 fraction (5 microg/ml) was similar to that obtained with 16.5 microg of native crotamine/ml. These results indicate that the mode of action of the F2 and F3 isoforms in beta-cells is different from that in muscle cells. This difference may be related to the binding affinity of each isoform for the Na(+) channels located in the beta-cell membrane. Crotamine isoforms may be valuable tools for studying the involvement of Na(+) channels in the mechanism of insulin secretion. PMID:10699490

  3. Neutralizing human anti crotoxin scFv isolated from a nonimmunized phage library.

    PubMed

    Cardoso, D F; Nato, F; England, P; Ferreira, M L; Vaughan, T J; Mota, I; Mazie, J C; Choumet, V; Lafaye, P

    2000-04-01

    Combinatorial phage display technology offers a new possibility for making human antibodies which could be used in immune therapy. We explored the use of this technology to make human scFvs specific for crotoxin, the main toxic component of the venom of the South-American rattlesnake Crotalus durissus terrificus. Crotoxin, a phospholipase A2 neurotoxin constituted by the association of two subunits, exerts its lethal action by blocking neuromuscular transmission. This is the first report of human anticrotoxin scFvs (scFv 1, scFv 6 and scFv 8) isolated from a naive library of more than 1010 scFv clones with in vivo neutralizing activity. Nevertheless, differences are observed at the level of biological and immunological effects. Only scFv 8 is able to reduce the myotoxicity induced by crotoxin and scFv 1 is capable of altering the in vitro enzymatic activity of this toxin. All three scFvs recognize a region of one subunit located at the junction with the other one. Moreover these scFvs share strong amino acid homologies at the level of either the heavy or the light chain. Taken together, our results suggest that the use of human anticrotoxin scFvs may lead to a new and less aggressive passive immune therapy against poisoning by the venom of Crotalus durissus terrificus. PMID:10736105

  4. Structural and pharmacological characterization of the crotamine isoforms III-4 (MYX4_CROCu) and III-7 (MYX7_CROCu) isolated from the Crotalus durissus cumanensis venom.

    PubMed

    Ponce-Soto, Luis Alberto; Martins-de-Souza, Daniel; Marangoni, Sergio

    2010-07-01

    Two major crotamine isoforms (III-4 and III-7) were obtained combining two chromatographic steps on molecular exclusion chromatography (Sephadex G-75) and ion-exchange column (Protein Pack SP 5PW) of the rattlesnake Crotalus durissus cumanensis venom. The "in vivo" myotoxic effect of the venom, its "in vitro" cytotoxicity in myoblasts and myotubes (C2C12) and the neurotoxic and edema-forming activity were characterized. The molecular masses of the crotamine isoforms were 4907.94 Da (III-4) and 4985.02 Da (III-7) and, as determined by mass spectrometry, both contained six Cys residues. Enzymatic hydrolysis followed by de novo sequencing through tandem mass spectrometry was used to determine the primary structure of both isoforms. III-4 and III-7 isoforms presented a 42-amino acid residues sequence and showed high molecular amino acid sequence identity with other crotamine-like proteins from Crotalus durissus terrificus. In vivo, both crotamine isoforms induced myotoxicty and a systemic interleukin-6 response upon intramuscular injection. These new crotamine isoforms induced low cytotoxicity in skeletal muscle myoblasts and myotubes (C2C12) and both induced a facilitatory effect on neuromuscular transmission in young chick biventer cervicis preparation. Edema-forming activity was also analyzed by injection of the crotamine isoforms into the right paw, since both crotamine isoforms exert a strong pro-inflammatory effect. PMID:20206199

  5. Studies on the low molecular weight RNA associated with 28S ribosomal RNA from Crotalus durissus terrificus liver.

    PubMed Central

    Giorgini, J F; De Lucca, F L

    1976-01-01

    A low molecular weight RNA was released from the purified rattlesnake 28 S RNA by brief heat treatment as well as by treatment with 80% dimethylsulfoxide or formamide. The sedimentation coeficient of this low molecular weight RNA was found to be 5.5 S, corresponding to a nucleotide number of 140 and a molecular weight of 46 000. It was also observed that 5.5S RNA is present in equimolar ratio to 5 S rRNA. Heat treatment of the purified 60 S ribosomal subunit also released the 5.5 S RNA. The possibility that this low molecular weight RNA is located on the surface of the large ribosomal subunit is discussed. PMID:1250695

  6. Neuromuscular effects of venoms and crotoxin-like proteins from Crotalus durissus ruruima and Crotalus durissus cumanensis.

    PubMed

    Cavalcante, Walter Luís Garrido; Ponce-Soto, Luis Alberto; Marangoni, Sérgio; Gallacci, Márcia

    2015-03-01

    A myographic study was performed to compare the neuromuscular effects of venoms and crotoxin-like proteins from Crotalus durissus ruruima and Crotalus durissus cumanensis in mice phrenic-diaphragm preparation. It was concluded that both venoms present neurotoxic activity as a consequence of their crotoxin content. Furthermore, crotoxin from C.d. cumanensis is more potent than that from C.d. ruruima venom. At the concentration range in which both venoms express neurotoxic activity, only C.d. cumanensis venom also manifest a direct myotoxic effect that probably involves the synergic participation of other components than crotoxin. PMID:25598498

  7. Is the population of Crotalus durissus (Serpentes, Viperidae) expanding in Brazil?

    PubMed Central

    2013-01-01

    Crotalus durissus are found from Mexico to northern Argentina in a highly disjunct distribution. According to some studies, this species is prone to occupy areas disturbed by human activities and floods comprise a plausible method of dispersal as inferred for some North American rattlesnakes. Based on the literature, it seems plausible that Crotalus durissus expanded their natural distribution in Brazil due to floods, but only in a few municipalities in Rio de Janeiro State. Data entries of Butantan Institute, in São Paulo, Brazil, from 1998 to 2012 show a declining tendency of snakes brought by donors. In addition, research shows no evidence of Crotalus durissus being an expanding species in the Brazilian territory. PMID:24314146

  8. Comparison of the effect of Crotalus simus and Crotalus durissus ruruima venoms on the equine antibody response towards Bothrops asper venom: implications for the production of polyspecific snake antivenoms.

    PubMed

    Dos-Santos, Maria Cristina; Arroyo, Cynthia; Solano, Sergio; Herrera, María; Villalta, Mauren; Segura, Alvaro; Estrada, Ricardo; Gutiérrez, José María; León, Guillermo

    2011-02-01

    Antivenoms are preparations of immunoglobulins purified from the plasma of animals immunized with snake venoms. Depending on the number of venoms used during the immunization, antivenoms can be monospecific (if venom from a single species is used) or polyspecific (if venoms from several species are used). In turn, polyspecific antivenoms can be prepared by purifying antibodies from the plasma of animals immunized with a mixture of venoms, or by mixing antibodies purified from the plasma of animals immunized separately with single venom. The suitability of these strategies to produce polyspecific antibothropic-crotalic antivenoms was assessed using as models the venoms of Bothrops asper, Crotalus simus and Crotalus durissus ruruima. It was demonstrated that, when used as co-immunogen, C. simus and C. durissus ruruima venoms exert a deleterious effect on the antibody response towards different components of B. asper venom and in the neutralization of hemorrhagic and coagulant effect of this venom when compared with a monospecific B. asper antivenom. Polyspecific antivenoms produced by purifying immunoglobulins from the plasma of animals immunized with venom mixtures showed higher antibody titers and neutralizing capacity than those produced by mixing antibodies purified from the plasma of animals immunized separately with single venom. Thus, despite the deleterious effect of Crotalus sp venoms on the immune response against B. asper venom, the use of venom mixtures is more effective than the immunization with separate venoms for the preparation of polyspecific bothropic-crotalic antivenoms. PMID:21130107

  9. Neutralization of venom-induced hemorrhage by equine antibodies raised by immunization with a plasmid encoding a novel P-II metalloproteinase from the lancehead pitviper Bothrops asper.

    PubMed

    Arce-Estrada, Viviana; Azofeifa-Cordero, Gabriela; Estrada, Ricardo; Alape-Girón, Alberto; Flores-Díaz, Marietta

    2009-01-14

    In this work, the cDNA encoding a novel P-II type metalloproteinase from Bothrops asper venom glands was cloned, sequenced and used for DNA immunization of animals with accelerated DNA-coated tungsten microparticles and the helius Gene Gun system. Specific antibodies against B. asper venom antigens were induced in mice co-immunized with the plasmid encoding the P-II metalloproteinase together with an expression plasmid encoding the murine IL-2. Similarly, specific antibodies against B. asper venom antigens were also induced in a horse co-immunized with the plasmid encoding the P-II metalloproteinase, together with a plasmid encoding the equine IL-6. The equine antibodies induced by immunization with the P-II metalloproteinase encoding plasmid cross react with several proteins of B. asper, Crotalus durissus durissus, and Lachesis stenophrys venoms in western blot, demonstrating antigenic similarity between the cloned metalloproteinase and other metalloproteinases present in these venoms. Furthermore, the equine antibodies induced by immunization with the P-II metalloproteinase encoding plasmid completely neutralized the hemorrhagic activity of the whole B. asper venom and partially the hemorrhagic activity of C. durissus durissus venom. The neutralizing ability of the produced antibodies raises, for the first time, the possibility of developing therapeutic antivenoms in horses by DNA immunization using tungsten microparticles. PMID:19013207

  10. Anti-Leptospira spp. antibodies in Crotalus durissus collilineatus kept in captivity and its zoonotic relevance.

    PubMed

    Rodrigues, T C S; Santos, A L Q; Lima, A M C; Gomes, D O; Brites, V L C

    2016-06-01

    Leptospirosis is a worldwide spread zoonosis that can affect all groups of vertebrates, including reptiles. Because it has been little studied in snakes, this study focused on determining the occurrence of anti-Leptospira spp. antibodies in 64 Crotalus durissus collilineatus kept in captivity and on identifying the most common serovars in these animals, using the microscopic agglutination test. Of these, almost 90% were positive and there were reactions to the 22 serovars used in the study. The most common serovar in these snakes was Javanica, Andamana and Patoc. Most frequent titers were 25 and 50, although high titers (such as 1600) were also recorded, despite the absence of clinical symptoms. The possibility should be considered of captive snakes serving as a serious source of leptospiral infection in humans, which is why it is essential to study, prevent and control the disease in breeding centers and serpentariums. PMID:26875762

  11. Identification of crotamine in the venom of Crotalus durissus collilineatus by three different methods.

    PubMed

    de Oliveira, Sayonara Ay More; Magalhães, Marta Regina; Salazar, Vania Cristina Rodríguez; Valadares, Marize Campos; da Cunha, Luiz Carlos

    2015-03-01

    The use of mice for the identification of crotamine has been the motive of discussions of bioethical character and technical (efficiency), so that a reassessment of the use of animals in experiments is global trend the search for alternative tests. The objective of this study was to standardize a method for HPLC-PDA to identify the presence of crotamine in the venom of rattlesnakes, aiming to propose an alternative methodology to reduce or replace the use of animals. The Cdc was evaluated as to the presence of crotamine by 3 methods: traditional test lethality in mice (Mus musculus) swiss albino male, 18-22 g (i.p.), polyacrylamide gel electrophoresis (SDS-PAGE) and HPLC-PDA. The venoms of 50 specimens of Crotalus durissus collilineatus, held in the serpentarium CEPB/PUC Goiás, were obtained by manual massage of the gland, making the collection individually. To identify the band corresponding to crotamine, the venoms of specimens, analysis was performed on SDS-PAGE and references. Procedure in mice with 20% of the samples tested positive for crotamine, 24% negative and 56% uncertain outcome. With the SDS-PAGE was identified crotamine in 26% of samples, 26% negative and 48% continued with uncertain outcome. By HPLC method showed the presence myotoxin in 86% of samples, with 14% negative. The tests conducted in this study indicated that methodology which utilizes animals for identifying the presence of crotamine the venom of C. durissus can safely be replaced by the test SDS-PAGE and HPLC, since the methods are reproducible, and do not undergo any interference biological animal and mainly contribute to reducing the number of animals used for laboratory tests. PMID:25553594

  12. Effects of low molecular weight sulfated galactan fragments from Botryocladia occidentalis on the pharmacological and enzymatic activity of sPLA2 from Crotalus durissus cascavella.

    PubMed

    Toyama, M H; Toyama, D O; Torres, V M; Pontes, G C; Farias, W R L; Melo, F R; Oliveira, S C B; Fagundes, F H R; Diz Filho, E B S; Cavada, B S

    2010-11-01

    Low molecular weight fragments of sulfated galactans (Boc-5 and Boc-10) from the red algae Botryocladia occidentalis significantly inhibited Crotalus durissus cascavella sPLA2 enzymatic activity. Equimolar ratios of sPLA2 to Boc-5 or Boc-10 resulted in allosteric inhibition of sPLA2. Under the conditions tested, we observed that both Boc-5 and Boc-10 strongly decreased edema, myonecrosis, and neurotoxicity induced by native sPLA2. PMID:21061146

  13. Neutralizer optimization

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Mohajeri, Kayhan

    1991-01-01

    The preliminary results of a test program to optimize a neutralizer design for 30 cm xenon ion thrusters are discussed. The impact of neutralizer geometry, neutralizer axial location, and local magnetic fields on neutralizer performance is discussed. The effect of neutralizer performance on overall thruster performance is quantified, for thruster operation in the 0.5-3.2 kW power range. Additionally, these data are compared to data published for other north-south stationkeeping (NSSK) and primary propulsion xenon ion thruster neutralizers.

  14. Alterations in the ultrastructure of cardiac autonomic nervous system triggered by crotoxin from rattlesnake (Crotalus durissus cumanensis) venom.

    PubMed

    Hernández, Miguelina; Scannone, Héctor; Finol, Héctor J; Pineda, Maria E; Fernández, Irma; Vargas, Alba M; Girón, María E; Aguilar, Irma; Rodríguez-Acosta, Alexis

    2007-10-01

    This study explored the toxic effects of crotoxin isolated from Crotalus durissus cumanensis venom on the ultrastructure of mice cardiac autonomic nervous system. Mice were intravenously injected with saline (control group) and crotoxin diluted in saline venom (study group) at a dose of 0.107 mg/kg mouse body weight. Samples from the inter-ventricular septum were prepared for electron microscopy after 6 h (G1), 12 h (G2), 24 h (G3) and 48 h (G4). The G1 group showed some cardiomyocyte with pleomorphic mitochondria. Capillary swollen walls, nerve cholinergic endings with depleted acetylcholine vesicles in their interior and other depletions were observed. A space completely lacking in contractile elements was noticed. The G2 group demonstrated a myelinic figure, a subsarcolemic region with few myofibrils and nervous cholinergic terminal with scarce vacuoles in their interior. The G3 group demonstrated a structure with a depleted axonic terminal, mitochondrias varying in size and enhanced electron density. In addition, muscular fibers with myofibrillar structure disorganization, a depleted nervous structure surrounded by a Schwann cell along with an abundance of natriuretic peptides, were seen. An amyelinic terminal with depleted Schwann cell and with scarce vesicles was also observed. Finally, axonic lysis with autophagic vacuoles in their interior and condensed mitochondria was observed in the G4 group. This work describes the first report of ultrastructural damage caused by crotoxin on mice cardiac autonomic nervous system. PMID:17616380

  15. A new structurally atypical bradykinin-potentiating peptide isolated from Crotalus durissus cascavella venom (South American rattlesnake).

    PubMed

    Lopes, Denise M; Junior, Norberto E G; Costa, Paula P C; Martins, Patrícia L; Santos, Cláudia F; Carvalho, Ellaine D F; Carvalho, Maria D F; Pimenta, Daniel C; Cardi, Bruno A; Fonteles, Manassés C; Nascimento, Nilberto R F; Carvalho, Krishnamurti M

    2014-11-01

    Venom glands of some snakes synthesize bradykinin-potentiating peptides (BPP's) which increase bradykinin-induced hypotensive effect and decrease angiotensin I vasopressor effect by angiotensin-converting enzyme (ACE) inhibition. The present study shows a new BPP (BPP-Cdc) isolated from Crotalus durissus cascavella venom: Pro-Asn-Leu-Pro-Asn-Tyr-Leu-Gly-Ile-Pro-Pro. Although BPP-Cdc presents the classical sequence IPP in the C-terminus, it has a completely atypical N-terminal sequence, which shows very low homology with all other BPPs isolated to date. The pharmacological effects of BPP-Cdc were compared to BBP9a from Bothrops jararaca and captopril. BPP-Cdc (1 μM) significantly increased BK-induced contractions (BK; 1 μM) on the guinea pig ileum by 267.8% and decreased angiotensin I-induced contractions (AngI; 10 nM) by 62.4% and these effects were not significantly different from those of BPP9a (1 μM) or captopril (200 nM). Experiments with 4-week hypertensive 2K-1C rats show that the vasopressor effect of AngI (10 ng) was decreased by 50 μg BPP-Cdc (69.7%), and this result was similar to that obtained with 50 μg BPP9a (69.8%). However, the action duration of BPP-Cdc (60 min) was 2 times greater than that of BPP-9a (30 min). On the other hand, the hypotensive effect of BK (250 ng) was significantly increased by 176.6% after BPP-Cdc (50 μg) administration, value 2.5 times greater than that obtained with BPP9a administered at the same doses (71.4%). In addition, the duration of the action of BPP-Cdc (120 min) was also at least 4 times greater than that of BPP-9a (30 min). Taken together, these results suggest that BPP-Cdc presents more selective action on arterial blood system than BPP9a. Besides the inhibition of ACE, it may present other mechanisms of action yet to be elucidated. PMID:25091347

  16. Expression of a new serine protease from Crotalus durissus collilineatus venom in Pichia pastoris and functional comparison with the native enzyme.

    PubMed

    Boldrini-França, Johara; Santos Rodrigues, Renata; Santos-Silva, Ludier Kesser; de Souza, Dayane Lorena Naves; Gomes, Mário Sérgio Rocha; Cologna, Camila Takeno; de Pauw, Edwin; Quinton, Loïc; Henrique-Silva, Flávio; de Melo Rodrigues, Veridiana; Arantes, Eliane Candiani

    2015-12-01

    Snake venom serine proteases (SVSPs) act primarily on plasma proteins related to blood clotting and are considered promising for the treatment of several hemostatic disorders. We report the heterologous expression of a serine protease from Crotalus durissus collilineatus, named collinein-1, in Pichia pastoris, as well as the enzymatic comparative characterization of the toxin in native and recombinant forms. The complementary DNA (cDNA) encoding collinein-1 was amplified from cDNA library of C. d. collilineatus venom gland and cloned into the pPICZαA vector. The recombinant plasmid was used to transform cells of KM71H P. pastoris. Heterologous expression was induced by methanol and yielded 56 mg of recombinant collinein-1 (rCollinein-1) per liter of culture. The native collinein-1 was purified from C. d. collilineatus venom, and its identity was confirmed by amino acid sequencing. The native and recombinant enzymes showed similar effects upon bovine fibrinogen by releasing preferentially fibrinopeptide A. Although both enzymes have induced plasma coagulation, native Colinein-1 has shown higher coagulant activity. The serine proteases were able to hydrolyze the chromogenic substrates S-2222, S-2238, and S2302. Both enzymes showed high stability on different pH and temperature, and their esterase activities were inhibited in the presence of Zn2+ and Cu2+. The serine proteases showed similar k cat/K m values in enzyme kinetics assays, suggesting no significant differences in efficiency of these proteins to hydrolyze the substrate. These results demonstrated that rCollinein-1 was expressed with functional integrity on the evaluated parameters. The success in producing a functionally active recombinant SVSP may generate perspectives to their future therapeutic applications. PMID:26227411

  17. Neutral beam monitoring

    DOEpatents

    Fink, Joel H.

    1981-08-18

    Method and apparatus for monitoring characteristics of a high energy neutral beam. A neutral beam is generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange neutralizes the high energy ion beam. The neutral beam is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are further identified.

  18. On neutral plasma oscillations

    SciTech Connect

    Shadwick, B.A.; Morrison, P.J.

    1993-06-01

    We examine the conditions for the existence of spectrally stable neutral modes in a Vlasov-Poisson plasma and show that for stable equilibria of systems that have unbounded spatial domain, the only possible neutral modes are those with phase velocities that correspond to stationary inflection points of the equilibrium distribution function. It is seen that these neutral modes can possess positive or negative free energy.

  19. ALEX neutral beam probe

    SciTech Connect

    Pourrezaei, K.

    1982-01-01

    A neutral beam probe capable of measuring plasma space potential in a fully 3-dimensional magnetic field geometry has been developed. This neutral beam was successfully used to measure an arc target plasma contained within the ALEX baseball magnetic coil. A computer simulation of the experiment was performed to refine the experimental design and to develop a numerical model for scaling the ALEX neutral beam probe to other cases of fully 3-dimensional magnetic field. Based on this scaling a 30 to 50 keV neutral cesium beam probe capable of measuring space potential in the thermal barrier region of TMX Upgrade was designed.

  20. Neutrality in Language Policy

    ERIC Educational Resources Information Center

    Wee, Lionel

    2010-01-01

    The unavoidability of language makes it critical that language policies appeal to some notion of language neutrality as part of their rationale, in order to assuage concerns that the policies might otherwise be unduly discriminatory. However, the idea of language neutrality is deeply ideological in nature, since it is not only an attempt to treat…

  1. Bilateral posterior circulation stroke secondary to a crotalid envenomation: case report.

    PubMed

    Vale, Thiago Cardoso; Leite, Alysson Ferreira; Hora, Priscila Ribeiro da; Coury, Marayra Inês França; Silva, Ricardo Cipriano da; Teixeira, Antônio Lúcio

    2013-01-01

    Snake bite envenoming is a disease with potential serious neurological complications. We report a case of an adolescent who was bitten by a rattlesnake and developed bilateral posterior circulation stroke. The rattlesnake was later identified as being Crotalus durissus terrificus. Stroke was probably due to toxic vasculitis or toxin-induced vascular spasm and endothelial damage. PMID:23740059

  2. Equivalent Neutral Wind

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Tang, Wenqing

    1996-01-01

    The definition of equivalent neutral wind and the rationale for using it as the geophysical product of a spaceborne scatterometer are reviewed. The differences between equivalent neutral wind and actual wind, which are caused by atmospheric density stratification, are demonstrated with measurements at selected locations. A method of computing this parameter from ship and buoy measurements is described and some common fallacies in accounting for the effects of atmospheric stratification on wind shear are discussed. The computer code for the model to derive equivalent neutral wind is provided.

  3. Solar Neutral Particles

    NASA Video Gallery

    This animation shows a neutral solar particle's path leaving the sun, following the magnetic field lines out to the heliosheath. The solar particle hits a hydrogen atom, stealing its electron, and ...

  4. A niche for neutrality.

    PubMed

    Adler, Peter B; Hillerislambers, Janneke; Levine, Jonathan M

    2007-02-01

    Ecologists now recognize that controversy over the relative importance of niches and neutrality cannot be resolved by analyzing species abundance patterns. Here, we use classical coexistence theory to reframe the debate in terms of stabilizing mechanisms (niches) and fitness equivalence (neutrality). The neutral model is a special case where stabilizing mechanisms are absent and species have equivalent fitness. Instead of asking whether niches or neutral processes structure communities, we advocate determining the degree to which observed diversity reflects strong stabilizing mechanisms overcoming large fitness differences or weak stabilization operating on species of similar fitness. To answer this question, we propose combining data on per capita growth rates with models to: (i) quantify the strength of stabilizing processes; (ii) quantify fitness inequality and compare it with stabilization; and (iii) manipulate frequency dependence in growth to test the consequences of stabilization and fitness equivalence for coexistence. PMID:17257097

  5. Is dispersal neutral?

    PubMed

    Lowe, Winsor H; McPeek, Mark A

    2014-08-01

    Dispersal is difficult to quantify and often treated as purely stochastic and extrinsically controlled. Consequently, there remains uncertainty about how individual traits mediate dispersal and its ecological effects. Addressing this uncertainty is crucial for distinguishing neutral versus non-neutral drivers of community assembly. Neutral theory assumes that dispersal is stochastic and equivalent among species. This assumption can be rejected on principle, but common research approaches tacitly support the 'neutral dispersal' assumption. Theory and empirical evidence that dispersal traits are under selection should be broadly integrated in community-level research, stimulating greater scrutiny of this assumption. A tighter empirical connection between the ecological and evolutionary forces that shape dispersal will enable richer understanding of this fundamental process and its role in community assembly. PMID:24962790

  6. Neutral particle lithography

    NASA Astrophysics Data System (ADS)

    Craver, Barry Paul

    Neutral particle lithography (NPL) is a high resolution, proximity exposure technique where a broad beam of energetic neutral particles floods a stencil mask and transmitted beamlets transfer the mask pattern to resist on a substrate, such that each feature is printed in parallel, rather than in the serial manner of electron beam lithography. It preserves the advantages of ion beam lithography (IBL), including extremely large depth-of-field, sub-5 nm resist scattering, and the near absence of diffraction, yet is intrinsically immune to charge-related artifacts including line-edge roughness and pattern placement errors due to charge accumulation on the mask and substrate. In our experiments, a neutral particle beam is formed by passing an ion beam (e.g., 30 keV He+) through a high pressure helium gas cell (e.g., 100 mTorr) to convert the ions to energetic neutrals through charge transfer scattering. The resolution of NPL is generally superior to that of IBL for applications involving insulating substrates, large proximity gaps, and ultra-small features. High accuracy stepped exposures with energetic neutral particles, where magnetic or electrostatic deflection is impossible, have been obtained by clamping the mask to the wafer, setting the proximity gap with a suitable spacer, and mechanically inclining the mask/wafer stack relative to the beam. This approach is remarkably insensitive to vibration and thermal drift; nanometer scale image offsets have been obtained with +/-2 nm placement accuracy for experiments lasting over one hour. Using this nanostepping technique, linewidth versus dose curves were obtained, from which the NPL lithographic blur was determined as 4.4+/-1.4 nm (1sigma), which is 2-3 times smaller than the blur of electron beam lithography. Neutral particle lithography has the potential to form high density, periodic patterns with sub-10 nm resolution.

  7. Ultracold neutral plasmas.

    PubMed

    Killian, Thomas C

    2007-05-01

    Ultracold neutral plasmas occupy an exotic regime of plasma physics in which electrons form a swarming, neutralizing background for ions that sluggishly move in a correlated manner. Strong interactions between the charged particles give rise to surprising dynamics such as oscillations of the average kinetic energy during equilibration and extremely fast recombination. Such phenomena offer stimulating and challenging problems for computational scientists, and the physics can be applied to other environments, such as the interior of gas giant planets and plasmas created by short-pulse laser irradiation of solid, liquid, and cluster targets. PMID:17478712

  8. Neutral beam development plan

    SciTech Connect

    Staten, H S

    1980-08-01

    The national plan is presented for developing advanced injection systems for use on upgrades of existing experiments, and use on future facilities such as ETF, to be built in the late 1980's or early 90's where power production from magnetic fusion will move closer to a reality. Not only must higher power and longer pulse length systems be developed , but they must operate reliably; they must be a tool for the experimenter, not the experiment itself. Neutral beam systems handle large amounts of energy and as such, they often are as complicated as the plasma physics experiment itself. This presents a significant challenge to the neutral beam developer.

  9. CO2-Neutral Fuels

    NASA Astrophysics Data System (ADS)

    Goede, Adelbert; van de Sanden, Richard

    2016-06-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy efficiency.

  10. Bleach Neutralizes Mold Allergens

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Researchers at National Jewish Medical and Research Center have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…

  11. Modeling thermospheric neutral density

    NASA Astrophysics Data System (ADS)

    Qian, Liying

    Satellite drag prediction requires determination of thermospheric neutral density. The NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) and the global-mean Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM) were used to quantify thermospheric neutral density and its variations, focusing on annual/semiannual variation, the effect of using measured solar irradiance on model calculations of solar-cycle variation, and global change in the thermosphere. Satellite drag data and the MSIS00 empirical model were utilized to compare to the TIEGCM simulations. The TIEGCM simulations indicated that eddy diffusion and its annual/semiannual variation is a mechanism for annual/semiannual density variation in the thermosphere. It was found that eddy diffusion near the turbopause can effectively influence thermospheric neutral density. Eddy diffusion, together with annual insolation variation and large-scale circulation, generated global annual/semiannual density variation observed by satellite drag. Using measured solar irradiance as solar input for the TIEGCM improved the solar-cycle dependency of the density calculation shown in F10.7 -based thermospheric empirical models. It has been found that the empirical models overestimate density at low solar activity. The TIEGCM simulations did not show such solar-cycle dependency. Using historic measurements of CO2 and F 10.7, simulations of the global-mean TIMEGCM showed that thermospheric neutral density at 400 km had an average long-term decrease of 1.7% per decade from 1970 to 2000. A forecast of density decrease for solar cycle 24 suggested that thermospheric density will decrease at 400 km from present to the end of solar cycle 24 at a rate of 2.7% per decade. Reduction in thermospheric density causes less atmospheric drag on earth-orbiting space objects. The implication of this long-term decrease of thermospheric neutral density is that it will increase the

  12. Neutral particle beam intensity controller

    DOEpatents

    Dagenhart, William K.

    1986-01-01

    A neutral beam intensity controller is provided for a neutral beam generator in which a neutral beam is established by accelerating ions from an ion source into a gas neutralizer. An amplitude modulated, rotating magnetic field is applied to the accelerated ion beam in the gas neutralizer to defocus the resultant neutral beam in a controlled manner to achieve intensity control of the neutral beam along the beam axis at constant beam energy. The rotating magnetic field alters the orbits of ions in the gas neutralizer before they are neutralized, thereby controlling the fraction of neutral particles transmitted out of the neutralizer along the central beam axis to a fusion device or the like. The altered path or defocused neutral particles are sprayed onto an actively cooled beam dump disposed perpendicular to the neutral beam axis and having a central open for passage of the focused beam at the central axis of the beamline. Virtually zero therough 100% intensity control is achieved by varying the magnetic field strength without altering the ion source beam intensity or its species yield.

  13. Between detection and neutralization.

    SciTech Connect

    Snell, Mark Kamerer; Green, Mary Wilson; Adams, Douglas Glenn; Pritchard, Daniel Allison

    2005-08-01

    Security system analytical performance analysis is generally based on the probability of system effectiveness. The probability of effectiveness is a function of the probabilities of interruption and neutralization. Interruption occurs if the response forces are notified in sufficient time to engage the adversary. Neutralization occurs if the adversary attack is defeated after the security forces have actively engaged the adversary. Both depend upon communications of data. This paper explores details of embedded communications functions that are often assumed to be inconsequential. It is the intent of the authors to bring focus to an issue in security system modeling that, if not well understood, has the potential to be a deciding factor in the overall system failure or effectiveness.

  14. Neutral atom traps.

    SciTech Connect

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  15. Antihypertensive neutral lipid

    DOEpatents

    Snyder, F.L.; Blank, M.L.

    1984-10-26

    The invention relates to the discovery of a class of neutral acetylated either-linked glycerolipids having the capacity to lower blood presure in warm-blooded animals. This physiological effect is structure sensitive requiring a long chain alkyl group at the sn-1 position and a short carbon chain acyl group (acetyl or propionyl) at the sn-2 position, and a hydroxyl group at the sn-3 position.

  16. Antihypertensive neutral lipid

    DOEpatents

    Snyder, Fred L.; Blank, Merle L.

    1986-01-01

    The invention relates to the discovery of a class of neutral acetylated ether-linked glycerolipids having the capacity to lower blood pressure in warm-blooded animals. This physiological effect is structure sensitive requiring a long chain alkyl group at the sn-1 position and a short carbon chain acyl group (acetyl or propionyl) at the sn-2 position, and a hydroxyl group at the sn-3 position.

  17. Neutral particle beam intensity controller

    DOEpatents

    Dagenhart, W.K.

    1984-05-29

    The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is accomplished by means of a magnetic field generator disposed about the neutralizer so that the field is transverse to the beam axis. The magnetic field intensity is varied to provide the selected partial beam defocusing of the ions prior to neutralization. The desired focused neutral beam portion passes along the beam path through a defining aperture in the beam dump, thereby controlling the desired fraction of neutral particles transmitted to a utilization device without altering the kinetic energy level of the desired neutral particle fraction. By proper selection of the magnetic field intensity, virtually zero through 100% intensity control of the neutral beam is achieved.

  18. Neutrality between Government and Religion.

    ERIC Educational Resources Information Center

    Mawdsley, Ralph D.

    1996-01-01

    The overall guiding principle of neutrality between government and religion masks a tension that exists between free exercise of religion and establishment of religion. Reviews the development and current status of "Lemon" as a test for neutrality; proposes a new test for neutrality, evenhandedness, that is common to both the Free Exercise and…

  19. Pulsed field sample neutralization

    DOEpatents

    Appelhans, Anthony D.; Dahl, David A.; Delmore, James E.

    1990-01-01

    An apparatus and method for alternating voltage and for varying the rate of extraction during the extraction of secondary particles, resulting in periods when either positive ions, or negative ions and electrons are extracted at varying rates. Using voltage with alternating charge during successive periods to extract particles from materials which accumulate charge opposite that being extracted causes accumulation of surface charge of opposite sign. Charge accumulation can then be adjusted to a ratio which maintains a balance of positive and negative charge emission, thus maintaining the charge neutrality of the sample.

  20. Cryoprotectant toxicity neutralization.

    PubMed

    Fahy, Gregory M

    2010-07-01

    Cryoprotectant toxicity is a fundamental limiting factor for the successful cryopreservation of living systems by both freezing and vitrification, and the ability to negate it would be attractive. Past attempts to demonstrate "cryoprotectant toxicity neutralization" (CTN) have had many ups and downs. First convincingly introduced by Baxter and Lathe in 1971, the concept that certain amides can block toxic effects of dimethyl sulfoxide (Me(2)SO) was contradicted by direct experiments in 1990. But in 1995, the opposite mode of CTN, in which Me(2)SO blocked the damaging effects of formamide, was robustly demonstrated. Recent experiments have verified the original 1995 results and extended them to urea and acetamide, but no CTN was detected for N-methylamides (N-methylformamide, N,N-dimethylformamide, and N-methylacetamide). On the theory that the latter amides and acetamide might serve as low-toxicity structural analogs of formamide, urea, or Me(2)SO, competition experiments were carried out between them and formamide or urea, but CTN was not observed for these amide-amide systems. The idea that the N-methylamides might have non-specific rather than specific toxicity was supported by the fact that the concentrations of these amides that cause toxicity are similar to the concentrations that denature model proteins. Clear examples of neutralization of the toxicity of glycerol, propylene glycol, ethylene glycol, or Me(2)SO are presently lacking, but effects of the latter that depend on sulfhydryl oxidation have been reversed with reducing agents. In summary, CTN is a useful phenomenon with significant theoretical and practical implications. PMID:19501081

  1. Transient ion neutralization by electrons.

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.

    1973-01-01

    The nonlinear initial-boundary-value problems describing the lateral neutralization of ion beams for the cases that (1) an auxiliary electric field accelerates the electrons into the ion space, and (2) the electrons are injected into the ion space at a prescribed current density are treated. Analytical solutions are derived which give the position and speed of the neutralization front as a function of time, and the temporal development of the electron density, velocity, and electric fields during the neutralization process.

  2. A proposed neutral line signature

    NASA Technical Reports Server (NTRS)

    Doxas, I.; Speiser, T. W.; Dusenbery, P. B.; Horton, W.

    1992-01-01

    An identifying signature is proposed for the existence and location of the neutral line in the magnetotail. The signature, abrupt density, and temperature changes in the Earthtail direction, was first discovered in test particle simulations. Such temperature variations have been observed in ISEE data (Huang et. al. 1992), but their connection to the possible existence of a neutral line in the tail has not yet been established. The proposed signature develops earlier than the ion velocity space ridge of Martin and Speiser (1988), but can only be seen by spacecraft in the vicinity of the neutral line, while the latter can locate a neutral line remotely.

  3. Chemistry of carotenoid neutral radicals.

    PubMed

    Ligia Focsan, A; Magyar, Adam; Kispert, Lowell D

    2015-04-15

    Proton loss from the carotenoid radical cations (Car(+)) to form neutral radicals (#Car) was investigated by numerous electrochemical, EPR, ENDOR and DFT studies described herein. The radical cation and neutral radicals were formed in solution electrochemically and stabilized on solid silica-alumina and MCM-41 matrices. Carotenoid neutral radicals were recently identified in Arabidopsis thaliana plant and photosystem II samples. Deprotonation at the terminal ends of a zeaxanthin radical cation could provide a secondary photoprotection pathway which involves quenching excited state chlorophyll by the long-lived zeaxanthin neutral radicals formed. PMID:25687648

  4. CO2-neutral fuels

    NASA Astrophysics Data System (ADS)

    Goede, A. P. H.

    2015-08-01

    The need for storage of renewable energy (RE) generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G) scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel cycle is

  5. NEUTRAL-BEAM INJECTION

    SciTech Connect

    Kunkel, W.B.

    1980-06-01

    The emphasis in the preceding chapters has been on magnetic confinement of high temperature plasmas. The question of production and heating of such plasmas has been dealt with relatively more briefly. It should not be inferred, however, that these matters must therefore be either trivial or unimportant. A review of the history reveals that in the early days all these aspects of the controlled fusion problem were considered to be on a par, and were tackled simultaneously and with equal vigor. Only the confinement problem turned out to be much more complex than initially anticipated, and richer in challenge to the plasma physicist than the questions of plasma production and heating. On the other hand, the properties of high-temperature plasmas and plasma confinement can only be studied experimentally after the problems of production and of heating to adequate temperatures are solved. It is the purpose of this and the next chapter to supplement the preceding discussions with more detail on two important subjects: neutral-beam injection and radio-frequency heating. These are the major contenders for heating in present and future tokamak and mirror fusion experiments, and even in several proposed reactors. For neutral beams we emphasize here the technology involved, which has undergone a rather remarkable development. The physics of particle and energy deposition in the plasma, and the discussion of the resulting effects on the confined plasma, have been included in previous chapters, and some experimental results are quoted there. Other heating processes of relevance to fusion are mentioned elsewhere in this book, in connection with the experiments where they are used: i.e. ohmic heating, adiabatic compression heating, and alpha-particle heating in Chapter 3 by H.P. Furth; more ohmic heating in Chapter 7, and shock-implosion heating, laser heating, and relativistic-electron beam heating in Chapter 8, both by W. E. Quinn. These methods are relatively straightforward in

  6. Neutral Buoyancy Simulator (NBS)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This is a cutaway illustration of the Neutral Buoyancy Simulator (NBS) at the Marshall Space Flight Center (MSFC ). The MSFC NBS provided an excellent environment for testing hardware to examine how it would operate in space and for evaluating techniques for space construction and spacecraft servicing. Here, engineers, designers, and astronauts performed various tests to develop basic concepts, preliminary designs, final designs, and crew procedures. The NBS was constructed of welded steel with polyester-resin coating. The water tank was 75-feet (22.9- meters) in diameter, 40-feet (12.2-meters) deep, and held 1.32 million gallons of water. Since it opened for operation in 1968, the NBS had supported a number of successful space missions, such as the Skylab, Solar Maximum Mission Satellite, Marned Maneuvering Unit, Experimental Assembly of Structures in Extravehicular Activity/Assembly Concept for Construction of Erectable Space Structures (EASE/ACCESS), the Hubble Space Telescope, and the Space Station. The function of the MSFC NBS was moved to the larger simulator at the Johnson Space Center and is no longer operational.

  7. Is science metaphysically neutral?

    PubMed

    Fry, Iris

    2012-09-01

    This paper challenges the claim that science is metaphysically neutral upheld by contenders of the separation of peacefully co-existent science and religion and by evolutionary theists. True, naturalistic metaphysical claims can neither be refuted nor proved and are thus distinct from empirical hypotheses. However, metaphysical assumptions not only regulate the theoretical and empirical study of nature, but are increasingly supported by the growing empirical body of science. This historically evolving interaction has contributed to the development of a naturalistic worldview that renounces the necessity of a transcendent god and of purposeful design. The thesis presented here differs not only from the claims of the "separatists" and of evolutionary theists. In pointing to the metaphysical aspects of science, I also criticize the failure of some evolutionary naturalists to distinguish between empirical and metaphysical contentions. Most important, based on the examination of science suggested here, creationists' false accusation that science is only a naturalistic dogma is refuted. Finally, the difficulties involved in the position endorsed here for the public support of evolution are acknowledged, taking into account the high religious profile of the American society and the social and political context in the US and in other countries. PMID:22771725

  8. Neutralization tests on the SERT 2 spacecraft

    NASA Technical Reports Server (NTRS)

    Kerslake, W. R.; Domitz, S.

    1979-01-01

    Neutralization test data obtained on the SERT 2 spacecraft are presented. Tests included ion beam neutralization of a thruster by a close (normal design) neutralizer as well as by a distant (1 meter) neutralizer. Parameters affecting neutralization, such as neutralizer bias voltage, neutralizer anode voltage, local spacecraft plasma density, and solar array voltage configuration were varied and changes in plasma potentials were measured. A plasma model is presented as an approximation of observed results.

  9. Neutral Sphingomyelinase 2

    PubMed Central

    Filosto, Simone; Castillo, Sianna; Danielson, Aaron; Franzi, Lisa; Khan, Elaine; Kenyon, Nick; Last, Jerold; Pinkerton, Kent; Tuder, Rubin; Goldkorn, Tzipora

    2011-01-01

    Chronic obstructive pulmonary disease (COPD) is caused by exposure to cigarette smoke (CS). One mechanism of CS-induced lung injury is aberrant generation of ceramide, which leads to elevated apoptosis of epithelial and endothelial cells in the alveolar spaces. Recently, we discovered that CS-induced ceramide generation and apoptosis in pulmonary cells is governed by neutral sphingomyelinase (nSMase) 2. In the current experiments, we expanded our studies to investigate whether nSMase2 governs ceramide generation and apoptosis in vivo using rodent and human models of CS-induced lung injury. We found that exposure of mice or rats to CS leads to colocalizing elevations of ceramide levels and terminal deoxynucleotidyl transferase mediated X-dUTP nick end labeling–positive cells in lung tissues. These increases are nSMase2 dependent, and are abrogated by treatment with N-acetyl cysteine or anti-nSMase2 small interfering RNA (siRNA). We further showed that mice that are heterozygous for nSMase2 demonstrate significant decrease in ceramide generation after CS exposure, whereas acidic sphingomyelinase (aSMase) knockout mice maintain wild-type ceramide levels, confirming our previous findings (in human airway epithelial cells) that only nSMase2, and not aSMase, is activated by CS exposure. Lastly, we found that lung tissues from patients with emphysema (smokers) display significantly higher levels of nSMase2 expression compared with lung tissues from healthy control subjects. Taken together, these data establish the central in vivo role of nSMase2 in ceramide generation, aberrant apoptosis, and lung injury under CS exposure, underscoring its promise as a novel target for the prevention of CS-induced airspace destruction. PMID:20448054

  10. Environmental neutralization of polonium-218

    SciTech Connect

    Goldstein, S.D.; Hopke, P.K.

    1985-01-01

    Previous work has indicated that two mechanisms of neutralization of the singly charged polonium ion exist. Charged Polonium-218 can be neutralized by reacting with oxygen to form a polonium oxide ion with a higher ionization potential than that of the polonium metal and then accepting an electron transferred from a lower ionization potential gas. In this present work, this mechanism has been verified by determining that the polonium oxide has an ionization potential in the range 10.35-10.53 eV. It was also previously reported that /sup 218/Po can be neutralized, in the absence of oxygen, by the scavenging of electrons by a trace gas such as water or nitrogen dioxide and their diffusion to the polonium ion. To verify this second neutralization mechanism, concentrations of nitrogen dioxide in nitrogen in the range of 50 ppb-1 ppm were examined for their ability to neutralize the polonium ion. Complete neutralization of /sup 218/Po was observed at nitrogen dioxide concentrations greater than 700 ppb. For concentrations below 700 ppb, the degree of neutralization was found to increase smoothly with the nitrogen dioxide concentration.

  11. [Neutral Medical Claim Management Committee].

    PubMed

    Komatsu, Mitsuru

    2013-03-01

    The Ibaraki Medical Association established the Committee for Alternative Dispute Resolution called the Neutral Medical Claim Management Committee in 2006. Among 64 claims presented to the committee, 29 were settled through mediation or consultation. Patients were generally satisfied that their claims were considered fairly by the committee and that they were able to talk directly with healthcare professionals. However, some did not consider the committee to be completely neutral. The healthcare professionals involved rated the committee highly because they felt that the processes were neutral and no emotional aspects were involved. PMID:23617190

  12. Incomplete Neutralization and Deviation from Sigmoidal Neutralization Curves for HIV Broadly Neutralizing Monoclonal Antibodies

    PubMed Central

    McCoy, Laura E.; Falkowska, Emilia; Doores, Katie J.; Le, Khoa; Sok, Devin; van Gils, Marit J.; Euler, Zelda; Burger, Judith A.; Seaman, Michael S.; Sanders, Rogier W.; Schuitemaker, Hanneke; Poignard, Pascal; Wrin, Terri; Burton, Dennis R.

    2015-01-01

    The broadly neutralizing HIV monoclonal antibodies (bnMAbs) PG9, PG16, PGT151, and PGT152 have been shown earlier to occasionally display an unusual virus neutralization profile with a non-sigmoidal slope and a plateau at <100% neutralization. In the current study, we were interested in determining the extent of non-sigmoidal slopes and plateaus at <100% for HIV bnMAbs more generally. Using both a 278 panel of pseudoviruses in a CD4 T-cell (U87.CCR5.CXCR4) assay and a panel of 117 viruses in the TZM-bl assay, we found that bnMAbs targeting many neutralizing epitopes of the spike had neutralization profiles for at least one virus that plateaued at <90%. Across both panels the bnMAbs targeting the V2 apex of Env and gp41 were most likely to show neutralization curves that plateaued <100%. Conversely, bnMAbs targeting the high-mannose patch epitopes were less likely to show such behavior. Two CD4 binding site (CD4bs) Abs also showed this behavior relatively infrequently. The phenomenon of incomplete neutralization was also observed in a large peripheral blood mononuclear cells (PBMC)-grown molecular virus clone panel derived from patient viral swarms. In addition, five bnMAbs were compared against an 18-virus panel of molecular clones produced in 293T cells and PBMCs and assayed in TZM-bl cells. Examples of plateaus <90% were seen with both types of virus production with no consistent patterns observed. In conclusion, incomplete neutralization and non-sigmoidal neutralization curves are possible for all HIV bnMAbs against a wide range of viruses produced and assayed in both cell lines and primary cells with implications for the use of antibodies in therapy and as tools for vaccine design. PMID:26267277

  13. Incomplete Neutralization and Deviation from Sigmoidal Neutralization Curves for HIV Broadly Neutralizing Monoclonal Antibodies.

    PubMed

    McCoy, Laura E; Falkowska, Emilia; Doores, Katie J; Le, Khoa; Sok, Devin; van Gils, Marit J; Euler, Zelda; Burger, Judith A; Seaman, Michael S; Sanders, Rogier W; Schuitemaker, Hanneke; Poignard, Pascal; Wrin, Terri; Burton, Dennis R

    2015-08-01

    The broadly neutralizing HIV monoclonal antibodies (bnMAbs) PG9, PG16, PGT151, and PGT152 have been shown earlier to occasionally display an unusual virus neutralization profile with a non-sigmoidal slope and a plateau at <100% neutralization. In the current study, we were interested in determining the extent of non-sigmoidal slopes and plateaus at <100% for HIV bnMAbs more generally. Using both a 278 panel of pseudoviruses in a CD4 T-cell (U87.CCR5.CXCR4) assay and a panel of 117 viruses in the TZM-bl assay, we found that bnMAbs targeting many neutralizing epitopes of the spike had neutralization profiles for at least one virus that plateaued at <90%. Across both panels the bnMAbs targeting the V2 apex of Env and gp41 were most likely to show neutralization curves that plateaued <100%. Conversely, bnMAbs targeting the high-mannose patch epitopes were less likely to show such behavior. Two CD4 binding site (CD4bs) Abs also showed this behavior relatively infrequently. The phenomenon of incomplete neutralization was also observed in a large peripheral blood mononuclear cells (PBMC)-grown molecular virus clone panel derived from patient viral swarms. In addition, five bnMAbs were compared against an 18-virus panel of molecular clones produced in 293T cells and PBMCs and assayed in TZM-bl cells. Examples of plateaus <90% were seen with both types of virus production with no consistent patterns observed. In conclusion, incomplete neutralization and non-sigmoidal neutralization curves are possible for all HIV bnMAbs against a wide range of viruses produced and assayed in both cell lines and primary cells with implications for the use of antibodies in therapy and as tools for vaccine design. PMID:26267277

  14. Neutral and Non-Neutral Evolution of Drosophila Mitochondrial DNA

    PubMed Central

    Rand, D. M.; Dorfsman, M.; Kann, L. M.

    1994-01-01

    To test hypotheses of neutral evolution of mitochondrial DNA (mtDNA), nucleotide sequences were determined for 1515 base pairs of the NADH dehydrogenase subunit 5 (ND5) gene in the mitochondrial DNA of 29 lines of Drosophila melanogaster and 9 lines of its sibling species Drosophila simulans. In contrast to the patterns for nuclear genes, where D. melanogaster generally exhibits much less nucleotide polymorphism, the number of segregating sites was slightly higher in a global sample of nine ND5 sequences in D. melanogaster (s = 8) than in the nine lines of D. simulans (s = 6). When compared to variation at nuclear loci, the mtDNA variation in D. melanogaster does not depart from neutral expectations. The ND5 sequences in D. simulans, however, show fewer than half the number of variable sites expected under neutrality when compared to sequences from the period locus. While this reduction in variation is not significant at the 5% level, HKA tests with published restriction data for mtDNA in D. simulans do show a significant reduction of variation suggesting a selective sweep of variation in the mtDNA in this species. Tests of neutral evolution based on the ratios of synonymous and replacement polymorphism and divergence are generally consistent with neutral expectations, although a significant excess of amino acid polymorphism within both species is localized in one region of the protein. The rate of mtDNA evolution has been faster in D. melanogaster than in D. simulans and the population structure of mtDNA is distinct in these species. The data reveal how different rates of mtDNA evolution between species and different histories of neutral and adaptive evolution within species can compromise historical inferences in population and evolutionary biology. PMID:7851771

  15. Gas cell neutralizers (Fundamental principles)

    SciTech Connect

    Fuehrer, B.

    1985-06-01

    Neutralizing an ion-beam of the size and energy levels involved in the neutral-particle-beam program represents a considerable extension of the state-of-the-art of neutralizer technology. Many different mediums (e.g., solid, liquid, gas, plasma, photons) can be used to strip the hydrogen ion of its extra electron. A large, multidisciplinary R and D effort will no doubt be required to sort out all of the ''pros and cons'' of these various techniques. The purpose of this particular presentation is to discuss some basic configurations and fundamental principles of the gas type of neutralizer cell. Particular emphasis is placed on the ''Gasdynamic Free-Jet'' neutralizer since this configuration has the potential of being much shorter than other type of gas cells (in the beam direction) and it could operate in nearly a continuous mode (CW) if necessary. These were important considerations in the ATSU design which is discussed in some detail in the second presentation entitled ''ATSU Point Design''.

  16. A Re-Examiniation of Phonological Neutralization.

    ERIC Educational Resources Information Center

    Dinnsen, D.

    1985-01-01

    Reviews research studies that raise serious questions about phonological neutralization, that is, the merger of a contrast in certain contexts. Some findings cast doubt on the very existence of neutralization and the correctness of the theoretical principles that make assumptions based on neutralization. Reanalyzes neutralization in light of these…

  17. Simulations of neutralized final focus

    SciTech Connect

    Welch, D.R.; Rose, D.V.; Genoni, T.C.; Yu, S.S.; Barnard, J.J.

    2005-01-18

    In order to drive an inertial fusion target or study high energy density physics with heavy ion beams, the beam radius must be focused to < 3 mm and the pulse length must be compressed to < 10 ns. The conventional scheme for temporal pulse compression makes use of an increasing ion velocity to compress the beam as it drifts and beam space charge to stagnate the compression before final focus. Beam compression in a neutralizing plasma does not require stagnation of the compression, enabling a more robust method. The final pulse shape at the target can be programmed by an applied velocity tilt. In this paper, neutralized drift compression is investigated. The sensitivity of the compression and focusing to beam momentum spread, plasma, and magnetic field conditions is studied with realistic driver examples. Using the 3D particle-in-cell code, we examine issues associated with self-field generation, stability, and vacuum-neutralized transport transition and focusing.

  18. RE: Pedagogy--After Neutrality

    ERIC Educational Resources Information Center

    I'Anson, John

    2010-01-01

    Within the UK and in many parts of the world, official accounts of what it is to make sense of religion are framed within a rhetorics of neutrality in which such study is premised upon the possibility of dispassionate engagement and analysis. This paper, which is largely theoretical in scope, explores both the affordances and the costs of such an…

  19. Neutralization kinetics for polonium-218

    SciTech Connect

    Chu, K.D.; Hopke, P.K.

    1988-06-01

    In a well-defined experimental system the neutralization of polonium-218 ions was investigated as a function of the physical and chemical properties of the controlled composition atmosphere. The diffusion coefficient of polonium-218 under various concentrations of trace gas NO/sub 2/ in nitrogen was measured. The mobilities of Po/sup +/ and PoO/sub 2//sup +/ are determined by combining experimental results with a computer model of the system. Three neutralization mechanisms were individually studied. The small-ion recombination rate has been found to be proportional to the square root of radon concentration. The electron-scavenging mechanism is responsible for the neutralization of Po/sup +/ in NO/sub 2/ or H/sub 2/O in nitrogen. When PoO/sub 2//sup +/ is formed, the electron-transfer mechanism dominates the neutralization process. The electron is transferred to PoO/sub 2//sup +/ from molecules with lower ionization potentials. The ionization molecules with lower ionization potentials. The ionization potential of PoO/sub 2//sup +/ is also determined to be 10.44 +/- 0.05 eV.

  20. Photodetachment process for beam neutralization

    DOEpatents

    Fink, Joel H. [Livermore, CA; Frank, Alan M. [Livermore, CA

    1979-02-20

    A process for neutralization of accelerated ions employing photo-induced charge detachment. The process involves directing a laser beam across the path of a negative ion beam such as to effect photodetachment of electrons from the beam ions. The frequency of the laser beam employed is selected to provide the maximum cross-section for the photodetachment process.

  1. Photodetachment process for beam neutralization

    DOEpatents

    Fink, J.H.; Frank, A.M.

    1979-02-20

    A process for neutralization of accelerated ions employing photo-induced charge detachment is disclosed. The process involves directing a laser beam across the path of a negative ion beam such as to effect photodetachment of electrons from the beam ions. The frequency of the laser beam employed is selected to provide the maximum cross-section for the photodetachment process. 2 figs.

  2. MSFC Skylab neutral buoyancy simulator

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The use of a neutral buoyancy simulator for developing extravehicular activity systems and for training astronauts in weightless activities is discussed. The construction of the facility and the operations are described. The types of tests and the training activities conducted in the simulator are reported. Photographs of the components of the simulator and actual training exercises are included.

  3. Electron-electron interactions in fast neutral-neutral collisions

    SciTech Connect

    DuBois, R.D. ); Manson, S.T. . Dept. of Physics and Astronomy)

    1992-11-01

    Differential electron emission is studied for 50--500 keV H[sup +] and H atom impact on helium. Using the first Born formulation, it is shown that projectile electron-target electron interactions are expected to dominate the differential cross sections for low energy target electron emission induced by fast neutral projectile impact on any target. Measurements of the 15[degrees] electron emission were made in order to investigate this prediction. For low impact energies, a constant ratio between the hydrogen atom and proton impact cross sections was found for emitted electron velocities less than half the projectile velocity, V[sub p] But as the collision energy increased, for electron velocities less than 0.25 V[sub p], the cross section ratio increased as the emitted electron velocity decreased. This is interpreted as a signature of projectile electron-target electron interactions becoming dominant for distant collisions between neutral particles.

  4. Electron-electron interactions in fast neutral-neutral collisions

    SciTech Connect

    DuBois, R.D.; Manson, S.T.

    1992-11-01

    Differential electron emission is studied for 50--500 keV H{sup +} and H atom impact on helium. Using the first Born formulation, it is shown that projectile electron-target electron interactions are expected to dominate the differential cross sections for low energy target electron emission induced by fast neutral projectile impact on any target. Measurements of the 15{degrees} electron emission were made in order to investigate this prediction. For low impact energies, a constant ratio between the hydrogen atom and proton impact cross sections was found for emitted electron velocities less than half the projectile velocity, V{sub p} But as the collision energy increased, for electron velocities less than 0.25 V{sub p}, the cross section ratio increased as the emitted electron velocity decreased. This is interpreted as a signature of projectile electron-target electron interactions becoming dominant for distant collisions between neutral particles.

  5. Coulomb blockade with neutral modes.

    PubMed

    Kamenev, Alex; Gefen, Yuval

    2015-04-17

    We study transport through a quantum dot in the fractional quantum Hall regime with filling factors ν=2/3 and ν=5/2, weakly coupled to the leads. We account for both injection of electrons to or from the leads, and quasiparticle rearrangement processes between the edge and the bulk of the quantum dot. The presence of neutral modes introduces topological constraints that modify qualitatively the features of the Coulomb blockade (CB). The periodicity of CB peak spacings doubles and the ratio of spacing between adjacent peaks approaches (in the low temperature and large dot limit) a universal value: 2∶1 for ν=2/3 and 3∶1 for ν=5/2. The corresponding CB diamonds alternate their width in the direction of the bias voltage and allow for the determination of the neutral mode velocity, and of the topological numbers associated with it. PMID:25933323

  6. Optimization of neutral atom imagers

    NASA Astrophysics Data System (ADS)

    Shappirio, M.; Coplan, M.; Balsamo, E.; Chornay, D.; Collier, M.; Hughes, P.; Keller, J.; Ogilvie, K.

    2008-12-01

    : The interactions between plasma structures and neutral atom populations in interplanetary space can be effectively studied with energetic neutral atom imagers. For neutral atoms with energies less than 1 keV, the most efficient detection method that preserves direction and energy information is conversion to negative ions on surfaces. We have examined a variety of surface materials and conversion geometries in order to identify the factors that determine conversion efficiency. For chemically and physically stable surfaces smoothness is of primary importance while properties such as work function have no obvious correlation to conversion efficiency. For the noble metals, tungsten, silicon, and graphite with comparable smoothness, conversion efficiency varies by a factor of two to three. We have also examined the way in which surface conversion efficiency varies with the angle of incidence of the neutral atom and have found that the highest efficiencies are obtained at angles of incidence greater then 80°. The conversion efficiency of silicon, tungsten and graphite were examined most closely and the energy dependent variation of conversion efficiency measured over a range of incident angles. We have also developed methods for micromachining silicon in order to reduce the volume to surface area over that of a single flat surface and have been able to reduce volume to surface area ratios by up to a factor of 60. With smooth micro-machined surfaces of the optimum geometry, conversion efficiencies can be increased by an order of magnitude over instruments like LENA on the IMAGE spacecraft without increase the instruments mass or volume. Work was supported by grant ACT-05-40 from the ESTO office of NASA

  7. Optimization of Neutral Atom Imagers

    NASA Technical Reports Server (NTRS)

    Shappirio, M.; Coplan, M.; Balsamo, E.; Chornay, D.; Collier, M.; Hughes, P.; Keller, J.; Ogilvie, K.; Williams, E.

    2008-01-01

    The interactions between plasma structures and neutral atom populations in interplanetary space can be effectively studied with energetic neutral atom imagers. For neutral atoms with energies less than 1 keV, the most efficient detection method that preserves direction and energy information is conversion to negative ions on surfaces. We have examined a variety of surface materials and conversion geometries in order to identify the factors that determine conversion efficiency. For chemically and physically stable surfaces smoothness is of primary importance while properties such as work function have no obvious correlation to conversion efficiency. For the noble metals, tungsten, silicon, and graphite with comparable smoothness, conversion efficiency varies by a factor of two to three. We have also examined the way in which surface conversion efficiency varies with the angle of incidence of the neutral atom and have found that the highest efficiencies are obtained at angles of incidence greater then 80deg. The conversion efficiency of silicon, tungsten and graphite were examined most closely and the energy dependent variation of conversion efficiency measured over a range of incident angles. We have also developed methods for micromachining silicon in order to reduce the volume to surface area over that of a single flat surface and have been able to reduce volume to surface area ratios by up to a factor of 60. With smooth micro-machined surfaces of the optimum geometry, conversion efficiencies can be increased by an order of magnitude over instruments like LENA on the IMAGE spacecraft without increase the instruments mass or volume.

  8. Plasma sources for spacecraft neutralization

    NASA Technical Reports Server (NTRS)

    Davis, V. A.; Katz, I.; Mandell, M. J.

    1990-01-01

    The principles of the operation of plasma sources for the neutralization of the surface of a spacecraft traveling in the presence of hot plasma are discussed with special attention given to the hollow-cathode-based plasma contactors. Techiques are developed that allow the calculation of the potentials and particle densities in the near environment of a hollow cathode plasma contactor in both the test tank and the LEO environment. The techniques and codes were validated by comparison of calculated and measured results.

  9. Neutral-current x-distributions

    DOE R&D Accomplishments Database

    Friedman, J. I.; Kendall, H. W.; Bogert, D.; Burnstein, R.; Fisk, R.; Fuess, S.; Bofill, J.; Busza, W.; Eldridge, T.; Abolins, M.; Brock, R.; et al.

    1984-06-01

    The role of the semi leptonic neutral current interaction as a probe of nucleon structure is examined. Previous measurements of neutral current x-distributions are reviewed, and new results from the Fermilab - MIT - MSU collaboration are presented.

  10. Plasma/Neutral-Beam Etching Apparatus

    NASA Technical Reports Server (NTRS)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  11. The Net Neutrality Debate: The Basics

    ERIC Educational Resources Information Center

    Greenfield, Rich

    2006-01-01

    Rich Greenfield examines the basics of today's net neutrality debate that is likely to be an ongoing issue for society. Greenfield states the problems inherent in the definition of "net neutrality" used by Common Cause: "Network neutrality is the principle that Internet users should be able to access any web content they choose and use any…

  12. Neutral beamline with improved ion energy recovery

    DOEpatents

    Kim, Jinchoon

    1984-01-01

    A neutral beamline employing direct energy recovery of unneutralized residual ions is provided which enhances the energy recovery of the full energy ion component of the beam exiting the neutralizer cell, and thus improves the overall neutral beamline efficiency. The unneutralized full energy ions exiting the neutralizer are deflected from the beam path and the electrons in the cell are blocked by a magnetic field applied transverse to the beam direction in the neutral izer exit region. The ions which are generated at essentially ground potential and accelerated through the neutralizer cell by a negative acceleration voltage are collected at ground potential. A neutralizer cell exit end region is provided which allows the magnetic and electric fields acting on the exiting ions to be loosely coupled. As a result, the fractional energy ions exiting the cell are reflected onto and collected at an interior wall of the neutralizer formed by the modified end geometry, and thus do not detract from the energy recovery efficiency of full energy ions exiting the cell. Electrons within the neutralizer are prevented from exiting the neutralizer end opening by the action of crossed fields drift (ExB) and are terminated to a collector collar around the downstream opening of the neutralizer. The correct combination of the extended neutralizer end structure and the magnet region is designed so as to maximize the exit of full energy ions and to contain the fractional energy ions.

  13. Magnetostatic traps for charged and neutral particles

    NASA Astrophysics Data System (ADS)

    Gomer, V.; Harms, O.; Haubrich, D.; Schadwinkel, H.; Strauch, F.; Ueberholz, B.; Aus der Wiesche, S.; Meschede, D.

    1997-08-01

    We have constructed magnetostatic traps from permanent magnets for trapping charged and neutral atoms. Two storage experiments are presented: a compact Penning trap for light ions and magnetic trapping of single neutral atoms. The dynamics of cold neutral atoms and their loss mechanisms in a quadrupole magnetostatic trap are discussed.

  14. Ion-beam Plasma Neutralization Interaction Images

    SciTech Connect

    Igor D. Kaganovich; Edward Startsev; S. Klasky; Ronald C. Davidson

    2002-04-09

    Neutralization of the ion beam charge and current is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because the excitation of nonlinear plasma waves may occur. Computer simulation images of plasma neutralization of the ion beam pulse are presented.

  15. 46 CFR 502.404 - Neutrals.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Dispute Resolution § 502.404 Neutrals. (a) A neutral may be a permanent or temporary officer or employee of the Federal Government or any other individual who is acceptable to the parties to a dispute... Maritime Commission Dispute Resolution Specialist will seek to provide a neutral in dispute...

  16. 46 CFR 502.404 - Neutrals.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Dispute Resolution § 502.404 Neutrals. (a) A neutral may be a permanent or temporary officer or employee of the Federal Government or any other individual who is acceptable to the parties to a dispute... Maritime Commission Dispute Resolution Specialist will seek to provide a neutral in dispute...

  17. Priming Effects for Affective vs. Neutral Faces

    ERIC Educational Resources Information Center

    Burton, Leslie A.; Rabin, Laura; Wyatt, Gwinne; Frohlich, Jonathan; Vardy, Susan B.; Dimitri, Diana

    2005-01-01

    Affective and Neutral Tasks (faces with negative or neutral content, with different lighting and orientation) requiring reaction time judgments of poser identity were administered to 32 participants. Speed and accuracy were better for the Affective than Neutral Task, consistent with literature suggesting facilitation of performance by affective…

  18. Gas Flow Measurements of a Novel Geometry for Neutral Beam Neutralizers.

    NASA Astrophysics Data System (ADS)

    Pirkle, David Ross

    The gas flow characteristics of a novel geometry (pumped neutralizer) for decreasing the flow of gas from neutral beam neutralizers were measured and compared with a conventional (passive) neutralizer. A passive neutralizer is typically a duct attached to the ion source. For the pumped neutralizer the top and bottom surfaces of the duct are replaced by a Venetian blind geometry which opens into ballast vacuum pumping volumes. With guidance from a Monte Carlo program which models gas flow at low pressure, a one-half scale model with pumped neutralizer geometry was built and compared to a passive neutralizer with comparable dimensions. With the vanes on the pumped neutralizer opened to 55 degrees, the line density of the pumped neutralizer was 1.6 times less than the passive neutralizer. The amount of gas flowing from the exit of the pumped neutralizer was from 2 to 5 times less than the amount flowing from the pumped neutralizer. Hence, the pumped neutralizer geometry appears to be a promising method of limiting the flow of gas from neutral beam gas cell neutralizers.

  19. Poliovirus neutralization epitopes: analysis and localization with neutralizing monoclonal antibodies.

    PubMed Central

    Emini, E A; Jameson, B A; Lewis, A J; Larsen, G R; Wimmer, E

    1982-01-01

    Two hybridomas (H3 and D3) secreting monoclonal neutralizing antibody to intact poliovirus type 1 (Mahoney strain) were established. Each antibody bound to a site qualitatively different from that to which the other antibody bound. The H3 site was located on intact virions and, to a lesser extent, on 80S naturally occurring empty capsids and 14S precursor subunits. The D3 site was found only on virions and empty capsids. Neither site was expressed on 80S heat-treated virions. The antibodies did not react with free denatured or undenatured viral structural proteins. Viral variants which were no longer capable of being neutralized by either one or the other antibody were obtained. Such variants arose during normal cell culture passage of wild-type virus and were present in the progeny viral population on the order of 10(-4) variant per wild-type virus PFU. Toluene-2,4-diisocyanate, a heterobifunctional covalent cross-linking reagent, was used to irreversibly bind the F(ab) fragments of the two antibodies to their respective binding sites. In this way, VP1 was identified as the structural protein containing both sites. PMID:6183443

  20. Kinetic Simulations of Ion Beam Neutralization

    SciTech Connect

    Wang, Joseph

    2010-05-21

    Ion beam emission/neutralization is one of the most fundamental problems in spacecraft plasma interactions and electric propulsion. Although ion beam neutralization is readily achieved in experiments, the understanding of the underlying physical process remains at a rather primitive level. No theoretical or simulation models have convincingly explained the detailed neutralization mechanism, and no conclusions have been reached. This paper presents a fully kinetic simulation of ion beam neutralization and plasma beam propagation and discusses the physics of electron-ion coupling and the resulting propagation of a neutralized mesothermal plasma.

  1. Space station neutral external environment

    NASA Technical Reports Server (NTRS)

    Ehlers, H.; Leger, L.

    1988-01-01

    Molecular contamination levels arising from the external induced neutral environment of the Space Station (Phase 1 configuration) were calculated using the MOLFLUX model. Predicted molecular column densities and deposition rates generally meet the Space Station contamination requirements. In the doubtful cases of deposition due to materials outgassing, proper material selection, generally excluding organic products exposed to the external environment, must be considered to meet contamination requirements. It is important that the Space Station configuration, once defined, is not significantly modified to avoid introducing new unacceptable contamination sources.

  2. Neutral gas dynamics in fireballs

    SciTech Connect

    Stenzel, R. L.; Ionita, C.; Schrittwieser, R.

    2011-06-01

    Fireballs are local discharge phenomena on positively biased electrodes in partially ionized plasmas. Electrons, energized at a double layer, heat neutral gas which expands. The gas pressure exceeds the plasma pressure, hence becomes important to the stability and transport in fireballs. The flow of gas moves the electrode and sensors similar to a mica pendulum. Flow speed and directions are measured. A fireball gun has been developed to partially collimate the flow of hot gas and heat objects in its path. New applications of fireballs are suggested.

  3. Neutral endopeptidase modulates neurogenic inflammation.

    PubMed

    Nadel, J A

    1991-06-01

    A noncholinergic, nonadrenergic nervous system has been described, involving the sensory nerves in the airways. Chemicals, dusts and other irritants stimulate these sensory nerves to release substance P and related neuropeptides. These neuropeptides have the remarkable ability to affect multiple cells in the airways and to provoke many responses including cough, mucus secretion, smooth muscle contraction, plasma extravasation and neutrophil adhesion. This series of effects is termed "neurogenic inflammation." An enzyme exists on the surfaces of all lung cells that contain receptors for these neuropeptides. This enzyme, neutral endopeptidase (NEP), by cleaving and thus inactivating the neuropeptides, limits the concentration of the neuropeptide that reaches the receptor on the cell surface. Thus, neurogenic inflammatory responses are normally mild and presumably protective in nature. However, when NEP is inhibited pharmacologically (with NEP inhibitors) or by cigarette smoke, respiratory viral infection, or by inhalation of the industrial pollutant toluene diisocyanate, neurogenic inflammatory responses are exaggerated. Delivery of exogenous human recombinant NEP inhibits neurogenic inflammation. Finally, evidence is provided that corticosteroids suppress neurogenic plasma extravasation and that this drug can upregulate NEP in human airway tissue. Neutral endopeptidase cleaves multiple peptides. Thus, its selectivity resides, at least in part, on its fixed location on the surfaces of specific cells where it can modulate effects of peptides exposed to the cells' surfaces. PMID:1889501

  4. Detailed Atomic Structure of Neutral and Near-Neutral Systems

    SciTech Connect

    Oliver, Paul; Hibbert, Alan

    2011-05-11

    This paper highlights the issues which need to be addressed in undertaking accurate calculations of multi-electron atoms and ions, particularly at or near the neutral end of an isoelectronic sequence. We illustrate the processes through two calculations--of transitions in Cl I and Sn II--and discuss the convergence of our results as well as updating previous work. In particular, in the case of Cl I, we propose new identifications of the levels involved in certain transitions which are important in determining the abundance of chlorine in the inter-stellar medium (ISM), while in singly ionised tin, our calculations suggest a re-evaluation of the the abundance of tin in the ISM. We also confirm recent identification of Sn II lines seen in tokamak plasmas.

  5. Site Neutral Payments: An Overview.

    PubMed

    Dresevic, Adrienne; Rojas, Leslie

    2015-01-01

    A site neutral payment policy would entail CMS paying the same rate for the same healthcare service regardless of the location in which the service is provided. From the government's perspective, the reason behind this policy is potentially billions of dollars in savings. The rationale for using various payment systems is that there are different costs associated with providing healthcare services in different locations. Each payment system has a separate methodology for determining rates for services based on these costs. Hospitals may choose to prepare early for the inevitable through accurate cost reporting, shifting certain ancillary services to more appropriate outpatient, off site locations, and participating in the Medicare Shared Savings Program. PMID:26571969

  6. High Resolution Neutral Atom Microscope

    NASA Astrophysics Data System (ADS)

    Bucay, Igal; Castillo-Garza, Rodrigo; Stratis, Georgios; Raizen, Mark

    2015-03-01

    We are developing a high resolution neutral atom microscope based on metastable atom electron spectroscopy (MAES). When a metastable atom of a noble gas is near a solid, a surface electron will tunnel to an empty energy level of the metastable atom, thereby ejecting the excited electron from the atom. The emitted electrons carry information regarding the local topography and electronic, magnetic, and chemical structures of most hard materials. Furthermore, using a chromatic aberration corrected magnetic hexapole lens we expect to attain a spatial resolution below 10 nm. We will use this microscope to investigate how local phenomena can give rise to macroscopic effects in materials that cannot be probed using a scanning tunneling microscope, namely insulating transition metal oxides.

  7. Neutral composition in the thermosphere.

    NASA Technical Reports Server (NTRS)

    Taeusch, D. R.; Carignan, G. R.

    1972-01-01

    Data obtained from the Ogo 6 neutral atmospheric composition (NAC) experiment for a period of more than 1 year are used to compare the average constituent composition at an altitude of 400 km with that predicted by the Jacchia 1971 and 1965 models. The comparison shows that the Jacchia 1971 model underestimates the molecular nitrogen densities at 400 km by a factor of 2. An atmosphere is constructed down to 120 km by means of the Stein and Walker technique. A fit is made with (1) the 400-km total densities from drag measurements and the composition from Ogo 6 NAC, (2) the 250-km measured molecular nitrogen densities, and (3) the 150-km total densities from drag. This fit shows that the Jacchia 1971 model overestimates the atomic oxygen content at 150 km.

  8. Ergonomically neutral arm support system

    DOEpatents

    Siminovitch, Michael J; Chung, Jeffrey Y; Dellinges, Steven; Lafever, Robin E

    2005-08-02

    An ergonomic arm support system maintains a neutral position for the forearm. A mechanical support structure attached to a chair or other mounting structure supports the arms of a sitting or standing person. The system includes moving elements and tensioning elements to provide a dynamic balancing force against the forearms. The support structure is not fixed or locked in a rigid position, but is an active dynamic system that is maintained in equipoise by the continuous operation of the opposing forces. The support structure includes an armrest connected to a flexible linkage or articulated or pivoting assembly, which includes a tensioning element such as a spring. The pivoting assembly moves up and down, with the tensioning element providing the upward force that balances the downward force of the arm.

  9. An accessible heavy neutral lepton

    NASA Astrophysics Data System (ADS)

    Chang, Chao-Hsi

    1982-09-01

    In the SUL(2) ⊗ SUR(2) ⊗ UB-L(1) model, an accessible heavy neutral lepton may exist owing to the mixing of generations. Based on a rough estimate, it is pointed out that the most hopeful experiments to observe this lepton are ν-production in an emulsion (because the track of a particle with lifetime 10-11-10-13 s could be seen) and e-production. The author thanks Professor J.D. Bjorken, Professor He Zuo-Xiu, Professor R.E. Mashark, Professor S.J. Chang, Professor Zhu Cong-Yuan and Professor M. Dine for helpful discussions and comments. He would like to thank the referee for valuable comments.

  10. After treatment ends: neutral time.

    PubMed

    Hurt, G J; McQuellon, R P; Barrett, R J

    1994-01-01

    For persons diagnosed with cancer, the remission period may be marked by increased anxiety and distress. While the medical team may view remission as an eagerly anticipated milestone, the decreased medical surveillance during this time can cause a heightened fear of recurrence for the patient. One author has called this period of remission "neutral time," a time characterized by uncertainty. The safety signal hypothesis, developed by Martin Seligman, may help to explain the anxiety experienced by some patients during the remission period. Because cancer is frequently a silent disease with no overt symptoms, patients in remission often have no safety signal to indicate that the disease will not return. A case study is presented and discussed in light of these two concepts. PMID:7697080

  11. BEAMS3D Neutral Beam Injection Model

    SciTech Connect

    Lazerson, Samuel

    2014-04-14

    With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.

  12. ION SOURCE WITH SPACE CHARGE NEUTRALIZATION

    DOEpatents

    Flowers, J.W.; Luce, J.S.; Stirling, W.L.

    1963-01-22

    This patent relates to a space charge neutralized ion source in which a refluxing gas-fed arc discharge is provided between a cathode and a gas-fed anode to provide ions. An electron gun directs a controlled, monoenergetic electron beam through the discharge. A space charge neutralization is effected in the ion source and accelerating gap by oscillating low energy electrons, and a space charge neutralization of the source exit beam is effected by the monoenergetic electron beam beyond the source exit end. The neutralized beam may be accelerated to any desired energy at densities well above the limitation imposed by Langmuir-Child' s law. (AEC)

  13. Influenza virus antigenicity and broadly neutralizing epitopes

    PubMed Central

    Air, Gillian M.

    2015-01-01

    A vaccine formulation that would be effective against all strains of influenza virus has long been a goal of vaccine developers, but antibodies after infection or vaccination were seen to be strain specific and there was little evidence of cross-reactive antibodies that neutralized across subtypes. Recently a number of broadly neutralizing monoclonal antibodies have been characterized. This review describes the different classes of broadly neutralizing antibodies and discusses the potential of their therapeutic use or for design of immunogens that induce a high proportion of broadly neutralizing antibodies. PMID:25846699

  14. Neutral Vlasov kinetic theory of magnetized plasmas

    SciTech Connect

    Tronci, Cesare; Camporeale, Enrico

    2015-02-15

    The low-frequency limit of Maxwell equations is considered in the Maxwell-Vlasov system. This limit produces a neutral Vlasov system that captures essential features of plasma dynamics, while neglecting radiation effects. Euler-Poincaré reduction theory is used to show that the neutral Vlasov kinetic theory possesses a variational formulation in both Lagrangian and Eulerian coordinates. By construction, the new model recovers all collisionless neutral models employed in plasma simulations. Then, comparisons between the neutral Vlasov system and hybrid kinetic-fluid models are presented in the linear regime.

  15. Neutralization efficiency estimation in a neutral beam source based on inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Vozniy, O. V.; Yeom, G. Y.

    2009-01-01

    This study examined the optimal conditions of neutral beam generation to maintain a high degree of neutralization and focusing during beam energy variation for a neutral beam source based on inductively coupled plasma with a three-grid ion beam acceleration system. The neutral beam energy distribution was estimated by measuring the energy profiles of ions that "survived" the neutralization after reflection. The energy measurements of the primary and reflected ions showed narrow distribution functions, each with only one peak. At higher beam energies, both the ratio of the ion energy loss to the primary energy and the degree of energy divergence decreased, confirming the precise alignment of the neutral beam. The neutralization efficiency of the neutral beam source with a three-grid acceleration system was found to be affected mainly by the beam angle divergence rather than by the particle translation energy.

  16. Neutralization efficiency estimation in a neutral beam source based on inductively coupled plasma

    SciTech Connect

    Vozniy, O. V.; Yeom, G. Y.

    2009-01-01

    This study examined the optimal conditions of neutral beam generation to maintain a high degree of neutralization and focusing during beam energy variation for a neutral beam source based on inductively coupled plasma with a three-grid ion beam acceleration system. The neutral beam energy distribution was estimated by measuring the energy profiles of ions that 'survived' the neutralization after reflection. The energy measurements of the primary and reflected ions showed narrow distribution functions, each with only one peak. At higher beam energies, both the ratio of the ion energy loss to the primary energy and the degree of energy divergence decreased, confirming the precise alignment of the neutral beam. The neutralization efficiency of the neutral beam source with a three-grid acceleration system was found to be affected mainly by the beam angle divergence rather than by the particle translation energy.

  17. Modelling the Neutral Sodium Tails of Comets

    NASA Astrophysics Data System (ADS)

    Birkett, K. S.; Jones, G. H.; Coates, A. J.

    2014-12-01

    Neutral sodium is typically easy to detect in active comets around perihelion, due to the very high efficiency of the sodium D transition, and at some comets a distinct neutral sodium tail is observed. The first distinct neutral sodium tail images were apparent in comet Hale-Bopp (C/1995 O1) data taken using CoCam [Cremonese et al, 1997], but since this initial detection similar features have been observed at a number of near-Sun comets using the SOHO/LASCO coronagraph. An understanding of the distribution and evolution of neutral cometary sodium may best be developed using a combination of spectra and images in different filters at multiple times throughout a comet's orbit. At present the source of neutral sodium in comets is unknown, primarily because the evolution of neutral cometary sodium is difficult to intuitively predict due to the Swings and Greenstein effects. Several authors [review presented in Cremonese et al, 1999] have suggested various combinations of sources of neutral sodium in the nuclear region, near-nuclear region, dust tail and ion tail. In order to understand the wide variety of cometary observations of neutral sodium available we have developed the first fully three dimensional, heliocentric distance dependent, versatile Monte Carlo neutral sodium tail model (initially based on a model developed by [Brown et al, 1998]). Our model is known as COMPASS (Cometary Orbital Motion at Perihelion: an Adaptable Sodium Simulation), and incorporates the unintuitive variation in radiation pressure influences on sodium atoms with different heliocentric velocities. We present the initial results of a comparison between COMPASS and observational data. We have found good agreement between the overall morphology of the neutral sodium tail imaged at comet Hale-Bopp and COMPASS, and have begun to extend the study to other comets of interest. We also present a comparison between simulated COMPASS spectra and observations. The versatility of COMPASS allows it to

  18. Targets for high power neutral beams

    SciTech Connect

    Kim, J.

    1980-01-01

    Stopping high-power, long-pulse beams is fast becoming an engineering challenge, particularly in neutral beam injectors for heating magnetically confined plasmas. A brief review of neutral beam target technology is presented along with heat transfer calculations for some selected target designs.

  19. 32 CFR 644.323 - Neutral language.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Neutral language. 644.323 Section 644.323 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal § 644.323 Neutral language. Wherever the words “man”, “men”, or their...

  20. 32 CFR 644.323 - Neutral language.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 4 2013-07-01 2013-07-01 false Neutral language. 644.323 Section 644.323 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal § 644.323 Neutral language. Wherever the words “man”, “men”, or their...

  1. 32 CFR 644.323 - Neutral language.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 4 2012-07-01 2011-07-01 true Neutral language. 644.323 Section 644.323 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal § 644.323 Neutral language. Wherever the words “man”, “men”, or their...

  2. 32 CFR 644.323 - Neutral language.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Neutral language. 644.323 Section 644.323 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal § 644.323 Neutral language. Wherever the words “man”, “men”, or their...

  3. Efficient laser production of energetic neutral beams

    NASA Astrophysics Data System (ADS)

    Mollica, F.; Antonelli, L.; Flacco, A.; Braenzel, J.; Vauzour, B.; Folpini, G.; Birindelli, G.; Schnuerer, M.; Batani, D.; Malka, V.

    2016-03-01

    Laser-driven ion acceleration by intense, ultra-short, laser pulse has received increasing attention in recent years, and the availability of much compact and versatile ions sources motivates the study of laser-driven sources of energetic neutral atoms. We demonstrate the production of a neutral and directional beam of hydrogen and carbon atoms up to 200 keV per nucleon, with a peak flow of 2.7× {{10}13} atom s-1. Laser accelerated ions are neutralized in a pulsed, supersonic argon jet with tunable density between 1.5× {{10}17} cm-3and 6× {{10}18} cm-3. The neutralization efficiency has been measured by a time-of-flight detector for different argon densities. An optimum is found, for which complete neutralization occurs. The neutralization rate can be explained only at high areal densities (>1× {{10}17} cm-2) by single electron charge transfer processes. These results suggest a new perspective for the study of neutral production by laser and open discussion of neutralization at a lower density.

  4. Controversial Issues: A Case for Neutrality?

    ERIC Educational Resources Information Center

    Cain, Paul

    1999-01-01

    Arguments against teachers asserting their own views about controversial issues say that neutrality enables students to develop autonomous reflection. Others claim that a nonneutral stance is morally preferable. There are some teaching situations in which a neutral stance may not be an option. (SK)

  5. Gender Neutrality: Women's Friend or Foe?

    ERIC Educational Resources Information Center

    Steuernagel, Trudy

    Gender neutral public policies are those that are either silent on the question of the existence of significant gender differences or incorporate a perspective which mandates that such differences be ignored. Prominent voices today contend that gender neutrality favors males and have held the male standard as the one for which women should aspire.…

  6. Ion-Neutral Coupling in Solar Prominences

    NASA Technical Reports Server (NTRS)

    Gilbert, Holly

    2011-01-01

    Interactions between ions and neutrals in a partially ionized plasma are important throughout heliophysics, including near the solar surface in prominences. Understanding how ion-neutral coupling affects formation, support, structure, and dynamics of prominences will advance our physical understanding of magnetized systems involving a transition from a weakly ionized dense gas to a fully ionized tenuous plasma. We address the fundamental physics of prominence support, which is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force, and the implications for observations. Because the prominence plasma is only partially ionized, it is necessary to consider the support of the both the ionized and neutral components. Support of the neutrals is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material.

  7. 6 CFR 27.305 - Neutral adjudications.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 6 Domestic Security 1 2012-01-01 2012-01-01 false Neutral adjudications. 27.305 Section 27.305 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.305 Neutral adjudications. (a) Any facility or other person who...

  8. 6 CFR 27.305 - Neutral adjudications.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 6 Domestic Security 1 2013-01-01 2013-01-01 false Neutral adjudications. 27.305 Section 27.305 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.305 Neutral adjudications. (a) Any facility or other person who...

  9. 6 CFR 27.305 - Neutral adjudications.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 6 Domestic Security 1 2014-01-01 2014-01-01 false Neutral adjudications. 27.305 Section 27.305 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.305 Neutral adjudications. (a) Any facility or other person who...

  10. 6 CFR 27.305 - Neutral adjudications.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 6 Domestic Security 1 2011-01-01 2011-01-01 false Neutral adjudications. 27.305 Section 27.305 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.305 Neutral adjudications. (a) Any facility or other person who...

  11. 6 CFR 27.305 - Neutral adjudications.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 6 Domestic Security 1 2010-01-01 2010-01-01 false Neutral adjudications. 27.305 Section 27.305 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.305 Neutral adjudications. (a) Any facility or other person who...

  12. The Dubious Value of Value Neutrality

    ERIC Educational Resources Information Center

    Balch, Stephen H.

    2006-01-01

    Hard science is properly value neutral. But when that ideological neutrality extends to the whole university, the traditional foundation crumbles. Steve Balch laments the moral vacuum that now substitutes for fundamental principles, because it is impossible to frame a program of education--especially in the humanities and social sciences--without…

  13. Types of Neutralization and Types of Delinquency.

    ERIC Educational Resources Information Center

    Mitchell, Jim; Dodder, Richard A.

    1983-01-01

    Neutralization theory was tested with questionnaires administered to a random sample of public high school students (N-298) and institutionalized male delinquents (N-53). Neutralization acceptance technique patterns were similar across subsamples; however, correlations between each technique and each type of delinquency were statistically…

  14. 32 CFR 644.323 - Neutral language.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Neutral language. 644.323 Section 644.323 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal § 644.323 Neutral language. Wherever the words “man”, “men”, or their...

  15. Neutral Buoyancy Simulator - Space Station

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Skylab's success proved that scientific experimentation in a low gravity environment was essential to scientific progress. A more permanent structure was needed to provide this space laboratory. President Ronald Reagan, on January 25, 1984, during his State of the Union address, claimed that the United States should exploit the new frontier of space, and directed NASA to build a permanent marned space station within a decade. The idea was that the space station would not only be used as a laboratory for the advancement of science and medicine, but would also provide a staging area for building a lunar base and manned expeditions to Mars and elsewhere in the solar system. President Reagan invited the international community to join with the United States in this endeavour. NASA and several countries moved forward with this concept. By December 1985, the first phase of the space station was well underway with the design concept for the crew compartments and laboratories. Pictured are two NASA astronauts, at Marshall Space Flight Center's (MSFC) Neutral Buoyancy Simulator (NBS), practicing construction techniques they later used to construct the space station after it was deployed.

  16. Neutral Models of Microbiome Evolution

    PubMed Central

    Zeng, Qinglong; Sukumaran, Jeet; Wu, Steven; Rodrigo, Allen

    2015-01-01

    There has been an explosion of research on host-associated microbial communities (i.e.,microbiomes). Much of this research has focused on surveys of microbial diversities across a variety of host species, including humans, with a view to understanding how these microbiomes are distributed across space and time, and how they correlate with host health, disease, phenotype, physiology and ecology. Fewer studies have focused on how these microbiomes may have evolved. In this paper, we develop an agent-based framework to study the dynamics of microbiome evolution. Our framework incorporates neutral models of how hosts acquire their microbiomes, and how the environmental microbial community that is available to the hosts is assembled. Most importantly, our framework also incorporates a Wright-Fisher genealogical model of hosts, so that the dynamics of microbiome evolution is studied on an evolutionary timescale. Our results indicate that the extent of parental contribution to microbial availability from one generation to the next significantly impacts the diversity of microbiomes: the greater the parental contribution, the less diverse the microbiomes. In contrast, even when there is only a very small contribution from a constant environmental pool, microbial communities can remain highly diverse. Finally, we show that our models may be used to construct hypotheses about the types of processes that operate to assemble microbiomes over evolutionary time. PMID:26200800

  17. The status of neutral currents

    SciTech Connect

    Zwirner, F.

    1987-11-01

    The situation of particle physics today is quite puzzling. On the one hand, the Standard Model (SM) of strong and electroweak interactions is consistent with all confirmed experimental data but theoretically rather unsatisfactory. On the other hand, none of the many theoretical speculations which try to go beyond the SM has (yet) received the slightest experimental support. The solution to this dilemma can only come from new data: either from the detection of a new particle threshold at high energy colliders, or from the appearance of some small discrepancy in high-precision experiments. A crucial sector for testing the SM and its extensions is that of neutral currents (NC), where an impressive amount of data has been collected in recent years. While waiting for the next generation of experiments, it is certainly useful to take stock of our knowledge, determining the NC parameters as precisely as we can and putting limits on possible deviations from the SM. The present talk contains the results of a recent analysis along these lines: the first part illustrates how a set of 'model-independent' parameters can be extracted from the available NC data, the second part particularizes the analysis to the SM and to some superstring-inspired models with an additional Z' in their low-energy spectrum. 27 refs., 3 figs., 1 tab.

  18. Neutral depletion and the helicon density limit

    SciTech Connect

    Magee, R. M.; Galante, M. E.; Carr, J. Jr.; Lusk, G.; McCarren, D. W.; Scime, E. E.

    2013-12-15

    It is straightforward to create fully ionized plasmas with modest rf power in a helicon. It is difficult, however, to create plasmas with density >10{sup 20} m{sup −3}, because neutral depletion leads to a lack of fuel. In order to address this density limit, we present fast (1 MHz), time-resolved measurements of the neutral density at and downstream from the rf antenna in krypton helicon plasmas. At the start of the discharge, the neutral density underneath the antenna is reduced to 1% of its initial value in 15 μs. The ionization rate inferred from these data implies that the electron temperature near the antenna is much higher than the electron temperature measured downstream. Neutral density measurements made downstream from the antenna show much slower depletion, requiring 14 ms to decrease by a factor of 1/e. Furthermore, the downstream depletion appears to be due to neutral pumping rather than ionization.

  19. Neutral particle beams for space defense

    NASA Astrophysics Data System (ADS)

    Botwin, Robert; Favale, Anthony

    Neutral particle beam (NPB) weapons direct highly focused high energy streams of electrically neutral atomic particles traveling at nearly the speed of light, escaping deflection from the earth's magnetic field and acting on the subatomic structure of a target, destroying it from within. The beam's brief contact with a reentry vehicle produces a nuclear reaction in the latter that yields particle emissions; by detecting and identifying those particles, it becomes possible to effectively distinguish warheads from decoys. Attention is given to the NPB program roles to be played by the Beam Experiment Aboard Rocket and Neutral Particle Beam Integrated Space Experiment projects.

  20. Neutral Supersymmetric Higgs Boson Searches

    SciTech Connect

    Robinson, Stephen Luke

    2008-07-01

    In some Supersymmetric extensions of the Standard Model, including the Minimal Supersymmetric Standard Model (MSSM), the coupling of Higgs bosons to b-quarks is enhanced. This enhancement makes the associated production of the Higgs with b-quarks an interesting search channel for the Higgs and Supersymmetry at D0. The identification of b-quarks, both online and offline, is essential to this search effort. This thesis describes the author's involvement in the development of both types of b-tagging and in the application of these techniques to the MSSM Higgs search. Work was carried out on the Level-3 trigger b-tagging algorithms. The impact parameter (IP) b-tagger was retuned and the effects of increased instantaneous luminosity on the tagger were studied. An extension of the IP-tagger to use the z-tracking information was developed. A new b-tagger using secondary vertices was developed and commissioned. A tool was developed to allow the use of large multi-run samples for trigger studies involving b-quarks. Offline, a neural network (NN) b-tagger was trained combining the existing offline lifetime based b-tagging tools. The efficiency and fake rate of the NN b-tagger were measured in data and MC. This b-tagger was internally reviewed and certified by the Collaboration and now provides the official b-tagging for all analyses using the Run IIa dataset at D0. A search was performed for neutral MSSM Higgs bosons decaying to a b{bar b} pair and produced in association with one or more b-quarks. Limits are set on the cross-section times the branching ratio for such a process. The limits were interpreted in various MSSM scenarios. This analysis uses the NN b-tagger and was the first to use this tool. The analysis also relies on triggers using the Level-3 IP b-tagging tool described previously. A likelihood discriminant was used to improve the analysis and a neural network was developed to cross-check this technique. The result of the analysis has been submitted to PRL and

  1. The Ethics of Evaluation Neutrality and Advocacy.

    ERIC Educational Resources Information Center

    Datta, Lois-ellin

    1999-01-01

    Examines arguments for and against evaluation advocacy in terms of the American Evaluation Association's "Guiding Principles for Evaluators" and other statements on advocacy and neutrality. Suggests revision of the "Guiding Principles." (Author/SLD)

  2. An autoneutralizing neutral molecular beam gun

    SciTech Connect

    Delmore, J.E.; Appelhans, A.D.; Dahl, D.A. )

    1990-01-01

    A high-energy (up to 28 keV) neutral molecular beam gun has been developed and put into routine use that takes advantage of the autoneutralization properties of the sulfur hexafluoride anion for the production of high-energy sulfur hexafluoride neutral molecules. The anions are produced in an electron-capture source, accelerated, and focused in a lens assembly designed to minimize residence time, allowed to drift at their terminal velocity for a suitable distance during which up to 30% auto-eject an electron, and all remaining charged particles are electrostatically skimmed, resulting in a focused neutral beam. Rasterable neutral beams focused to a 5-mm spot size up to 3 m from the source have been produced with beam currents up to 40 pA equivalent. Spot sizes of 1 mm can be produced with intensity levels of a few picoamperes equivalent.

  3. Neutral gas heating in helium microplasmas

    NASA Astrophysics Data System (ADS)

    Jugroot, M.

    2009-01-01

    The present study details a self-consistent model of charged and neutral particle dynamics which is applied to atmospheric small-space (200 μm) discharges in helium. Hydrodynamic transport equations of the self-consistent and time-dependant model are described with an emphasis on the different terms involved in the close coupling among charged species, neutral species, and the electric field. Those equations are solved by two-dimensional numerical schemes for both species transport and electric field. The microplasmas are studied from an initial cloud until the stages of charged particle overamplification in small spaces, where transients are particularly important. Gas heating, neutral depletion initiation, and electric field reversal are observed, highlighting the close interaction between neutral gas and charged species in governing the evolution of the microplasma.

  4. Ion-Neutral Coupling in Solar Prominence

    NASA Technical Reports Server (NTRS)

    Gilbert, H.; DeVore, C. R.; Karpen, J.; Kucera, T.; Antiochos, S.; Kawashima, R.

    2011-01-01

    Coupling between ions and neutrals in magnetized plasmas is fundamentally important to many aspects of heliophysics, including our ionosphere, the solar chromosphere, the solar wind interaction with planetary atmospheres, and the interface between the heliosphere and the interstellar medium. Ion-neutral coupling also plays a major role in the physics of solar prominences. By combining theory, modeling, and observations we are working toward a better understanding of the structure and dynamics of partially ionized prominence plasma. Two key questions are addressed in the present work: 1) what physical mechanism(s) sets the cross-field scale of prominence threads? 2) Are ion-neutral interactions responsible for the vertical flows and structure in prominences? We present initial results from a study investigating what role ion-neutral interactions play in prominence dynamics and structure. This research was supported by NASA.

  5. Neutralized transport of high intensity beams

    SciTech Connect

    Henestroza, E.; Yu, S.S.; Eylon, S.; Roy, P.K.; Anders, A.; Sharp, W.; Efthimion, P.; Gilson, E.; Welch, D.; Rose, D.

    2003-05-01

    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. A converging ion beam at the exit of the final focus magnetic system is injected into a neutralized drift section. The neutralization is provided by a metal arc source and an RF plasma source. Effects of a ''plasma plug'', where electrons are extracted from a localized plasma in the upstream end of the drift section, and are then dragged along by the ion potential, as well as the ''volumetric plasma'', where neutralization is provided by the plasma laid down along the ion path, are both studied and their relative effects on the beam spot size are compared. Comparisons with 3-D PIC code predictions will also be presented.

  6. Kinetics of neutralization of Po-218

    SciTech Connect

    Chu, K.D.

    1987-01-01

    In a well-defined experimental system the neutralization of polonium-218 ions was investigated as a function of the physical and chemical properties of the controlled composition atmosphere. The mobilities of Po/sup +/ and PoO/sub 2//sup +/ are determined by combining experimental results with a computer model of the system. Three neutralization mechanisms were individually studied. The small ion recombination rate has been found to be proportional to the square root of radon concentration. The electron scavenging mechanism is responsible for the neutralization of Po/sup +/ in NO/sub 2/ or H/sub 2/O in nitrogen. When PoO/sub 2//sup +/ is formed, the electron transfer mechanism dominates the neutralization process. The electron is transferred to PoO/sub 2//sup +/ from molecules with lower ionization potentials. The ionization potential of PoO/sub 2//sup +/ is also determined to be 10.44 +/- 0.05 eV.

  7. Neutral hydrogen survey of andromeda galaxy.

    PubMed

    Brundage, W D; Kraus, J D

    1966-07-22

    A neutral hydrogen survey of the Andromeda galaxy (M31) has been conducted with the 260-foot (80m) Ohio State University radio telescope. The neutral hydrogen is concentrated in the spiral arm regions, with but relatively small amounts near the center of the galaxy. Similar deficiencies have been found near the center of M33 and our galaxy, suggesting similar evolutionary processes in the three galaxies. PMID:17839713

  8. Nitrogen-neutrality: a step towards sustainability

    NASA Astrophysics Data System (ADS)

    Leip, Adrian; Leach, Allison; Musinguzi, Patrick; Tumwesigye, Trust; Olupot, Giregon; Tenywa, John Stephen; Mudiope, Joseph; Hutton, Olivia; Cordovil, Claudia M. d. S.; Bekunda, Mateete; Galloway, James

    2014-11-01

    We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, N-neutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US 3050 was collected from the participants and used to offset the conference’s N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.

  9. Anion formation by neutral resonant ionization

    NASA Astrophysics Data System (ADS)

    Vogel, John S.

    2015-10-01

    A collision-radiation model of the cesium plasma that forms within a pitted or recessed sample in a Middleton-type sputter ion source showed that excited states of Cs formed. These excited states of neutral Cs undergo resonant electron transfer with neutral sputtered atoms of AMS samples to produce the accelerated anions. Numerous reported effects from over 30 years are readily explained by this mechanism, including several that puzzled Middleton.

  10. Enhanced HIV-1 neutralization by antibody heteroligation

    PubMed Central

    Mouquet, Hugo; Warncke, Malte; Scheid, Johannes F.; Seaman, Michael S.; Nussenzweig, Michel C.

    2012-01-01

    Passive transfer of broadly neutralizing human antibodies against HIV-1 protects macaques against infection. However, HIV-1 uses several strategies to escape antibody neutralization, including mutation of the gp160 viral surface spike, a glycan shield to block antibody access to the spike, and expression of a limited number of viral surface spikes, which interferes with bivalent antibody binding. The latter is thought to decrease antibody apparent affinity or avidity, thereby interfering with neutralizing activity. To test the idea that increasing apparent affinity might enhance neutralizing activity, we engineered bispecific anti–HIV-1 antibodies (BiAbs) that can bind bivalently by virtue of one scFv arm that binds to gp120 and a second arm to the gp41 subunit of gp160. The individual arms of the BiAbs preserved the binding specificities of the original anti-HIV IgG antibodies and together bound simultaneously to gp120 and gp41. Heterotypic bivalent binding enhanced neutralization compared with the parental antibodies. We conclude that antibody recognition and viral neutralization of HIV can be improved by heteroligation. PMID:22219363

  11. The Phobos neutral and ionized torus

    NASA Astrophysics Data System (ADS)

    Poppe, A. R.; Curry, S. M.; Fatemi, S.

    2016-05-01

    Charged particle sputtering, micrometeoroid impact vaporization, and photon-stimulated desorption are fundamental processes operating at airless surfaces throughout the solar system. At larger bodies, such as Earth's Moon and several of the outer planet moons, these processes generate tenuous surface-bound exospheres that have been observed by a variety of methods. Phobos and Deimos, in contrast, are too gravitationally weak to keep ejected neutrals bound and, thus, are suspected to generate neutral tori in orbit around Mars. While these tori have not yet been detected, the distribution and density of both the neutral and ionized components are of fundamental interest. We combine a neutral Monte Carlo model and a hybrid plasma model to investigate both the neutral and ionized components of the Phobos torus. We show that the spatial distribution of the neutral torus is highly dependent on each individual species (due to ionization rates that span nearly 4 orders of magnitude) and on the location of Phobos with respect to Mars. Additionally, we present the flux distribution of torus pickup ions throughout the Martian system and estimate typical pickup ion fluxes. We find that the predicted pickup ion fluxes are too low to perturb the ambient plasma, consistent with previous null detections by spacecraft around Mars.

  12. Automated facial coding software outperforms people in recognizing neutral faces as neutral from standardized datasets

    PubMed Central

    Lewinski, Peter

    2015-01-01

    Little is known about people’s accuracy of recognizing neutral faces as neutral. In this paper, I demonstrate the importance of knowing how well people recognize neutral faces. I contrasted human recognition scores of 100 typical, neutral front-up facial images with scores of an arguably objective judge – automated facial coding (AFC) software. I hypothesized that the software would outperform humans in recognizing neutral faces because of the inherently objective nature of computer algorithms. Results confirmed this hypothesis. I provided the first-ever evidence that computer software (90%) was more accurate in recognizing neutral faces than people were (59%). I posited two theoretical mechanisms, i.e., smile-as-a-baseline and false recognition of emotion, as possible explanations for my findings. PMID:26441761

  13. Modeling Neutral Densities Downstream of a Gridded Ion Thruster

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2010-01-01

    The details of a model for determining the neutral density downstream of a gridded ion thruster are presented. An investigation of the possible sources of neutrals emanating from and surrounding a NEXT ion thruster determined that the most significant contributors to the downstream neutral density include discharge chamber neutrals escaping through the perforated grids, neutrals escaping from the neutralizer, and vacuum facility background neutrals. For the neutral flux through the grids, near- and far-field equations are presented for rigorously determining the neutral density downstream of a cylindrical aperture. These equations are integrated into a spherically-domed convex grid geometry with a hexagonal array of apertures for determining neutral densities downstream of the ion thruster grids. The neutrals escaping from an off-center neutralizer are also modeled assuming diffuse neutral emission from the neutralizer keeper orifice. Finally, the effect of the surrounding vacuum facility neutrals is included and assumed to be constant. The model is used to predict the neutral density downstream of a NEXT ion thruster with and without neutralizer flow and a vacuum facility background pressure. The impacts of past simplifying assumptions for predicting downstream neutral densities are also examined for a NEXT ion thruster.

  14. Neutral beamline with improved ion energy recovery

    DOEpatents

    Dagenhart, William K.; Haselton, Halsey H.; Stirling, William L.; Whealton, John H.

    1984-01-01

    A neutral beamline generator with unneutralized ion energy recovery is provided which enhances the energy recovery of the full energy ion component of the beam exiting the neutralizer cell of the beamline. The unneutralized full energy ions exiting the neutralizer are deflected from the beam path and the electrons in the cell are blocked by a magnetic field applied transverse to the beamline in the cell exit region. The ions, which are generated at essentially ground potential and accelerated through the neutralizer cell by a negative acceleration voltage, are collected at ground potential. A neutralizer cell exit end region is provided which allows the magnetic and electric fields acting on the exiting ions to be closely coupled. As a result, the fractional energy ions exiting the cell with the full energy ions are reflected back into the gas cell. Thus, the fractional energy ions do not detract from the energy recovery efficiency of full energy ions exiting the cell which can reach the ground potential interior surfaces of the beamline housing.

  15. Neutralization of thoron progeny in gases.

    PubMed

    Cheng, Y S; Yu, C C; Tung, C J; Hopke, P K

    1994-08-01

    This paper reports charge neutralization phenomena of 212Pb particles in nitrogen or oxygen atmospheres with trace amounts of other gases. Newly produced thoron or radon progeny are positively charged, stable molecular clusters that are subsequently neutralized by several mechanisms. The charged clusters have a smaller diffusion coefficient than neutral clusters of the same size due to the interaction of the charge with the surrounding gas molecules. In this study, we have found that the diffusion coefficients of 212Pb in O2, N2, NH3/O2, NH3/N2, and C6H12/N2 (IPs between 15.58 and 9.8 eV) ranged between 0.015 and 0.030 cm2 s-1. In the case of C6H12/O2, NO2/O2, NO/O2, and dimethylamine/O2 (ionization potential between 9.8 and 8.23 eV), the diffusion coefficients have increased to between 0.046 and 0.69 cm2 s-1. These results are consistent with previous results of 218Po, indicating that charged progeny are neutralized by electron transfer from a gas molecule with a lower ionization potential than lead oxide. We estimate the ionization potential of lead oxide to range between 9.8 and 10.2 eV. 212Pb was also neutralized by an electron scavenging mechanism in NO2/nitrogen. PMID:8026969

  16. Species ages in neutral biodiversity models.

    PubMed

    Chisholm, Ryan A; O'Dwyer, James P

    2014-05-01

    Biogeography seeks to understand the mechanisms that drive biodiversity across long temporal and large spatial scales. Theoretical models of biogeography can be tested by comparing their predictions of quantities such as species ages against empirical estimates. It has previously been claimed that the neutral theory of biodiversity and biogeography predicts species ages that are unrealistically long. Any improved theory of biodiversity must rectify this problem, but first it is necessary to quantify the problem precisely. Here we provide analytical expressions for species ages in neutral biodiversity communities. We analyse a spatially implicit metacommunity model and solve for both the zero-sum and non-zero-sum cases. We explain why our new expressions are, in the context of biodiversity, usually more appropriate than those previously imported from neutral molecular evolution. Because of the time symmetry of the spatially implicit neutral model, our expressions also lead directly to formulas for species persistence times and species lifetimes. We use our new expressions to estimate species ages of forest trees under a neutral model and find that they are about an order of magnitude shorter than those predicted previously but still unrealistically long. In light of our results, we discuss different models of biogeography that may solve the problem of species ages. PMID:24530891

  17. Focusing and neutralization of intense beams

    SciTech Connect

    Yu, Simon S.; Anders, Andre; Bieniosek, F.M.; Eylon, Shmuel; Henestroza, Enrique; Roy, Prabir; Shuman, Derek; Waldron, William; Sharp, William; Rose, Dave; Welch, Dale; Efthimion, Philip; Gilson, Eric

    2003-05-01

    In heavy ion inertial confinement fusion systems, intense beams of ions must be transported from the exit of the final focus magnet system through the target chamber to hit millimeter spot sizes on the target. Effective plasma neutralization of intense ion beams through the target chamber is essential for the viability of an economically competitive heavy ion fusion power plant. The physics of neutralized drift has been studied extensively with PIC simulations. To provide quantitative comparisons of theoretical predictions with experiment, the Heavy Ion Fusion Virtual National Laboratory has completed the construction and has begun experimentation with the NTX (Neutralized Transport Experiment) as shown in Figure 1. The experiment consists of 3 phases, each with physics issues of its own. Phase 1 is designed to generate a very high brightness potassium beam with variable perveance, using a beam aperturing technique. Phase 2 consists of magnetic transport through four pulsed quadrupoles. Here, beam tuning as well as the effects of phase space dilution through higher order nonlinear fields must be understood. In Phase 3, a converging ion beam at the exit of the magnetic section is transported through a drift section with plasma sources for beam neutralization, and the final spot size is measured under various conditions of neutralization. In this paper, we present first results from all 3 phases of the experiment.

  18. Structural basis of influenza virus neutralization

    PubMed Central

    Han, Thomas; Marasco, Wayne A.

    2010-01-01

    Although seasonal influenza vaccines play a valuable role in reducing the spread of the virus at the population level, ongoing viral evolution to evade immune responses remains problematic. No current vaccines are likely to elicit enduring protection in the face of emerging and re-emerging influenza viruses that rapidly undergoing antigenic drift. Eliciting broadly cross-neutralizing antibody responses against influenza virus is a crucial goal for seasonal and pandemic influenza vaccine preparation. Recent three-dimensional structure information obtained from crystallization of influenza antigens in complex with neutralizing antibodies (nAbs) have provided a framework for interpreting antibody-based viral neutralization that should aid in the design of vaccine immunogens. Here, we will review current knowledge of the structure-based mechanisms contributing to the neutralization and neutralization escape of influenza viruses. We will also explore the potential for this structure-based approach to overcome the challenge of obtaining the highly desired “universal” influenza vaccine. PMID:21251008

  19. BEAMS3D Neutral Beam Injection Model

    NASA Astrophysics Data System (ADS)

    McMillan, Matthew; Lazerson, Samuel A.

    2014-09-01

    With the advent of applied 3D fields in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous slowing down, and pitch angle scattering are modeled with the ADAS atomic physics database. Elementary benchmark calculations are presented to verify the collisionless particle orbits, NBI model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields. Notice: this manuscript has been authored by Princeton University under Contract Number DE-AC02-09CH11466 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  20. A Label as a Hidden Persuader: Chemists' Neutralization Concept.

    ERIC Educational Resources Information Center

    Schmidt, Hans-Jurgen

    1991-01-01

    Identifies and describes the problems students have with the concept of neutralization. Analysis of over 7,500 students' answers to test questions over neutralization showed that many students understand the concept in its original meaning. Students assumed that in any neutralization reaction a neutral solution is formed, even if a weak acid or…

  1. Broadly neutralizing antibodies against influenza viruses

    PubMed Central

    Laursen, Nick S.; Wilson, Ian A.

    2014-01-01

    Despite available antivirals and vaccines, influenza infections continue to be a major cause of mortality worldwide. Vaccination generally induces an effective, but strain-specific antibody response. As the virus continually evolves, new vaccines have to be administered almost annually when a novel strain becomes dominant. Furthermore, the sporadic emerging resistance to neuraminidase inhibitors among circulating strains suggests an urgent need for new therapeutic agents. Recently, several cross-reactive antibodies have been described, which neutralize an unprecedented spectrum of influenza viruses. These broadly neutralizing antibodies generally target conserved functional regions on the major influenza surface glycoprotein hemagglutinin (HA). The characterization of their neutralization breadth and epitopes on HA could stimulate the development of new antibody-based antivirals and broader influenza vaccines. PMID:23583287

  2. Phage display and Shiga toxin neutralizers.

    PubMed

    Bernedo-Navarro, Robert Alvin; Yano, Tomomasa

    2016-04-01

    The current work presents an overview of the use of phage display technology for the identification and characterization of potential neutralizing agents for Shiga toxins. The last major Shiga toxin-associated disease outbreak, which took place in Germany in 2011, showed the international community that Shiga toxins remain a serious threat to public health. This is also demonstrated by the lack of specific therapies against Shiga toxin-induced Hemolytic Uremic Syndrome (HUS). Since its inception, phage display technology has played a key role in the development of antigen-specific (poly)-peptides or antibody fragments with specific biological properties. Herein, we review the current literature regarding the application of phage display to identify novel neutralizing agents against Shiga toxins. We also briefly highlight reported discoveries of peptides and heavy chain antibodies (VHH fragments or nanobodies) that can neutralize the cellular damage caused by these potent toxins. PMID:26898657

  3. Landau-like states in neutral particles

    NASA Astrophysics Data System (ADS)

    Banerjee, Saikat; Ågren, Hans; Balatsky, A. V.

    2016-06-01

    We show the emergence of a new type of dispersion relation for neutral atoms with an interesting similarity to the spectrum of two-dimensional electrons in an applied perpendicular constant magnetic field. These neutral atoms can be confined in toroidal optical traps and give quasi-Landau spectra. In strong contrast to the equidistant infinitely degenerate Landau levels for charged particles, the spectral gap for such two-dimensional neutral particles increases in particular electric-field configurations. The idea in the paper is motivated by the development in cold atom experiments and builds on the seminal paper of Aharonov and Casher [Phys. Rev. Lett. 53, 319 (1984), 10.1103/PhysRevLett.53.319].

  4. Kinetic Simulations of Ion Beam Neutralization

    SciTech Connect

    Chang, O.; Wang, J.

    2011-05-20

    Full particle PIC simulations are performed to study the neutralization of an ion beam in the cohesionless, mesothermal regime. Simulations further confirmed that neutralization is achieved through interactions between the trapped electrons and the potential well established by the propagation of the beam front along the beam direction and is not through plasma instabilities as previous studies suggested. In the transverse direction, the process is similar to that of the expansion of mesothermal plasma into vacuum. Parametric simulations are also performed to investigate the effects of beam radius and domain boundary condition on the neutralization process. The results suggests that, while the qualitative behavior may be similar in ground tests, quantitative parameters such as the beam potential will be affected significantly by the vacuum chamber because of the limits imposed on the expansion process by the finite chamber space.

  5. Methods for neutralizing anthrax or anthrax spores

    DOEpatents

    Sloan, Mark A; Vivekandanda, Jeevalatha; Holwitt, Eric A; Kiel, Johnathan L

    2013-02-26

    The present invention concerns methods, compositions and apparatus for neutralizing bioagents, wherein bioagents comprise biowarfare agents, biohazardous agents, biological agents and/or infectious agents. The methods comprise exposing the bioagent to an organic semiconductor and exposing the bioagent and organic semiconductor to a source of energy. Although any source of energy is contemplated, in some embodiments the energy comprises visible light, ultraviolet, infrared, radiofrequency, microwave, laser radiation, pulsed corona discharge or electron beam radiation. Exemplary organic semiconductors include DAT and DALM. In certain embodiments, the organic semiconductor may be attached to one or more binding moieties, such as an antibody, antibody fragment, or nucleic acid ligand. Preferably, the binding moiety has a binding affinity for one or more bioagents to be neutralized. Other embodiments concern an apparatus comprising an organic semiconductor and an energy source. In preferred embodiments, the methods, compositions and apparatus are used for neutralizing anthrax spores.

  6. Apparatus for neutralization of accelerated ions

    DOEpatents

    Fink, Joel H.; Frank, Alan M.

    1979-01-01

    Apparatus for neutralization of a beam of accelerated ions, such as hydrogen negative ions (H.sup.-), using relatively efficient strip diode lasers which emit monochromatically at an appropriate wavelength (.lambda. = 8000 A for H.sup.- ions) to strip the excess electrons by photodetachment. A cavity, formed by two or more reflectors spaced apart, causes the laser beams to undergo multiple reflections within the cavity, thus increasing the efficiency and reducing the illumination required to obtain an acceptable percentage (.about. 85%) of neutralization.

  7. High-current plasma contactor neutralizer system

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Williamson, W. S.; Matossian, J. N.; Vourgourakis, E. J.; Burch, J. L.

    1989-01-01

    A plasma-contactor neutralizer system is described, for the stabilizing the Orbiter's potential during flights of the Atmospheric Laboratory for Applications and Science missions. The plasma contactor neutralizer will include a Xe plasma source that can provide steady-state ion-emission currents of up to 1.5 A. The Orbiter's potential will be maintained near that of the surrounding space plasma during electron-beam accelerator firings through a combination of ion emission from the Xe plasma source and electron collection from the ambient space plasma. Configuration diagrams and block diagrams are presented along with the performance characteristics of the system.

  8. Neutral Beam Ion Confinement in NSTX

    SciTech Connect

    D.S. Darrow; E.D. Fredrickson; S.M. Kaye; S.S. Medley; and A.L. Roquemore

    2001-07-24

    Neutral-beam (NB) heating in the National Spherical Torus Experiment (NSTX) began in September 2000 using up to 5 MW of 80 keV deuterium (D) beams. An initial assessment of beam ion confinement has been made using neutron detectors, a neutral particle analyzer (NPA), and a Faraday cup beam ion loss probe. Preliminary neutron results indicate that confinement may be roughly classical in quiescent discharges, but the probe measurements do not match a classical loss model. MHD activity, especially reconnection events (REs) causes substantial disturbance of the beam ion population.

  9. SAXS study of crotapotin at low pH.

    PubMed Central

    Abrego, J R; Craievich, A F; Mascarenhas, Y P; Laure, C J

    1993-01-01

    The structure of crotapotin, a protein extracted, from the venom of the Crotalus durissus terrificus, in solution at pH = 1.5, was studied by SAXS. The experimental results yield structural parameter values of the molecular radius of gyration Rg = 13.6 A, volume v = 16.2 x 10(3) A3 A3 and maximal dimension Dmax = 46 A. The distance distribution function deduced from the scattering measurements is consistent with an overall molecular shape of an oblate ellipsoid of revolution with asymmetry parameter v = 0.45. PMID:8457680

  10. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission.

    PubMed

    Chrystal, C; Burrell, K H; Grierson, B A; Pace, D C

    2015-10-01

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access. PMID:26520957

  11. Neutralization escape mutants define a dominant immunogenic neutralization site on hepatitis A virus

    SciTech Connect

    Stapleton, J.T.; Lemon, S.M.

    1987-02-01

    Hepatitis A virus is an hepatotrophic human picornavirus which demonstrates little antigenic variability. To topologically map immunogenic sites on hepatitis A virus which elicit neutralizing antibodies, eight neutralizing monoclonal antibodies were evaluated in competition immunoassays employing radiolabeled monoclonal antibodies and HM-175 virus. Whereas two antibodies (K3-4C8 and K3-2F2) bound to intimately overlapping epitopes, the epitope bound by a third antibody (B5-B3) was distinctly different as evidenced by a lack of competition between antibodies for binding to the virus. The other five antibodies variably blocked the binding of both K3-4C8-K3-2F2 and B5-B3, suggesting that these epitopes are closely spaced and perhaps part of a single neutralization immunogenic site. Several combinations of monoclonal antibodies blocked the binding of polyclonal human convalescent antibody by greater than 96%, indicating that the neutralization epitopes bound by these antibodies are immunodominant in humans. Spontaneously arising HM-175 mutants were selected for resistance to monoclonal antibody-mediated neutralization. Neutralization resistance was associated with reduced antibody binding. These results suggest that hepatitis A virus may differ from poliovirus in possessing a single, dominant neutralization immunogenic site and therefore may be a better candidate for synthetic peptide or antiidiotype vaccine development.

  12. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

    SciTech Connect

    Chrystal, C.; Burrell, K. H.; Pace, D. C.; Grierson, B. A.

    2015-10-15

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

  13. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

    NASA Astrophysics Data System (ADS)

    Chrystal, C.; Burrell, K. H.; Grierson, B. A.; Pace, D. C.

    2015-10-01

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

  14. Color appearance: neutral surrounds and spatial contrast.

    PubMed

    Smith, V C; Jin, Q; Pokorny, J

    1998-11-01

    The experimental data in this paper show that chromatic bars presented in alternation with equiluminant neutral-appearing bars are seen as more saturated than the same chromaticity presented as a uniform rectangle. This effect was diminished but not eliminated when test and match stimuli were presented within a slightly dimmer neutral surround. The test stimulus was a 2 x 5 degrees rectangle with a 0.7 cpd square wave grating composed of alternating equiluminant chromatic test bars and neutral bars. Asymmetric matching was used to match the test bar appearance to a uniform 2 x 5 degrees comparison rectangle. Test and comparison stimuli were presented to separate eyes in a haploscope and appeared flanking a central fixation target. Data were collected with test and inducing stimuli on the cardinal axes of color space. Test bars separated by neutral bars appeared more saturated than the comparison rectangle for both the l- and s-axis directions. Manipulation of excitation on one cardinal axis did not affect the appearance matches made for the other cardinal axis. PMID:9893836

  15. Laser neutralization of surface and buried munitions

    NASA Astrophysics Data System (ADS)

    Habersat, James D.; Schilling, Bradley W.; Alexander, Joe; Lehecka, Thomas

    2012-06-01

    In recent years NVESD has been investigating laser-based neutralization of buried mines and minelike targets. This paper covers the most recent efforts in this area. A field-test was conducted to demonstrate the state-of-the-art capability for standoff laser neutralization of surface and buried mines. The neutralization laser is a Ytterbium fiber laser with a nominal power output of 10 kW and a beam quality of M2 ~ 1.8 at maximum power. Test trials were conducted at a standoff range of 50 meters with a 20° angle of attack. The laser was focused to a submillimeter spot using a Cassegrain telescope with a 12.5 inch diameter primary mirror. The targets were 105 mm artillery rounds with a composition B explosive fill. Three types of overburden were studied: sand, soil, and gravel. Laser neutralization capability was demonstrated under these conditions for live rounds buried under 7 cm of dry sand, 4 cm of soil, and 2 cm of gravel.

  16. Tissue dissociation enzyme neutral protease assessment.

    PubMed

    Breite, A G; Dwulet, F E; McCarthy, R C

    2010-01-01

    Neutral proteases, essential components of purified tissue dissociation enzymes required for successful human islet isolation, show variable activities and effects of substrate on their activities. Initially we used a spectrophotometric endpoint assay with azocasein substrate to measure neutral protease activity. After critical review of the results, we observed these data to be inconsistent and not correlating expected differences in specific activities between thermolysin and Bacillus polymyxa proteases. This observation led to the development of a fluorescent microplate assay using fluorescein isothyocyanate-conjugated bovine serum albumin (FITC-BSA) as the substrate. This simpler, more flexible method offered a homogeneous, kinetic enzyme assay allowing determination of steady state reaction rates of sample replicates at various dilutions. The assay had a linear range of 4- to 8-fold and interassay coefficients of variation for B polymyxa protease and thermolysin of <9% and <15%, respectively, which were lower than those using the spectrophotometric endpoint assay, namely, 54% and 36%, respectively. This format allowed for incorporation of enzyme inhibitors, as illustrated by addition of sulfhydryl protease inhibitors, which, consistent with earlier reports, strongly indicated that the main contaminant in purified collagenase preparations was clostripain. Determination of the specific activities for several purified neutral proteases showed that the B polymyxa and Clostridium histolyticum proteases had approximately 40% and 15% specific activities, respectively, of those obtained with purified thermolysin, indicating the different characteristics of neutral protease enzymes for cell isolation procedures. PMID:20692405

  17. The LIPSS search for light neutral bosons

    SciTech Connect

    Andrei Afanasev; Oliver K. Baker; Kevin Beard; George Biallas; James Boyce; Minarni Minarni; Roopchan Ramdon; Michelle D. Shinn; Penny Slocum

    2009-07-01

    An overview is presented of the LIPSS experimental search for very light neutral bosons using laser light from Jefferson Lab's Free Electron Laser. This facility provides very high power beams of photons over a large optical range, particularly at infrared wavelengths. Data has been collected in several experimental runs during the course of the past three years, most recently in the Fall of 2009.

  18. TPX Neutral Beam Injection System design

    SciTech Connect

    von Halle, A.; Bowen, O.N.; Edwards, J.W.

    1993-11-01

    The existing Tokamak Fusion Test Reactor Neutral Beam system is proposed to be modified for long pulse operation on the Tokamak Physics Experiment (TPX). Day one of TPX will call for one TFTR beamline modified for 1000 second pulse lengths oriented co-directional to the plasma current. The system design will be capable of accommodating an additional co-directional and a single counter directional beamline. For the TPX conceptual design, every attempt was made to use existing Neutral Beam hardware, plant facilities, auxiliary systems, service infrastructure, and control systems. This paper describes the moderate modifications required to the power systems, the ion sources, and the beam impinged surfaces of the ion dumps, the calorimeters, the various beam scrapers, and the neutralizers. Also described are the minimal modifications required to the vacuum, cryogenic, and gas systems and the major modification of replacing the beamline-torus duct in its entirety. Operational considerations for Neutral Beam subsystems over 1000 second pulse lengths will be explored including proposed operating scenarios for full steady state operation.

  19. Semiconductor etching by hyperthermal neutral beams

    NASA Technical Reports Server (NTRS)

    Minton, Timothy K. (Inventor); Giapis, Konstantinos P. (Inventor)

    1999-01-01

    An at-least dual chamber apparatus and method in which high flux beams of fast moving neutral reactive species are created, collimated and used to etch semiconductor or metal materials from the surface of a workpiece. Beams including halogen atoms are preferably used to achieve anisotropic etching with good selectivity at satisfactory etch rates. Surface damage and undercutting are minimized.

  20. Dynamics of evolutionary radiation under ecological neutrality.

    PubMed

    Suzuki, Takanori Mizuno; Chiba, Satoshi

    2016-10-01

    The most spectacular phenomenon of evolutionary biota is the explosive radiation that occurs in depauperate environments in which there are fewer competitors and predators, such as oceanic islands and crater lakes. Adaptation to divergent niches has been proposed as a major cause for this accelerated speciation. Here, we show that neutral mutation, genetic drift, and neutral community dynamics are sufficient to lead to radiation. In addition, these processes yield overshooting dynamics with a decline in species richness in the later stages of radiation. We constructed an ecologically neutral model for a community on an island with a uniform environment. For the speciation process, we introduced a null model with minimal assumptions in which the incompatibilities between alleles in different lineages evolve by a random accumulation of mutations via genetic drift. Our simulations showed that the speciation rate, extinction rate and genetic variation of the species colonizing the island rapidly increased to a sharp peak followed by a decrease that approached zero. Because the extinction rate reached a peak later than the speciation rate, the species richness initially increased, but declined in the later stage, exhibiting "overshooting". The highest species richness was found for the largest island at the largest initial population size. Accordingly, speciation is accelerated by the large population size of depauperate biota, whereas it is decelerated with increasing species richness from the decreasing population size. Explosive radiation without ecological divergence can occur in depauperate environments via neutral stochastic processes. PMID:27297287

  1. CP Violation, Neutral Currents, and Weak Equivalence

    DOE R&D Accomplishments Database

    Fitch, V. L.

    1972-03-23

    Within the past few months two excellent summaries of the state of our knowledge of the weak interactions have been presented. Correspondingly, we will not attempt a comprehensive review but instead concentrate this discussion on the status of CP violation, the question of the neutral currents, and the weak equivalence principle.

  2. Intraprostatic injection of neutralized zinc in rats

    SciTech Connect

    Fahim, M.S.; Wang, M.; Sutcu, M.F.; Fahim, Z.; Safron, J.A.; Ganjam, V.K. Xian Medical University )

    1991-03-11

    Zinc has been implicated in steroid endocrinology of the prostate gland. The conversion of testosterone to dihydrotestosterone (DHT) by 5{alpha}-reductase enzyme is believed to express androgenic responses in the prostate. To note the effect of neutralized zinc on the prostate, 50 sexually mature rats, weighing 325 {plus minus} 20 grams, were divided into 5 groups as follows: (1) control, (2) sham, (3) castrated, (4) injected intraprostatically with 10 mg. neutralized zinc, and (5) injected intraprostatically with 20 mg. neutralized zinc. Results in the treated groups indicated significant reduction of prostate weights, 12% and 53% and histologically normal prostate; no significant change in weight and histological structure of testes, epididymides, and seminal vesicles; significant reduction in 5{alpha}-reductase activity and total protein and DNA concentrations in prostate tissue; and no significant effect on progeny of treated animals. These results suggest that direct application of neutralized zinc to the prostate offers a new modality for treatment of prostatitis without affecting spermatogenesis and testosterone production.

  3. Ion Acoustic Waves in Ultracold Neutral Plasmas

    SciTech Connect

    Castro, J.; McQuillen, P.; Killian, T. C.

    2010-08-06

    We photoionize laser-cooled atoms with a laser beam possessing spatially periodic intensity modulations to create ultracold neutral plasmas with controlled density perturbations. Laser-induced fluorescence imaging reveals that the density perturbations oscillate in space and time, and the dispersion relation of the oscillations matches that of ion acoustic waves, which are long-wavelength, electrostatic, density waves.

  4. Method of purifying neutral organophosphorus extractants

    DOEpatents

    Horwitz, E. Philip; Gatrone, Ralph C.; Chiarizia, Renato

    1988-01-01

    A method for removing acidic contaminants from neutral mono and bifunctional organophosphorous extractants by contacting the extractant with a macroporous cation exchange resin in the H.sup.+ state followed by contact with a macroporous anion exchange resin in the OH.sup.- state, whereupon the resins take up the acidic contaminants from the extractant, purifying the extractant and improving its extraction capability.

  5. DESIGN MANUAL: NEUTRALIZATION OF ACID MINE DRAINAGE

    EPA Science Inventory

    This manual was prepared to assist designers and operators of mine drainage treatment plants in the selection of processes, equipment, and procedures. Included is a review of the most popular neutralizing agents and the methods used to handle, prepare, and feed these alkalies. Al...

  6. Gluons in a color-neutral nucleus

    SciTech Connect

    Mahlon, Gregory

    1999-10-04

    We improve the McLerran-Venugopalan model [1,2] by introducing a charge-density correlation function which is consistent with the observation that nucleons carry no net color charge. The infrared divergence in the transverse coordinates that was present in the McLerran-Venugoplan model is eliminated by the enforcement of color neutrality.

  7. Gluons in a color-neutral nucleus

    NASA Astrophysics Data System (ADS)

    Mahlon, Gregory

    1999-10-01

    We improve the McLerran-Venugopalan model [1,2] by introducing a charge-density correlation function which is consistent with the observation that nucleons carry no net color charge. The infrared divergence in the transverse coordinates that was present in the McLerran-Venugoplan model is eliminated by the enforcement of color neutrality.

  8. Neutralization of rainwater acidity at Kanpur, India

    NASA Astrophysics Data System (ADS)

    Shukla, Sheo Prasad; Sharma, Mukesh

    2010-07-01

    Particulate matter (PM) levels show significant seasonal variability and this can influence the neutralization of rainwater acidity. Months were grouped in two periods: monsoon (July to October) and non-monsoon (November to June) for studying the seasonal variability in PM and rainwater composition. To clearly establish the cause effect relationship of acid rain neutralization, a two tier model was proposed involving source apportionment of particulates at two levels: (i) ambient air and (ii) rainwater particulate interaction. For modelling purpose, PM10 (n = 100), soil (n = 4) and rainwater (n = 83) samples were collected at Kanpur, India during 2000-2002. The collected samples were analysed for metals and water soluble ion composition to employ factor analysis for source identification. Knowledge of statistical correlation and chemistry fundamentals were combined to estimate the sources for acid rain neutralization. NH4+ was a dominating ion responsible for neutralizing the acidity of rainwater in monsoon period and Ca2+ was dominating in non-monsoon period. Components of secondary particles (SO42- and NO3-) showed affinity with NH4+, signifying the major role that ammonia can play if present in excess of stoichiometric requirements.

  9. Absence of neutral alkali atoms in rhodizite

    USGS Publications Warehouse

    Donnay, G.; Thorpe, A.N.; Senftle, F.E.; Sioda, R.

    1966-01-01

    The formula CsB12Be4Al4O28 has been proposed by others for the mineral rhodizite. Electron-spin-resonance and magnetic susceptibility measurements prove the absence of neutral cesium atoms. An ionic formula CsB11Be4Al4O 26(OH)2is proposed.

  10. Economic and Legal Justifications of Fiscal Neutrality

    ERIC Educational Resources Information Center

    Aiken, John S.; Clune, William H., III

    1973-01-01

    The principle of fiscal neutrality is that school spending may not depend on the wealth of localities: if local units are to select spending levels, the state must eliminate the influence of the varying wealth of these units by matching grants. (Author/JM)

  11. SODA ASH TREATMENT OF NEUTRALIZED MINE DRAINAGE

    EPA Science Inventory

    Utilization of acid mine drainage (AMD) streams as a source of potable and industrial water has become a major goal of several proposed AMD treatment schemes. From among the various schemes available, the lime neutralization/soda ash softening process was selected for use at Alto...

  12. If It's Neutral, It's Not Technology

    ERIC Educational Resources Information Center

    Strate, Lance

    2012-01-01

    Taking a media ecology perspective, this article argues that technology cannot be neutral, because it is a form of change, and it has an inherent bias based on the properties of its materials and methods. Additionally, the application of a technology is an intrinsic part of the technology itself, as is technique, instructions, software, or…

  13. OGO-6 neutral atmospheric composition experiment

    NASA Technical Reports Server (NTRS)

    Taeusch, D. R.

    1973-01-01

    The continued analysis of data obtained from the neutral atmospheric composition experiment flown on OGO-V6 is discussed. The effort was directed toward the study of five specific areas of interest for which the OGO-V6 data were especially useful.

  14. Atmospheric Measurements of Neutral Nucleating Clusters (Invited)

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Eisele, F. L.; Smith, J. N.; Chen, M.; Jiang, J.; Kuang, C.; McMurry, P. H.

    2010-12-01

    Nanoparticles produced by nucleation can subsequently grow to cloud condensation nuclei (CCN) within one or two days and hence affect cloud formation, precipitation, and atmospheric radiation budgets. As an intermediate stage between molecules and nanoparticles, neutral molecular clusters are believed to play an important role in processes that lead to boundary layer nucleation. Therefore, knowledge of chemical composition, concentrations, thermodynamic properties, and evolution of neutral molecular clusters is essential to better elucidate the nucleation mechanism and to reduce the uncertainty in nucleation rates used in global climate models. Here we present laboratory and field measurements from a recently developed chemical ionization mass spectrometer (the Cluster-CIMS) designed to measure atmospheric neutral clusters (Zhao et al., 2010). The sensitivity of the Cluster-CIMS was significantly improved by using a unique conical octopole device in the first vacuum stage for transmitting and focusing ions, which was further confirmed by ion trajectory simulations using SIMION. The ion cluster formation in the atmospheric-pressure inlet was controlled by two processes: neutral ionization and ion-induced clustering (IIC), which can be differentiated from the time independency of the intensity ratio between the cluster and monomer ions. Two methods were employed to separate neutral clusters from the ion-induced clustering. The concentrations and distribution of the neutral nucleating clusters containing up to 4 H2SO4 are estimated from the above methods at three measurement sites in the US (NCAR foothill laboratory, Manitou Forest Observatory, and Atlanta). Typically, the molecular cluster concentrations are well correlated with the concentrations of nanoparticles measured simultaneously during the nucleation event periods. The Cluster-CIMS was employed to measure clusters containing both sulfuric acid and amines in summer 2010 at NCAR foothill laboratory

  15. Selectionism and Neutralism in Molecular Evolution

    PubMed Central

    Nei, Masatoshi

    2006-01-01

    Charles Darwin proposed that evolution occurs primarily by natural selection, but this view has been controversial from the beginning. Two of the major opposing views have been mutationism and neutralism. Early molecular studies suggested that most amino acid substitutions in proteins are neutral or nearly neutral and the functional change of proteins occurs by a few key amino acid substitutions. This suggestion generated an intense controversy over selectionism and neutralism. This controversy is partially caused by Kimura's definition of neutrality, which was too strict (|2Ns| ≤ 1). If we define neutral mutations as the mutations that do not change the function of gene products appreciably, many controversies disappear because slightly deleterious and slightly advantageous mutations are engulfed by neutral mutations. The ratio of the rate of nonsynonymous nucleotide substitution to that of synonymous substitution is a useful quantity to study positive Darwinian selection operating at highly variable genetic loci, but it does not necessarily detect adaptively important codons. Previously, multigene families were thought to evolve following the model of concerted evolution, but new evidence indicates that most of them evolve by a birth-and-death process of duplicate genes. It is now clear that most phenotypic characters or genetic systems such as the adaptive immune system in vertebrates are controlled by the interaction of a number of multigene families, which are often evolutionarily related and are subject to birth-and-death evolution. Therefore, it is important to study the mechanisms of gene family interaction for understanding phenotypic evolution. Because gene duplication occurs more or less at random, phenotypic evolution contains some fortuitous elements, though the environmental factors also play an important role. The randomness of phenotypic evolution is qualitatively different from allele frequency changes by random genetic drift. However, there is

  16. Compact Ion and Neutral Mass Spectrometer with Ion Drifts, Temperatures and Neutral Winds

    NASA Astrophysics Data System (ADS)

    Paschalidis, Nikolaos

    2016-07-01

    In situ measurements of atmospheric neutral and ion composition and density, temperatures, ion drifts and neutral winds, are in high demand to study the dynamics of the ionosphere-theremosphere-mesosphere system. This paper presents a compact Ion and Neutral Mass Spectrometer (INMS) with impended ion drifts and temperature, and neutral winds capability for in situ measurements of ions and neutrals H, He, N, O, N2, O2. The mass resolution M/dM is approximately 10 at an incoming energy range of 0-20eV. The goal is to resolve ion drifts in the range 0 to 3000m/sec with a resolution better than 50m/sec, and neutral winds in the range of 0 to 1000m/sec with similar resolution. For temperatures the goal is to cover a dynamic range of 0 to 5000K. The INMS is based on front end optics for ions and neutrals, pre acceleration, gated time of flight, top hat ESA, MCP detectors and compact electronics. The instrument is redundant for ions and neutrals with the ion and neutral sensor heads on opposite sides and with full electronics in the middle. The ion front end includes RPA for temperature scanning and neutral front end includes angular modulation and thermionic ionization and ion blocking grids. The electronics include fast electric gating, TOF electronics, TOF binning and C&DH digital electronics. The data package includes 400 mass bins each for ions and neutrals and key housekeeping data for instrument health and calibration. The data sampling can be commanded from 0.1 to 10 sec with 1sec nominal setting. The instrument has significant onboard storage capability and a data compression scheme. The mass spectrometer version of the instrument has been flown on the Exocube mission. The instrument occupied 1.5U volume, weighed only 560 g and required nominal power of 1.6W The ExoCube mission was designed to acquire global knowledge of in-situ densities of [H], [He], [O] and H+, He+, O+ in the upper ionosphere and lower exosphere in combination with incoherent scatter radar and

  17. A field-ionization neutral detector - FIND. [neutral particle mass spectrometer

    NASA Technical Reports Server (NTRS)

    Curtis, C. C.; Hsieh, K. C.; Fan, C. Y.; Swanson, L. W.

    1975-01-01

    The field ionization neutral detector FIND operates according to the following principle: Neutral atoms are attracted toward the field ionization tips since they are polarized by the electric field of the tips. The atoms are singly ionized and repelled by the positive potential of the tips toward the detector situated behind a grid at ground potential. The ions deposit in the detector their kinetic energies, typically 26 keV, corresponding to the potential difference between the ionization region and the detector. Laboratory results show that FIND can have the resolution, sensitivities and durability required to perform in situ measurements of neutral H and He fluxes in interplanetary space, cometary halos and exospheres.

  18. Applications and Implications of Neutral versus Non-neutral Markers in Molecular Ecology

    PubMed Central

    Kirk, Heather; Freeland, Joanna R.

    2011-01-01

    The field of molecular ecology has expanded enormously in the past two decades, largely because of the growing ease with which neutral molecular genetic data can be obtained from virtually any taxonomic group. However, there is also a growing awareness that neutral molecular data can provide only partial insight into parameters such as genetic diversity, local adaptation, evolutionary potential, effective population size, and taxonomic designations. Here we review some of the applications of neutral versus adaptive markers in molecular ecology, discuss some of the advantages that can be obtained by supplementing studies of molecular ecology with data from non-neutral molecular markers, and summarize new methods that are enabling researchers to generate data from genes that are under selection. PMID:21747718

  19. Study of electrical resistivity and thermal conductivity into neutral plasma

    SciTech Connect

    Nath, G. Rout, R. K.

    2015-07-31

    The major portion of the bulk plasma in magnetospheric space, interplanetary plasma belts and the solar winds contain neutral particles. Evidently these neutral particles undergo binary collisions with the charged particles and among themselves so as to contribute significantly to the transport and diffusion process in a singly charged electron – ion magnetoplasma. The effects of the neutral particles collisions on various diffusion transport coefficients are studied for magnetised electron-ion plasma and appropriately modified coefficients are derived analytically. The results reveal that these coefficients increase significantly owing to the effect of the charge -neutral and neutral-neutral collisions.

  20. The production of low-energy neutral oxygen beams by grazing-incidence neutralization

    NASA Technical Reports Server (NTRS)

    Albridge, R. G.; Haglund, R. F.; Tolk, N. H.; Daech, A. F.

    1987-01-01

    The Vanderbilt University neutral oxygen facility produces beams of low-energy neutral oxygen atoms by means of grazing-incidence collisions between ion beams and metal surfaces. Residual ions are reflected by applied electric fields. This method can utilize initial ion beams of either O(+) or O2(+) since a very large percentage of molecular oxygen ions are dissociated when they undergo grazing-incidence neutralization. The method of neutralization is applicable to low-energy beams and to all ions. Particular emphasis is on O and N2 beams for simulation of the low Earth orbit space environment. Since the beam is a pure O-neutral beam and since measurements of the interaction of the beam with solid surfaces are made spectroscopically, absolute reaction rates can be determined. The technique permits the beams to be used in conjunction with electron and photon irradiation for studies of synergistic effects. Comparisons of optical spectra of Kapton excited by 2.5-keV O, O(+), and O2(+) show significant differences. Optical spectra of Kapton excited by neutral oxygen beams of less than 1 keV have been recorded.

  1. Fluorometric assay using naphthylamide substrates for assessing novel venom peptidase activities.

    PubMed

    Gasparello-Clemente, Elaine; Silveira, Paulo Flávio

    2002-11-01

    In the present study we examined the feasibility of using the fluorometry of naphthylamine derivatives for revealing peptidase activities in venoms of the snakes Bothrops jararaca, Bothrops alternatus, Bothrops atrox, Bothrops moojeni, Bothrops insularis, Crotalus durissus terrificus and Bitis arietans, of the scorpions Tityus serrulatus and Tityus bahiensis, and of the spiders Phoneutria nigriventer and Loxosceles intermedia. Neutral aminopeptidase (APN) and prolyl-dipeptidyl aminopeptidase IV (DPP IV) activities were presented in all snake venoms, with the highest levels in B. alternatus. Although all examined peptidase activities showed relatively low levels in arthropod venoms, basic aminopeptidase (APB) activity from P. nigriventer venom was the exception. Compared to the other peptidase activities, relatively high levels of acid aminopeptidase (APA) activity were restricted to B. arietans venom. B. arietans also exhibited a prominent content of APB activity which was lower in other venoms. Relatively low prolyl endopeptidase and proline iminopeptidase activities were, respectively, detectable only in T. bahiensis and B. insularis. Pyroglutamate aminopeptidase activity was undetectable in all venoms. All examined peptidase activities were undetectable in T. serrulatus venom. In this study, the specificities of a diverse array of peptidase activities from representative venoms were demonstrated for the first time, with a description of their distribution which may contribute to guiding further investigations. The expressive difference between snake and arthropod venoms was indicated by APN and DPP IV activities while APA and APB activities distinguished the venom of B. arietans from those of Brazilian snakes. The data reflected the relatively uniform qualitative distribution of the peptidase activities investigated, together with their unequal quantitative distribution, indicating the evolutionary divergence in the processing of peptides in these different

  2. Monochromaticity in neutral evolutionary network models.

    PubMed

    Halu, Arda; Bianconi, Ginestra

    2012-12-01

    Recent studies on epistatic networks of model organisms have unveiled a certain type of modular property called monochromaticity in which the networks are clustered into functional modules that interact with each other through the same type of epistasis. Here, we propose and study three epistatic network models that are inspired by the duplication-divergence mechanism to gain insight into the evolutionary basis of monochromaticity and to test if it can be explained as the outcome of a neutral evolutionary hypothesis. We show that the epistatic networks formed by these stochastic evolutionary models have monochromaticity conflict distributions that are centered close to zero and are statistically significantly different from their randomized counterparts. In particular, the last model we propose yields a strictly monochromatic solution. Our results agree with the monochromaticity findings in real organisms and point toward the possible role of a neutral mechanism in the evolution of this phenomenon. PMID:23367998

  3. EDITORIAL: Negative ion based neutral beam injection

    NASA Astrophysics Data System (ADS)

    Hemsworth, R. S.

    2006-06-01

    It is widely recognized that neutral beam injection (NBI), i.e. the injection of high energy, high power, beams of H or D atoms, is a flexible and reliable system that has been the main heating system on a large variety of fusion devices, and NBI has been chosen as one of the three heating schemes of the International Tokomak Reactor (ITER). To date, all the NBI systems but two have been based on the neutralization (in a simple gas target) of positive hydrogen or deuterium ions accelerated to <100 keV/nucleon. Above that energy the neutralization of positive ions falls to unacceptably low values, and higher energy neutral beams have to be created by the neutralization of accelerated negative ions (in a simple gas target), as this remains high (approx60%) up to >1 MeV/nucleon. Unfortunately H- and D- are difficult to create, and the very characteristic that makes them attractive, the ease with which the electron is detached from the ion, means that it is difficult to create high concentrations or fluxes of them, and it is difficult to avoid substantial, collisional, losses in the extraction and acceleration processes. However, there has been impressive progress in negative ion sources and accelerators over the past decade, as demonstrated by the two pioneering, operational, multi-megawatt, negative ion based, NBI systems at LHD (180 keV, H0) and JT-60U (500 keV, D0), both in Japan. Nevertheless, the system proposed for ITER represents a substantial technological challenge as an increase is required in beam energy, to 1 MeV, D0, accelerated ion (D-) current, to 40 A, accelerated current density, 200 A m-2 of D-, and pulse length, to 1 h. At the Fourth IAEA Technical Meeting on Negative Ion Based Neutral Beam Injectors, hosted by the Consorzio RFX, Padova, Italy, 9-11 May 2005, the status of the R&D aimed at the realization of the injectors for ITER was presented. Because of the importance of this development to the success of the ITER project, participants at that

  4. Non-neutral theory of biodiversity

    NASA Astrophysics Data System (ADS)

    Bianconi, G.; Ferretti, L.; Franz, S.

    2009-07-01

    We present a non-neutral stochastic model for the dynamics taking place in a meta-community ecosystems in the presence of migration. The model provides a framework for describing the emergence of multiple ecological scenarios and behaves in two extreme limits either as the unified neutral theory of biodiversity or as the Bak-Sneppen model. Interestingly, the model shows a condensation phase transition where one species becomes the dominant one, the diversity in the ecosystems is strongly reduced and the ecosystem is non-stationary. This phase transition extends the principle of competitive exclusion to open ecosystems and might be relevant for the study of the impact of invasive species in native ecologies.

  5. Time reversal violation for entangled neutral mesons

    NASA Astrophysics Data System (ADS)

    Bernabéu, J.

    2013-07-01

    A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique opportunity for a search of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and PHI, Factories. The two quantum effects of the first decay as a filtering measurement and the transfer of information to the still living partner allow performing a genuine TRV asymmetry with the exchange of "in" and "out" states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system.

  6. The neutral diffuse ISM after Herschel

    NASA Astrophysics Data System (ADS)

    Neufeld, David A.

    2015-08-01

    Observations with the Herschel Space Observatory have greatly enhanced our understanding of neutral diffuse material in the interstellar medium. In particular, high-resolution absorption line spectroscopy at THz frequencies has led to the discovery of several new interstellar molecules - including SH+, OH+, H2O, H2Cl+, HCl+, and ArH+ (the first known astrophysical molecule containing a noble gas atom) - and has enabled astrochemical studies in which the abundances of multiple species are measured and modeled. Because of the different chemical pathways responsible for their formation and destruction, different molecules probe specific aspects of the interstellar environment. Carefully interpreted, they provide unique information about the cosmic ray density, the molecular fraction, the ultraviolet radiation field, and the dissipation of energy within the turbulent interstellar medium. Future spectroscopic observations with ALMA and SOFIA promise to extend further our understanding of fundamental physical and chemical processes the neutral diffuse ISM.

  7. Thermospheric ion and neutral composition and chemistry

    NASA Technical Reports Server (NTRS)

    Breig, E. L.

    1987-01-01

    A summary is presented of research contributions by U.S. scientists during the years 1983-1986, toward an increased understanding of the properties and behavior of the earth's thermosphere and F-region ionosphere. As part of the more extensive aeronomy report to IUGG, this review addresses specifically the composition and relevant chemical and thermal processes that influence this region of the atmosphere. The discussion focuses on the separate neutral and ion species, and on the temperatures of the electrons, ions, and neutral gas. Related aspects of the solar radiation and photoelectrons are also included. Direct observational results and analyses are emphasized, along with references to pertinent findings from basic laboratory and theoretical studies.

  8. Quasi-Neutral Theory of Epidemic Outbreaks

    PubMed Central

    Pinto, Oscar A.; Muñoz, Miguel A.

    2011-01-01

    Some epidemics have been empirically observed to exhibit outbreaks of all possible sizes, i.e., to be scale-free or scale-invariant. Different explanations for this finding have been put forward; among them there is a model for “accidental pathogens” which leads to power-law distributed outbreaks without apparent need of parameter fine tuning. This model has been claimed to be related to self-organized criticality, and its critical properties have been conjectured to be related to directed percolation. Instead, we show that this is a (quasi) neutral model, analogous to those used in Population Genetics and Ecology, with the same critical behavior as the voter-model, i.e. the theory of accidental pathogens is a (quasi)-neutral theory. This analogy allows us to explain all the system phenomenology, including generic scale invariance and the associated scaling exponents, in a parsimonious and simple way. PMID:21760930

  9. Low-energy neutral-atom spectrometer

    SciTech Connect

    Voss, D.E.; Cohen, S.A.

    1982-04-01

    The design, calibration, and performance of a low energy neutral atom spectrometer are described. Time-of-flight analysis is used to measure the energy spectrum of charge-exchange deuterium atoms emitted from the PLT tokamak plasma in the energy range from 20 to 1000 eV. The neutral outflux is gated on a 1 ..mu..sec time scale by a slotted rotating chopper disc, supported against gravity in vacuum by magnetic levitation, and is detected by secondary electron emission from a Cu-Be plate. The energy dependent detection efficiency has been measured in particle beam experiments and on the tokamak so that the diagnostic is absolutely calibrated, allowing quantitative particle fluxes to be determined with 200 ..mu..sec time resolution. In addition to its present application as a plasma diagnostic, the instrument is capable of making a wide variety of measurements relevant to atomic and surface physics.

  10. Particle reflection and TFTR neutral beam diagnostics

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Kugel, H.W.; O`Connor, T.E.; Newman, R.A.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1992-04-01

    Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12{degrees}). Beamline calorimeters, of a ``V``-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the ``V``, complicating the fitting technique, and increasing the power density on axis by 10 to 20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected.

  11. Particle reflection and TFTR neutral beam diagnostics

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Kugel, H.W.; O'Connor, T.E.; Newman, R.A.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1992-04-01

    Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12{degrees}). Beamline calorimeters, of a V''-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the V'', complicating the fitting technique, and increasing the power density on axis by 10 to 20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected.

  12. Monochromaticity in neutral evolutionary network models

    NASA Astrophysics Data System (ADS)

    Halu, Arda; Bianconi, Ginestra

    2012-12-01

    Recent studies on epistatic networks of model organisms have unveiled a certain type of modular property called monochromaticity in which the networks are clustered into functional modules that interact with each other through the same type of epistasis. Here, we propose and study three epistatic network models that are inspired by the duplication-divergence mechanism to gain insight into the evolutionary basis of monochromaticity and to test if it can be explained as the outcome of a neutral evolutionary hypothesis. We show that the epistatic networks formed by these stochastic evolutionary models have monochromaticity conflict distributions that are centered close to zero and are statistically significantly different from their randomized counterparts. In particular, the last model we propose yields a strictly monochromatic solution. Our results agree with the monochromaticity findings in real organisms and point toward the possible role of a neutral mechanism in the evolution of this phenomenon.

  13. Quasi-neutral theory of epidemic outbreaks.

    PubMed

    Pinto, Oscar A; Muñoz, Miguel A

    2011-01-01

    Some epidemics have been empirically observed to exhibit outbreaks of all possible sizes, i.e., to be scale-free or scale-invariant. Different explanations for this finding have been put forward; among them there is a model for "accidental pathogens" which leads to power-law distributed outbreaks without apparent need of parameter fine tuning. This model has been claimed to be related to self-organized criticality, and its critical properties have been conjectured to be related to directed percolation. Instead, we show that this is a (quasi) neutral model, analogous to those used in Population Genetics and Ecology, with the same critical behavior as the voter-model, i.e. the theory of accidental pathogens is a (quasi)-neutral theory. This analogy allows us to explain all the system phenomenology, including generic scale invariance and the associated scaling exponents, in a parsimonious and simple way. PMID:21760930

  14. Neutral line chaos and phase space structure

    NASA Technical Reports Server (NTRS)

    Burkhart, Grant R.; Speiser, Theodore W.; Martin, Richard F., Jr.; Dusenbery, Paul B.

    1991-01-01

    Phase space structure and chaos near a neutral line are studied with numerical surface-of-section (SOS) techniques and analytic methods. Results are presented for a linear neutral line model with zero crosstail electric field. It was found that particle motion can be divided into three regimes dependening on the value of the conserved canonical momentum, Py, and the conserved Hamiltonian, h. The phase space structure, using Poincare SOS plots, is highly sensitive to bn = Bn/B0 variations, but not to h variations. It is verified that the slow motion preserves the action, Jz, as evaluated by Sonnerup (1971), when the period of the fast motion is smaller than the time scale of the slow motion. Results show that the phase space structure and particle chaos depend sensitively upon Py and bn, but are independent of h.

  15. The Neutralization of Ion-Rocket Beams

    NASA Technical Reports Server (NTRS)

    Kaufman, Harold R.

    1961-01-01

    The experimental ion-beam behavior obtained without neutralizers is compared with both simple collision theory and plasma-wave theory. This comparison indicates that plasma waves play an important part in beam behavior, although the present state of plasma-wave theory does not permit more than a qualitative comparison. The theories of immersed-emitter and electron-trap neutralizer operation are discussed; and, to the extent permitted by experimental data, the theory is compared with experimental results. Experimental data are lacking completely at the present time for operation in space. The results that might be expected in space and the means of simulating such operation in Earth-bound facilities, however, are discussed.

  16. Neutralization enzyme immunoassay for influenza virus.

    PubMed Central

    Benne, C A; Harmsen, M; De Jong, J C; Kraaijeveld, C A

    1994-01-01

    A neutralization enzyme immunoassay (N-EIA) was developed for the detection of antibody titer rises in sera of patients infected with influenza A (H3N2) virus. In this N-EIA, a selected strain of influenza A (H3N2) virus was added to monolayers of LLC-MK2 cells in microtiter plates. After 24 h, the replicated virus could be demonstrated with a virus-specific enzyme-labeled monoclonal antibody. Preincubation of the influenza virus with convalescent-phase sera of patients infected with influenza A (H3N2) virus resulted 1 day later in decreased absorbance values that could be used for calculation of neutralization titers. From use of paired serum samples from 10 patients with a history of flu-like symptoms, the results obtained with N-EIA correlated well (r = 0.83) with those of the standard hemagglutination inhibition test. PMID:8027355

  17. Neutral beam source commercialization study. Final report

    SciTech Connect

    King, H.J.

    1980-06-01

    The basic tasks of this Phase II project were to: generate a set of design drawings suitable for quantity production of sources of this design; fabricate a functional neutral beam source incorporating as many of the proposed design changes as proved feasible; and document the procedures and findings developed during the contract. These tasks have been accomplished and represent a demonstrated milestone in the industrialization of this complete device.

  18. A neutral redox-switchable [2]rotaxane.

    PubMed

    Olsen, J-C; Fahrenbach, A C; Trabolsi, A; Friedman, D C; Dey, S K; Gothard, C M; Shveyd, A K; Gasa, T B; Spruell, J M; Olson, M A; Wang, C; Jacquot de Rouville, H-P; Botros, Y Y; Stoddart, J F

    2011-10-21

    A limited range of redox-active, rotaxane-based, molecular switches exist, despite numerous potential applications for them as components of nanoscale devices. We have designed and synthesised a neutral, redox-active [2]rotaxane, which incorporates an electron-deficient pyromellitic diimide (PmI)-containing ring encircling two electron-rich recognition sites in the form of dioxynaphthalene (DNP) and tetrathiafulvalene (TTF) units positioned along the rod section of its dumbbell component. Molecular modeling using MacroModel guided the design of the mechanically interlocked molecular switch. The binding affinities in CH(2)Cl(2) at 298 K between the free ring and two electron-rich guests--one (K(a) = 5.8 × 10(2) M(-1)) containing a DNP unit and the other (K(a) = 6.3 × 10(3) M(-1)) containing a TTF unit--are strong: the one order of magnitude difference in their affinities favouring the TTF unit suggested to us the feasibility of integrating these three building blocks into a bistable [2]rotaxane switch. The [2]rotaxane was obtained in 34% yield by relying on neutral donor-acceptor templation and a double copper-catalysed azide-alkyne cycloaddition (CuAAC). Cyclic voltammetry (CV) and spectroelectrochemistry (SEC) were employed to stimulate and observe switching by this neutral bistable rotaxane in solution at 298 K, while (1)H NMR spectroscopy was enlisted to investigate switching upon chemical oxidation. The neutral [2]rotaxane is a chemically robust and functional switch with potential for applications in device settings. PMID:21879130

  19. Cluster Observations of Neutral Sheet Oscillations

    NASA Astrophysics Data System (ADS)

    Volwerk, M.; Baumjohann, W.; Nakamura, R.; Zhang, T. L.; Eichelberger, H.-U.; Glassmeier, K.-H.; Balogh, A.

    In the period of early July through the end of October 2001, the Cluster spacecraft had their apogee in the Earth's magnetotail at approximately 19 R_{rm E}. This allowed us to study substorm related phenomena in the neutral sheet. We investigated the FGM data for neutral sheet crossings during strong activity (AE), and in particular looked at ULF waves. For this presentation we will first look at three days: July 17, August 22 and September 15, 2001. Spectral analysis shows that the main power is in compressional waves, similar to the results of {em Bauer et al.} [JGR 100, 23737, 1995] with a significant peak at 30 - 60 mHz. Having four spacecraft, we can de- termine the propagation direction and velocity of the waves, using cross correlation of the bandpass filtered data to get the time lag between the spacecraft and the rela- tive location of the spacecraft. As expected, we find that the waves propagate mainly perpendicular to the magnetic field, either earthward or tailward. The velocity of the waves varies from 60 - 250 km s^{-1}. The propagation direction of the waves may be dependent on the local plasma flow direction or amplitude. Not every neutral sheet crossing shows evidence of these ULF waves near 30 - 60 mHz. There are several days in which the spectral power falls off much more quickly than in the days men- tioned before. Examples are: August 12 and 29 and September 24, 2001. The main spectral power for these days is at frequencies of 60 - 200 mHz. An indication for the difference between these two sets of observations can be found in the AE index. The days with strong ULF wave power at 30 - 60 mHz are during neutral sheet crossings at the onset or expansion phase of a substorm, whereas the days without these waves are crossings that occur during substorm recovery phase, or during quiescent times.

  20. Stability of Stochastic Neutral Cellular Neural Networks

    NASA Astrophysics Data System (ADS)

    Chen, Ling; Zhao, Hongyong

    In this paper, we study a class of stochastic neutral cellular neural networks. By constructing a suitable Lyapunov functional and employing the nonnegative semi-martingale convergence theorem we give some sufficient conditions ensuring the almost sure exponential stability of the networks. The results obtained are helpful to design stability of networks when stochastic noise is taken into consideration. Finally, two examples are provided to show the correctness of our analysis.

  1. Atomic Transition Probabilities for Neutral Cerium

    NASA Astrophysics Data System (ADS)

    Lawler, J. E.; den Hartog, E. A.; Wood, M. P.; Nitz, D. E.; Chisholm, J.; Sobeck, J.

    2009-10-01

    The spectra of neutral cerium (Ce I) and singly ionized cerium (Ce II) are more complex than spectra of other rare earth species. The resulting high density of lines in the visible makes Ce ideal for use in metal halide (MH) High Intensity Discharge (HID) lamps. Inclusion of cerium-iodide in a lamp dose can improve both the Color Rendering Index and luminous efficacy of a MH-HID lamp. Basic spectroscopic data including absolute atomic transition probabilities for Ce I and Ce II are needed for diagnosing and modeling these MH-HID lamps. Recent work on Ce II [1] is now being augmented with similar work on Ce I. Radiative lifetimes from laser induced fluorescence measurements [2] on neutral Ce are being combined with emission branching fractions from spectra recorded using a Fourier transform spectrometer. A total of 14 high resolution spectra are being analyzed to determine branching fractions for 2000 to 3000 lines from 153 upper levels in neutral Ce. Representative data samples and progress to date will be presented. [4pt] [1] J. E. Lawler, C. Sneden, J. J. Cowan, I. I. Ivans, and E. A. Den Hartog, Astrophys. J. Suppl. Ser. 182, 51-79 (2009). [0pt] [2] E. A. Den Hartog, K. P. Buettner, and J. E. Lawler, J. Phys. B: Atomic, Molecular & Optical Physics 42, 085006 (7pp) (2009).

  2. Imaging space plasmas in energetic neutral atoms

    NASA Astrophysics Data System (ADS)

    Roelof, E. C.; Demajistre, R.; Mitchell, D. G.; C:Son Brandt, P.

    2004-11-01

    Many space plasmas contain energetic singly-charged ions immersed in a cold gas of neutral atoms and molecules. When the energetic ions undergo charge-exchange collisions with the background cold neutrals, they become energetic neutral atoms (ENAs). Thus the space plasma Â"glowsÂ" in the ENAs which escape the plasma on straight-line trajectories. Properly designed 2-dimentsional particle telescopes that deflect ions using electro-static fields become ENA Â"camerasÂ". Such cameras are now operating on the NASA IMAGE spacecraft in orbit around Earth and the NASA/ESA Cassini spacecraft in orbit around Saturn. They are providing all-sky global images of the singly-charged trapped ion populations of these planets with time resolution of a few minutes. Each pixel contains an energy spectra from 10 to 200 keV/nucleon of the major singly-charged ions (protons and O^+), thus providing a quantitative diagnostic of energetic ion injection, acceleration, and transport. ENA imaging has now taken its place as a fundamental tool in magnetospheric research, and new missions are moving forward to apply ENA imaging to the heliosphere itself (the domain of the solar wind) and its termination ˜100 AU from the Sun where it interacts with the local interstellar gas.

  3. Water dynamics at neutral and ionic interfaces

    PubMed Central

    Fenn, Emily E.; Wong, Daryl B.; Fayer, M. D.

    2009-01-01

    The orientational dynamics of water at a neutral surfactant reverse micelle interface are measured with ultrafast infrared spectroscopy of the hydroxyl stretch, and the results are compared to orientational relaxation of water interacting with an ionic interface. The comparison provides insights into the influence of a neutral vs. ionic interface on hydrogen bond dynamics. Measurements are made and analyzed for large nonionic surfactant Igepal CO-520reverse micelles (water nanopool with a 9-nm diameter). The results are compared with those from a previous study of reverse micelles of the same size formed with the ionic surfactant Aerosol-OT (AOT). The results demonstrate that the orientational relaxation times for interfacial water molecules in the two types of reverse micelles are very similar (13 ps for Igepal and 18 ps for AOT) and are significantly slower than that of bulk water (2.6 ps). The comparison of water orientational relaxation at neutral and ionic interfaces shows that the presence of an interface plays the dominant role in determining the hydrogen bond dynamics, whereas the chemical nature of the interface plays a secondary role. PMID:19706895

  4. Experimental Measurement of Micrometeoroid-Produced Neutrals

    NASA Astrophysics Data System (ADS)

    Collette, A.; Sternovsky, Z.; Horanyi, M.; Munsat, T. L.

    2013-12-01

    We describe the first laboratory measurement of vapor produced by simulated micrometeoroid bombardment. Exospheric gas measurements remain one of the outstanding accomplishments of the Apollo era, and are a clear scientific goal for future exploration of airless objects. New in-situ observations of the surface-bounded exosphere (SBE) at Mercury by MESSENGER, and the Moon by LRO/LAMP, have highlighted the uncertainty surrounding the role of micrometeoroid impacts in sustaining planetary SBEs. In a recent series of experiments, the quantity of neutral molecules generated by impacts of simulated micrometeoroids (0.1-1 micron radius, 1-10 km/s speed) was measured in the lab using a fast ionization gauge inside an ultrahigh-vacuum system. The quantity of neutrals released was found to be consistent with a power law N = mv^a in projectile speed v, mass m and exponent a ~ 2.4 We present these experimental results and discuss their implications for the upcoming LADEE mission, which carries both neutral mass and optical spectrometers for exospheric measurements, capable of identifying micrometeoroid-sourced gases.

  5. Antibody neutralization of retargeted measles viruses.

    PubMed

    Lech, Patrycja J; Pappoe, Roland; Nakamura, Takafumi; Tobin, Gregory J; Nara, Peter L; Russell, Stephen J

    2014-04-01

    The measles virus (MV) vaccine lineage is a promising oncolytic but prior exposure to the measles vaccine or wild-type MV strains limits treatment utility due to the presence of anti-measles antibodies. MV entry can be redirected by displaying a polypeptide ligand on the Hemagglutinin (H) C-terminus. We hypothesized that retargeted MV would escape neutralization by monoclonal antibodies (mAbs) recognizing the H receptor-binding surface and be less susceptible to neutralization by human antisera. Using chimeric H proteins, with and without mutations that ablate MV receptor binding, we show that retargeted MVs escape mAbs that target the H receptor-binding surface by virtue of mutations that ablate infection via SLAM and CD46. However, C-terminally displayed domains do not mediate virus entry in the presence of human antibodies that bind to the underlying H domain. In conclusion, utility of retargeted oncolytic measles viruses does not extend to evasion of human serum neutralization. PMID:24725950

  6. Solar-Driven Neutral Density Waves

    NASA Technical Reports Server (NTRS)

    Blum, P.; Gangopadhyay, P.; Ogawa, H. S.; Judge, D. L.

    1993-01-01

    Interstellar neutral hydrogen atoms flowing into the solar system are attracted by the solar gravitational force, repelled by solar hydrogen Ly-alpha radiation pressure, and are ionized, primarily, through charge exchange with the solar wind protons. The solar cycle variation of the radiation pressure causes the net central solar force to fluctuate between attraction and repulsion resulting in the modulation of the neutral hydrogen density about the usual time independent model. The calculation presented here shows that the time dependent downstream density is strongly modulated by a large number of travelling neutral density waves. The waves possess a continuous range of wavelengths as is to be expected for a Maxwellian gas subjected to several eleven year cycle variations during its journey through the solar system. The amplitudes of the density modulation were found to be quite large. The backscattered glow was found to depend on the position of the detector and the phase of the solar cycle. At the most favorable condition a deviation of the order of 25% from the time dependent glow might be observed.

  7. Neutral color semitransparent microstructured perovskite solar cells.

    PubMed

    Eperon, Giles E; Burlakov, Victor M; Goriely, Alain; Snaith, Henry J

    2014-01-28

    Neutral-colored semitransparent solar cells are commercially desired to integrate solar cells into the windows and cladding of buildings and automotive applications. Here, we report the use of morphological control of perovskite thin films to form semitransparent planar heterojunction solar cells with neutral color and comparatively high efficiencies. We take advantage of spontaneous dewetting to create microstructured arrays of perovskite "islands", on a length-scale small enough to appear continuous to the eye yet large enough to enable unattenuated transmission of light between the islands. The islands are thick enough to absorb most visible light, and the combination of completely absorbing and completely transparent regions results in neutral transmission of light. Using these films, we fabricate thin-film solar cells with respectable power conversion efficiencies. Remarkably, we find that such discontinuous films still have good rectification behavior and relatively high open-circuit voltages due to the inherent rectification between the n- and p-type charge collection layers. Furthermore, we demonstrate the ease of "color-tinting" such microstructured perovksite solar cells with no reduction in performance, by incorporation of a dye within the hole transport medium. PMID:24467381

  8. Niche versus neutrality: a dynamical analysis.

    PubMed

    Kalyuzhny, Michael; Seri, Efrat; Chocron, Rachel; Flather, Curtis H; Kadmon, Ronen; Shnerb, Nadav M

    2014-10-01

    Understanding the forces shaping ecological communities is of crucial importance for basic science and conservation. After 50 years in which ecological theory has focused on either stable communities driven by niche-based forces or nonstable "neutral" communities driven by demographic stochasticity, contemporary theories suggest that ecological communities are driven by the simultaneous effects of both types of mechanisms. Here we examine this paradigm using the longest available records for the dynamics of tropical trees and breeding birds. Applying a macroecological approach and fluctuation analysis techniques borrowed from statistical physics, we show that both stabilizing mechanisms and demographic stochasticity fail to play a dominant role in shaping assemblages over time. Rather, community dynamics in these two very different systems is predominantly driven by environmental stochasticity. Clearly, the current melding of niche and neutral theories cannot account for such dynamics. Our results highlight the need for a new theory of community dynamics integrating environmental stochasticity with weak stabilizing forces and suggest that such theory may better describe the dynamics of ecological communities than current neutral theories, deterministic niche-based theories, or recent hybrids. PMID:25226179

  9. Intense diagnostic neutral beam development for ITER

    SciTech Connect

    Rej, D.J.; Henins, I.; Fonck, R.J.; Kim, Y.J.

    1992-05-01

    For the next-generation, burning tokamak plasmas such as ITER, diagnostic neutral beams and beam spectroscopy will continue to be used to determine a variety of plasma parameters such as ion temperature, rotation, fluctuations, impurity content, current density profile, and confined alpha particle density and energy distribution. Present-day low-current, long-pulse beam technology will be unable to provide the required signal intensities because of higher beam attenuation and background bremsstrahlung radiation in these larger, higher-density plasmas. To address this problem, we are developing a short-pulse, intense diagnostic neutral beam. Protons or deuterons are accelerated using magnetic-insulated ion-diode technology, and neutralized in a transient gas cell. A prototype 25-kA, 100-kV, 1-{mu}s accelerator is under construction at Los Alamos. Initial experiments will focus on ITER-related issues of beam energy distribution, current density, pulse length, divergence, propagation, impurity content, reproducibility, and maintenance.

  10. Intense diagnostic neutral beam development for ITER

    SciTech Connect

    Rej, D.J.; Henins, I. ); Fonck, R.J.; Kim, Y.J. . Dept. of Nuclear Engineering and Engineering Physics)

    1992-01-01

    For the next-generation, burning tokamak plasmas such as ITER, diagnostic neutral beams and beam spectroscopy will continue to be used to determine a variety of plasma parameters such as ion temperature, rotation, fluctuations, impurity content, current density profile, and confined alpha particle density and energy distribution. Present-day low-current, long-pulse beam technology will be unable to provide the required signal intensities because of higher beam attenuation and background bremsstrahlung radiation in these larger, higher-density plasmas. To address this problem, we are developing a short-pulse, intense diagnostic neutral beam. Protons or deuterons are accelerated using magnetic-insulated ion-diode technology, and neutralized in a transient gas cell. A prototype 25-kA, 100-kV, 1-{mu}s accelerator is under construction at Los Alamos. Initial experiments will focus on ITER-related issues of beam energy distribution, current density, pulse length, divergence, propagation, impurity content, reproducibility, and maintenance.

  11. Neutral behavior of shared polymorphism

    PubMed Central

    Clark, Andrew G.

    1997-01-01

    Several cases have been described in the literature where genetic polymorphism appears to be shared between a pair of species. Here we examine the distribution of times to random loss of shared polymorphism in the context of the neutral Wright–Fisher model. Order statistics are used to obtain the distribution of times to loss of a shared polymorphism based on Kimura’s solution to the diffusion approximation of the Wright–Fisher model. In a single species, the expected absorption time for a neutral allele having an initial allele frequency of ½ is 2.77 N generations. If two species initially share a polymorphism, that shared polymorphism is lost as soon as either of two species undergoes fixation. The loss of a shared polymorphism thus occurs sooner than loss of polymorphism in a single species and has an expected time of 1.7 N generations. Molecular sequences of genes with shared polymorphism may be characterized by the count of the number of sites that segregate in both species for the same nucleotides (or amino acids). The distribution of the expected numbers of these shared polymorphic sites also is obtained. Shared polymorphism appears to be more likely at genetic loci that have an unusually large number of segregating alleles, and the neutral coalescent proves to be very useful in determining the probability of shared allelic lineages expected by chance. These results are related to examples of shared polymorphism in the literature. PMID:9223256

  12. Ground Levels and Ionization Energies for the Neutral Atoms

    National Institute of Standards and Technology Data Gateway

    SRD 111 Ground Levels and Ionization Energies for the Neutral Atoms (Web, free access)   Data for ground state electron configurations and ionization energies for the neutral atoms (Z = 1-104) including references.

  13. Choline for neutralizing naphthenic acid in fuel and lubricating oils

    SciTech Connect

    Ries, D.G.; Roof, G.L.

    1986-07-15

    A method is described of neutralizing at least a portion of the naphthenic acids present in fuel and lubricating oils which contain naphthenic acids which comprises treating these oils with a neutralizing amount of choline.

  14. International Thermonuclear Experimental Reactor (ITER) neutral beam design

    SciTech Connect

    Myers, T.J.; Brook, J.W.; Spampinato, P.T.; Mueller, J.P.; Luzzi, T.E.; Sedgley, D.W. . Space Systems Div.)

    1990-10-01

    This report discusses the following topics on ITER neutral beam design: ion dump; neutralizer and module gas flow analysis; vacuum system; cryogenic system; maintainability; power distribution; and system cost.

  15. The influence of stray magnetic fields on ion beam neutralization

    NASA Technical Reports Server (NTRS)

    Feng, Y.-C.; Wilbur, P. J.

    1982-01-01

    An experimental investigation is described of a comparison between the ion beam neutralization characteristics of a local neutralizer (within approximately 5 cm of the beam edge) and those associated with a distant one (approximately 1 meter away from the thruster). The influence of magnetic fields in the vicinity of the neutralizer cathode orifice which are either parallel or normal to the neutralizer axis is assessed. The plasma property profiles which reflect the influence of the magnetic fields are measured. The results suggest that magnetic fields at the region of a neutralizer cathode orifice influence its ability to couple to the ion beam. They reveal that there is a potential jump from the neutralizer cathode orifice to the plasma which exists close to the orifice. This potential drop is found to increase as the axial component of magnetic flux density increases. A magnetic field perpendicular to the neutralizer axis induces a potential rise a few centimeters downstream from the neutralizer cathode.

  16. 67. INTERIOR VIEW OF THE NEUTRALIZER BUILDING, LOOKING AT CONDENSERS, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    67. INTERIOR VIEW OF THE NEUTRALIZER BUILDING, LOOKING AT CONDENSERS, NEUTRALIZERS AND STORAGE TANKS, APRIL 11, 1919. - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  17. Neutral theory and the species abundance distribution: recent developments and prospects for unifying niche and neutral perspectives.

    PubMed

    Matthews, Thomas J; Whittaker, Robert J

    2014-06-01

    Published in 2001, The Unified Neutral Theory of Biodiversity and Biogeography (UNTB) emphasizes the importance of stochastic processes in ecological community structure, and has challenged the traditional niche-based view of ecology. While neutral models have since been applied to a broad range of ecological and macroecological phenomena, the majority of research relating to neutral theory has focused exclusively on the species abundance distribution (SAD). Here, we synthesize the large body of work on neutral theory in the context of the species abundance distribution, with a particular focus on integrating ideas from neutral theory with traditional niche theory. First, we summarize the basic tenets of neutral theory; both in general and in the context of SADs. Second, we explore the issues associated with neutral theory and the SAD, such as complications with fitting and model comparison, the underlying assumptions of neutral models, and the difficultly of linking pattern to process. Third, we highlight the advances in understanding of SADs that have resulted from neutral theory and models. Finally, we focus consideration on recent developments aimed at unifying neutral- and niche-based approaches to ecology, with a particular emphasis on what this means for SAD theory, embracing, for instance, ideas of emergent neutrality and stochastic niche theory. We put forward the argument that the prospect of the unification of niche and neutral perspectives represents one of the most promising future avenues of neutral theory research. PMID:25360266

  18. Neutral theory and the species abundance distribution: recent developments and prospects for unifying niche and neutral perspectives

    PubMed Central

    Matthews, Thomas J; Whittaker, Robert J

    2014-01-01

    Published in 2001, The Unified Neutral Theory of Biodiversity and Biogeography (UNTB) emphasizes the importance of stochastic processes in ecological community structure, and has challenged the traditional niche-based view of ecology. While neutral models have since been applied to a broad range of ecological and macroecological phenomena, the majority of research relating to neutral theory has focused exclusively on the species abundance distribution (SAD). Here, we synthesize the large body of work on neutral theory in the context of the species abundance distribution, with a particular focus on integrating ideas from neutral theory with traditional niche theory. First, we summarize the basic tenets of neutral theory; both in general and in the context of SADs. Second, we explore the issues associated with neutral theory and the SAD, such as complications with fitting and model comparison, the underlying assumptions of neutral models, and the difficultly of linking pattern to process. Third, we highlight the advances in understanding of SADs that have resulted from neutral theory and models. Finally, we focus consideration on recent developments aimed at unifying neutral- and niche-based approaches to ecology, with a particular emphasis on what this means for SAD theory, embracing, for instance, ideas of emergent neutrality and stochastic niche theory. We put forward the argument that the prospect of the unification of niche and neutral perspectives represents one of the most promising future avenues of neutral theory research. PMID:25360266

  19. Emotionally Neutral Stimuli Are Not Neutral in Schizophrenia: A Mini Review of Functional Neuroimaging Studies.

    PubMed

    Potvin, Stéphane; Tikàsz, Andràs; Mendrek, Adrianna

    2016-01-01

    Reliable evidence shows that schizophrenia patients tend to experience negative emotions when presented with emotionally neutral stimuli. Similarly, several functional neuroimaging studies show that schizophrenia patients have increased activations in response to neutral material. However, results are heterogeneous. Here, we review the functional neuroimaging studies that have addressed this research question. Based on the 36 functional neuroimaging studies that we retrieved, it seems that the increased brain reactivity to neutral stimuli is fairly common in schizophrenia, but that the regions involved vary considerably, apart from the amygdala. Prefrontal and cingulate sub-regions and the hippocampus may also be involved. By contrasts, results in individuals at risk for psychosis are less consistent. In schizophrenia patients, results are less consistent in the case of studies using non-facial stimuli, explicit processing paradigms, and/or event-related designs. This means that human faces may convey subtle information (e.g., trustworthiness) other than basic emotional expressions. It also means that the aberrant brain reactivity to neutral stimuli is less likely to occur when experimental paradigms are too cognitively demanding as well as in studies lacking statistical power. The main hypothesis proposed to account for this increased brain reactivity to neutral stimuli is the aberrant salience hypothesis of psychosis. Other investigators propose that the aberrant brain reactivity to neutral stimuli in schizophrenia results from abnormal associative learning, untrustworthiness judgments, priming effects, and/or reduced habituation to neutral stimuli. In the future, the effects of antipsychotics on this aberrant brain reactivity will need to be determined, as well as the potential implication of sex/gender. PMID:27445871

  20. Emotionally Neutral Stimuli Are Not Neutral in Schizophrenia: A Mini Review of Functional Neuroimaging Studies

    PubMed Central

    Potvin, Stéphane; Tikàsz, Andràs; Mendrek, Adrianna

    2016-01-01

    Reliable evidence shows that schizophrenia patients tend to experience negative emotions when presented with emotionally neutral stimuli. Similarly, several functional neuroimaging studies show that schizophrenia patients have increased activations in response to neutral material. However, results are heterogeneous. Here, we review the functional neuroimaging studies that have addressed this research question. Based on the 36 functional neuroimaging studies that we retrieved, it seems that the increased brain reactivity to neutral stimuli is fairly common in schizophrenia, but that the regions involved vary considerably, apart from the amygdala. Prefrontal and cingulate sub-regions and the hippocampus may also be involved. By contrasts, results in individuals at risk for psychosis are less consistent. In schizophrenia patients, results are less consistent in the case of studies using non-facial stimuli, explicit processing paradigms, and/or event-related designs. This means that human faces may convey subtle information (e.g., trustworthiness) other than basic emotional expressions. It also means that the aberrant brain reactivity to neutral stimuli is less likely to occur when experimental paradigms are too cognitively demanding as well as in studies lacking statistical power. The main hypothesis proposed to account for this increased brain reactivity to neutral stimuli is the aberrant salience hypothesis of psychosis. Other investigators propose that the aberrant brain reactivity to neutral stimuli in schizophrenia results from abnormal associative learning, untrustworthiness judgments, priming effects, and/or reduced habituation to neutral stimuli. In the future, the effects of antipsychotics on this aberrant brain reactivity will need to be determined, as well as the potential implication of sex/gender. PMID:27445871

  1. Components of fitness become effectively neutral in equilibrium populations.

    PubMed Central

    Reeve, R; Smith, E; Wallace, B

    1990-01-01

    If, because of trade-offs or similar considerations, components of fitness are negatively correlated in equilibrium populations, they may then exhibit no correlation with total fitness. Lack of correlation with fitness is a fundamental characteristic of selective neutrality. Hence, selectively important traits become subsumed under neutral traits when the definition of neutrality is extended to include factors (genetic or phenotypic) that "behave as if they are neutral." PMID:2308960

  2. Plasma heating with multi-MeV neutral impurity beams

    SciTech Connect

    Grisham, L.R.; Post, D.E.; Eubank, H.P.; Firestone, M.; Mikkelsen, D.R.; Singer, C.E.; Weisheit, J.

    1981-03-01

    The utility of neutral beams of A greater than or equal to 6 AMU formed from negative ions, accelerated to approx. 1 MeV/AMU and neutralized, is explored for heating toroidally confined plasmas. Such beams offer the promise of significant advantages relative to conventional neutral beams based upon positive or negative hydrogen ions at 100 to 200 keV/AMU.

  3. Energy spectrum of neutrals formed in an ion accelerator

    SciTech Connect

    Fink, J.H.

    1982-03-15

    This work presents an estimate of the energy distribution of the neutrals formed in the ion beam accelerator. However it does not determine the fraction of those neutrals which leave the neutral beam injector and go on into the reactor. To do that, more details of the beam line performance are needed.

  4. Modeling of neutral entrainment in an FRC thruster

    SciTech Connect

    Brackbill, Jeremiah; Gimelshein, Natalia; Gimelshein, Sergey; Cambier, Jean-Luc; Ketsdever, Andrew

    2012-11-27

    Neutral entrainment in a field reversed configuration thruster is modeled numerically with an implicit PIC code extended to include thermal and chemical interactions between plasma and neutral particles. The contribution of charge exchange and electron impact ionization reactions is analyzed, and the sensitivity of the entrainment efficiency to the plasmoid translation velocity and neutral density is evaluated.

  5. 47 CFR 64.617 - Neutral Video Communication Service Platform.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 3 2014-10-01 2014-10-01 false Neutral Video Communication Service Platform... Related Customer Premises Equipment for Persons With Disabilities § 64.617 Neutral Video Communication... Neutral Video Communication Service Platform to process VRS calls. Each VRS CA service provider shall...

  6. 47 CFR 64.617 - Neutral Video Communication Service Platform.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 3 2013-10-01 2013-10-01 false Neutral Video Communication Service Platform... Related Customer Premises Equipment for Persons With Disabilities § 64.617 Neutral Video Communication... Neutral Video Communication Service Platform to process VRS calls. Each VRS CA service provider shall...

  7. Neutral-beam development plan, FY 1982-1987

    SciTech Connect

    Not Available

    1981-09-01

    The following chapters are included: (1) status of BNL negative ion source development, (2) source development program plan, (3) status of beam transport and acceleration, (4) accelerator development program plan, (5) neutralizer concepts, (6) neutralization program plan, (7) neutral beam systems, (8) test facilities, (9) program milestones and time schedules, (10) organization and Grumman participation, and (11) funding tables. (MOW)

  8. Influence of Neutralization Attitude in Academic Dishonesty among Undergraduates

    ERIC Educational Resources Information Center

    Meng, Chan Ling; Othman, Jamilah; D'Silva, Jeffrey Lawrence; Omar, Zoharah

    2014-01-01

    Previous literature had proposed that individuals tend to use neutralization to motivate their decisions to engage in deviant behaviours. This indicated that even though students have strong motivations not to cheat may do so anyway after employing neutralizing strategies. Hence, this study attempted to examine the role of neutralization in…

  9. POLIOVIRUS TYPE 1: NEUTRALIZATION BY PAPAIN-DIGESTED ANTIBODIES.

    PubMed

    VOGT, A; KOPP, R; MAASS, G; REICH, L

    1964-09-25

    Papain-digested rabbit antibody (Porter's fractions I and II) can neutralize poliovirus. Neutralizing capacity after digestion ranged from 35 to 45 percent of that of the undigested antibody. No definite dissociation of the antibody fragments from the virus was observed after the reaction mixture had been diluted in a neutral medium. PMID:14175107

  10. Fiscal Neutrality and Local Choice in Public Education.

    ERIC Educational Resources Information Center

    Weber, William L.

    1991-01-01

    Extends Feldstein's notion of wealth neutrality to embrace fiscal neutrality, using a representative consumer context. Employs an "ideal" demand system to model school district expenditures in a general equilibrium framework. Rejects constant price and income elasticity demand models. Supports the fiscally neutral elasticity model varying by…

  11. Communication: Classical threshold law for ion-neutral-neutral three-body recombination

    SciTech Connect

    Pérez-Ríos, Jesús; Greene, Chris H.

    2015-07-28

    A very recently method for classical trajectory calculations for three-body collision [Pérez-Ríos et al., J. Chem. Phys. 140, 044307 (2014)] has been applied to describe ion-neutral-neutral ternary processes for low energy collisions: 0.1 mK–10 mK. As a result, a threshold law for the three-body recombination cross section is obtained and corroborated numerically. The derived threshold law predicts the formation of weakly bound dimers, with binding energies comparable to the collision energy of the collisional partners. In this low energy range, this analysis predicts that molecular ions should dominate over molecular neutrals as the most products formed.

  12. Mechanism of Neutralization by the Broadly Neutralizing HIV-1 Monoclonal Antibody VRC01▿†

    PubMed Central

    Li, Yuxing; O'Dell, Sijy; Walker, Laura M.; Wu, Xueling; Guenaga, Javier; Feng, Yu; Schmidt, Stephen D.; McKee, Krisha; Louder, Mark K.; Ledgerwood, Julie E.; Graham, Barney S.; Haynes, Barton F.; Burton, Dennis R.; Wyatt, Richard T.; Mascola, John R.

    2011-01-01

    The structure of VRC01 in complex with the HIV-1 gp120 core reveals that this broadly neutralizing CD4 binding site (CD4bs) antibody partially mimics the interaction of the primary virus receptor, CD4, with gp120. Here, we extended the investigation of the VRC01-gp120 core interaction to the biologically relevant viral spike to better understand the mechanism of VRC01-mediated neutralization and to define viral elements associated with neutralization resistance. In contrast to the interaction of CD4 or the CD4bs monoclonal antibody (MAb) b12 with the HIV-1 envelope glycoprotein (Env), occlusion of the VRC01 epitope by quaternary constraints was not a major factor limiting neutralization. Mutagenesis studies indicated that VRC01 contacts within the gp120 loop D, the CD4 binding loop, and the V5 region were necessary for optimal VRC01 neutralization, as suggested by the crystal structure. In contrast to interactions with the soluble gp120 monomer, VRC01 interaction with the native viral spike did not occur in a CD4-like manner; VRC01 did not induce gp120 shedding from the Env spike or enhance gp41 membrane proximal external region (MPER)-directed antibody binding to the Env spike. Finally, VRC01 did not display significant reactivity with human antigens, boding well for potential in vivo applications. The data indicate that VRC01 interacts with gp120 in the context of the functional spike in a manner distinct from that of CD4. It achieves potent neutralization by precisely targeting the CD4bs without requiring alterations of Env spike configuration and by avoiding steric constraints imposed by the quaternary structure of the functional Env spike. PMID:21715490

  13. Temporal behavior of neutral particle fluxes in TFTR (Tokamak Fusion Test Reactor) neutral beam injectors

    SciTech Connect

    Kamperschroer, J.H.; Gammel, G.M.; Roquemore, A.L.; Grisham, L.R.; Kugel, H.W.; Medley, S.S.; O'Connor, T.E.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1989-09-01

    Data from an E {parallel} B charge exchange neutral analyzer (CENA), which views down the axis of a neutral beamline through an aperture in the target chamber calorimeter of the TFTR neutral beam test facility, exhibit two curious effects. First, there is a turn-on transient lasting tens of milliseconds having a magnitude up to three times that of the steady-state level. Second, there is a 720 Hz, up to 20% peak-to-peak fluctuation persisting the entire pulse duration. The turn-on transient occurs as the neutralizer/ion source system reaches a new pressure equilibrium following the effective ion source gas throughput reduction by particle removal as ion beam. Widths of the transient are a function of the gas throughput into the ion source, decreasing as the gas supply rate is reduced. Heating of the neutalizer gas by the beam is assumed responsible, with gas temperature increasing as gas supply rate is decreased. At low gas supply rates, the transient is primarliy due to dynamic changes in the neutralizer line density and/or beam species composition. Light emission from the drift duct corroborate the CENA data. At high gas supply rates, dynamic changes in component divergence and/or spatial profiles of the source plasma are necessary to explain the observations. The 720 Hz fluctuation is attributed to a 3% peak-to-peak ripple of 720 Hz on the arc power supply amplified by the quadratic relationship between beam divergence and beam current. Tight collimation by CENA apertures cause it to accept a very small part of the ion source's velocity space, producing a signal linearly proportional to beam divergence. Estimated fluctuations in the peak power density delivered to the plasma under these conditions are a modest 3--8% peak to peak. The efffects of both phenomena on the injected neutral beam can be ameliorated by careful operion of the ion sources. 21 refs., 11 figs., 2 tabs.

  14. A neutral sampling formula for multiple samples and an 'exact' test of neutrality.

    PubMed

    Etienne, Rampal S

    2007-07-01

    As the utility of the neutral theory of biodiversity is increasingly being recognized, there is also an increasing need for proper tools to evaluate the relative importance of neutral processes (dispersal limitation and stochasticity). One of the key features of neutral theory is its close link to data: sampling formulas, giving the probability of a data set conditional on a set of model parameters, have been developed for parameter estimation and model comparison. However, only single local samples can be handled with the currently available sampling formulas, whereas data are often available for many small spatially separated plots. Here, I present a sampling formula for multiple, spatially separated samples from the same metacommunity, which is a generalization of earlier sampling formulas. I also provide an algorithm to generate data sets with the model and I introduce a general test of neutrality that does not require an alternative model; this test compares the probability of the observed data (calculated using the new sampling formula) with the probability of model-generated data sets. I illustrate this with tree abundance data from three large Panamanian neotropical forest plots. When the test is performed with model parameters estimated from the three plots, the model cannot be rejected; however, when parameter estimates previously reported for BCI are used, the model is strongly rejected. This suggests that neutrality cannot explain the structure of the three Panamanian tree communities on the local (BCI) and regional (Panama Canal Zone) scale simultaneously. One should be aware, however, that aspects of the model other than neutrality may be responsible for its failure. I argue that the spatially implicit character of the model is a potential candidate. PMID:17542939

  15. Exploring potential Pluto-generated neutral tori

    NASA Astrophysics Data System (ADS)

    Smith, Howard T.; Hill, Matthew; KollMann, Peter; McHutt, Ralph

    2015-11-01

    The NASA New Horizons mission to Pluto is providing unprecedented insight into this mysterious outer solar system body. Escaping molecular nitrogen is of particular interest and possibly analogous to similar features observed at moons of Saturn and Jupiter. Such escaping N2 has the potential of creating molecular nitrogen and N (as a result of molecular dissociation) tori or partial toroidal extended particle distributions. The presence of these features would present the first confirmation of an extended toroidal neutral feature on a planetary scale in our solar system. While escape velocities are anticipated to be lower than those at Enceladus, Io or even Europa, particle lifetimes are much longer in Pluto’s orbit because as a result of much weaker solar interaction processes along Pluto’s orbit (on the order of tens of years). Thus, with a ~248 year orbit, Pluto may in fact be generating an extended toroidal feature along it orbit.For this work, we modify and apply our 3-D Monte Carlo neutral torus model (previously used at Saturn, Jupiter and Mercury) to study/analyze the theoretical possibility and scope of potential Pluto-generated neutral tori. Our model injects weighted particles and tracks their trajectories under the influence of all gravitational fields with interactions with other particles, solar photons and Pluto collisions. We present anticipated N2 and N tori based on current estimates of source characterization and environmental conditions. We also present an analysis of sensitivity to assumed initial conditions. Such results can provide insight into the Pluto system as well as valuable interpretation of New Horizon’s observational data.

  16. Neutralizing Antibodies Against Interferon-Beta

    PubMed Central

    2008-01-01

    The development of neutralizing antibodies (NAbs) is a major problem in multiple sclerosis (MS) patients treated with interferon-beta (IFN-ß). Whereas binding antibodies (BAbs) can be demonstrated in the vast majority of patients, only a smaller proportion of patients develop NAbs. The principle in NAb in vitro assays is the utilization of cultured cell lines that are responsive to IFN-ß. The cytopathic effect (CPE) assay measures the capacity of NAbs to neutralize IFN- ß's protective effect on cells challenged with virus and the MxA induction assay measures the ability of NAbs to reduce the IFN-ß-induced expression of MxA, either at the mRNA or the protein level. A titer of >20 neutralizing units/ml traditionally defines NAb posi-tivity. NAbs in high titers completely abrogate the in vivo response to IFN-ß, whereas the effect of low and intermediate titers is unpredictable. As clinically important NAbs appear only after 9-18 months IFN- ß0 therapy, short-term studies of two years or less are unsuitable for evaluation of clinical NAb effects. All long-term trials of three years or more concordantly show evidence of a detrimental effect of NAbs on relapses, disease activity on MRI, or on disease progression. Persistent high titers of NAbs indicate an abrogation of the biological response and, hence, absence of therapeutic efficacy, and this observation should lead to a change of therapy. As low and medium titers are ambiguous treatment decisions in patients with low NAb titres should be guided by determination of in vivo mRNA MxA induction and clinical disease activity. PMID:21180570

  17. VLA neutral hydrogen imaging of compact groups

    NASA Technical Reports Server (NTRS)

    Williams, B. A.; Mcmahon, P. M.; Vangorkom, J. H.

    1990-01-01

    Images of the neutral hydrogen (H I) in the direction of the compact groups of galaxies, HCG 31, HCG 44, and HCG 79 are presented. The authors find in HCG 31 and HCG 79, emission contained within a cloud much larger than the galaxies as well as the entire group. The H I emission associated with HCG 44 is located within the individual galaxies but shows definite signs of tidal interactions. The authors imaged the distribution and kinematics of neutral hydrogen at the two extremes of group sizes represented in Hickson's sample. HCG 44 is at the upper limit while HCG 18, HCG 31, and HCG 79 are at the lower end. Although the number of groups that have been imaged is still very small, there may be a pattern emerging which describes the H I morphology of compact groups. The true nature of compact groups has been the subject of considerable debate and controversy. The most recent observational and theoretical evidence strongly suggests that compact groups are physically dense, dynamical systems that are in the process of merging into a single object (Williams and Rood 1987, Hickson and Rood 1988, Barnes 1989). The neutral hydrogen deficiency observed by Williams and Rood (1987) is consistent with a model in which frequent galactic collisions and interactions have heated some of the gas during the short lifetime of the group. The H I disks which are normally more extended than the luminous ones are expected to be more sensitive to collisions and to trace the galaxy's response to recent interactions. Very Large Array observations can provide in most cases the spatial resolution needed to confirm the dynamical interactions in these systems.

  18. Neutral Wind Observations below 200 km altitudes

    NASA Astrophysics Data System (ADS)

    Watanabe, S.; Abe, T.; Habu, H.; Kakinami, Y.; Larsen, M. F.; Pfaff, R. F., Jr.; Yamamoto, M.

    2015-12-01

    Neutral Wind Observations below 200 km altitudesS. Watanabe1, T. Abe2, H. Habu2, Y. Kakinami3, M. Larsen4, R. Pfaff5, M. Yamamoto6, M-Y. Yamamoto31Hokkaido University/Hokkaido Information University, 2JAXA/ISAS, 3Kochi University of Technology, 4Clemson University, 5NASA/Goddard Space Flight Center, 6Kyoto University, Neutral wind in the thermosphere is one of the key parameters to understand the ionosphere-thermosphere coupling process. JAXA/ISAS successfully launched sounding rockets from Uchinoura Space Center (USC) on September 2, 2007, January 12, 2012, and July 20, 2013, and NASA launched sounding rockets from Kwajalein on May 7, 2013 and from Wallops on July 4, 2013. The rockets installed Lithium and/or TMA canisters as well as instruments for plasma and electric and magnetic fields. The atomic Lithium gases were released at altitudes between 150 km and 300 km in the evening on September 2, 2007, at altitude of ~100 km in the morning on January 12, 2012, at altitude of ~120km in the midnight on July 20, 2013, at altitude between 150 km and 300 km in the evening on May 7, 2013 and at altitude of ~150 km in the noon on July 4, 2013. The Lithium atoms were scattering sunlight by resonance scattering with wavelength of 670nm. However, the Lithium atoms scattered moon light on July 20, 2013. The moon light scattering is the first time to use for thermospheric wind measurement in the midnight. The Lithium clouds/trails and TMA trails showed clearly the neutral wind shears and atmospheric waves at ~150 km altitude in the lower thermosphere for all local time.

  19. Gallium Nitride: Charge Neutrality Level and Interfaces

    NASA Astrophysics Data System (ADS)

    Brudnyi, V. N.

    2016-03-01

    An analysis of experimental data revealed the dependence of the metal/ n-GaN GaN(0001) barrier height on the metal work function, as predicted by the model that takes into account the charge neutrality level of the semiconductor. In case of the metal/ p-GaN(Mg) barriers, significant scatter of the corresponding experimental data is observed and pinning of the near-surface Fermi level near E v + 2.5 eV takes place in most structures, which is due to the influence of high density of interface defect states formed during the process of the GaN doping by Mg impurity.

  20. Turbulence attenuation by large neutrally buoyant particles

    NASA Astrophysics Data System (ADS)

    Cisse, M.; Saw, E.-W.; Gibert, M.; Bodenschatz, E.; Bec, J.

    2015-06-01

    Turbulence modulation by inertial-range-size, neutrally buoyant particles is investigated experimentally in a von Kármán flow. Increasing the particle volume fraction Φv, maintaining constant impellers Reynolds number attenuates the fluid turbulence. The inertial-range energy transfer rate decreases as ∝ Φv 2 / 3 , suggesting that only particles located on a surface affect the flow. Small-scale turbulent properties, such as structure functions or acceleration distribution, are unchanged. Finally, measurements hint at the existence of a transition between two different regimes occurring when the average distance between large particles is of the order of the thickness of their boundary layers.

  1. Neutral Gas Plasma Interactions in Space Plasma

    NASA Astrophysics Data System (ADS)

    Liou, Kan

    A sounding rocket experiment, CRIT-II, involving the injection of shaped-charge barium in ionospheric plasma was conducted on May 7, 1989, to investigate Alfven's critical ionization velocity (CIV) hypothesis in space. The CRIT -II main payload was instrumented to make in situ measurements within the neutral barium beam. Among the detectors, UNH provided three energetic particle detectors and two photometers. The data from these detectors are presented. The typical features of the CIV effect were observed including plasma density enhancement, energy and momentum loss of a fast ion beam, excitation of plasma waves, and electron heating. It was found by optical observations that about 4% of the neutral barium was ionized. We believe that about one half of these barium ions were created by electron impact ionization --a CIV mechanism. The cross section for collisions between the barium atoms and the ionospheric oxygen ions was also calculated, assuming that the other half of ionizing barium ions were mainly generated by charge exchange, and found to be in the range from 1 times 10 ^{-17} cm^{-2} at a velocity of 4 km/s to 1 times 10^{-15} cm^{-2} at a velocity of 20 km/s. We also confirmed that the early observed ions were originally from the collisionally accelerated neutral oxygen which charge exchanges with the local oxygen ions. The early stage of electron heating was confirmed to be the result of lower hybrid instabilities excited by the precursor ion beam, using our quasi-linear model calculation. However, the wave spectrum during the passage of main streaming barium was found to be inconsistent with the lower hybrid instabilities proposed by current CIV theories. This could be the main reason for a relatively low ionization yield that one otherwise would expect from CRIT-II. A multi-fluid model of the wave dispersion relation for an unmagnetized beam with finite width in a magnetized plasma was also derived. We found that the nonuniform beam density effect

  2. Neutral changes during divergent evolution of hemoglobins

    NASA Technical Reports Server (NTRS)

    Jukes, T. H.

    1978-01-01

    A comparison of the mRNAs for rabbit and human beta-hemoglobins shows that synonymous changes in codons have accumulated three times as rapidly as nucleotide replacements that produced changes in amino acids. This agrees with predictions based on the so-called neutral theory. In addition, seven codon changes that appear to be single-base changes (according to maximum parsimony) are actually two-base changes. This indicates that the construction of primordial sequences is of limited significance when based on inferences that assume minimum base changes for amino acid replacements.

  3. Inductive coupled radio frequency plasma bridge neutralizer.

    PubMed

    Scholze, F; Tartz, M; Neumann, H

    2008-02-01

    A 13.56 MHz radio frequency plasma bridge neutralizer (rf-PBN) for ion thruster applications as well as ion beam surface processing of insulating materials is presented. The energy for the plasma excitation is inductively coupled into the plasma chamber. Because no components are located inside the plasma, the lifetime of the rf-PBN is expected to be very long. A compact tuning system adapts the input power to the plasma impedance. The electron current may be controlled over a wide range by the rf input power. An electron current of up to 1.6 A has been extracted. PMID:18315215

  4. Unitary constraints on neutral pion electroproduction

    SciTech Connect

    Laget, J. -M.

    2010-11-10

    At large virtuality $Q^2$, the coupling to the vector meson production channels provides us with a natural explanation of the surprisingly large cross section of the neutral pion electroproduction recently measured at Jefferson Laboratory, without destroying the good agreement between the Regge pole model and the data at the real photon point. Lastly, elastic rescattering of the $\\pi^0$ provides us with a way to explain why the node, that appears at $t\\sim -0.5$~GeV$^2$ at the real photon point, disappears as soon as $Q^2$ differs from zero.

  5. Unitary constraints on neutral pion electroproduction

    DOE PAGESBeta

    Laget, J. -M.

    2010-11-10

    At large virtualitymore » $Q^2$, the coupling to the vector meson production channels provides us with a natural explanation of the surprisingly large cross section of the neutral pion electroproduction recently measured at Jefferson Laboratory, without destroying the good agreement between the Regge pole model and the data at the real photon point. Lastly, elastic rescattering of the $$\\pi^0$$ provides us with a way to explain why the node, that appears at $$t\\sim -0.5$$~GeV$^2$ at the real photon point, disappears as soon as $Q^2$ differs from zero.« less

  6. Neutral atomic carbon in dense molecular clouds

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.; Betz, A. L.; Boreiko, R. T.; Goldhaber, D. M.

    1988-01-01

    The 370 micron 3P2-3P1 fine-structure line of neutral carbon was detected in seven sources: OMC 1, NGC 2024, S140, W3, DR 21, M17, and W51. Simultaneous analysis of J = 2-1 data and available observations of the J = 1-0 line make it possible to deduce optical depths and excitation temperatures for these lines. These data indicate that both C I lines are likely to be optically thin, and that the ratio of C I to CO column densities in these clouds is typically about 0.1.

  7. TPX/TFTR Neutral Beam energy absorbers

    SciTech Connect

    Dahlgren, F.; Wright, K.; Kamperschroer, J.; Grisham, L.; Lontai, L.; Peters, C.; VonHalle, A.

    1993-11-01

    The present beam energy absorbing surfaces on the TFTR Neutral Beams such as Ion Dumps, Calorimeters, beam defining apertures, and scrapers, are simple water cooled copper plates which wee designed to absorb (via their thermal inertia) the incident beam power for two seconds with a five minute coal down interval between pulses. These components are not capable of absorbing the anticipated beam power loading for 1000 second TPX pulses and will have to be replaced with an actively cooled design. While several actively cooled energy absorbing designs were considered,, the hypervapotron elements currently being used on the JET beamlines were chosen due to their lower cooling water demands and reliable performance on JET.

  8. TFTR neutral-beam power system

    SciTech Connect

    Winje, R.A.

    1982-10-01

    The TFTR Neutral Beam Power System (NBPS) consists of the accelerator grid power supply and the auxiliary power supplies required to operate the TFTR 120-keV ion sources. The current configuration of the NBPS including the 11-MVA accelerator grid power supply and the Arc and Filament power supplies isolated for operation at accelerator grid voltages up to 120 kV, is described. The prototype NBPS has been assembled at the Princeton Plasma Physics Laboratory and has been operated. The results of the initial operation and the description and resolution of some of the technical problems encountered during the commissioning tests are presented.

  9. Flavor Changing Neutral Current at the Tevatron

    SciTech Connect

    Morello, Michael Joseph; CDF, for the; Collaborations, D0

    2009-12-01

    Processes involving flavor changing neutral currents (FCNC) provide excellent signatures with which to search for evidence of new physics. They have very small branching fractions in the Standard Model since they are highly suppressed by Glashow-Iliopoulos-Maiani (GIM) mechanism. They occur only through higher order diagrams, and new particles contributions can provide a significant enhancements, which would be an unique vocal signs of physics beyond the Standard Model. In this paper we present the most recent measurements on FCNC processes performed by CDF and D0 Collaborations, while last section is devote to the charm physics at CDF.

  10. Collisionless Relaxation in Non-Neutral Plasmas

    SciTech Connect

    Levin, Yan; Pakter, Renato; Teles, Tarcisio N.

    2008-02-01

    A theoretical framework is presented which allows us to quantitatively predict the final stationary state achieved by a non-neutral plasma during a process of collisionless relaxation. As a specific application, the theory is used to study relaxation of charged-particle beams. It is shown that a fully matched beam relaxes to the Lynden-Bell distribution. However, when a mismatch is present and the beam oscillates, parametric resonances lead to a core-halo phase separation. The approach developed accounts for both the density and the velocity distributions in the final stationary state.

  11. Neutral versus polycationic coordination cages: a comparison regarding neutral guest inclusion.

    PubMed

    Szalóki, György; Croué, Vincent; Allain, Magali; Goeb, Sébastien; Sallé, Marc

    2016-08-21

    A neutral self-assembled container synthesized from a concave π-extended tetrathiafulvalene (exTTF) ligand and the cis-Pd(dctfb)2(cod) complex (dctfb = 3,5-dichloro-2,4,6-trifluorobenzene; cod = 1,5-cyclooctadiene) is described. This molecular host exhibits a good binding ability for fused polyaromatic substrates. The corresponding inclusion properties are compared with those of a previously described analogous octacationic cage, offering therefore the opportunity to address the effect of the cavity charge state over the binding of neutral molecules. PMID:27440274

  12. Neutralizing antibodies to HIV-1 induced by immunization

    PubMed Central

    McCoy, Laura E.

    2013-01-01

    Most neutralizing antibodies act at the earliest steps of viral infection and block interaction of the virus with cellular receptors to prevent entry into host cells. The inability to induce neutralizing antibodies to HIV has been a major obstacle to HIV vaccine research since the early days of the epidemic. However, in the past three years, the definition of a neutralizing antibody against HIV has been revolutionized by the isolation of extremely broad and potent neutralizing antibodies from HIV-infected individuals. Considerable hurdles remain for inducing neutralizing antibodies to a protective level after immunization. Meanwhile, novel technologies to bypass the induction of antibodies are being explored to provide prophylactic antibody-based interventions. This review addresses the challenge of inducing HIV neutralizing antibodies upon immunization and considers notable recent advances in the field. A greater understanding of the successes and failures for inducing a neutralizing response upon immunization is required to accelerate the development of an effective HIV vaccine. PMID:23401570

  13. Neutral polyampholyte in an ionic solution

    NASA Astrophysics Data System (ADS)

    Diehl, Alexandre; Barbosa, Marcia C.; Levin, Yan

    1996-12-01

    The behavior of a neutral polyampholyte (PA) chain with N monomers, in an ionic solution, is analyzed in the framework of the full Debye-Hückel-Bjerrum-Flory (DHBjF) theory. A PA chain, that in addition to the neutral monomers, also contains an equal number of positively and negatively charged monomers, is dissolved in an ionic solution. For high concentrations of salt and at high temperatures, the PA exists in an extended state. As the temperature is decreased, the electrostatic energy becomes more relevant and at a T=Tθ the system collapses into a dilute globular state, or microelectrolyte. This state contains a concentration of salt higher than the surrounding medium. As the temperature is decreased even further, association between the monomers of the polymer and the ions of the salt becomes relevant and there is a crossover from this globular state to a low temperature extended state. For low densities of salt, the system is collapsed for almost all temperatures and exhibits a first-order phase transition to an extended state at an unphysical low temperature.

  14. Time reversal violation for entangled neutral mesons

    SciTech Connect

    Bernabeu, J.

    2014-07-23

    A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique solution for the test of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and φ, Factories. The two quantum effects of the decays as filtering measurements of the meson states and the transfer of information of the first decay to the still living partner allow performing a genuine TRV asymmetry with the exchange of “in” and “out” states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system. The perspectives for future additional studies of TRV are discussed.

  15. Time reversal violation for entangled neutral mesons

    NASA Astrophysics Data System (ADS)

    Bernabeu, J.

    2014-07-01

    A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique solution for the test of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and φ, Factories. The two quantum effects of the decays as filtering measurements of the meson states and the transfer of information of the first decay to the still living partner allow performing a genuine TRV asymmetry with the exchange of "in" and "out" states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system. The perspectives for future additional studies of TRV are discussed.

  16. Neutral Einstein metrics in four dimensions

    NASA Astrophysics Data System (ADS)

    Law, Peter R.

    1991-11-01

    In Matsushita [J. Math. Phys. 22, 979-982 (1981), ibid. 24, 36-40 (1983)], for curvature endomorphisms for the pseudo-Euclidean space R2,2, an analog of the Petrov classification as a basis for applications to neutral Einstein metrics on compact, orientable, four-dimensional manifolds is provided. This paper points out flaws in Matsushita's classification and, moreover, that an error in Chern's [``Pseudo-Riemannian geometry and the Gauss-Bonnet formula,'' Acad. Brasileira Ciencias 35, 17-26 (1963) and Shiing-Shen Chern: Selected Papers (Springer-Verlag, New York, 1978)] Gauss-Bonnet formula for pseudo-Riemannian geometry was incorporated in Matsushita's subsequent analysis. A self-contained account of the subject of the title is presented to correct these errors, including a discussion of the validity of an appropriate analog of the Thorpe-Hitchin inequality of the Riemannian case. When the inequality obtains in the neutral case, the Euler characteristic is nonpositive, in contradistinction to Matsushita's deductions.

  17. Neutral solar wind evolution during solar cycle

    NASA Technical Reports Server (NTRS)

    Bzowski, M.; Rucinski, D.

    1995-01-01

    The time dependent model of the expected fluxes of the neutral H and He components of the solar wind in the inner heliosphere is discussed. The model takes into account typical temporal evolution of the distribution of neutral interstellar gases (hydrogen and helium) in the interplanetary space due to solar cycle effects and the long term variability of the solar wind. The contribution of different charge exchange processes to the production of particular NSW element is presented. The distribution of the NSW flux is analysed with respect to the heliocentric distance and azimuthal angle from the Interstellar Wind apex. It demonstrates significant, time-dependent upwind/downwind H and He flux asymmentries. It is shown that the most pronounced modulation of the NSW flux is expected around the solar maximum epoch, when a strong decrease of the energetic H flux by two three orders of magnitude at 1 AU is predicted. The computations show that in the inner solar system (approx. 1 AU) energetic helium atoms production in the downwind region usually dominates the production of the hydrogen component This leads to the conclusion that the NSW composition at the Earth orbit strongly depends on time and the position of the observation point in reference to the apex direction.

  18. Neutral Beam Power System for TPX

    SciTech Connect

    Ramakrishnan, S.; Bowen, O.N.; O`Conner, T.; Edwards, J.; Fromm, N.; Hatcher, R.; Newman, R.; Rossi, G.; Stevenson, T.; von Halle, A.

    1993-11-01

    The Tokamak Physics Experiment (TPX) will utilize to the maximum extent the existing Tokamak Fusion Test Reactor (TFTR) equipment and facilities. This is particularly true for the TFTR Neutral Beam (NB) system. Most of the NB hardware, plant facilities, auxiliary sub-systems, power systems, service infrastructure, and control systems can be used as is. The major changes in the NB hardware are driven by the new operating duty cycle. The TFTR Neutral Beam was designed for operation of the Sources for 2 seconds every 150 seconds. The TPX requires operation for 1000 seconds every 4500 seconds. During the Conceptual Design Phase of TPX every component of the TFTR NB Electrical Power System was analyzed to verify whether the equipment can meet the new operational requirements with our without modifications. The Power System converts 13.8 kV prime power to controlled pulsed power required at the NB sources. The major equipment involved are circuit breakers, auto and rectifier transformers surge suppression components, power tetrodes, HV Decks, and HVDC power transmission to sources. Thermal models were developed for the power transformers to simulate the new operational requirements. Heat runs were conducted for the power tetrodes to verify capability. Other components were analyzed to verify their thermal limitations. This paper describes the details of the evaluation and redesign of the electrical power system components to meet the TPX operational requirements.

  19. A quirky probe of neutral naturalness

    NASA Astrophysics Data System (ADS)

    Chacko, Zackaria; Curtin, David; Verhaaren, Christopher B.

    2016-07-01

    We consider the signals arising from top partner pair production at the LHC as a probe of theories of neutral naturalness. We focus on scenarios in which top partners carry electroweak charges, such as folded supersymmetry or the quirky little Higgs. In this class of theories the top partners are pair produced as quirky bound states, since they are charged under a mirror color group whose lightest states are hidden glueballs. The quirks promptly de-excite and annihilate into glueballs, which decay back to Standard Model fermions via Higgs mixing. This can give rise to spectacular signatures at the LHC, such displaced decays, or high-multiplicity prompt production of many hard b ¯b or τ+τ- pairs. We show that signals arising from top partner pair production constitute the primary discovery channel for this class of theories in most regions of parameter space, and might provide the only experimental probe of scenarios with sub-cm glueball decay lengths. The measurement of top partner masses and couplings, which could be used to test the neutral naturalness mechanism directly, is also a tantalizing possibility.

  20. Skylab Astronauts' Neutral Buoyancy Simulator Training

    NASA Technical Reports Server (NTRS)

    1970-01-01

    After the end of the Apollo missions, NASA's next adventure into space was the marned spaceflight of Skylab. Using an S-IVB stage of the Saturn V launch vehicle, Skylab was a two-story orbiting laboratory, one floor being living quarters and the other a work room. The objectives of Skylab were to enrich our scientific knowledge of the Earth, the Sun, the stars, and cosmic space; to study the effects of weightlessness on living organisms, including man; to study the effects of the processing and manufacturing of materials utilizing the absence of gravity; and to conduct Earth resource observations. At the Marshall Space Flight Center (MSFC), astronauts and engineers spent hundreds of hours in an MSFC Neutral Buoyancy Simulator (NBS) rehearsing procedures to be used during the Skylab mission, developing techniques, and detecting and correcting potential problems. The NBS was a 40-foot deep water tank that simulated the weightlessness environment of space. This photograph shows astronaut Ed Gibbon (a prime crew member of the Skylab-4 mission) during the neutral buoyancy Skylab extravehicular activity training at the Apollo Telescope Mount (ATM) mockup. One of Skylab's major components, the ATM was the most powerful astronomical observatory ever put into orbit to date.

  1. Ion Neutral Mass Spectrometer Measurements from Titan

    NASA Technical Reports Server (NTRS)

    Waite, J. H., Jr.; Niemann, H.; Yelle, R. V.; Kasprzak, W.; Cravens, T.; Luhmann, J.; McNutt, R.; Ip, W.-H.; Gell, D.; Muller-Wordag, I. C. F.

    2005-01-01

    Introduction: The Ion Neutral Mass Spectrometer (INMS) aboard the Cassini orbiter has obtained the first in situ composition measurements of the neutral densities of molecular nitrogen, methane, argon, and a host of stable carbon-nitrile compounds in its first flyby of Titan. The bulk composition and thermal structure of the moon s upper atmosphere do not appear to be changed since the Voyager flyby in 1979. However, the more sensitive techniques provided by modern in-situ mass spectrometry also give evidence for large-spatial-scale large-amplitude atmospheric waves in the upper atmosphere and for a plethora of stable carbon-nitrile compounds above 1174 km. Furthermore, they allow the first direct measurements of isotopes of nitrogen, carbon, and argon, which provide interesting clues about the evolution of the atmosphere. The atmosphere was first accreted as ammonia and ammonia ices from the Saturn sub-nebula. Subsequent photochemistry likely converted the atmosphere into molecular nitrogen. The early atmosphere was 1.5 to 5 times more substantial and was lost via escape over the intervening 4.5 billion years due to the reduced gravity associated with the relatively small mass of Titan. Carbon in the form of methane has continued to outgas over time from the interior with much of it being deposited in the form of complex hydrocarbons on the surface and some of it also being lost to space.

  2. Charge neutralization apparatus for ion implantation system

    DOEpatents

    Leung, Ka-Ngo; Kunkel, Wulf B.; Williams, Malcom D.; McKenna, Charles M.

    1992-01-01

    Methods and apparatus for neutralization of a workpiece such as a semiconductor wafer in a system wherein a beam of positive ions is applied to the workpiece. The apparatus includes an electron source for generating an electron beam and a magnetic assembly for generating a magnetic field for guiding the electron beam to the workpiece. The electron beam path preferably includes a first section between the electron source and the ion beam and a second section which is coincident with the ion beam. The magnetic assembly generates an axial component of magnetic field along the electron beam path. The magnetic assembly also generates a transverse component of the magnetic field in an elbow region between the first and second sections of the electron beam path. The electron source preferably includes a large area lanthanum hexaboride cathode and an extraction grid positioned in close proximity to the cathode. The apparatus provides a high current, low energy electron beam for neutralizing charge buildup on the workpiece.

  3. Nonplanar solitons collision in ultracold neutral plasmas

    SciTech Connect

    El-Tantawy, S. A.; Moslem, W. M.; El-Metwally, M.; Sabry, R.; El-Labany, S. K.; Schlickeiser, R.

    2013-09-15

    Collisions between two nonplanar ion-acoustic solitons in strongly coupled ultracold neutral plasmas composed of ion fluid and non-Maxwellian (nonthermal or superthermal) electron distributions are investigated. The extended Poincare-Lighthill-Kuo method is used to obtain coupled nonplanar Kortweg-de Vries equations for describing the system. The nonplanar phase shifts after the interaction of the two solitons are calculated. It is found that the properties of the nonplanar colliding solitons and its corresponding phase shifts are different from those in the planar case. The polarity of the colliding solitons strongly depends on the type of the non-Maxwellian electron distributions. A critical nonthermality parameter β{sub c} is identified. For values of β ≤ β{sub c} solitons with double polarity exist, while this behavior cannot occur for superthermal plasmas. The phase shift for nonthermal plasmas increases below β{sub c} for a positive soliton, but it decreases for β > β{sub c} for a negative soliton. For superthermal plasmas, the phase shift enhances rapidly for low values of spectral index κ and higher values of ions effective temperature ratio σ{sub *}. For 2 ≲ κ<10, the phase shift decreases but does not change for κ > 10. The nonlinear structure, as reported here, is useful for controlling the solitons created in forthcoming ultracold neutral plasma experiments.

  4. On geometric factors for neutral particle analyzers

    SciTech Connect

    Stagner, L.; Heidbrink, W. W.

    2014-11-15

    Neutral particle analyzers (NPA) detect neutralized energetic particles that escape from plasmas. Geometric factors relate the counting rate of the detectors to the intensity of the particle source. Accurate geometric factors enable quick simulation of geometric effects without the need to resort to slower Monte Carlo methods. Previously derived expressions [G. R. Thomas and D. M. Willis, “Analytical derivation of the geometric factor of a particle detector having circular or rectangular geometry,” J. Phys. E: Sci. Instrum. 5(3), 260 (1972); J. D. Sullivan, “Geometric factor and directional response of single and multi-element particle telescopes,” Nucl. Instrum. Methods 95(1), 5–11 (1971)] for the geometric factor implicitly assume that the particle source is very far away from the detector (far-field); this excludes applications close to the detector (near-field). The far-field assumption does not hold in most fusion applications of NPA detectors. We derive, from probability theory, a generalized framework for deriving geometric factors that are valid for both near and far-field applications as well as for non-isotropic sources and nonlinear particle trajectories.

  5. Structural basis of hepatitis C virus neutralization by broadly neutralizing antibody HCV1

    SciTech Connect

    Kong, Leopold; Giang, Erick; Robbins, Justin B.; Stanfield, Robyn L.; Burton, Dennis R.; Wilson, Ian A.; Law, Mansun

    2012-10-29

    Hepatitis C virus (HCV) infects more than 2% of the global population and is a leading cause of liver cirrhosis, hepatocellular carcinoma, and end-stage liver diseases. Circulating HCV is genetically diverse, and therefore a broadly effective vaccine must target conserved T- and B-cell epitopes of the virus. Human mAb HCV1 has broad neutralizing activity against HCV isolates from at least four major genotypes and protects in the chimpanzee model from primary HCV challenge. The antibody targets a conserved antigenic site (residues 412-423) on the virus E2 envelope glycoprotein. Two crystal structures of HCV1 Fab in complex with an epitope peptide at 1.8-{angstrom} resolution reveal that the epitope is a {beta}-hairpin displaying a hydrophilic face and a hydrophobic face on opposing sides of the hairpin. The antibody predominantly interacts with E2 residues Leu{sup 413} and Trp{sup 420} on the hydrophobic face of the epitope, thus providing an explanation for how HCV isolates bearing mutations at Asn{sup 415} on the same binding face escape neutralization by this antibody. The results provide structural information for a neutralizing epitope on the HCV E2 glycoprotein and should help guide rational design of HCV immunogens to elicit similar broadly neutralizing antibodies through vaccination.

  6. Crystallization and preliminary X-ray crystallographic analysis of the heterodimeric crotoxin complex and the isolated subunits crotapotin and phospholipase A{sub 2}

    SciTech Connect

    Santos, K. F.; Murakami, M. T.; Toyama, M. H.; Marangoni, S.; Forrer, V. P.; Brandão Neto, J. R.; Polikarpov, I.; Arni, R. K.

    2007-04-01

    Crotoxin, a potent neurotoxin from the venom of the South American rattlesnake Crotalus durissus terrificus, exists as a heterodimer formed between a phospholipase A{sub 2} and a catalytically inactive acidic phospholipase A{sub 2} analogue (crotapotin). Large single crystals of the crotoxin complex and of the isolated subunits have been obtained. Crotoxin, a potent neurotoxin from the venom of the South American rattlesnake Crotalus durissus terrificus, exists as a heterodimer formed between a phospholipase A{sub 2} and a catalytically inactive acidic phospholipase A{sub 2} analogue (crotapotin). Large single crystals of the crotoxin complex and of the isolated subunits have been obtained. The crotoxin complex crystal belongs to the orthorhombic space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 38.2, b = 68.7, c = 84.2 Å, and diffracted to 1.75 Å resolution. The crystal of the phospholipase A{sub 2} domain belongs to the hexagonal space group P6{sub 1}22 (or its enantiomorph P6{sub 5}22), with unit-cell parameters a = b = 38.7, c = 286.7 Å, and diffracted to 2.6 Å resolution. The crotapotin crystal diffracted to 2.3 Å resolution; however, the highly diffuse diffraction pattern did not permit unambiguous assignment of the unit-cell parameters.

  7. Low energy energetic neutral atom imaging in the Jovian system

    NASA Astrophysics Data System (ADS)

    Futaana, Yoshifumi; Wieser, Martin; Barabash, Stas

    2013-04-01

    We modeled low energy energetic neutral atoms fluxes originating from the interaction of Jovian magnetospheric plasma with the surface of Ganymede and from charge exchange reactions in the Io torus. We then calculated the instrument response of the Jovian Neutrals Analyzer instrument (JNA) to these fluxes. JNA is part of the proposed Particle Environment Package (PEP) for ESA's JUICE mission and is based on the Energetic Neutral Atom instrument (ENA) built for the BepiColombo Magnetospheric Orbiter. JNA is an imaging energetic neutral atom instrument for energies from 10eV to 3.3keV and it provides angular as well as mass resolution for major neutral species. Depending on magnetic field configuration magnetospheric plasma is able to precipitate onto the surface of Ganymede. The plasma surface interaction produces energetic neutral atoms by backscattering and/or sputtering that travel on ballistic trajectories. Imaging of the energetic neutral atoms fluxes allows to remotely study the precipitation pattern onto the surface, its dependence on magnetic field configuration and its evolution over time. Simulated JNA images are shown for typical conditions. Energetic neutral atoms are also generated by charge exchange reactions in the Io torus. Energetic neutral atoms allow us to study torus dynamics remotely. We show expected energetic neutral atoms fluxes and simulated JNA data from imaging the Io torus from a vantage point outside of Europa's orbit well reachable by the JUICE mission.

  8. Variation and infectivity neutralization in influenza

    PubMed Central

    Knossow, Marcel; Skehel, John J

    2006-01-01

    Worldwide epidemics of influenza are caused by viruses that normally infect other species, particularly waterfowl, and that contain haemagglutinin membrane glycoproteins (HAs) to which the human population has no immunity. Anti-HA immunoglobulins neutralize influenza virus infectivity. In this review we outline structural differences that distinguish the HAs of the 16 antigenic subtypes (H1–16) found in viruses from avian species. We also describe structural changes in HA required for the effective transfer to humans of viruses containing three of them, H1, H2 and H3, in the 1918 (Spanish), the 1957 (Asian) and the 1968 (Hong Kong) pandemics, respectively. In addition, we consider changes that may be required before the current avian H5 viruses could pass from human to human. PMID:16925526

  9. Neutral sphingomyelinase and breast cancer research.

    PubMed

    Hwang, Sun-Yong; Kim, Tae-Hee; Lee, Hae-Hyeog

    2015-04-01

    Our understanding of the functions of neutral sphingomyelinase (N-SMase) signaling has advanced over the past decade. In this review, we focus on the roles and regulation of N-SMase 1, N-SMase 2, N-SMase 3, an enzyme that generates the bioactive lipid ceramide through the hydrolysis of the membrane lipid sphingomyelin. A large body of work has now implicated N-SMase 2 in a diverse set of cellular functions, physiological processes, and disease pathologies. We focus on different aspects of this enzyme's regulation from transcriptional, post-translational, and biochemical. Furthermore, we expected N-SMase involvement in cellular processes including inflammatory signaling, cell growth, apoptosis, and tumor necrosis factor which in turn play important roles in pathologies such as cancer metastasis, variable disease, and other organ system disorders. Lastly, we examine avenues where targeted N-SMase inhibition may be clinically beneficial in disease scenarios. PMID:26046034

  10. Neutral Beam Ion Loss Modeling for NSTX

    SciTech Connect

    D. Mikkelsen; D.S. Darrow; L. Grisham; R. Akers; S. Kaye

    1999-06-01

    A numerical model, EIGOL, has been developed to calculate the loss rate of neutral beam ions from NSTX and the resultant power density on the plasma facing components. This model follows the full gyro-orbit of the beam ions, which can be a significant fraction of the minor radius. It also includes the three-dimensional structure of the plasma facing components inside NSTX. Beam ion losses from two plasma conditions have been compared: {beta} = 23%, q{sub 0} = 0.8, and {beta} = 40%, q{sub 0} = 2.6. Global losses are computed to be 4% and 19%, respectively, and the power density on the rf antenna is near the maximum tolerable levels in the latter case.

  11. Dual neutral particle transmutation in CINDER2008

    SciTech Connect

    Martin, W. J.; De Oliveira, C. R. E.

    2012-07-01

    A capability has been built for the CINDER2008 (beta) transmutation code that expands the capability from only neutron induced reactions to photon induced reactions. This allows for two incident neutral particles to cause nuclear transmutation in a given material simultaneously. The CINDER2008 code, a modular rewrite of the CINDER'90 transmutation code from Los Alamos National Laboratory, was modified to allow for the dual sets of physics. A photonuclear cross section and photofission product yield library was also created using ENDF-B/VII data and translated neutron fission product yields. The code and library have been combined to create a unique transmutation code. The scope of use is broad; it is capable of modeling the transmutation caused by photons released from the decay of daughter and fission products as well as transmutation in photon rich environments. A brief code description and a verification and validation of the contributions are given. (authors)

  12. Incoherent neutral pion photoproduction on 12C.

    PubMed

    Tarbert, C M; Watts, D P; Aguar, P; Ahrens, J; Annand, J R M; Arends, H J; Beck, R; Bekrenev, V; Boillat, B; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Codling, R; Downie, E J; Föhl, K; Glazier, D I; Grabmayr, P; Gregor, R; Heid, E; Hornidge, D; Jahn, O; Kashevarov, V L; Knezevic, A; Kondratiev, R; Korolija, M; Kotulla, M; Krambrich, D; Krusche, B; Lang, M; Lisin, V; Livingston, K; Lugert, S; Macgregor, I J D; Manley, D M; Martinez, M; McGeorge, J C; Mekterovic, D; Metag, V; Nefkens, B M K; Nikolaev, A; Novotny, R; Owens, R O; Pedroni, P; Polonski, A; Prakhov, S N; Price, J W; Rosner, G; Rost, M; Rostomyan, T; Schadmand, S; Schumann, S; Sober, D; Starostin, A; Supek, I; Thomas, A; Unverzagt, M; Walcher, Th; Zehr, F

    2008-04-01

    We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The 12C(gamma,pi(0))(12)C*(4.4 MeV) reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a pi(0) spectrometer and to detect decay photons from the excited residual nucleus. The technique has potential applications to a broad range of future nuclear measurements with the Crystal Ball and similar detector systems elsewhere. Such data are sensitive to the propagation of the Delta in the nuclear medium and will give the first information on matter transition form factors from measurements with an electromagnetic probe. The incoherent cross sections are compared to two theoretical predictions including a Delta-hole model. PMID:18517938

  13. TFTR neutral-beam test facility

    SciTech Connect

    Turitzin, N.M.; Newman, R.A.

    1981-11-01

    TFTR Neutral Beam System will have thirteen discharge ion sources, each with its own power supply. Twelve of these will be utilized for supplemental heating of the TFTR tokamak plasma, while the thirteenth will be dedicated to an off-machine test chamber for source development and/or conditioning. A test installation for one source was set up using prototype equipment to discover and correct possible deficiencies, and to properly coordinate the equipment. This test facility represents the first opportunity for assembling an integrated system of hardware supplied by diverse vendors, each of whom designed and built his equipment to performance specifications. For the installation and coordination of the different portions of the total system, particular attention was given to personnel safety and safe equipment operation. This paper discusses various system components, their characteristics, interconnection and control. Results of the recently initiated test phase will be reported at a later date.

  14. Meson exchange and neutral weak currents

    SciTech Connect

    Beck, D.H.

    1994-04-01

    Measurements of parity-violating electron scattering asymmetries to determine weak neutral currents in nuclei will be effected by the presence of meson exchange currents. Present low momentum transfer calculations, based on a flavor independent framework, show these effects to be small. In general, however, as the momentum transfer increases to values typical of deep-inelastic scattering, fragmentation functions show a clear flavor dependence. It is suggested that a good experimental starting point for understanding the flavor dependence of meson production and exchange currents is the Q{sup 2} dependence of parity-violating asymmetry in inclusive single pion electroproduction. A CEBAF facility with doubled energy is necessary to approach momentum transfers where this process begins to scale.

  15. [Neutrality, bisexuality and androgyny of the psychoanalyst].

    PubMed

    Molfino, F

    1993-06-01

    Proceeding from the fact that Western thought is based on Greek philosophy, the author pinpoints a feature specific to psychoanalysis. Unlike other sciences, which are grounded in the central (and latently homosexual) relation of rhetoric and dialogue between teacher and pupil, psychoanalytic dialogue centers around a heterosexual (male/female) relationship. Prototypic for this is the confrontation of the psychoanalyst with the "complex burden of female love". The fascination of philosophy lies in similarity, that of psychoanalysis in difference. The gender question, and more specifically the sex of the analyst, has been given little attention in connection with the transference/countertransference paradigm. With a discussion of the concepts of neutrality (Freud), bisexuality (Freud, Jung) and with reference to literary sources on androgyny (V. Woolf, Balzac, Le Guin) Molfino undertakes the attempt to take the gender discussion in psychoanalytic theory and practice a stage further. PMID:8351399

  16. Dual-Species Ultracold Neutral Plasma

    NASA Astrophysics Data System (ADS)

    Woodbury, Daniel; Erikson, Alex; Bergeson, Scott

    2015-05-01

    We present the design and characterization of a dual species Ca/Yb 2D/3D MOT. This setup allows us to create a mixed calcium and ytterbium ultracold neutral plasma to study transport mechanisms in a strongly coupled environment. This system is an analogue to electron-ion transport, that is not readily understood in dense plasmas. We report on the creation and optimization of the dual species trap and preliminary results for separate calcium and ytterbium plasma. These results demonstrate a robust method for trapping a large number of atoms in the trap and creating a dual-species plasma. This work supported in part by the NSF (Grant No. PHY-0969856) and the Air Force (Grant No. FA9950-12-1-0308).

  17. Neutral particle beam sensing and steering

    DOEpatents

    Maier, II, William B.; Cobb, Donald D.; Robiscoe, Richard T.

    1991-01-01

    The direction of a neutral particle beam (NPB) is determined by detecting Ly.alpha. radiation emitted during motional quenching of excited H(2S) atoms in the beam during movement of the atoms through a magnetic field. At least one detector is placed adjacent the beam exit to define an optical axis that intercepts the beam at a viewing angle to include a volume generating a selected number of photons for detection. The detection system includes a lens having an area that is small relative to the NPB area and a pixel array located in the focal plane of the lens. The lens viewing angle and area pixel array are selected to optimize the beam tilt sensitivity. In one embodiment, two detectors are placed coplanar with the beam axis to generate a difference signal that is insensitive to beam variations other than beam tilt.

  18. Charge neutralization as studied experimentally and theoretically

    NASA Technical Reports Server (NTRS)

    Linson, L. M.

    1982-01-01

    Problems regarding an isolated sphere which emits negative charge are considered. Such a sphere could charge up to large potentials which would inhibit the electron beam from leaving the vicinity of the body. In order to avoid charging to high potentials, a vehicle must attract a return current equal to the emitted current. The present investigation is concerned with theoretical models of some processes believed to be important for the vehicle neutralization problem under various conditions. Attention is given to general time-scale considerations, the low-altitude regime, the high-altitude regime, vehicle-induced discharge, and beam-plasma discharge. The general pattern which emeres as a result of measurements is that below altitudes of approximately 125 + or - 5 km the vehicle potential rarely rises more than several tens of volts.

  19. Age-abundance relationships for neutral communities.

    PubMed

    Danino, Matan; Shnerb, Nadav M

    2015-10-01

    Neutral models for the dynamics of a system of competing species are often used to describe a wide variety of empirical communities. These models are used in many situations, ranging from population genetics and ecological biodiversity to macroevolution and cancer tumors. One of the main issues discussed within this framework is the relationships between the abundance of a species and its age. Here we provide a comprehensive analysis of the age-abundance relationships for fixed-size and growing communities. Explicit formulas for the average and the most likely age of a species with abundance n are given, together with the full probability distribution function. We further discuss the universality of these results and their applicability to the tropical forest community. PMID:26565271

  20. Age-abundance relationships for neutral communities

    NASA Astrophysics Data System (ADS)

    Danino, Matan; Shnerb, Nadav M.

    2015-10-01

    Neutral models for the dynamics of a system of competing species are often used to describe a wide variety of empirical communities. These models are used in many situations, ranging from population genetics and ecological biodiversity to macroevolution and cancer tumors. One of the main issues discussed within this framework is the relationships between the abundance of a species and its age. Here we provide a comprehensive analysis of the age-abundance relationships for fixed-size and growing communities. Explicit formulas for the average and the most likely age of a species with abundance n are given, together with the full probability distribution function. We further discuss the universality of these results and their applicability to the tropical forest community.

  1. Neutralized current acid waste consolidation management plan

    SciTech Connect

    Powell, W.J.; Brown, R.G.; Galbraith, J.; Jensen, C.; Place, D.E.; Reddick, G.W.; Zuroff, W.; Brothers, A.J.

    1996-01-01

    The scope of this evaluation is to recommend a management plan for the high-heat tank waste, including neutralized current acid waste (NCAW) in AY and AZ Tank Farms, and tank C-106 waste. The movement of solids, liquids and salt cake in the designated tank farms is included. Decision analysis techniques were used to determine a recommended alternative. The recommended course of action was replacement of a 75-hp mixer pump in tank AY-102 and in-tank concentration of tank AZ-102 supernate. The alternative includes transfer fo tank C-106 sludge to tank AY-102, then transfer to tank AY-102 and tank C-106 sludge to tank AZ-101 using the new 75-hp mixer pump installed in tank AY-102. Tank AZ-101 becomes a storage tank for high-level waste (HLW) sludge, with the capacity to mix and transfer sludge as desired.

  2. The neutral-atmosphere temperature instrument.

    NASA Technical Reports Server (NTRS)

    Spencer, N. W.; Niemann, H. B.; Carignan, G. R.

    1973-01-01

    The determination of the temperature of the neutral gas at the location of the satellite is based on measurement of the velocity distribution of the molecular nitrogen. Measurement of the thermal-velocity component in the presence of the free-stream velocity will be obtained through application of the velocity-scan technique and, independently, through use of a baffle technique. A 3-cm diameter spherical sampling chamber with a 0.5-cm diameter precisely knife-edged orifice is located at the satellite equator to permit free diffusion of atmosphere gases between the chamber interior and the atmosphere. The spherical chamber is connected through a high-conductance tube to a quadrupole mass-spectrometer sensor to permit accurate quantitative evaluation of the density of the gas.

  3. Neutral Buoyancy Simulator - Hubble Space Telescope Training

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This photograph shows STS-61 crewmemmbers training for the Hubble Space Telescope (HST) servicing mission in the Marshall Space Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS). Two months after its deployment in space, scientists detected a 2-micron spherical aberration in the primary mirror of the HST that affected the telescope's ability to focus faint light sources into a precise point. This imperfection was very slight, one-fiftieth of the width of a human hair. A scheduled Space Service servicing mission (STS-61) in 1993 permitted scientists to correct the problem. The MSFC NBS provided an excellent environment for testing hardware to examine how it would operate in space and for evaluating techniques for space construction and spacecraft servicing.

  4. Astronaut Training in the Neutral Buoyancy Simulator

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This photograph shows an STS-61 astronaut training for the Hubble Space Telescope (HST) servicing mission (STS-61) in the Marshall Space Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS). Two months after its deployment in space, scientists detected a 2-micron spherical aberration in the primary mirror of the HST that affected the telescope's ability to focus faint light sources into a precise point. This imperfection was very slight, one-fiftieth of the width of a human hair. A scheduled Space Service servicing mission (STS-61) in 1993 permitted scientists to correct the problem. The MSFC NBS provided an excellent environment for testing hardware to examine how it would operate in space and for evaluating techniques for space construction and spacecraft servicing.

  5. Electrostatic attraction between overall neutral surfaces.

    PubMed

    Adar, Ram M; Andelman, David; Diamant, Haim

    2016-08-01

    Two overall neutral surfaces with positively and negatively charged domains ("patches") have been shown in recent experiments to exhibit long-range attraction when immersed in an ionic solution. Motivated by the experiments, we calculate analytically the osmotic pressure between such surfaces within the Poisson-Boltzmann framework, using a variational principle for the surface-averaged free energy. The electrostatic potential, calculated beyond the linear Debye-Hückel theory, yields an overall attraction at large intersurface separations, over a wide range of the system's controlled length scales. In particular, the attraction is stronger and occurs at smaller separations for surface patches of larger size and charge density. In this large patch limit, we find that the attraction-repulsion crossover separation is inversely proportional to the square of the patch-charge density and to the Debye screening length. PMID:27627373

  6. Acceleration of neutrals in a nanosecond laser produced nickel plasma

    SciTech Connect

    Smijesh, N.; Chandrasekharan, K.; Philip, Reji

    2014-12-15

    Time of flight dynamics of slow neutrals, fast neutrals, and ions from a nanosecond laser produced nickel (Ni) plasma are investigated. Species arrival times confirm the hypothesis that fast neutrals are formed by the recombination of fast ions with free electrons. Both neutrals and ions are found to accelerate for a short interval immediately after ablation, which is attributed to internal Coulomb forces which create electrostatic potentials resulting in the charged particle acceleration. This process is further enhanced by laser-plasma energy coupling. Emission from neutrals could be measured for longer axial distances in the plume compared to that of ions confirming that the ions recombine to form neutrals as they move away from the target surface.

  7. Observation of quantized conductance in neutral matter

    NASA Astrophysics Data System (ADS)

    Krinner, Sebastian; Stadler, David; Husmann, Dominik; Brantut, Jean-Philippe; Esslinger, Tilman

    2015-01-01

    In transport experiments, the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps, with a size determined solely by Planck's constant h. Observations of quantized steps in electrical conductance have provided important insights into the physics of mesoscopic systems and have allowed the development of quantum electronic devices. Even though quantized conductance should not rely on the presence of electric charges, it has never been observed for neutral, massive particles. In its most fundamental form, it requires a quantum-degenerate Fermi gas, a ballistic and adiabatic transport channel, and a constriction with dimensions comparable to the Fermi wavelength. Here we report the observation of quantized conductance in the transport of neutral atoms driven by a chemical potential bias. The atoms are in an ultraballistic regime, where their mean free path exceeds not only the size of the transport channel, but also the size of the entire system, including the atom reservoirs. We use high-resolution lithography to shape light potentials that realize either a quantum point contact or a quantum wire for atoms. These constrictions are imprinted on a quasi-two-dimensional ballistic channel connecting the reservoirs. By varying either a gate potential or the transverse confinement of the constrictions, we observe distinct plateaux in the atom conductance. The conductance in the first plateau is found to be equal to the universal conductance quantum, 1/h. We use Landauer's formula to model our results and find good agreement for low gate potentials, with all parameters determined a priori. Our experiment lets us investigate quantum conductors with wide control not only over the channel geometry, but also over the reservoir properties, such as interaction strength, size and thermalization rate.

  8. A Blind Search for Neutral Hydrogen

    NASA Astrophysics Data System (ADS)

    Gross, Julia; Momjian, Emmanuel; Van Gorkom, Jacqueline H.

    2015-01-01

    Measurements of neutral hydrogen (HI) are important in our understanding of the universe. Hydrogen within galaxies passes through a neutral phase as it cools and collapses into stars. The reservoir and distribution of HI associated with galaxies is therefore closely tied to how galaxies grow and evolve. Unfortunately, most of our observational information on HI is limited to the local universe, impeding our ability to see how the HI properties of galaxies change over time. Using the newly upgraded Very Large Array (VLA) radio telescope, located in Socorro, New Mexico, we are working on a far-reaching survey of HI gas around galaxies: The COSMOS HI Large Extragalactic Survey (CHILES). For the first time, we can search for HI over one-third of the age of the universe in a single observation. This survey will provide HI mass, morphology, and kinematics over a substantial, continuous distance range, and in a wide range of cosmic environments. Detection of HI sources is typically done by eye and sometimes with the help of optical catalogs of galaxies with known locations. Given that this is a blind search over a very large volume and that these HI sources can be very faint, this standard approach is unlikely to allow us to fully exploit these rich data. In light of this, we are looking into the use of algorithms to aid in the detection of HI sources. We present a source-finding application and discuss its strengths and limitations for these kinds of data. This is a step in advancing data-analysis tools to keep up with the technological advancements of radio telescopes. Once fully tested and applied, our application will help provide the most reliable, complete data set for us to gain insight into the evolution of galaxies as traced by HI and as function of location in the underlying large-scale structure of the universe.

  9. Neutral Particle Analyzer Measurements of Ion Behavior in NSTX

    SciTech Connect

    S.S. Medley; R.E. Bell; D.S. Darrow; A.L. Roquemore

    2002-02-06

    Initial results obtained with the Neutral Particle Analyzer (NPA) diagnostic on the National Spherical Torus Experiment (NSTX) are presented. Magnetohydrodynamic activity and reconnection events cause depletion of the deuterium energetic ion distribution created by neutral-beam injection. Adding High Harmonic Fast Wave Heating to neutral-beam-heated discharges results in the generation of an energetic ion tail above the beam injection energy. NPA measurements of the residual hydrogen ion temperature are in good agreement with those from recombination spectroscopy.

  10. Coherent and neutral pion production results from MINERνA

    SciTech Connect

    Palomino, J. L.; Higuera, A.

    2015-05-15

    MINERνA is a neutrino-nucleus scattering experiment employing multiple nuclear targets. The experiment is studying neutral pion production due to coherent, resonant and deep-inelastic processes, from both charged current and neutral current reactions. Neutral pions are detected through their two photon decay and the resultant electromagnetic showers. We will describe the analysis for the cross sections of inclusive and exclusive processes.

  11. Towards a Revised Monte Carlo Neutral Particle Surface Interaction Model

    SciTech Connect

    D.P. Stotler

    2005-06-09

    The components of the neutral- and plasma-surface interaction model used in the Monte Carlo neutral transport code DEGAS 2 are reviewed. The idealized surfaces and processes handled by that model are inadequate for accurately simulating neutral transport behavior in present day and future fusion devices. We identify some of the physical processes missing from the model, such as mixed materials and implanted hydrogen, and make some suggestions for improving the model.

  12. A Statistical Model of the Magnetotail Neutral Sheet

    NASA Astrophysics Data System (ADS)

    Xiao, Sudong; Zhang, Tielong; Baumjohann, Wolfgang; Nakamura, Rumi; Ge, Yasong; Du, Aimin; Wang, Guoqiang; Lu, Quanming

    2015-04-01

    The neutral sheet of the magnetotail is characterized by weak magnetic field, strong cross tail current, and a reversal of the magnetic field direction across it. The dynamics of the earth's magnetosphere is greatly influenced by physical processes that occur near the neutral sheet. However, the exact position of the neutral sheet is variable in time. It is therefore essential to have a reliable estimate of the average position of the neutral sheet. Magnetic field data from ten years of Cluster, nineteen years of Geotail, four years of TC 1, and seven years of THEMIS observations have been incorporated to obtain a model of the magnetotail neutral sheet. All data in aberrated GSM (Geocentric Solar Magnetospheric) coordinate system are normalized to the same solar wind pressure condition. The shape and position of the neutral sheet, illustrated directly by the separator of positive and negative Bx on the YZ cross sections, are fitted with a displaced ellipse model. It is consistent with previous studies that the neutral sheet becomes curvier in the YZ cross section when the dipole tilt increases, yet our model shows the curviest neutral sheet compared with previous models. The new model reveals a hinging distance very close to 10 RE at a reference solar wind dynamic pressure of 2 nPa. We find that the earth dipole tilt angle not only affects the neutral sheet configuration in the YZ cross section but also in the XZ cross section. The neutral sheet becomes more tilting in the XZ cross section when the dipole tilt increases. The effect of an interplanetary magnetic field (IMF) penetration is studied, and an IMF By-related twisting of about 3° is found. Anticlockwise twisting of the neutral sheet is observed, looking along the downtail direction, for a positive IMF By, and clockwise twisting of the neutral sheet for a negative IMF By.

  13. Reactive formulations for a neutralization of toxic industrial chemicals

    SciTech Connect

    Tucker, Mark D.; Betty, Rita G.

    2006-10-24

    Decontamination formulations for neutralization of toxic industrial chemicals, and methods of making and using same. The formulations are effective for neutralizing malathion, hydrogen cyanide, sodium cyanide, butyl isocyanate, carbon disulfide, phosgene gas, capsaicin in commercial pepper spray, chlorine gas, anhydrous ammonia gas; and may be effective at neutralizing hydrogen sulfide, sulfur dioxide, formaldehyde, ethylene oxide, methyl bromide, boron trichloride, fluorine, tetraethyl pyrophosphate, phosphorous trichloride, arsine, and tungsten hexafluoride.

  14. A preliminary model of ion beam neutralization. [in thruster plasmas

    NASA Technical Reports Server (NTRS)

    Parks, D. E.; Katz, I.

    1979-01-01

    A theoretical model of neutralized thruster ion beam plasmas has been developed. The basic premise is that the beam forms an electrostatic trap for the neutralizing electrons. A Maxwellian spectrum of electron energies is maintained by collisions between trapped electrons and by collective randomization of velocities of electrons injected from the neutralizer into the surrounding plasma. The theory contains the observed barometric law relationship between electron density and electron temperatures and ion beam spreading in good agreement with measured results.

  15. Drift compression of an intense neutralized ion beam

    SciTech Connect

    Roy, P.K.; Yu, S.S.; Henestroza, E.; Anders, A.; Bieniosek, F.M.; Coleman, J.; Eylon, S.; Greenway, W.G.; Leitner, M.; Logan, B.G.; Waldron, W.L.; Welch, D.R.; Thoma, C.; Sefkow, A.B.; Gilson, E.P.; Efthimion, P.C.; Davidson, R.C.

    2004-10-25

    Longitudinal compression of a tailored-velocity, intense neutralized ion beam has been demonstrated. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. this measurement has been confirmed independently with two different diagnostic systems.

  16. Simplification of power electronics for ion thruster neutralizers

    NASA Technical Reports Server (NTRS)

    Gruber, R. P.

    1982-01-01

    A need exists for less complex and lower cost ion thruster systems. Design approaches and the demonstration of neutralizer power electronics for relaxed neutralizer keeper, tip heater, and vaporizer requirements are discussed. The neutralizer circuitry is operated from a 200 to 400 V bus and demonstrates an order of magnitude reduction in parts count. Furthermore, a new technique is described for regulating tip heater power and automatically switching over to provide keeper power with only four additional components. A new design to control the flow rate of the neutralizer with one integrated circuit is also presented.

  17. Feedback between neutral winds and auroral arc electrodynamics

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.; Walterscheid, R. L.

    1986-01-01

    The feedback between neutral atmospheric winds and the electrodynamics of a stable, discrete auroral arc is analyzed. The ionospheric current continuity equation and the equation for neutral gas acceleration by ion drag are solved simultaneously, as a function of time. The results show that, in general, the electric field in the ionosphere adjusts to neutral wind acceleration so as to keep auroral field-aligned currents and electron acceleration approximately independent of time. It is thus concluded that the neutral winds that develop as a result of the electrodynamical forcing associated with an arc do not significantly affect the intensity of the arc.

  18. Plasma heating with multi-MeV neutral atom beams

    SciTech Connect

    Grisham, L.R.; Post, D.E.; Mikkelsen, D.R.; Eubank, H.P.

    1981-10-01

    We explore the utility and feasibility of neutral beams of greater than or equal to 6 AMU formed from negative ions, and also of D/sup 0/ formed from D/sup -/. The negative ions would be accelerated to approx. 1 to 2 MeV/AMU and neutralized, whereupon the neutral atoms would be used to heat and, perhaps, to drive current in magnetically confined plasmas. Such beams appear feasible and offer the promise of significant advantages relative to conventional neutral beams based on positive deuterium ions at approx. 150 keV.

  19. Patterns of Neutral Genetic Variation on Recombining Sex Chromosomes

    PubMed Central

    Kirkpatrick, Mark; Guerrero, Rafael F.; Scarpino, Samuel V.

    2010-01-01

    Many animals and plants have sex chromosomes that recombine over much of their length. Here we develop coalescent models for neutral sites on these chromosomes. The emphasis is on expected coalescence times (proportional to the expected amount of neutral genetic polymorphism), but we also derive some results for linkage disequilibria between neutral sites. We analyze the standard neutral model, a model with polymorphic Y chromosomes under balancing selection, and the invasion of a neo-Y chromosome. The results may be useful for testing hypotheses regarding how new sex chromosomes originate and how selection acts upon them. PMID:20124026

  20. Neutral Particle Analysis on ITER and requirements for DEMO

    SciTech Connect

    Afanasyev, V. I.; Mironov, M. I.; Khudoleev, A. V.; Petrov, M. P.; Nesenevich, V. G.; Petrov, S. Ya.; Kislyakov, A. I.; Chernyshev, F. V.; Melnik, A. D.; Konovalov, S. V.; Kozlovsky, S. S.; Lyublin, B. V.

    2008-03-12

    The use of the neutral particle analysis (NPA) to study the ion component of plasma on ITER has been reviewed. Both thermal (10-200 keV) and supra-thermal (0.2-4 MeV) energy ranges of neutral fluxes are studied in respect to feasibility of the fusion fuel isotopic composition measurements. Influence of heating neutral beams and diagnostic neutral beam on the measurements is also shown. Possible application of the NPA to measure the energy distribution function of fusion alpha particles is discussed. Low- and high-energy NPA monitors have been proposed for DEMO machine to control the DT fuel isotope ratio.

  1. Space charge neutralization in inertial electrostatic confinement plasmas

    SciTech Connect

    Evstatiev, E. G.; Nebel, R. A.; Chacon, L.; Park, J.; Lapenta, G.

    2007-04-15

    A major issue for electron injected inertial electrostatic confinement (IEC) devices is space charge neutralization. A new formalism is developed that will allow this neutralization to occur for both oscillating and steady-state IEC plasmas. Results indicate that there are limits on the amount of compression that can be achieved by oscillating plasmas while simultaneously maintaining space charge neutralization and parabolic background potential. For steady-state plasmas, there are no such limits and space charge neutralization can be achieved even when the plasma becomes quasineutral.

  2. Intense ion beam neutralization using underdense background plasma

    SciTech Connect

    Berdanier, William; Roy, Prabir K.; Kaganovich, Igor

    2015-01-15

    Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimes of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.

  3. Neutralization of a proton at adsorbate-covered metal surfaces

    NASA Astrophysics Data System (ADS)

    Kato, M.; O'Connor, D. J.; Yamamoto, K.; Souda, R.

    1996-08-01

    Charge exchange between a proton and adatoms on the metal substrates has been studied theoretically. The neutral fraction may increase or decrease, depending on the electronic environments of the adatom. The neutral yield of a proton depends significantly on the interaction between the adatom and the substrate metal. One remarkable aspect is the creative or destructive interference between two charge-exchange processes: one is the neutralization between the proton and the adatom, and the other is the neutralization between the proton and the substrate metal. Using the parameter values derived from molecular orbital calculations for cluster atoms, the remarkable interference effect is demonstrated.

  4. RAMI Analyses of Heating Neutral Beam and Diagnostic Neutral Beam Systems for ITER

    NASA Astrophysics Data System (ADS)

    Chang, D. H.; Lee, S.; Hemsworth, R.; van Houtte, D.; Okayama, K.; Sagot, F.; Schunke, B.; Svensson, L.

    2011-09-01

    A RAMI (Reliability, Availability, Maintainability, Inspectability) analysis has been performed for the heating (& current drive) neutral beam (HNB) and diagnostic neutral beam (DNB) systems of the ITER device [1-3]. The objective of these analyses is to implement RAMI engineering requirements for design and testing to prepare a reliability-centred plan for commissioning, operation, and maintenance of the system in the framework of technical risk control to support the overall ITER Project. These RAMI requirements will correspond to the RAMI targets for the ITER project and the compensating provisions to reach them as deduced from the necessary actions to decrease the risk level of the function failure modes. The RAMI analyses results have to match with the procurement plan of the systems.

  5. Low-energy energetic neutral atom imaging of Io plasma and neutral tori

    NASA Astrophysics Data System (ADS)

    Futaana, Yoshifumi; Barabash, Stas; Wang, Xiao-Dong; Wieser, Martin; Wieser, Gabriella S.; Wurz, Peter; Krupp, Norbert; Brandt, Pontus C.:son

    2015-04-01

    Io's plasma and neutral tori play significant roles in the Jovian magnetosphere. We present feasibility studies of measuring low-energy energetic neutral atoms (LENAs) generated from the Io tori. We calculate the LENA flux between 10 eV and 3 keV. The energy range includes the corotational plasma flow energy. The expected differential flux at Ganymede distance is typically 103-105 cm-2 s-1 sr-1 eV-1 near the energy of the corotation. It is above the detection level of the planned LENA sensor that is to be flown to the Jupiter system with integration times of 0.01-1 s. The flux has strong asymmetry with respective to the Io phase. The observations will exhibit periodicities, which can be attributed to the Jovian magnetosphere rotation and the rotation of Io around Jupiter. The energy spectra will exhibit dispersion signatures, because of the non-negligible flight time of the LENAs from Io to the satellite. In 2030, the Jupiter exploration mission JUICE will conduct a LENA measurement with a LENA instrument, the Jovian Neutrals Analyzer (JNA). From the LENA observations collected by JNA, we will be able to derive characteristic quantities, such as the density, velocity, velocity distribution function, and composition of plasma-torus particles. We also discuss the possible physics to be explored by JNA in addition to the constraints for operating the sensor and analyzing the obtained dataset.

  6. Development of a Coxsackievirus A16 neutralization assay based on pseudoviruses for measurement of neutralizing antibody titer in human serum.

    PubMed

    Jin, Jun; Ma, Hongxia; Xu, Lin; An, Dong; Sun, Shiyang; Huang, Xueyong; Kong, Wei; Jiang, Chunlai

    2013-02-01

    Serum neutralizing antibody titers are indicative of protective immunity against Coxsackievirus A16 (CV-A16) and Enterovirus 71 (EV71), the two main etiological agents of hand, foot and mouth disease (HFMD), and provide the basis for evaluating vaccine efficacy. The current CV-A16 neutralization assay based on inhibition of cytopathic effects requires manual microscopic examination, which is time-consuming and labor-intensive. In this study, a high-throughput neutralization assay was developed by employing CV-A16 pseudoviruses expressing luciferase for detecting infectivity in rhabdomyosarcoma (RD) cells and measuring serum viral neutralizing antibodies. Without the need to use infectious CV-A16 strains, the neutralizing antibody titer against CV-A16 could be determined within 15h by measuring luciferase signals by this assay. The pseudovirus CV-A16 neutralization assay (pCNA) was validated by comparison with a conventional CV-A16 neutralization assay (cCNA) in testing 174 human serum samples collected from children (age <5 years). The neutralizing antibody titers determined by these two assays were well correlated (R(2)=0.7689). These results suggest that the pCNA can serve as a rapid and objective procedure for the measurement of neutralizing antibodies against CV-A16. PMID:23178532

  7. Development of a poliovirus neutralization test with poliovirus pseudovirus for measurement of neutralizing antibody titer in human serum.

    PubMed

    Arita, Minetaro; Iwai, Masae; Wakita, Takaji; Shimizu, Hiroyuki

    2011-11-01

    In the Global Polio Eradication Initiative, laboratory diagnosis plays a critical role by isolating and identifying poliovirus (PV) from the stool samples from acute flaccid paralysis (AFP) cases. In recent years, reestablishment of PV circulation in countries where PV was previously eliminated has occurred because of decreased herd immunity, possibly due to poor vaccination coverage. To monitor the vulnerability of countries to PV circulation, surveillance of neutralizing-antibody titers against PV in susceptible populations is essential in the end game of the polio eradication program. In this study, we have developed a PV neutralization test with type 1, 2, and 3 PV pseudoviruses to determine the neutralizing-antibody titer against PV in human serum samples. With this test, the neutralizing-antibody titer against PV could be determined within 2 days by automated interpretation of luciferase signals without using infectious PV strains. We validated the pseudovirus PV neutralization test with 131 human serum samples collected from a wide range of age groups (ages 1 to >60 years) by comparison with a conventional neutralization test. We found good correlation in the neutralizing-antibody titers determined by these tests. These results suggest that a pseudovirus PV neutralization test would serve as a safe and simple procedure for the measurement of the neutralizing-antibody titer against PV. PMID:21880850

  8. Neutral Buoyancy Test - NB23 - Space Telescope

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Once the United States' space program had progressed from Earth's orbit into outerspace, the prospect of building and maintaining a permanent presence in space was realized. To accomplish this feat, NASA launched a temporary workstation, Skylab, to discover the effects of low gravity and weightlessness on the human body, and also to develop tools and equipment that would be needed in the future to build and maintain a more permanent space station. The structures, techniques, and work schedules had to be carefully designed to fit this unique construction site. The components had to be lightweight for transport into orbit, yet durable. The station also had to be made with removable parts for easy servicing and repairs by astronauts. All of the tools necessary for service and repairs had to be designed for easy manipulation by a suited astronaut. And construction methods had to be efficient due to limited time the astronauts could remain outside their controlled environment. In lieu of all the specific needs for this project, an environment on Earth had to be developed that could simulate a low gravity atmosphere. A Neutral Buoyancy Simulator (NBS) was constructed by NASA Marshall Space Flight Center (MSFC) in 1968. Since then, NASA scientists have used this facility to understand how humans work best in low gravity and also provide information about the different kinds of structures that can be built. Included in the plans for the space station was a space telescope. This telescope would be attached to the space station and directed towards outerspace. Astronomers hoped that the space telescope would provide a look at space that is impossible to see from Earth because of Earth's atmosphere and other man made influences. In an effort to make replacement and repairs easier on astronauts the space telescope was designed to be modular. Practice makes perfect as demonstrated in this photo: an astronaut practices moving modular pieces of the space telescope in the Neutral

  9. Predictions for ASKAP neutral hydrogen surveys

    NASA Astrophysics Data System (ADS)

    Duffy, Alan R.; Meyer, Martin J.; Staveley-Smith, Lister; Bernyk, Maksym; Croton, Darren J.; Koribalski, Bärbel S.; Gerstmann, Derek; Westerlund, Stefan

    2012-11-01

    The Australian Square Kilometre Array Pathfinder (ASKAP) will revolutionize our knowledge of gas-rich galaxies in the universe. Here we present predictions for two proposed extragalactic ASKAP neutral hydrogen (H I) emission-line surveys, based on semi-analytic models applied to cosmological N-body simulations. The ASKAP H I All-Sky Survey, known as Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY), is a shallow 3 π survey (z = 0-0.26) which will probe the mass and dynamics of over 6 × 105 galaxies. A much deeper small-area H I survey, called Deep Investigation of Neutral Gas Origins (DINGO), aims to trace the evolution of H I from z = 0 to 0.43, a cosmological volume of 4 × 107 Mpc3, detecting potentially 105 galaxies. The high-sensitivity 30 antenna ASKAP core (diameter ˜2 km) will provide an angular resolution of 30 arcsec (at z = 0). Our simulations show that the majority of galaxies detected in WALLABY (87.5 per cent) will be resolved. About 5000 galaxies will be well resolved, i.e. more than five beams (2.5 arcmin) across the major axis, enabling kinematic studies of their gaseous discs. This number would rise to 1.6 × 105 galaxies if all 36 ASKAP antennas could be used; the additional six antennas provide baselines up to 6 km, resulting in an angular resolution of 10 arcsec. For DINGO this increased resolution is highly desirable to minimize source confusion, reducing confusion rates from a maximum of 10 per cent of sources at the survey edge to 3 per cent. We estimate that the sources detected by WALLABY and DINGO will span four orders of magnitude in total halo mass (from 1011 to 1015 M⊙) and nearly seven orders of magnitude in stellar mass (from 105 to 1012 M⊙), allowing us to investigate the process of galaxy formation across the last four billion years.

  10. Envenomations by Bothrops and Crotalus snakes induce the release of mitochondrial alarmins.

    PubMed

    Zornetta, Irene; Caccin, Paola; Fernandez, Julián; Lomonte, Bruno; Gutierrez, José María; Montecucco, Cesare

    2012-01-01

    Skeletal muscle necrosis is a common manifestation of viperid snakebite envenomations. Venoms from snakes of the genus Bothrops, such as that of B. asper, induce muscle tissue damage at the site of venom injection, provoking severe local pathology which often results in permanent sequelae. In contrast, the venom of the South American rattlesnake Crotalus durissus terrificus, induces a clinical picture of systemic myotoxicity, i.e., rhabdomyolysis, together with neurotoxicity. It is known that molecules released from damaged muscle might act as 'danger' signals. These are known as 'alarmins', and contribute to the inflammatory reaction by activating the innate immune system. Here we show that the venoms of B. asper and C. d. terrificus release the mitochondrial markers mtDNA (from the matrix) and cytochrome c (Cyt c) from the intermembrane space, from ex vivo mouse tibialis anterior muscles. Cyt c was released to a similar extent by the two venoms whereas B. asper venom induced the release of higher amounts of mtDNA, thus reflecting hitherto some differences in their pathological action on muscle mitochondria. At variance, injection of these venoms in mice resulted in a different time-course of mtDNA release, with B. asper venom inducing an early onset increment in plasma levels and C. d. terrificus venom provoking a delayed release. We suggest that the release of mitochondrial 'alarmins' might contribute to the local and systemic inflammatory events characteristic of snakebite envenomations. PMID:22363828

  11. A Study of Neutral-Tone Syllables in Taiwan Mandarin

    ERIC Educational Resources Information Center

    Huang, Karen

    2012-01-01

    This dissertation studies the realization of the rhythm of Taiwan Mandarin and focuses on the quality of its unstressed (neutral-tone) syllables. Taiwan Mandarin (TM) is often described as more syllable-timed than Standard Mandarin (SM). In TM, the unstressed syllables occur less frequently. The quality of the unstressed (neutral-tone) syllables…

  12. A Case Study of Gender Neutral Policies in University Housing

    ERIC Educational Resources Information Center

    Chave, Josh

    2014-01-01

    Gender neutral housing is an innovative new policy being developed in colleges around the country. One reason to create these policies is an attempt to meet the unique needs and challenges of lesbian, gay, bisexual, and transgender students. As the number of gender neutral housing policies in the United States continues to rise, research has been…

  13. Phenotypic complexity and local variations in neutral degree.

    PubMed

    Lehre, Per Kristian; Haddow, Pauline C

    2007-02-01

    Neutrality is important in natural, molecular and artificial evolution. This work studies how local neutral degree varies over the genospace in a simple class of Lindenmayer-systems, and investigates whether this variation relates to Lempel-Ziv complexity of the phenotype. PMID:17188803

  14. Transport of neutral atoms and molecules in TFCX

    SciTech Connect

    Boley, C.D.

    1984-09-01

    The distribution of neutrals in the proposed reactor TFCX has been modeled by the 3-D Monte Carlo neutral transport code DEGAS, which has been run in conjunction with the 1-1/2-D time-dependent plasma transport code WHIST. The former code contains the best available treatment of neutral-particle physics, including a selection of wall reflection models. The latter code has a comprehensive set of plasma transport coefficients, an MHD equilibrium package, and provision for source terms such as those involving neutrals. It has a simple scrape-off model involving sound-speed flow to the neutralizer plates. The codes are run in iteration, so that the flux-surface averaged particle and energy sources due to interactions with neutrals are consistent with the plasma profiles. The design considered here has a bottom limiter with a pumping plenum. Results are given for the power balance, the mutually consistent plasma and neutral distributions set up in the edge region, the neutral density in the plenum, and the charge-exchange power deposition and erosion along the limiter.

  15. Autonomous mine detection system (AMDS) neutralization payload module

    NASA Astrophysics Data System (ADS)

    Majerus, M.; Vanaman, R.; Wright, N.

    2010-04-01

    The Autonomous Mine Detection System (AMDS) program is developing a landmine and explosive hazards standoff detection, marking, and neutralization system for dismounted soldiers. The AMDS Capabilities Development Document (CDD) has identified the requirement to deploy three payload modules for small robotic platforms: mine detection and marking, explosives detection and marking, and neutralization. This paper addresses the neutralization payload module. There are a number of challenges that must be overcome for the neutralization payload module to be successfully integrated into AMDS. The neutralizer must meet stringent size, weight, and power (SWaP) requirements to be compatible with a small robot. The neutralizer must be effective against a broad threat, to include metal and plastic-cased Anti-Personnel (AP) and Anti-Tank (AT) landmines, explosive devices, and Unexploded Explosive Ordnance (UXO.) It must adapt to a variety of threat concealments, overburdens, and emplacement methods, to include soil, gravel, asphalt, and concrete. A unique neutralization technology is being investigated for adaptation to the AMDS Neutralization Module. This paper will describe review this technology and how the other two payload modules influence its design for minimizing SWaP. Recent modeling and experimental efforts will be included.

  16. 40 CFR 721.10436 - Amine neutralized phosphated polyesters (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... polyesters (generic). 721.10436 Section 721.10436 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10436 Amine neutralized phosphated polyesters (generic). (a) Chemical... as amine neutralized phosphated polyesters (PMN P-99-1217 and P-99-1218) are subject to...

  17. 40 CFR 721.10436 - Amine neutralized phosphated polyesters (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... polyesters (generic). 721.10436 Section 721.10436 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10436 Amine neutralized phosphated polyesters (generic). (a) Chemical... as amine neutralized phosphated polyesters (PMN P-99-1217 and P-99-1218) are subject to...

  18. Neutral injection experiments on the ISX-B tokamak

    SciTech Connect

    Scott, S.D.

    1983-01-01

    The following topics are described: (1) review of confinement scaling in ISX-B with strong neutral injection in clean plasmas, (2) discussion of observed energy confinement improvement in slightly contaminated discharges (factor less than or equal to 2), and (3) preliminary evaluation of confinement with balanced neutral beam injection. (MOW)

  19. 42 CFR 412.352 - Budget neutrality adjustment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Budget neutrality adjustment. 412.352 Section 412.352 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 412.352 Budget neutrality adjustment. For FY 1992 through FY 1995, CMS will determine an adjustment...

  20. 42 CFR 412.352 - Budget neutrality adjustment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Budget neutrality adjustment. 412.352 Section 412.352 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 412.352 Budget neutrality adjustment. For FY 1992 through FY 1995, CMS will determine an adjustment...

  1. 42 CFR 412.352 - Budget neutrality adjustment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Budget neutrality adjustment. 412.352 Section 412.352 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 412.352 Budget neutrality adjustment. For FY 1992 through FY 1995, CMS will determine an adjustment...

  2. 42 CFR 412.352 - Budget neutrality adjustment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Budget neutrality adjustment. 412.352 Section 412.352 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 412.352 Budget neutrality adjustment. For FY 1992 through FY 1995, CMS will determine an adjustment...

  3. Genetic mapping of day-neutrality in cultivated strawberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Day-neutrality is a highly desirable trait in strawberry (Fragaria L.) breeding programs worldwide due to its importance in extending the harvest season in commercial production. Day-neutral genotypes are photoperiod insensitive and will initiate flowers under any photoperiod conditions as long as t...

  4. The Relationship between Neutralization Techniques and Induced Abortion

    PubMed Central

    Kalateh Sadati, Ahmad; Tabei, Seyed Ziaaddin; Salehzadeh, Hamzeh; Rahnavard, Farnaz; Namavar Jahromi, Bahia; Hemmati, Soroor

    2014-01-01

    Background: Induced abortion is not only a serious threat for women’s health, but also a controversial topic for its ethical and moral problems. We aimed to evaluate the relationship between neutralization techniques and attempting to commit abortion in married women with unintended pregnancy. Methods: After in-depth interviews with some women who had attempted abortion, neutralization themes were gathered. Next, to analyze the data quantitatively, a questionnaire was created including demographic and psychosocial variables specifically related to neutralization. The participants were divided into two groups (abortion and control) of unintended pregnancy and were then compared. Results: Analysis of psychosocial variables revealed a significant difference in the two groups at neutralization, showing that neutralization in the control group (56.97±10.24) was higher than that in the abortion group (44.19±12.44). To evaluate the findings more accurately, we examined the causal factors behind the behaviors of the abortion group. Binary logistic regression showed that among psychosocial factors, neutralization significantly affected abortion (95% CI=1.07-1.35). Conclusion: Despite the network of many factors affecting induced abortion, neutralization plays an important role in reinforcing the tendency to attempt abortion. Furthermore, the decline of religious beliefs, as a result of the secular context of the modern world, seems to have an important role in neutralizing induced abortion. PMID:25349851

  5. You Said "Neutral", but What Do You Mean?

    ERIC Educational Resources Information Center

    Jasien, Paul G.

    2010-01-01

    Using the term "neutral" as an example, this discussion examines difficulties that chemistry students face when trying to contextualize chemical terminology. Interview responses of 20 undergraduate students (majors in either chemistry or biology) indicate that some of students' context-based interpretations of "neutral" are shared, although up to…

  6. Spectroscopy of transient neutral species via negative ion photoelectron spectroscopy

    SciTech Connect

    Weaver, A.

    1991-12-01

    Negative ion photoelectron spectroscopy has been used to study two types of transient neutral species: bound free radicals (NO{sub 2} and NO{sub 3}) and unstable neutral species ((IHI) and (FH{sub 2})). The negative ion time-of-flight photoelectron spectrometer used for these experiments is described in detail.

  7. Spectroscopy of transient neutral species via negative ion photoelectron spectroscopy

    SciTech Connect

    Weaver, A.

    1991-12-01

    Negative ion photoelectron spectroscopy has been used to study two types of transient neutral species: bound free radicals (NO{sub 2} and NO{sub 3}) and unstable neutral species ([IHI] and [FH{sub 2}]). The negative ion time-of-flight photoelectron spectrometer used for these experiments is described in detail.

  8. 46 CFR 111.05-15 - Neutral grounding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Neutral grounding. 111.05-15 Section 111.05-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Equipment Ground, Ground Detection, and Grounded Systems § 111.05-15 Neutral grounding. (a)...

  9. 46 CFR 111.05-15 - Neutral grounding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Neutral grounding. 111.05-15 Section 111.05-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Equipment Ground, Ground Detection, and Grounded Systems § 111.05-15 Neutral grounding. (a)...

  10. 46 CFR 111.05-15 - Neutral grounding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Neutral grounding. 111.05-15 Section 111.05-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL... propulsion, power, lighting, or distribution system having a neutral bus or conductor must have the...

  11. 46 CFR 111.05-15 - Neutral grounding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Neutral grounding. 111.05-15 Section 111.05-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL... propulsion, power, lighting, or distribution system having a neutral bus or conductor must have the...

  12. 46 CFR 111.05-15 - Neutral grounding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Neutral grounding. 111.05-15 Section 111.05-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL... propulsion, power, lighting, or distribution system having a neutral bus or conductor must have the...

  13. Thermochemical Analysis of Neutralization Reactions: An Introductory Discovery Experiment

    ERIC Educational Resources Information Center

    Mills, Kenneth V.; Gullmette, Louise W.

    2007-01-01

    The article describes a new discovery experiment that uses thermodynamical analysis to study neutralization reactions based on neutralization of citric acid. The experiment would be able to reinforce students' understanding of stoichiometry and allow for the discovery of basic concepts of thermochemistry.

  14. Collegiate Drinking Behavior: A Test of Neutralization Theory.

    ERIC Educational Resources Information Center

    Dodder, Richard; Hughes, Stella P.

    1987-01-01

    Surveyed drinking patterns and problem-related behavior of 534 college students. Modified Norris-Dodder Neutralization Scale for juvenile delinquency to measure orientations toward drinking. Results indicated that greater acceptance of neutralizations related consistently to greater quantity and frequency of drinking as well as to more…

  15. Neutralization and Delinquency: A Comparison by Sex and Ethnicity.

    ERIC Educational Resources Information Center

    Mitchell, Jim; And Others

    1990-01-01

    Path model illustrating relationships between church attendance, delinquent peer association, tendency to neutralize delinquency, and self-reported delinquent behavior was compared between males and females and between Mexican-American and Anglo college students (N=694). In all four subsamples, strongest paths were between neutralization and…

  16. Seawater neutralization of alkaline bauxite residue and implications for revegetation.

    PubMed

    Menzies, N W; Fulton, I M; Morrell, W J

    2004-01-01

    Reaction of bauxite residue with seawater results in neutralization of alkalinity through precipitation of Mg-, Ca-, and Al-hydroxide and carbonate minerals. In batch studies, the initial pH neutralization reaction was rapid (<5 min), with further reaction continuing to reduce pH for several weeks. Reaction with seawater produced a residue pH of 8 to 8.5. Laboratory leaching column studies were undertaken to provide information on seawater neutralization of the coarse-textured fraction of the waste, residue sand (RS), under conditions comparable with those that might be applied in the field. An 0.80-m-deep column of RS was neutralized by the application of the equivalent of 2-m depth of seawater. In addition to lowering the pH and Na content of the residue, seawater neutralization resulted in the addition of substantial amounts of the plant nutrients Ca, Mg, and K to the profile. Similar results were also obtained from a field-scale assessment of neutralization. However, the accumulation of precipitate, consisting of hydrotalcite, aragonite, and pyroaurite, in the drainage system may preclude the use of in situ seawater neutralization as a routine rehabilitation practice. Following seawater neutralization, RS remains too saline to support plant growth and would require fresh water leaching before revegetation. PMID:15356249

  17. 27 CFR 19.457 - Neutralizing denatured spirits.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Neutralizing denatured spirits. 19.457 Section 19.457 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... spirits, if the intended effect of the denaturants is not reduced. Proprietors who neutralize...

  18. Troubling Neutrality: Toward a Philosophy of Teacher Ambiguity

    ERIC Educational Resources Information Center

    Heybach, Jessica A.

    2014-01-01

    Who is keeping watch to warn when policies and practices become essentially the same as those used in previous eras to justify the destruction of human beings? This question is asked by author Jessica Heybach, as she describes the etymological roots of the word "neutrality," the social function of teacher as neutral, and its relationship…

  19. Approximate neutral point of a subsonic canard aircraft

    NASA Technical Reports Server (NTRS)

    Phillips, J. D.

    1985-01-01

    An approximate formula is derived for the position of the neutral point in canard aircraft. This formula accounts for the aerodynamic interference between the wing (rear wing) and the canard (forward wing). Topics covered include determination of the canard downwash derivative, determination of the canard and wing liftslopes including the aerodynamic interference, and calculation of the neutral point position.

  20. Emergence of structural patterns in neutral trophic networks.

    PubMed

    Canard, Elsa; Mouquet, Nicolas; Marescot, Lucile; Gaston, Kevin J; Gravel, Dominique; Mouillot, David

    2012-01-01

    Interaction networks are central elements of ecological systems and have very complex structures. Historically, much effort has focused on niche-mediated processes to explain these structures, while an emerging consensus posits that both niche and neutral mechanisms simultaneously shape many features of ecological communities. However, the study of interaction networks still lacks a comprehensive neutral theory. Here we present a neutral model of predator-prey interactions and analyze the structural characteristics of the simulated networks. We find that connectance values (complexity) and complexity-diversity relationships of neutral networks are close to those observed in empirical bipartite networks. High nestedness and low modularity values observed in neutral networks fall in the range of those from empirical antagonist bipartite networks. Our results suggest that, as an alternative to niche-mediated processes that induce incompatibility between species ("niche forbidden links"), neutral processes create "neutral forbidden links" due to uneven species abundance distributions and the low probability of interaction between rare species. Neutral trophic networks must be seen as the missing endpoint of a continuum from niche to purely stochastic approaches of community organization. PMID:22899987

  1. Statistical Analysis of the Heavy Neutral Atoms Measured by IBEX

    NASA Astrophysics Data System (ADS)

    Park, Jeewoo; Kucharek, Harald; Möbius, Eberhard; Galli, André; Livadiotis, George; Fuselier, Steve A.; McComas, David J.

    2015-10-01

    We investigate the directional distribution of heavy neutral atoms in the heliosphere by using heavy neutral maps generated with the IBEX-Lo instrument over three years from 2009 to 2011. The interstellar neutral (ISN) O&Ne gas flow was found in the first-year heavy neutral map at 601 keV and its flow direction and temperature were studied. However, due to the low counting statistics, researchers have not treated the full sky maps in detail. The main goal of this study is to evaluate the statistical significance of each pixel in the heavy neutral maps to get a better understanding of the directional distribution of heavy neutral atoms in the heliosphere. Here, we examine three statistical analysis methods: the signal-to-noise filter, the confidence limit method, and the cluster analysis method. These methods allow us to exclude background from areas where the heavy neutral signal is statistically significant. These methods also allow the consistent detection of heavy neutral atom structures. The main emission feature expands toward lower longitude and higher latitude from the observational peak of the ISN O&Ne gas flow. We call this emission the extended tail. It may be an imprint of the secondary oxygen atoms generated by charge exchange between ISN hydrogen atoms and oxygen ions in the outer heliosheath.

  2. Reactions of Kr+2 with various neutrals

    NASA Astrophysics Data System (ADS)

    Praxmarer, C.; Hansel, A.; Jordan, A.; Kraus, H.; Lindinger, W.

    1993-11-01

    Earlier studies performed by Shul and co-workers [R.J. Schul, B.L. Upschulte, R. Pasarella, R.G. Keesee and A.W. Castleman, Jr., J. Chem. Phys. 91 (1987) 2557; R.J. Schul, R. Pasarella, B.L. Upschulte, R.G. Keesee and A.W. Castleman, Jr., J. Chem. Phys., 86 (1987) 4446] reporting room temperature data on 14 reactions of Kr+2 have been extended by investigating the energy dependences of the overall rate coefficients and the branching ratios of Kr+2 reactions with 11 neutral reactants using a selected ion flow drift tube. Switching is the main reaction channel in parallel with charge transfer in many of the reactions investigated. The charge transfer observed in these reactions is discussed using a Franck--Condon model, due to Bearman . [G.H. Bearman, J.D. Earl, R.J. Pieper, H.H. Harris and J.J. Leventhal, Phys. Rev. A, 13 (1976) 1734]. The binding energies obtained for KrCO+ and KrCO+2 are (1.07±0.08) eV and (0.82±0.03) eV respectively, and that obtained for (CO2)+2 is (0.65±0.03) eV. The reduced mobility of Kr+2 in He in the range 10 Td [less-than-or-equals, slant]E/N[less-than-or-equals, slant] 150 Td is also reported.

  3. Neutral Beam Ion Loss Modelling for NSTX

    NASA Astrophysics Data System (ADS)

    Darrow, D. S.; Akers, R.; Kaye, S. M.; Mikkelsen, D. R.

    1999-11-01

    The loss of 80 keV D neutral beam ions to the walls has been modeled for a range of plasma conditions in NSTX using the EIGOL code[1]. Initial results of the code are in reasonable agreement with those from the LOCUST code[2]. Both codes predict loss fractions of 20% for a discharge with β_T=40% and q_0=2.6. Losses are strongly concentrated on the front face and edges of the high-harmonic fast wave antenna as it projects farther inward than other internal structures at the midplane. The edges of the passive stabilizer plates near the midplane are also subject to a large flux of lost beam ions under some conditions. The dependence of the loss upon the plasma density profile, I_p, and BT will be presented. [1] D. S. Darrow, et al., in Proceedings of the 26th EPS Conference on Controlled Fusion and Plasma Physics, Maastricht, The Netherlands, 14-18 June 1999. [2] R. Akers, et al., ibid.

  4. High Precision Spectroscopy of Neutral Beryllium-9

    NASA Astrophysics Data System (ADS)

    Lau, Chui Yu; Williams, Will

    2015-05-01

    We report on the progress of high precision spectroscopy of the 2s2p singlet and triplet states in beryllium-9. Our goal is to improve the experimental precision on the energy levels of the 2s2p triplet J = 0, 1, and 2 states by a factor of 500, 100, and 500 respectively in order to delineate various theoretical predictions. The goal for the 2s2p singlet (J = 1) state is to improve the experimental precision on the energy level by a factor of 600 as a test of quantum electrodynamics. Our experimental setup consists of an oven capable of 1400 C that produces a collimated beam of neutral beryllium-9. The triplet states are probed with a 455 nm ECDL stabilized to a tellurium-210 line. The singlet state is probed with 235nm light from a frequency quadrupled titanium sapphire laser, where the frequency doubled light at 470 nm is stabilized to another tellurium-210 line. We also present our progress on improving the absolute accuracy of our frequency reference by using an ultrastable/low drift fiber coupled cavity.

  5. SPARQL Assist language-neutral query composer

    PubMed Central

    2012-01-01

    Background SPARQL query composition is difficult for the lay-person, and even the experienced bioinformatician in cases where the data model is unfamiliar. Moreover, established best-practices and internationalization concerns dictate that the identifiers for ontological terms should be opaque rather than human-readable, which further complicates the task of synthesizing queries manually. Results We present SPARQL Assist: a Web application that addresses these issues by providing context-sensitive type-ahead completion during SPARQL query construction. Ontological terms are suggested using their multi-lingual labels and descriptions, leveraging existing support for internationalization and language-neutrality. Moreover, the system utilizes the semantics embedded in ontologies, and within the query itself, to help prioritize the most likely suggestions. Conclusions To ensure success, the Semantic Web must be easily available to all users, regardless of locale, training, or preferred language. By enhancing support for internationalization, and moreover by simplifying the manual construction of SPARQL queries through the use of controlled-natural-language interfaces, we believe we have made some early steps towards simplifying access to Semantic Web resources. PMID:22373327

  6. Observation of quantized conductance in neutral matter

    NASA Astrophysics Data System (ADS)

    Husmann, Dominik; Krinner, Sebastian; Lebrat, Martin; Grenier, Charles; Nakajima, Shuta; Häusler, Samuel; Brantut, Jean-Philippe; Esslinger, Tilman

    2015-05-01

    In transport experiments, the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps, with a size determined solely by Planck's constant h. Here we report the observation of quantized conductance in the transport of neutral atoms driven by a chemical potential bias. We use high-resolution lithography to shape light potentials that realize either a quantum point contact or a quantum wire for atoms. These constrictions are imprinted on a quasi-two-dimensional ballistic channel connecting the reservoirs. By varying either a gate potential or the transverse confinement of the constrictions, we observe distinct plateaux in the atom conductance. The conductance in the first plateau is found to be equal to the universal conductance quantum, 1/h. We use Landauer's formula to model our results and find good agreement for low gate potentials, with all parameters determined a priori. We eventually explore the behavior of a strongly interacting Fermi gas in the same configuration, and the consequences of the emergence of superfluidity.

  7. Neutral surface layer turbulence over complex terrain

    SciTech Connect

    Bowen, B.M.

    1995-09-01

    Accurate turbulence estimates are important input to atmospheric dispersion models since they characterize downwind dispersion and hence, potential pollutant concentrations. When only basic wind information is available, an atmospheric modeler must first estimate roughness length (z{sub 0},) at the location of interest, ({mu}*) from similarity theory using average wind speed ({mu}) and z{sub 0}, and finally apply experimentally derived relationships to determine the turbulence intensities. Even when turbulence coefficients are measured, the turbulence profile must be estimated in the surface layer, using, for example, the power law recommended in a US Environmental Protection Agency guidance document. In this study, turbulent intensities and wind profiles are analyzed in eight direction sectors during near neutral stability. ``Local`` and ``regional`` roughness lengths are calculated from wind speed profiles and from longitudinal turbulence intensities ({sigma}{sub {mu}}) at both sites. With ``regional`` roughness length, complex terrain features are in effect the roughness elements. Profiles of median, 15-minute averaged turbulence intensities {sigma}{sub {mu}}, {sigma}{sub {nu}} and {sigma}{sub w} are calculated at both sites. Profiles of median {sigma}{sub {theta}} and {sigma}{sub {phi}} are also calculated using four mean values of regional z{sub 0} at both sites. Finally, differences between widely-used turbulence relationships and the relationships determined in this study, and their possible effect on model results, are discussed.

  8. Neutral particle mass spectrometry with nanomechanical systems

    PubMed Central

    Sage, Eric; Brenac, Ariel; Alava, Thomas; Morel, Robert; Dupré, Cécilia; Hanay, Mehmet Selim; Roukes, Michael L.; Duraffourg, Laurent; Masselon, Christophe; Hentz, Sébastien

    2015-01-01

    Current approaches to mass spectrometry (MS) require ionization of the analytes of interest. For high-mass species, the resulting charge state distribution can be complex and difficult to interpret correctly. Here, using a setup comprising both conventional time-of-flight MS (TOF-MS) and nano-electromechanical systems-based MS (NEMS-MS) in situ, we show directly that NEMS-MS analysis is insensitive to charge state: the spectrum consists of a single peak whatever the species’ charge state, making it significantly clearer than existing MS analysis. In subsequent tests, all the charged particles are electrostatically removed from the beam, and unlike TOF-MS, NEMS-MS can still measure masses. This demonstrates the possibility to measure mass spectra for neutral particles. Thus, it is possible to envisage MS-based studies of analytes that are incompatible with current ionization techniques and the way is now open for the development of cutting-edge system architectures with unique analytical capability. PMID:25753929

  9. Neutral Excitations in the Gaffnian state

    NASA Astrophysics Data System (ADS)

    Kang, Byungmin; Moore, Joel E.

    The Fractional Quantum Hall Effect (FQHE) is one of the most well-studied systems having topological order. Starting with the pioneering work by Laughlin, the model wave function approach has been shown to provide essential information for understanding topological order in gapped incompressible states. We study a model wave function called the Gaffnian state which is believed to represent a gapless, strongly correlated state that is very different from conventional metals. To understand this exotic gapless state better, we provide a representation in which the pairing structure of the Gaffnian state becomes more explicit. We employ the single-mode approximation of the Girvin-MacDonald-Platzman (GMP) mode, which is a neutral collective exitation mode, in order to have a physical picture of the gaplessness of the Gaffnian state. In particular, we discuss how to extract systematically the relevant physics in the long-distance, large electron number limit of the FQH states using a numerical calculation with relatively few electrons.

  10. Unconventional electromagnetic mode in neutral Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Ferreiros, Yago; Cortijo, Alberto

    2016-05-01

    We study light propagation in a neutral Weyl semimetal with the Fermi level lying at the Weyl nodes in the weak self-interacting regime. The nontrivial topology induces a screening effect in one of the two transverse gauge fields, for which we find two branches of attenuated collective excitations. In addition to the known topologically gapped photon mode, a different massless and slightly damped excitation appears. Strikingly, at low energies, this excitation has a linear dispersion and it propagates with the same velocity as the electrons, while at energies well above the electron-hole continuum threshold it behaves as a massive attenuated photon with velocity similar to the speed of light in the material. There is a crossover at a certain momentum in the direction perpendicular to the separation of the Weyl nodes above which this gapless mode enters into an overdamped regime. Regarding the unscreened gauge field, we show that it is also attenuated, which is a nontopological property shared by Dirac semimetals as well.

  11. Neutral Buoyancy Simulator- NB38 -Space Telescope

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Pictured is MSFC's Neutral Buoyancy Simulator (NBS) that served as the test center for shuttle astronauts training for Hubble related missions. Shown are astronauts Bruce McCandless and Sharnon Lucid being fitted for their space suits prior to entering the NBS to begin training on the space telescope axial scientific instrument changeout.

  12. Neutral beam processing of semiconductor materials

    SciTech Connect

    Cross, J.; Hoffbauer, M.

    1996-09-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The most important challenge facing the US and global microelectronics industry is to identify and develop the next generation of processing technology to produce device structures with dimensions substantially less than 0.25 microns. This project sought to develop controlled, contamination-free etching techniques that are more selective and less damaging than current methods, which are based on inducing surface chemical reactions by rather crude ion-damage mechanisms. The use of non-charged particle etching and cleaning processes in the production of memory and microprocessor chips has been identified by The National Technology Roadmap for Semiconductors as a new manufacturing technique that may aid in the quest for feature sizes of 0.1 micron and lower. The Hyperthermal Neutral Beam Facility at Los Alamos has demonstrated significant improvement over ion-assisted etching in experiments using energetic oxygen and chlorine atoms.

  13. Electromagnetic charged and neutral kaon form factors

    SciTech Connect

    Roberts, C.D.; Burden, C.J.; Thomson, M.J.

    1995-08-01

    The electromagnetic form factor of the charged and neutral kaon is calculated using the approach applied in the successful study of the pion form factor, described above. The charged kaon form factor will be measured in forthcoming experiments at CEBAF. Our calculation involves the dressed strange quark propagator, to which F{sub {pi}}(q{sup 2}) is not sensitive, and hence it provides us with constraints on the strange-quark sector of QCD. Our preliminary results are encouraging. We find that the strange and up/down quark propagators are not too different, once the change in the current-quark-mass is accounted for. However, the difference that remains is important since it allows {l_angle}{bar s}s{r_angle}<{l_angle}{bar u}u{r_angle}. This calculation is the first to yield a value of f{sub K}/f{sub {pi}} that is in good agreement with experiment and also yields r{sub K+}/r{sub {pi}} in good agreement with experiment. Our calculated charged kaon form factor provides a prediction that will be tested in the forthcoming CEBAF experiments. Our studies also show that K{sup 0} has a negative charge radius, as is to be expected. Our calculated value will be compared with that measured in K{sub s}{sup 0} regeneration from electrons.

  14. Neutralization and biodegradation of sulfur mustard

    SciTech Connect

    Harvey, S.P.; Beaudry, W.T.; Szafraniec, L.L.

    1995-12-31

    One technology recommended for consideration for the disposal of the U.S. Chemical Stockpile is chemical neutralization followed by biodegradation. In the case of sulfur mustard ({open_quotes}mustard gas{close_quotes}, 2,2{prime}-dichlorodiethyl sulfide), alkaline hydrolysis yields a detoxified and biodegradable product. The hydrolysis reaction was studied with respect to the effects of temperature and sulfur mustard concentration on the rate and products of the reaction. A 28-fold overall rate enhancement was observed at 70{degrees}C vs. 30{degrees}C corresponding to an enthalpy of activation value of 17.9 Kcal/mole. Material balance studies conducted by {sup 1}H Nuclear Magnetic Resonance analysis showed that the products of the reaction consisted of thiodiglycol was relatively greater at lower sulfur mustard concentrations and higher temperatures. As temperatures were decreased or sulfur mustard concentrations was increased, the proportion of ether-type compounds increased accordingly. Conditions of 1% (vol//vol) sulfur mustard, 5% stoichiometric excess of NaOH and 90{degrees}C were selected for generation of the hydrolyzed bioreactor influent material. The bioreactor was seeded with activated sludge and was initially operated as 5 liter sequencing batch reactor with a hydraulic residence time of approximately days. Early results show total organic carbon removal of greater than 90%.

  15. Augmenting Transition Probabilities for Neutral Atomic Nitrogen

    NASA Technical Reports Server (NTRS)

    Terrazas-Salines, Imelda; Park, Chul; Strawa, Anthony W.; Hartman, G. Joseph (Technical Monitor)

    1996-01-01

    The transition probability values for a number of neutral atomic nitrogen (NI) lines in the visible wavelength range are determined in order to augment those given in the National Bureau of Standards Tables. These values are determined from experimentation as well as by using the published results of other investigators. The experimental determination of the lines in the 410 to 430 nm range was made from the observation of the emission from the arc column of an arc-heated wind tunnel. The transition probability values of these NI lines are determined to an accuracy of +/- 30% by comparison of their measured intensities with those of the atomic oxygen (OI) multiplet at around 615 nm. The temperature of the emitting medium is determined both using a multiple-layer model, based on a theoretical model of the flow in the arc column, and an empirical single-layer model. The results show that the two models lead to the same values of transition probabilities for the NI lines.

  16. Neutral hydrogen in compact groups of galaxies

    SciTech Connect

    Williams, B.A.; Rood, H.J.

    1987-02-01

    Integrated H I profiles were detected for 34 of 51 Hickson compact groups (HCGs) of galaxies, and sensitive upper limits to the H I flux density were measured for the other 17. About 60 percent of the galaxies within compact groups are spirals, and a significant tendency exists for the fraction of elliptical galaxies to increase with group surface brightness. The amount of dark matter within the compact group region is negligibly small. An HCG on average contains half as much neutral hydrogen as a loose group with a similar spectrum of galaxy luminosities and morphological types, implying that compact groups are independent dynamical entities and not transient or projected configurations of loose groups. The observed fraction of galaxies which are luminous enough to be possible merger products of compact groups is small compared with the fraction required by the theory of dynamical friction. A clear discrepancy thus exists between solid empirical evidence and a straightforward prediction of Newtonian dynamical theory in a setting which does not permit a dark matter explanation. 44 references.

  17. Electron attenuation in free, neutral ethane clusters.

    PubMed

    Winkler, M; Myrseth, V; Harnes, J; Børve, K J

    2014-10-28

    The electron effective attenuation length (EAL) in free, neutral ethane clusters has been determined at 40 eV kinetic energy by combining carbon 1s x-ray photoelectron spectroscopy and theoretical lineshape modeling. More specifically, theory is employed to form model spectra on a grid in cluster size (N) and EAL (λ), allowing N and λ to be determined by optimizing the goodness-of-fit χ(2)(N, λ) between model and observed spectra. Experimentally, the clusters were produced in an adiabatic-expansion setup using helium as the driving gas, spanning a range of 100-600 molecules in mean cluster size. The effective attenuation length was determined to be 8.4 ± 1.9 Å, in good agreement with an independent estimate of 10 Å formed on the basis of molecular electron-scattering data and Monte Carlo simulations. The aggregation state of the clusters as well as the cluster temperature and its importance to the derived EAL value are discussed in some depth. PMID:25362297

  18. Electron attenuation in free, neutral ethane clusters

    SciTech Connect

    Winkler, M.; Harnes, J.; Børve, K. J.; Myrseth, V.

    2014-10-28

    The electron effective attenuation length (EAL) in free, neutral ethane clusters has been determined at 40 eV kinetic energy by combining carbon 1s x-ray photoelectron spectroscopy and theoretical lineshape modeling. More specifically, theory is employed to form model spectra on a grid in cluster size (N) and EAL (λ), allowing N and λ to be determined by optimizing the goodness-of-fit χ{sup 2}(N, λ) between model and observed spectra. Experimentally, the clusters were produced in an adiabatic-expansion setup using helium as the driving gas, spanning a range of 100–600 molecules in mean cluster size. The effective attenuation length was determined to be 8.4 ± 1.9 Å, in good agreement with an independent estimate of 10 Å formed on the basis of molecular electron-scattering data and Monte Carlo simulations. The aggregation state of the clusters as well as the cluster temperature and its importance to the derived EAL value are discussed in some depth.

  19. Universality in a Neutral Evolution Model

    NASA Astrophysics Data System (ADS)

    King, Dawn; Scott, Adam; Maric, Nevena; Bahar, Sonya

    2013-03-01

    Agent-based models are ideal for investigating the complex problems of biodiversity and speciation because they allow for complex interactions between individuals and between individuals and the environment. Presented here is a ``null'' model that investigates three mating types - assortative, bacterial, and random - in phenotype space, as a function of the percentage of random death δ. Previous work has shown phase transition behavior in an assortative mating model with variable fitness landscapes as the maximum mutation size (μ) was varied (Dees and Bahar, 2010). Similarly, this behavior was recently presented in the work of Scott et al. (submitted), on a completely neutral landscape, for bacterial-like fission as well as for assortative mating. Here, in order to achieve an appropriate ``null'' hypothesis, the random death process was changed so each individual, in each generation, has the same probability of death. Results show a continuous nonequilibrium phase transition for the order parameters of the population size and the number of clusters (analogue of species) as δ is varied for three different mutation sizes of the system. The system shows increasing robustness as μ increases. Universality classes and percolation properties of this system are also explored. This research was supported by funding from: University of Missouri Research Board and James S. McDonnell Foundation

  20. Nuclear pumping of a neutral carbon laser

    NASA Technical Reports Server (NTRS)

    Prelas, M. A.; Anderson, J. H.; Boody, F. P.; Nagalingam, S. J. S.; Miley, G. H.

    1978-01-01

    Nuclear pumped lasing on the neutral carbon line at 1.45 microns has been achieved in mixtures of He-CO, He-N2-CO, He-CO2, and Ne-CO and Ne-CO2. A minimum thermal neutron flux of 2 x 10 to the 14th n/sq cm-sec was sufficient for oscillation in the helium mixtures. The peak of the laser output was delayed up to 5.5 ms relative to the neutron pulse in He-CO2, He-N2-CO, Ne-CO and Ne-CO2 mixtures while no delay was observed in He-CO mixtures. Lasing was obtained with helium pressures from 20 to 800 T, Ne pressures from 100 to 200 T, CO from 0.25 to 20 mT, N2 from 0.5 to 5 mT, and CO2 from 0.1 to 25 mT in the respective mixtures.

  1. Nuclear pumping of a neutral carbon laser

    NASA Technical Reports Server (NTRS)

    Prelas, M. A.; Anderson, J. H.; Boody, F. P.; Nagalingam, S. J. S.; Miley, G. H.

    1978-01-01

    Nuclear pumped lasing on the neutral carbon line at 1.45 micron was achieved in mixtures of He-CO, He-N2-CO, He-CO2, and Ne-CO and Ne-CO2. A minimum thermal neutron flux of 2 x 10 to the 14th power sq cm-sec was sufficient for oscillation in the helium mixtures. The peak of the laser output was delayed up to 5.5 ms relative to the neutron pulse in He-CO2, He-N2-CO, Ne-CO, and Ne-CO2 mixtures while no delay was observed in He-CO mixtures. Lasing was obtained with helium pressures from 20 to 800 T, Ne pressures from 100 to 200 T, CO from 0.25 to 20 mT, N2 from 0.5 mT, and CO2 from 0.1 to 25 mT in the respective mixtures.

  2. Adiabatic Quantum Computation with Neutral Atoms

    NASA Astrophysics Data System (ADS)

    Biedermann, Grant

    2013-03-01

    We are implementing a new platform for adiabatic quantum computation (AQC)[2] based on trapped neutral atoms whose coupling is mediated by the dipole-dipole interactions of Rydberg states. Ground state cesium atoms are dressed by laser fields in a manner conditional on the Rydberg blockade mechanism,[3,4] thereby providing the requisite entangling interactions. As a benchmark we study a Quadratic Unconstrained Binary Optimization (QUBO) problem whose solution is found in the ground state spin configuration of an Ising-like model. In collaboration with Lambert Parazzoli, Sandia National Laboratories; Aaron Hankin, Center for Quantum Information and Control (CQuIC), University of New Mexico; James Chin-Wen Chou, Yuan-Yu Jau, Peter Schwindt, Cort Johnson, and George Burns, Sandia National Laboratories; Tyler Keating, Krittika Goyal, and Ivan Deutsch, Center for Quantum Information and Control (CQuIC), University of New Mexico; and Andrew Landahl, Sandia National Laboratories. This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories

  3. The buffer effect in neutral electrolyte supercapacitors

    NASA Astrophysics Data System (ADS)

    Vindt, Steffen T.; Skou, Eivind M.

    2016-02-01

    The observation that double-layer capacitors based on neutral aqueous electrolytes can have significantly wider usable potential windows than those based on acidic or alkaline electrolytes is studied. This effect is explained by a local pH change taking place at the electrode surfaces, leading to a change in the redox potential of water in opposite directions on the two electrodes, resulting in the wider stability window. The magnitude of this effect is suggested to be dependent on the buffer capacity, rather than the intrinsic pH value of the electrolyte. This is confirmed by studying the impact of addition of a buffer to such systems. It is shown that a 56 % higher dynamic storage capacity may be achieved, simply by controlling the buffer capacity of the electrolyte. The model system used, is based on a well-known commercial activated carbon (NORIT™ A SUPRA) as the electrode material, aqueous potassium nitrate as the electrolyte and potassium phosphates as the buffer system.

  4. Ultracold plasma expansion as a function of charge neutrality

    SciTech Connect

    Witte, Craig; Roberts, Jacob L.

    2014-10-15

    Ultracold plasmas (UCPs) are created under conditions of near but not perfect neutrality. In the limit of zero electron temperature, electron screening results in non-neutrality manifesting itself as an interior region of the UCP with both electrons and ions and an exterior region composed primarily of ions. The interior region is the region of the most scientific interest for 2-component ultracold plasma physics. This work presents a theoretical model through which the time evolution of non-neutral UCPs is calculated. Despite Debye screening lengths much smaller than the characteristic plasma spatial size, model calculations predict that the expansion rate and the electron temperature of the UCP interior is sensitive to the neutrality of the UCP. The predicted UCP dependence on neutrality has implications for the correct measurement of several UCP properties, such as electron temperature, and a proper understanding of evaporative cooling of the electrons in the UCP.

  5. Neutral Atom Diffusion in a Partially Ionized Prominence Plasma

    NASA Technical Reports Server (NTRS)

    Gilbert, Holly

    2010-01-01

    The support of solar prominences is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force. Because the prominence plasma is only partially ionized. it is necessary to consider in addition the support of the neutral component of the prominence plasma. This support is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material,

  6. Investigation of Relationship between QBO and Ionospheric Neutral Temperature

    NASA Astrophysics Data System (ADS)

    Saǧır, Selçuk; Atıcı, Ramazan; Özcan, Osman

    2016-07-01

    The relationship between Quasi Biennial Oscillation (QBO) measured at 10 hPa altitude and neutral temperature obtained from NRLMSIS-00 model for 90 km altitude of ionosphere is statistically investigated. For this study, multiple-regression model is used. To see effect on neutral temperature of QBO directions, Dummy variables are added to model established. In the results of performed analysis, it is observed that QBO is effected on neutral temperature of ionosphere. It is determined that 57% of variations at neutral temperature can be explainable by QBO. According to the established model, statistical explainable ratio was determined as 1% that it is the highest rate. Also, it is seen that an increase/a decrease of 1 meter per second at QBO give rise to an increase/a decrease of 0,07 K at neutral temperature.

  7. Neutralization tests on the SERT II spacecraft. [of ion beams

    NASA Technical Reports Server (NTRS)

    Kerslake, W. R.; Domitz, S.

    1979-01-01

    Orbit precession returned the SERT II spacecraft to continuous sunlight in January 1979 for the first time since early 1972, and new experiments were planned and conducted. Neutralization of an ion beam was accomplished by a second neutralizer cathode located 1 meter away. Plasma potential measurements were made of the plasma surrounding the ion beam and connecting the beam to the second neutralizer. When the density of the connecting plasma was increased by turning on the main discharge of a neighboring ion thruster, the neutralization of the ion beam occurred with improved (lower) coupling voltage. These and other tests reported should aid in the future design of spacecraft using electric thruster systems. Data taken indicate that cross neutralization of ion thrusters in a multiple thruster array should occur readily.

  8. Surface conversion techniques for low energy neutral atom imagers

    NASA Technical Reports Server (NTRS)

    Quinn, J. M.

    1995-01-01

    This investigation has focused on development of key technology elements for low energy neutral atom imaging. More specifically, we have investigated the conversion of low energy neutral atoms to negatively charged ions upon reflection from specially prepared surfaces. This 'surface conversion' technique appears to offer a unique capability of detecting, and thus imaging, neutral atoms at energies of 0.01 - 1 keV with high enough efficiencies to make practical its application to low energy neutral atom imaging in space. Such imaging offers the opportunity to obtain the first instantaneous global maps of macroscopic plasma features and their temporal variation. Through previous in situ plasma measurements, we have a statistical picture of large scale morphology and local measurements of dynamic processes. However, with in situ techniques it is impossible to characterize or understand many of the global plasma transport and energization processes. A series of global plasma images would greatly advance our understanding of these processes and would provide the context for interpreting previous and future in situ measurements. Fast neutral atoms, created from ions that are neutralized in collisions with exospheric neutrals, offer the means for remotely imaging plasma populations. Energy and mass analysis of these neutrals provides critical information about the source plasma distribution. The flux of neutral atoms available for imaging depends upon a convolution of the ambient plasma distribution with the charge exchange cross section for the background neutral population. Some of the highest signals are at relatively low energies (well below 1 keV). This energy range also includes some of the most important plasma populations to be imaged, for example the base of the cleft ion fountain.

  9. Studies of Magnetized Plasmas Interacting with Neutral Gas

    NASA Astrophysics Data System (ADS)

    Chiu, Gordon San-Yin

    1995-01-01

    Experiments and computer simulations have been performed in a linear magnetized helium and argon plasma column of similar collisionalities to that expected in ITER to examine heat flow and particle parameters. Plasma properties are found to differ significantly at low and high ambient neutral pressures. At pressures below 100 mT, plasmas obey the low -recycling prediction of approximate plasma pressure balance. Density decreases by a factor of about 2 to 3 with respect to that upstream, and T_{e} remains isothermal. Power flow is predominantly convective. Results obtained with varying neutral pressures and input power are consistent with zero-dimensional modeling of particle and energy balances. Ion are found to be heated by the electrons via classical energy equilibration, moderated by charge-exchange. Neutrals are heated above room temperatures. They exhibit a two-temperature population, the hotter neutrals due to charge-exchange with ions, and the colder via electron -neutral elastic collisions. The 2-d fluid code B2 has been modified to simulate the experimental conditions. Results are in good agreement. A novel regime of abrupt collapse in plasma pressure, affecting both density and T_{e} and accompanied by a dramatic increase in neutral line radiation, has been observed in high (>100 mT) pressure discharges. A potential structure akin to a double layer is calculated to exist. This phenomenon of thermal collapse is favored by a high neutral pressure, a large positive target bias, and a sufficiently long column. It is postulated that the disparate rates of momentum exchange between electrons and ions with neutrals are responsible for the formation of such collapses. The large increase in radiation is partly attributed to 3-body recombination during stagnated flow, although the estimated power loss is insufficient to account for the observations. The B2 neutral particle treatment has been found to be inadequate at these higher pressures. These results motivate

  10. ExoCube INMS with Neutral Hydrogen Mode

    NASA Astrophysics Data System (ADS)

    Jones, S.; Paschalidis, N.; Rodriguez, M.; Sittler, E. C., Jr.; Chornay, D. J.; Cameron, T.; Uribe, P.; Nanan, G.; Noto, J.; Waldrop, L.; Mierkiewicz, E. J.; Gardner, D.; Nossal, S. M.; Puig-Suari, J.; Bellardo, J.

    2015-12-01

    The ExoCube mission launched on Jan 31 2015 into a polar orbit to acquire global knowledge of in situ densities of neutral and ionized H, He, and O in the upper ionosphere and lower exosphere. The CubeSat platform is used in combination with incoherent scatter radar and optical ground stations distributed throughout the Americas. ExoCube seeks to obtain the first in situ measurement of neutral exospheric hydrogen and will measure in situ atomic oxygen for the first time in decades. The compact Ion and Neutral Mass Spectrometer (INMS) developed by GSFC uses the gated Time of Flight technique for in situ measurements of ions and neutrals (H, He, N, O, N2, O2) with M/dM of approximately 10. The compact sensor has a dual symmetric configuration with ion and neutral sensor heads. Neutral particles are ionized by electron impact using a thermionic emitter. In situ measurements of neutral hydrogen are notoriously difficult as historically the signal has been contaminated by hydrogen outgassing which persists even years after commissioning. In order to obtain neutral atmospheric hydrogen fluxes, either the atmospheric peak and outgassing peak must be well resolved, or the outgassing component subtracted off. The ExoCube INMS employs a separate mode, specifically for measuring neutral Hydrogen. The details of this mode and lessons learned will be presented as well as in flight instrument validation data for the neutral channel and preliminary flight ion spectra. At the time of abstract submission, the ExoCube spacecraft is currently undergoing attitude control maneuvers to orient INMS in the ram direction for science operations.

  11. Lunar Neutral Exposphere Properties from Pickup Ion Analysis

    NASA Technical Reports Server (NTRS)

    Hartle, R. E.; Sarantos, M.; Killen, R.; Sittler, E. C. Jr.; Halekas, J.; Yokota, S.; Saito, Y.

    2009-01-01

    Composition and structure of neutral constituents in the lunar exosphere can be determined through measurements of phase space distributions of pickup ions borne from the exosphere [1]. An essential point made in an early study [ 1 ] and inferred by recent pickup ion measurements [2, 3] is that much lower neutral exosphere densities can be derived from ion mass spectrometer measurements of pickup ions than can be determined by conventional neutral mass spectrometers or remote sensing instruments. One approach for deriving properties of neutral exospheric source gasses is to first compare observed ion spectra with pickup ion model phase space distributions. Neutral exosphere properties are then inferred by adjusting exosphere model parameters to obtain the best fit between the resulting model pickup ion distributions and the observed ion spectra. Adopting this path, we obtain ion distributions from a new general pickup ion model, an extension of a simpler analytic description obtained from the Vlasov equation with an ion source [4]. In turn, the ion source is formed from a three-dimensional exospheric density distribution, which can range from the classical Chamberlain type distribution to one with variable exobase temperatures and nonthermal constituents as well as those empirically derived. The initial stage of this approach uses the Moon's known neutral He and Na exospheres to deriv e He+ and Na+ pickup ion exospheres, including their phase space distributions, densities and fluxes. The neutral exospheres used are those based on existing models and remote sensing studies. As mentioned, future ion measurements can be used to constrain the pickup ion model and subsequently improve the neutral exosphere descriptions. The pickup ion model is also used to estimate the exosphere sources of recently observed pickup ions on KAGUYA [3]. Future missions carrying ion spectrometers (e.g., ARTEMIS) will be able to study the lunar neutral exosphere with great sensitivity

  12. Magnetospheric imaging with low-energy neutral atoms.

    PubMed Central

    McComas, D J; Barraclough, B L; Elphic, R C; Funsten, H O; Thomsen, M F

    1991-01-01

    Global imaging of the magnetospheric charged particle population can be achieved by remote measurement of the neutral atoms produced when magnetospheric ions undergo charge exchange with cold exospheric neutral atoms. Previously suggested energetic neutral atom imagers were only able to measure neutral atoms with energies typically greater than several tens of keV. A laboratory prototype has been built and tested for a different type of space plasma neutral imaging instrument, which allows neutral atoms to be imaged down to <1 keV. Such low-energy measurements provide greater sensitivity for imaging the terrestrial magnetosphere and allow the bulk of the magnetospheric ion distribution, typically centered below 10 keV, to be observed rather than just the high-energy tail of the distribution. The low-energy neutral atom measurements are made possible by utilizing charge state modifications that occur when an initially neutral atom passes through an ultrathin carbon foil. Oxygen, for example, is highly electronegative, and for energies of approximately 10-30 keV, the O- yield is approximately 30%, essentially independent of the charge state of the incident oxygen atom. These ions are energy per charge analyzed, and the UV background is rejected by using an electrostatic analyzer. Imaging of other ion species, such as hydrogen, could also be accomplished by using ultrathin foil-induced charge state modifications. The technique described in this paper provides a method for imaging charge exchange neutrals from the terrestrial magnetosphere and would also have applications for similar imaging in other planetary or cometary environs. The Inner Magnetosphere Imaging Mission, which the National Aeronautics and Space Administration is presently considering, would provide a nearly ideal platform for low-energy neutral atom imaging, and such measurements would substantially enhance the scientific yield of this mission. PMID:11607229

  13. Cross-clade neutralizing antibodies against HIV-1 induced in rabbits by focusing the immune response on a neutralizing epitope

    SciTech Connect

    Zolla-Pazner, Susan; Cohen, Sandra; Pinter, Abraham; Krachmarov, Chavdar; Wrin, Terri; Wang Shixia; Lu Shan

    2009-09-15

    Studies were performed to induce cross-clade neutralizing antibodies (Abs) by testing various combinations of prime and boost constructs that focus the immune response on structurally-conserved epitopes in the V3 loop of HIV-1 gp120. Rabbits were immunized with gp120 DNA containing a V3 loop characterized by the GPGR motif at its tip, and/or with gp120 DNA with a V3 loop carrying the GPGQ motif. Priming was followed by boosts with V3-fusion proteins (V3-FPs) carrying the V3 sequence from a subtype B virus (GPGR motif), and/or with V3 sequences from subtypes A and C (GPGQ motif). The broadest and most consistent neutralizing responses were generated when using a clade C gp120 DNA prime and with the V3{sub B}-FP boost. Immune sera displayed neutralizing activity in three assays against pseudoviruses and primary isolates from subtypes A, AG, B, C, and D. Polyclonal Abs in the immune rabbit sera neutralized viruses that were not neutralized by pools of human anti-V3 monoclonal Abs. Greater than 80% of the neutralizing Abs were specific for V3, showing that the immune response could be focused on a neutralizing epitope and that vaccine-induced anti-V3 Abs have cross-clade neutralizing activity.

  14. Relative contributions of neutral and non-neutral genetic differentiation to inform conservation of steelhead trout across highly variable landscapes.

    PubMed

    Matala, Andrew P; Ackerman, Michael W; Campbell, Matthew R; Narum, Shawn R

    2014-06-01

    Mounting evidence of climatic effects on riverine environments and adaptive responses of fishes have elicited growing conservation concerns. Measures to rectify population declines include assessment of local extinction risk, population ecology, viability, and genetic differentiation. While conservation planning has been largely informed by neutral genetic structure, there has been a dearth of critical information regarding the role of non-neutral or functional genetic variation. We evaluated genetic variation among steelhead trout of the Columbia River Basin, which supports diverse populations distributed among dynamic landscapes. We categorized 188 SNP loci as either putatively neutral or candidates for divergent selection (non-neutral) using a multitest association approach. Neutral variation distinguished lineages and defined broad-scale population structure consistent with previous studies, but fine-scale resolution was also detected at levels not previously observed. Within distinct coastal and inland lineages, we identified nine and 22 candidate loci commonly associated with precipitation or temperature variables and putatively under divergent selection. Observed patterns of non-neutral variation suggest overall climate is likely to shape local adaptation (e.g., potential rapid evolution) of steelhead trout in the Columbia River region. Broad geographic patterns of neutral and non-neutral variation demonstrated here can be used to accommodate priorities for regional management and inform long-term conservation of this species. PMID:25067950

  15. Relative contributions of neutral and non-neutral genetic differentiation to inform conservation of steelhead trout across highly variable landscapes

    PubMed Central

    Matala, Andrew P; Ackerman, Michael W; Campbell, Matthew R; Narum, Shawn R

    2014-01-01

    Mounting evidence of climatic effects on riverine environments and adaptive responses of fishes have elicited growing conservation concerns. Measures to rectify population declines include assessment of local extinction risk, population ecology, viability, and genetic differentiation. While conservation planning has been largely informed by neutral genetic structure, there has been a dearth of critical information regarding the role of non-neutral or functional genetic variation. We evaluated genetic variation among steelhead trout of the Columbia River Basin, which supports diverse populations distributed among dynamic landscapes. We categorized 188 SNP loci as either putatively neutral or candidates for divergent selection (non-neutral) using a multitest association approach. Neutral variation distinguished lineages and defined broad-scale population structure consistent with previous studies, but fine-scale resolution was also detected at levels not previously observed. Within distinct coastal and inland lineages, we identified nine and 22 candidate loci commonly associated with precipitation or temperature variables and putatively under divergent selection. Observed patterns of non-neutral variation suggest overall climate is likely to shape local adaptation (e.g., potential rapid evolution) of steelhead trout in the Columbia River region. Broad geographic patterns of neutral and non-neutral variation demonstrated here can be used to accommodate priorities for regional management and inform long-term conservation of this species. PMID:25067950

  16. Neutral polyfluoroalkyl substances in the global atmosphere.

    PubMed

    Gawor, A; Shunthirasingham, C; Hayward, S J; Lei, Y D; Gouin, T; Mmereki, B T; Masamba, W; Ruepert, C; Castillo, L E; Shoeib, M; Lee, S C; Harner, T; Wania, F

    2014-03-01

    Concentrations of neutral per- and polyfluoroalkyl substances (nPFAS) in the atmosphere are of interest because nPFAS are highly mobile percursors for perfluoroalkyl acids. Two calibration studies in Ontario, Canada and Costa Rica established the feasibility of using XAD 2-resin based passive air samplers (XAD-PAS) to reliably determine long term average air concentrations of nPFAS under temperate and tropical climatic conditions. The temporal and spatial distribution of nPFAS was investigated by analyzing XAD-PAS deployed for one year at between 17 and 46 sites on six continents between 2006 and 2011 as part of the Global Atmospheric Passive Sampling (GAPS) study. Higher levels of fluorotelomer alcohols (FTOHs) compared to fluorinated sulfonamides (FOSAs), and fluorinated sulfonamidoethanols (FOSEs) were observed at all sites. Urban sites had the highest levels of nPFAS compared to rural and remote sites, which is also apparent in a positive correlation of nPFAS levels with the proximity of a sampling site to areas of high population density. Levels of FOSAs and FOSEs tended to decrease during the six years of measurements, whereas an initial decline in the concentrations of FTOHs from 2006 to 2008 did not continue in 2009 to 2011. A comparison of nPFAS levels measured in national XAD-PAS networks in Costa Rica and Botswana revealed that the GAPS sites in Tapanti and the Kalahari are representative of the more remote regions in those countries. XAD-PAS derived absolute nPFAS levels at GAPS sites are lower than those measured using another PAS, but are within the range of levels measured with active air samplers. Agreement of relative nPFAS composition is better between samplers, suggesting that the discrepancy is due to uncertain sampling rates. PMID:24232015

  17. Toxins not neutralized by brown snake antivenom

    SciTech Connect

    Judge, Roopwant K.; Henry, Peter J.; Mirtschin, Peter; Jelinek, George; Wilce, Jacqueline A. . E-mail: Jackie.Wilce@med.monash.edu.au

    2006-06-01

    The Australian snakes of the genus Pseudonaja (dugite, gwardar and common brown) account for the majority of snake bite related deaths in Australia. Without antivenom treatment, the risk of mortality is significant. There is an accumulating body of evidence to suggest that the efficacy of the antivenom is limited. The current study investigates the protein constituents recognized by the antivenom using 2-DE, immuno-blot techniques and rat tracheal organ bath assays. The 2-DE profiles for all three snake venoms were similar, with major species visualized at 78-132 kDa, 32-45 kDa and 6-15 kDa. Proteins characterized by LC-MS/MS revealed a coagulant toxin ({approx}42 kDa) and coagulant peptide ({approx}6 kDa), as well as two PLA{sub 2} ({approx}14 kDa). Peptides isolated from {approx}78 kDa and 15-32 kDa protein components showed no similarity to known protein sequences. Protein recognition by the antivenom occurred predominantly for the higher molecular weight components with little recognition of 6-32 kDa MW species. The ability of antivenom to neutralize venom activity was also investigated using rat tracheal organ bath assays. The venoms of Pseudonaja affinis affinis and Pseudonaja nuchalis incited a sustained, significant contraction of the trachea. These contractions were attributed to PLA{sub 2} enzymatic activity as pre-treatment with the PLA{sub 2} inhibitor 4-BPB attenuated the venom-induced contractions. The venom of Pseudonaja textilis incited tracheal contractility through a non-PLA{sub 2} enzymatic activity. Neither activity was attenuated by the antivenom treatment. These results represent the first proteomic investigation of the venoms from the snakes of the genus Pseudonaja, revealing a possible limitation of the brown snake antivenom in binding to the low MW protein components.

  18. Neutral atom lithography with metastable helium

    NASA Astrophysics Data System (ADS)

    Allred, Claire Shean

    In this dissertation we describe our performance of resist assisted neutral atom lithography using a bright beam of metastable 23S1 Helium (He*). Metastable Helium atoms have 20 eV of internal energy making them easy to detect and able to destroy a resist. The He* is produced by a reverse flow DC discharge source and then collimated with the bichromatic force, followed by three optical molasses velocity compression stages. The atoms in the resulting beam have a mean longitudinal velocity of 1125 m/s and a divergence of 1.1 mrad. The typical beam flux is 2 x 109 atoms/mm2s through a 0.1mm diameter aperture 70 cm away from the source. The internal energy of the atoms damages the molecules of a self assembled monolayer (SAM) of nonanethiol. The undisturbed SAM protects a 200 A layer of gold that has been evaporated onto a prepared Silicon wafer from a wet chemical etch. Two methods are used to pattern the He* atoms before they destroy the SAM. First, a Nickel micro mesh was used to protect the SAM. These experiments established an appropriate dosage and etch time for patterning. The samples were analyzed with an atomic force microscope and found to have an edge resolution of 63 nm. Then, patterning was accomplished using the dipole force the atoms experience while traversing a standing wave of lambda = 1083nm light tuned 500MHz below the 23S 1 → 23P2 transition. Depending on the intensity of the light, the He* atoms are focused or channeled into lines separated by lambda/2. The lines cover the entire exposed length of the substrate, about 3 mm. They are about 3 mm long, corresponding to about twice the beam waist of the laser standing wave. Thus there are 6 x 10 3 lines of length 5500lambda. These results agree with our numerical simulations of the experiment.

  19. Neutral Buoyancy underwater electrical cornector test

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Once the United States' space program had progressed from Earth's orbit into outerspace, the prospect of building and maintaining a permanent presence in space was realized. To accomplish this feat, NASA launched a temporary workstation, Skylab, to discover the effects of low gravity and weightlessness on the human body, and also to develop tools and equipment that would be needed in the future to build and maintain a more permanent space station. The structures, techniques, and work schedules had to be carefully designed to fit this unique construction site. The components had to be lightweight for transport into orbit, yet durable. The station also had to be made with removable parts for easy servicing and repairs by astronauts. All of the tools necessary for service and repairs had to be designed for easy manipulation by a suited astronaut. And construction methods had to be efficient due to limited time the astronauts could remain outside their controlled environment. In lieu of all the specific needs for this project, an environment on Earth had to be developed that could simulate a low gravity atmosphere. A Neutral Buoyancy Simulator (NBS) was constructed by NASA Marshall Space Flight Center (MSFC) in 1968. Since then, NASA scientists have used this facility to understand how humans work best in low gravity and also provide information about the different kinds of structures that can be built. Included in the plans for the space station was a space telescope. This telescope would be attached to the space station and directed towards outerspace. Astronomers hoped that the space telescope would provide a look at space that is impossible to see from Earth because of Earth's atmosphere and other man made influences. Pictured is a large structure that is being used as the antenna base for the space telescope.

  20. Neutral Buoyancy Simulator - EASE Project (NB32)

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Once the United States' space program had progressed from Earth's orbit into outerspace, the prospect of building and maintaining a permanent presence in space was realized. To accomplish this feat, NASA launched a temporary workstation, Skylab, to discover the effects of low gravity and weightlessness on the human body, and also to develop tools and equipment that would be needed in the future to build and maintain a more permanent space station. The structures, techniques, and work schedules had to be carefully designed to fit this unique construction site. The components had to be lightweight for transport into orbit, yet durable. The station also had to be made with removable parts for easy servicing and repairs by astronauts. All of the tools necessary for service and repairs had to be designed for easy manipulation by a suited astronaut. Construction methods had to be efficient due to the limited time the astronauts could remain outside their controlled environment. In lieu of all the specific needs for this project, an environment on Earth had to be developed that could simulate a low gravity atmosphere. A Neutral Buoyancy Simulator (NBS) was constructed by NASA's Marshall Space Flight Center (MSFC) in 1968. Since then, NASA scientists have used this facility to understand how humans work best in low gravity and also provide information about the different kinds of structures that can be built. Pictured is a Massachusetts Institute of Technology (MIT) student working in a spacesuit on the Experimental Assembly of Structures in Extravehicular Activity (EASE) project which was developed as a joint effort between MFSC and MIT. The EASE experiment required that crew members assemble small components to form larger components, working from the payload bay of the space shuttle. The MIT student in this photo is assembling two six-beam tetrahedrons.

  1. Association with emotional information alters subsequent processing of neutral faces

    PubMed Central

    Riggs, Lily; Fujioka, Takako; Chan, Jessica; McQuiggan, Douglas A.; Anderson, Adam K.; Ryan, Jennifer D.

    2014-01-01

    The processing of emotional as compared to neutral information is associated with different patterns in eye movement and neural activity. However, the ‘emotionality’ of a stimulus can be conveyed not only by its physical properties, but also by the information that is presented with it. There is very limited work examining the how emotional information may influence the immediate perceptual processing of otherwise neutral information. We examined how presenting an emotion label for a neutral face may influence subsequent processing by using eye movement monitoring (EMM) and magnetoencephalography (MEG) simultaneously. Participants viewed a series of faces with neutral expressions. Each face was followed by a unique negative or neutral sentence to describe that person, and then the same face was presented in isolation again. Viewing of faces paired with a negative sentence was associated with increased early viewing of the eye region and increased neural activity between 600 and 1200 ms in emotion processing regions such as the cingulate, medial prefrontal cortex, and amygdala, as well as posterior regions such as the precuneus and occipital cortex. Viewing of faces paired with a neutral sentence was associated with increased activity in the parahippocampal gyrus during the same time window. By monitoring behavior and neural activity within the same paradigm, these findings demonstrate that emotional information alters subsequent visual scanning and the neural systems that are presumably invoked to maintain a representation of the neutral information along with its emotional details. PMID:25566024

  2. Higher Throughput Quantification of Neutralizing Antibody to Herpes Simplex Viruses

    PubMed Central

    Blevins, Tamara P.; Mitchell, Michelle C.; Korom, Maria; Wang, Hong; Yu, Yinyi; Morrison, Lynda A.; Belshe, Robert B.

    2015-01-01

    We report a rapid, higher throughput method for measuring neutralizing antibody to herpes simplex virus (HSV) in human sera. Clinical isolates and sera from the Herpevac Trial for Women were used in a colorimetric assay in which infection of tissue culture (lack of neutralization) was indicated by substrate metabolism by beta-galactosidase induced in the ELVIS cell line. The neutralization assay was optimized by addition of guinea pig complement, which particularly enhanced neutralizing antibody titers to HSV-2. Higher neutralizing antibody titers were also achieved using virus particles isolated from the supernatant of infected cells rather than lysate of infected cells as the source of virus. The effect of assay incubation time and incubation time with substrate were also optimized. We found that incubating with substrate until a standard optical density of 1.0 was reached permitted a better comparison among virus isolates, and achieved reliable measurement of neutralizing antibody activity. Interestingly, in contrast to results in the absence of complement, addition of complement allowed sera from HSV-2 gD-vaccinated subjects to neutralize HSV-1 and HSV-2 clinical and laboratory isolates with equal potency. PMID:26658766

  3. When Can Species Abundance Data Reveal Non-neutrality?

    PubMed Central

    Al Hammal, Omar; Alonso, David; Etienne, Rampal S.; Cornell, Stephen J.

    2015-01-01

    Species abundance distributions (SAD) are probably ecology’s most well-known empirical pattern, and over the last decades many models have been proposed to explain their shape. There is no consensus over which model is correct, because the degree to which different processes can be discerned from SAD patterns has not yet been rigorously quantified. We present a power calculation to quantify our ability to detect deviations from neutrality using species abundance data. We study non-neutral stochastic community models, and show that the presence of non-neutral processes is detectable if sample size is large enough and/or the amplitude of the effect is strong enough. Our framework can be used for any candidate community model that can be simulated on a computer, and determines both the sampling effort required to distinguish between alternative processes, and a range for the strength of non-neutral processes in communities whose patterns are statistically consistent with neutral theory. We find that even data sets of the scale of the 50 Ha forest plot on Barro Colorado Island, Panama, are unlikely to be large enough to detect deviations from neutrality caused by competitive interactions alone, though the presence of multiple non-neutral processes with contrasting effects on abundance distributions may be detectable. PMID:25793889

  4. When can species abundance data reveal non-neutrality?

    PubMed

    Al Hammal, Omar; Alonso, David; Etienne, Rampal S; Cornell, Stephen J

    2015-03-01

    Species abundance distributions (SAD) are probably ecology's most well-known empirical pattern, and over the last decades many models have been proposed to explain their shape. There is no consensus over which model is correct, because the degree to which different processes can be discerned from SAD patterns has not yet been rigorously quantified. We present a power calculation to quantify our ability to detect deviations from neutrality using species abundance data. We study non-neutral stochastic community models, and show that the presence of non-neutral processes is detectable if sample size is large enough and/or the amplitude of the effect is strong enough. Our framework can be used for any candidate community model that can be simulated on a computer, and determines both the sampling effort required to distinguish between alternative processes, and a range for the strength of non-neutral processes in communities whose patterns are statistically consistent with neutral theory. We find that even data sets of the scale of the 50 Ha forest plot on Barro Colorado Island, Panama, are unlikely to be large enough to detect deviations from neutrality caused by competitive interactions alone, though the presence of multiple non-neutral processes with contrasting effects on abundance distributions may be detectable. PMID:25793889

  5. Higher Throughput Quantification of Neutralizing Antibody to Herpes Simplex Viruses.

    PubMed

    Blevins, Tamara P; Mitchell, Michelle C; Korom, Maria; Wang, Hong; Yu, Yinyi; Morrison, Lynda A; Belshe, Robert B

    2015-01-01

    We report a rapid, higher throughput method for measuring neutralizing antibody to herpes simplex virus (HSV) in human sera. Clinical isolates and sera from the Herpevac Trial for Women were used in a colorimetric assay in which infection of tissue culture (lack of neutralization) was indicated by substrate metabolism by beta-galactosidase induced in the ELVIS cell line. The neutralization assay was optimized by addition of guinea pig complement, which particularly enhanced neutralizing antibody titers to HSV-2. Higher neutralizing antibody titers were also achieved using virus particles isolated from the supernatant of infected cells rather than lysate of infected cells as the source of virus. The effect of assay incubation time and incubation time with substrate were also optimized. We found that incubating with substrate until a standard optical density of 1.0 was reached permitted a better comparison among virus isolates, and achieved reliable measurement of neutralizing antibody activity. Interestingly, in contrast to results in the absence of complement, addition of complement allowed sera from HSV-2 gD-vaccinated subjects to neutralize HSV-1 and HSV-2 clinical and laboratory isolates with equal potency. PMID:26658766

  6. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    NASA Astrophysics Data System (ADS)

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.

    2016-04-01

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established ˜5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-μs surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of μs after the high voltage pulse is applied. It is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

  7. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    DOE PAGESBeta

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.

    2016-04-27

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15V before neutralization to 0.3 V,more » implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established similar to –5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-mu s surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of mu s after the high voltage pulse is applied. Lastly, it is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.« less

  8. Near-Neutrality: the Leading Edge of the Neutral Theory of Molecular Evolution

    PubMed Central

    Hughes, Austin L.

    2009-01-01

    The nearly-neutral theory represents a development of Kimura’s Neutral Theory of Molecular Evolution that makes testable predictions that go beyond a mere null model. Recent evidence has strongly supported several of these predictions, including the prediction that slightly deleterious variants will accumulate in a species that has undergone a severe bottleneck or in cases where recombination is reduced or absent. Because bottlenecks often occur in speciation and slightly deleterious mutations in coding regions will usually be nonsynonymous, we should expect that the ratio of nonsynonymous to synonymous fixed differences between species should often exceed the ratio of nonsynonymous to synonymous polymorphisms within species. Numerous data support this prediction, although they have often been wrongly interpreted as evidence for positive Darwinian selection. The use of conceptually flawed tests for positive selection has become widespread in recent years, seriously harming the quest for an understanding of genome evolution. When properly analyzed, many (probably most) claimed cases of positive selection will turn out to involve the fixation of slightly deleterious mutations by genetic drift in bottlenecked populations. Slightly deleterious variants are a transient feature of evolution in the long term, but they have had substantial impact on contemporary species, including our own. PMID:18559820

  9. Laser ablated zirconium plasma: A source of neutral zirconium

    SciTech Connect

    Yadav, Dheerendra; Thareja, Raj K.

    2010-10-15

    The authors report spectroscopic investigations of laser produced zirconium (Zr) plasma at moderate laser fluence. At low laser fluence the neutral zirconium species are observed to dominate over the higher species of zirconium. Laser induced fluorescence technique is used to study the velocity distribution of ground state neutral zirconium species. Two-dimensional time-resolved density distributions of ground state zirconium is mapped using planner laser induced fluorescence imaging and total ablated mass of neutral zirconium atoms is estimated. Temporal and spatial evolutions of electron density and temperature are discussed by measuring Stark broadened profile and ratio of intensity of emission lines, respectively.

  10. The San Marco 3 neutral atmosphere composition experiment

    NASA Technical Reports Server (NTRS)

    Pelz, D. T.; Newton, G. P.; Kasprzak, W. T.; Clem, T. D.

    1973-01-01

    The experimental instrumentation of the San Marco 3 satellite is described along with the calibration and operation. The instrumentation for the following experiments was included: an air density experiment for measuring the instantaneous drag force, and thus the neutral particle total mass density; a neutral atmosphere composition experiment for measuring the densities of helium, atomic and molecular oxygen, molecular nitrogen and argon; and a neutral atmosphere temperature experiment to determine the gas kinetic temperature by measuring molecular nitrogen density variations in an orificed spherical chamber as a function of angle of attack.

  11. Neoclassical electron transport in tokamaks with neutral-beam injection

    SciTech Connect

    Helander, P.; Akers, R.J.

    2005-04-15

    The collisional interaction between neutral-beam ions and bulk plasma electrons leads to convective transport of particles and energy similar to the well-known Ware pinch. These transport fluxes are calculated, and it is found that the particle flux is outward when the neutral beams are in the same direction as the plasma current and inward otherwise, while the opposite holds for the electron heat transport. This effectively shifts the neutral-beam fueling profile approximately one fast-ion banana width outward during coinjection and inward during counterinjection, and could help to explain why very different plasma behavior is sometimes observed when the direction of the plasma current is reversed.

  12. Expansion of a cold non-neutral plasma slab

    SciTech Connect

    Karimov, A. R.; Yu, M. Y.; Stenflo, L.

    2014-12-15

    Expansion of the ion and electron fronts of a cold non-neutral plasma slab with a quasi-neutral core bounded by layers containing only ions is investigated analytically and exact solutions are obtained. It is found that on average, the plasma expansion time scales linearly with the initial inverse ion plasma frequency as well as the degree of charge imbalance, and no expansion occurs if the cold plasma slab is stationary and overall neutral. However, in both cases, there can exist prominent oscillations on the electron front.

  13. Experimental Studies of Ion Beam Neutralization: Preliminary Results

    SciTech Connect

    Ding, N.; Polansky, J.; Downey, R.; Wang, J.

    2011-05-20

    A testing platform is designed to study ion beam neutralization in the mesothermal, collisionless region. In the experimental setup, argon neutrals were ionized in a microwave cavity and accelerated by a plasma lens system which was biased to 2500 V above the system ground. Electrons were boiled off from two hot tungsten filaments to neutralize the ion beam. The plasma is diagnosed using Langmuir probe and Faraday probe. A 3-D traversing system and a complete data acquisition loop were developed to efficiently measure 3-D beam profile. Preliminary measurements of beam profiles are presented for different operating conditions.

  14. Photon neutralizer as an example of an open billiard.

    PubMed

    Kotelnikov, I A; Popov, S S; Romé, M

    2013-01-01

    A simple photon cavity consisting of three flat mirrors is considered, which provides a model for a photon neutralizer of negative ion beams to be used in a neutral beam injector for plasma heating in fusion devices. Treating the system as an open mathematical billiard, the mechanism of photon scattering on the sharp boundary between two mirrors is described. Assuming a balance between the continuous injection of the photons into the device and their loss through its open ends, the stationary angular distribution of the photons in the trap is computed in closed form and an estimate for the confinement time of the photons in the neutralizer is provided. PMID:23410450

  15. Neutral red assay in minimum fungicidal concentrations of antifungal agents.

    PubMed

    Fukuda, T; Naka, W; Tajima, S; Nishikawa, T

    1996-01-01

    We assayed the fungicidal effects of antifungal agents using neutral red staining. Fungal elements of Trichophyton mentagrophytes and T. rubrum were treated with various concentrations of antifungal agents in 96-well filtration plates and then stained with neutral red. The amount of neutral red incorporated by the surviving viable cells was determined from the automated spectrophotometric readings at 550 nm. The minimum fungicidal concentrations (MFCs) of antifungal agents determined by this assay correlated well with those determined by conventional assay. This newly developed procedure should provide a rapid, reproducible, quantitative, qualitative and semi-automated susceptibility test for determination of the MFCs of the fungicidal agents. PMID:8912170

  16. A DFT study of hydration in neutral and zwitterionic norfloxacin

    NASA Astrophysics Data System (ADS)

    Pinto Vitorino, Graciela; Barrera, Gustavo D.; Rosa Mazzieri, María; Binning, R. C., Jr.; Bacelo, Daniel E.

    2006-12-01

    Hydration of the fluoroquinolone antibiotic norfloxacin has been examined in B3LYP/6-31+G ∗ calculations. The neutral and zwitterionic forms and their one- and two-water complexes have been optimized both as isolated molecules and within a solvation field simulated by the polarizable continuum model. The explicitly included water molecules are found to affect solvation energies of both neutrals and zwitterions, but overall their inclusion does not improve the average solvated neutral-zwitterion energy separation. The calculated separations of 3-5 kcal/mol are consistent with experimental observations that the two forms coexist in solution under physiological conditions.

  17. The transition between the niche and neutral regimes in ecology

    PubMed Central

    Fisher, Charles K.; Mehta, Pankaj

    2014-01-01

    An ongoing debate in ecology concerns the impacts of ecological drift and selection on community assembly. Here, we show that there is a transition in diverse ecological communities between a selection-dominated regime (the niche phase) and a drift-dominated regime (the neutral phase). Simulations and analytic arguments show that the niche phase is favored in communities with large population sizes and relatively constant environments, whereas the neutral phase is favored in communities with small population sizes and fluctuating environments. Our results demonstrate how apparently neutral populations may arise even in communities inhabited by species with varying traits. PMID:25157131

  18. Energy neutral and low power wireless communications

    NASA Astrophysics Data System (ADS)

    Orhan, Oner

    Wireless sensor nodes are typically designed to have low cost and small size. These design objectives impose restrictions on the capacity and efficiency of the transceiver components and energy storage units that can be used. As a result, energy becomes a bottleneck and continuous operation of the sensor network requires frequent battery replacements, increasing the maintenance cost. Energy harvesting and energy efficient transceiver architectures are able to overcome these challenges by collecting energy from the environment and utilizing the energy in an intelligent manner. However, due to the nature of the ambient energy sources, the amount of useful energy that can be harvested is limited and unreliable. Consequently, optimal management of the harvested energy and design of low power transceivers pose new challenges for wireless network design and operation. The first part of this dissertation is on energy neutral wireless networking, where optimal transmission schemes under different system setups and objectives are investigated. First, throughput maximization for energy harvesting two-hop networks with decode-and-forward half-duplex relays is studied. For a system with two parallel relays, various combinations of the following four transmission modes are considered: Broadcast from the source, multi-access from the relays, and successive relaying phases I and II. Next, the energy cost of the processing circuitry as well as the transmission energy are taken into account for communication over a broadband fading channel powered by an energy harvesting transmitter. Under this setup, throughput maximization, energy maximization, and transmission completion time minimization problems are studied. Finally, source and channel coding for an energy-limited wireless sensor node is investigated under various energy constraints including energy harvesting, processing and sampling costs. For each objective, optimal transmission policies are formulated as the solutions of a

  19. Empirical Neutral Thermosphere Models; Then and Now

    NASA Astrophysics Data System (ADS)

    Drob, Douglas; Emmert, John; McDonald, Sarah; Picone, J. Michael

    The empirical Mass Spectrometer Incoherent Scatter (MSIS) upper atmospheric model pro-vides a readily available framework for summarizing the results of five solar cycles of density, composition, and temperature information from multi-agency satellite missions, rocket flights, and ground-based observations. The MSIS versions described in Hedin et al. (1987), Hedin et al. (1991), and Picone et al., (2002) have been cited over 2500 times in the peer reviewed scientific literature. The cross-listed subject areas include Astronomy (50%), Atmospheric Sci-ences (40%), Geophysics (25%), Multidisciplinary (23%), Aerospace (16%), Remote Sensing (4%), Instrumentation (3%), and Telecommunications (2%). The MSIS model even has its own Wikipedia entry; it is also included in commercial applications such as the Satellite Tool Kit and the MATLAB Aerospace Toolbox. In addition, the recently updated Horizontal Wind Model (HWM07) of Drob et al. (2008) provides a statistical representation of the horizontal wind fields from the ground to the exosphere (> 500 km), representing over 35-years of satellite, rocket, and ground-based wind measurements via a compact Fortran 90 subroutine. Together, these models approximately describe the compositional, thermal, and dynamical state of the neutral upper atmosphere. These low overhead, high-availability computer subroutines are a function of geographic location, altitude, day of the year, solar local time, and geomagnetic activity. In contrast to General Circulation Models, they provide a set of precompiled spectral patterns bypassing the need to compute them directly from first principles. They include representations of the zonal mean state, stationary planetary waves, migrating tides, and the seasonal modulation thereof; as well as the influences of geomagnetic activity and solar flux. End-users interact with a statistical summary of the underlying knowledgebase via a single subroutine interface which encapsulates much of the system

  20. Neutral Buoyancy Simulator-Solar Max Testing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ) Neutral Buoyancy Simulator (NBS) practicing retrieval maneuvers, piloting the MMU, and training on equipment so they could make the needed repairs to Solar Max. Pictured are crew members training on repair tasks.

  1. Neutral Buoyancy Simulator-Solar Max Testing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    In February 1980, a satellite called Solar Maximum Mission Spacecraft, or Solar Max, was launched into Earth's orbit. Its primary objective was to provide a detailed study of solar flares, active regions on the Sun's surface, sunspots, and other solar activities. Additionally, it was to measure the total output of radiation from the Sun. Not much was known about solar activity at that time except for a slight knowledge of solar flares. After its launch, Solar Max fulfilled everyone's expectations. However, after a year in orbit, Solar Max's Altitude Control System malfunctioned, preventing the precise pointing of instruments at the Sun. NASA scientists were disappointed at the lost data, but not altogether dismayed because Solar Max had been designed for Space Shuttle retrievability enabling repair of the satellite. On April 6, 1984, Space Shuttle Challenger (STS-41C), Commanded by astronaut Robert L. Crippen and piloted by Francis R. Scobee, launched on a historic voyage. This voyage initiated a series of firsts for NASA; the first satellite retrieval, the first service use of a new space system called the Marned Maneuvering Unit (MMU), the first in-orbit repair, the first use of the Remote Manipulator System (RMS), and the Space Shuttle Challenger's first space flight. The mission was successful in retrieving Solar Max. Mission Specialist Dr. George D. Nelson, using the MMU, left the orbiter's cargo bay and rendezvoused with Solar Max. After attaching himself to the satellite, he awaited the orbiter to maneuver itself nearby. Using the RMS, Solar Max was captured and docked in the cargo bay while Dr. Nelson replaced the altitude control system and the coronagraph/polarimeter electronics box. After the repairs were completed, Solar Max was redeposited in orbit with the assistance of the RMS. Prior to the April 1984 launch, countless man-hours were spent preparing for this mission. The crew of Challenger spent months at Marshall Space Flight Center's (MSFC) Neutral

  2. Neutral Buoyancy Simulator-Solar Max Testing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ) Neutral Buoyancy Simulator (NBS) practicing retrieval maneuvers, piloting the MMU, and training on equipment so they could make the needed repairs to Solar Max. Pictured is Dr. Nelson performing a replacement task on the Solar Max mock-up in the NBS.

  3. Neutral Buoyancy Simulator-Solar Max Testing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    In February 1980, a satellite called Solar Maximum Mission Spacecraft, or Solar Max, was launched into Earth's orbit. Its primary objective was to provide a detailed study of solar flares,active regions on the Sun's surface, sunspots, and other solar activities. Additionally, it was to measure the total output of radiation from the Sun. Not much was known about solar activity at that time except for a slight knowledge of solar flares. After its launch, Solar Max fulfilled everyone's expectations. However, after a year in orbit, Solar Max's Altitude Control System malfunctioned, preventing the precise pointing of instruments at the Sun. NASA scientists were disappointed at the lost data, but not altogether dismayed because Solar Max had been designed for Space Shuttle retrievability, enabling repair to the satellite. On April 6, 1984, Space Shuttle Challenger (STS-41C), Commanded by astronaut Robert L. Crippen and piloted by Francis R. Scobee, launched on a historic voyage. This voyage initiated a series of firsts for NASA; the first satellite retrieval, the first service use of a new space system called the Marned Maneuvering Unit (MMU), the first in-orbit repair, the first use of the Remote Manipulator System (RMS), and the Space Shuttle Challenger's first space flight. The mission was successful in retrieving Solar Max. Mission Specialist Dr. George D. Nelson, using the MMU, left the orbiter's cargo bay and rendezvoused with Solar Max. After attaching himself to the satellite, he awaited the orbiter to maneuver itself nearby. Using the RMS, Solar Max was captured and docked in the cargo bay while Dr. Nelson replaced the altitude control system and the coronagraph/polarimeter electronics box. After the repairs were completed, Solar Max was redeposited in orbit with the assistance of the RMS. Prior to the April 1984 launch, countless man-hours were spent preparing for this mission. The crew of Challenger spent months at Marshall Space Flight Center's (MSFC) Neutral

  4. Neutral Buoyancy Simulator-Solar Max Testing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ) Neutral Buoyancy Simulator (NBS) practicing retrieval maneuvers, piloting the MMU, and training on equipment so they could make the needed repairs to Solar Max. Pictured are crew members training for repair tasks.

  5. Neutral Buoyancy Simulator-Solar Max Testing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ) Neutral Buoyancy Simulator (NBS) practicing retrieval maneuvers, piloting the MMU, and training on equipment so they could make the needed repairs to Solar Max. Pictured is Dr. Nelson performing a replacement task on the Solar Max mock-up in the NBS.

  6. Neutral Buoyancy Simulator-Solar Max Testing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ) Neutral Buoyancy Simulator (NBS) practicing retrieval maneuvers, piloting the MMU, and training on equipment so they could make the needed repairs to Solar Max. Pictured are crew members training on a satellite mock-up.

  7. Neutral Buoyancy Simulator Test - Scientific Airlock

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Once the United States' space program had progressed from Earth's orbit into outerspace, the prospect of building and maintaining a permanent presence in space was realized. To accomplish this feat, NASA launched a temporary workstation, Skylab, to discover the effects of low gravity and weightlessness on the human body, and also to develop tools and equipment that would be needed in the future to build and maintain a more permanent space station. The structures, techniques, and work schedules had to be carefully designed to fit this unique construction site. The components had to be lightweight for transport into orbit, yet durable. The station also had to be made with removable parts for easy servicing and repairs by astronauts. All of the tools necessary for service and repairs had to be designed for easy manipulation by a suited astronaut. Construction methods had to be efficient due to the limited time the astronauts could remain outside their controlled environment. In lieu of all the specific needs for this project, an environment on Earth had to be developed that could simulate a low gravity atmosphere. A Neutral Buoyancy Simulator (NBS) was constructed by NASA Marshall Space Flight Center (MSFC) in 1968. Since then, NASA scientists have used this facility to understand how humans work best in low gravity and also provide information about the different kinds of structures that can be built. With the help of the NBS, building a space station became more of a reality. Pictured is Astronaut Paul Weitz training on a mock-up of Spacelab's airlock-hatch cover. Training was also done on the use of foot restraints which had recently been developed to help astronauts maintain their positions during space walks rather than having their feet float out from underneath them while they tried to perform maintenance and repair operations. Every aspect of every space mission was researched and demonstrated in the NBS. Using the airlock hatch cover and foot restraints were

  8. Strain-Specific V3 and CD4 Binding Site Autologous HIV-1 Neutralizing Antibodies Select Neutralization-Resistant Viruses

    SciTech Connect

    Moody, M.  Anthony; Gao, Feng; Gurley, Thaddeus  C.; Amos, Joshua  D.; Kumar, Amit; Hora, Bhavna; Marshall, Dawn  J.; Whitesides, John  F.; Xia, Shi-Mao; Parks, Robert; Lloyd, Krissey  E.; Hwang, Kwan-Ki; Lu, Xiaozhi; Bonsignori, Mattia; Finzi, Andrés; Vandergrift, Nathan  A.; Alam, S.  Munir; Ferrari, Guido; Shen, Xiaoying; Tomaras, Georgia  D.; Kamanga, Gift; Cohen, Myron  S.; Sam, Noel  E.; Kapiga, Saidi; Gray, Elin S.; Tumba, Nancy  L.; Morris, Lynn; Zolla-Pazner, Susan; Gorny, Miroslaw  K.; Mascola, John  R.; Hahn, Beatrice H.; Shaw, George  M.; Sodroski, Joseph  G.; Liao, Hua-Xin; Montefiori, David C.; Hraber, Peter T.; Korber, Bette T.; Haynes, Barton F.

    2015-09-09

    The third variable (V3) loop and the CD4 binding site (CD4bs) of the viral envelope are frequently targeted by neutralizing antibodies (nAbs) in HIV-1-infected individuals. In chronic infection, virus escape mutants repopulate the plasma and V3 and CD4bs nAbs emerge that can neutralize heterologous tier 1 easy-to-neutralize, but not tier 2 difficult-to-neutralize HIV-1 isolates. However, neutralization sensitivity of autologous plasma viruses to this type of nAb response has not been studied. We describe the development and evolution in vivo of antibodies distinguished by their target specificity for V3and CD4bs epitopes on autologous tier 2 viruses but not on heterologous tier 2 viruses. A surprisingly high fraction of autologous circulating viruses was sensitive to these antibodies. These findings demonstrate a role for V3 and CD4bs antibodies in constraining the native envelope trimer in vivo to a neutralization-resistant phenotype, explaining why HIV-1 transmission generally occurs by tier 2 neutralization-resistant viruses.

  9. Let's not be indifferent about neutrality: Neutral ratings in the International Affective Picture System (IAPS) mask mixed affective responses.

    PubMed

    Schneider, Iris K; Veenstra, Lotte; van Harreveld, Frenk; Schwarz, Norbert; Koole, Sander L

    2016-06-01

    The International Affective Picture System (IAPS) is a picture set used by researchers to select pictures that have been prerated on valence. Researchers rely on the ratings in the IAPS to accurately reflect the degree to which the pictures elicit affective responses. Here we show that this may not always be a safe assumption. More specifically, the scale used to measure valence in the IAPS ranges from positive to negative, implying that positive and negative feelings are end-points of the same construct. This makes interpretation of midpoint, or neutral ratings, especially problematic because it is impossible to tell whether these ratings are the result of neutral, or of mixed feelings. In other words, neutral ratings may not be as neutral as researchers assume them to be. Investigating this, in this work we show that pictures that seem neutral according to the valence ratings in the IAPS indeed vary in levels of ambivalence they elicit. Furthermore, the experience of ambivalence in response to these pictures is predictive of the arousal that people report feeling when viewing these pictures. These findings are of particular importance because neutrality differs from ambivalence in its specific psychological consequences, and by relying on seemingly neutral valance ratings, researchers may unwillingly introduce these consequences into their research design, undermining their level of experimental control. (PsycINFO Database Record PMID:26950363

  10. The global morphology of the Europa neutral torus from Cassini Energetic Neutral Atom (ENA) observations and implications for JUICE

    NASA Astrophysics Data System (ADS)

    Brandt, P. C.; Mauk, B.; Mitchell, D. G.; Paranicas, C.; Barabash, S. V.

    2013-12-01

    From about December 2000 to January 2001 the Ion Neutral Camera (INCA) on board the Cassini spacecraft imaged Jupiter in Energetic Neutral Atoms (ENA) that are created when singly charged ions charge exchange with neutral gas atoms or molecules. The INCA observations were obtained from a distance of about 137-250 Jovian planetary radii (RJ) over an energy range from about 10 to 300 keV. We present underlying neutral torus gas morphologies by simulating INCA images using an empirical ion distribution model and a range of theoretical gas model distributions. Just like Mauk et al. (2003), who used a different analysis technique, we find that the INCA images are consistent with a neutral torus at the orbital distance of Europa (9.5 RJ). However, within the limitations of instrument resolution, we present also possible solutions of a longitudinally asymmetric torus distribution and its implication for neutral gas release and loss rates from Europa. The Jovian Energetic Neutral and Ions (JENI) camera is the second generation ENA camera based on INCA and was selected for the science payload of the Jupiter Icy Moon Explorer (JUICE) mission, planned for launch around 2022 and orbit insertion around Jupiter in 2030. Using the same forward simulation technique as above, we use the INCA observations to demonstrate what we expect the JENI camera to observe in orbit around Jupiter and Ganymede.

  11. Strain-Specific V3 and CD4 Binding Site Autologous HIV-1 Neutralizing Antibodies Select Neutralization-Resistant Viruses

    DOE PAGESBeta

    Moody, M.  Anthony; Gao, Feng; Gurley, Thaddeus  C.; Amos, Joshua  D.; Kumar, Amit; Hora, Bhavna; Marshall, Dawn  J.; Whitesides, John  F.; Xia, Shi-Mao; Parks, Robert; et al

    2015-09-09

    The third variable (V3) loop and the CD4 binding site (CD4bs) of the viral envelope are frequently targeted by neutralizing antibodies (nAbs) in HIV-1-infected individuals. In chronic infection, virus escape mutants repopulate the plasma and V3 and CD4bs nAbs emerge that can neutralize heterologous tier 1 easy-to-neutralize, but not tier 2 difficult-to-neutralize HIV-1 isolates. However, neutralization sensitivity of autologous plasma viruses to this type of nAb response has not been studied. We describe the development and evolution in vivo of antibodies distinguished by their target specificity for V3and CD4bs epitopes on autologous tier 2 viruses but not on heterologous tiermore » 2 viruses. A surprisingly high fraction of autologous circulating viruses was sensitive to these antibodies. These findings demonstrate a role for V3 and CD4bs antibodies in constraining the native envelope trimer in vivo to a neutralization-resistant phenotype, explaining why HIV-1 transmission generally occurs by tier 2 neutralization-resistant viruses.« less

  12. Effects of stream topology on ecological community results from neutral models

    EPA Science Inventory

    While neutral theory and models have stimulated considerable literature, less well investigated is the effect of topology on neutral metacommunity model simulations. We implemented a neutral metacommunity model using two different stream network topologies, a widely branched netw...

  13. Comet Halley neutral gas density profile along the Vega 1 trajectory measured by NGE. [Neutral Gas Experiment (NGE)

    NASA Technical Reports Server (NTRS)

    Curtis, C. C.; Fan, C. Y.; Hsieh, K. C.; Hunten, D. M.; Ip, WING-H.; Keppler, E.; Richter, A. K.; Umlauft, G.; Afonin, V. V.; Dyachkov, A. V.

    1986-01-01

    Data from the Vega 1 permitted the determination of the total neutral gas density profile along the spacecraft trajectory. Discounting small fluctuations, the field ionization source instrument measured a density profile which varied approximately as the inverse radial distance squared. Data from the electron impact ionization instrument yielded a series of calibration points; e.g., the neutral density at 100,000 km is 10,000/cc. The combined data provide a calibrated total density profile, and imply a neutral production rate of 10 to the 30th power molecules/sec.

  14. Spacewalk and Suit Testing in the Neutral Buoyancy Lab

    NASA Video Gallery

    NASA is taking steps to make spacewalking on an asteroid a reality. In the Neutral Buoyancy Laboratory (NBL) near the agency's Johnson Space Center in Houston, engineers are testing a modified vers...

  15. Automation of neutral beam source conditioning with artificial intelligence techniques

    SciTech Connect

    Johnson, R.R.; Canales, T.W.; Lager, D.L.

    1985-01-01

    This paper describes a system that automates neutral beam source conditioning. The system achieves this with artificial intelligence techniques. The architecture of the system is presented followed by a description of its performance.

  16. Neutralizing antibodies in Borna disease virus-infected rats.

    PubMed Central

    Hatalski, C G; Kliche, S; Stitz, L; Lipkin, W I

    1995-01-01

    Borna disease is a neurologic syndrome caused by infection with a nonsegmented, negative-strand RNA virus, Borna disease virus. Infected animals have antibodies to two soluble viral proteins, p40 and p23, and a membrane-associated viral glycoprotein, gp18. We examined the time course for the development of neutralization activity and the expression of antibodies to individual viral proteins in sera of infected rats. The appearance of neutralizing activity correlated with the development of immunoreactivity to gp18, but not p40 or p23. Monospecific and monoclonal antibodies to native gp18 and recombinant nonglycosylated gp18 were also found to have neutralizing activity and to immunoprecipitate viral particles or subparticles. These findings suggest that gp18 is likely to be present on the surface of the viral particles and is likely to contain epitopes important for virus neutralization. PMID:7815538

  17. Neutral bimetallic transition metal phenoxyiminato catalysts and related polymerization methods

    DOEpatents

    Marks, Tobin J.; Rodriguez, Brandon A.; Delferro, Massimiliano

    2012-08-07

    A catalyst composition comprising a neutral bimetallic diphenoxydiiminate complex of group 10 metals or Ni, Pd or Pt is disclosed. The compositions can be used for the preparation of homo- and co-polymers of olefinic monomer compounds.

  18. Neutral particle measurements of fusion tritons in JET

    SciTech Connect

    Afanasyev, V. I.; Khudoleev, A. V.

    2010-08-15

    A neutral particle analyzer [A.D. Izvozchikov et al., JET Report No. JET-R(91)-12, 1991] operating in the MeV energy range was used to measure the flux of neutralized d-d fusion tritons emitted from the hot-ion H-mode deuterium plasma heated by deuterium neutral beams. It was found that tritons in the energy range of 0.3-1.1 MeV were largely neutralized by the beam atoms and the beam halo atoms. This enabled us to find the localized energy distribution function of the fusion tritons in the central plasma region. Simulation of the triton energy distribution function shows that MeV ions in the JET hot-ion H-mode plasma behave classically.

  19. Energy distributions of sputtered copper neutrals and ions

    NASA Technical Reports Server (NTRS)

    Lundquist, T. R.

    1978-01-01

    Direct quantitative analysis of surfaces by secondary ion mass spectrometry will depend on an understanding of the yield ratio of ions to neutrals. This ratio as a function of the energy of the sputtered particles has been obtained for a clean polycrystalline copper surface sputtered by 1000-3000 eV Ar(+). The energy distributions of both neutral and ionized copper were measured with a retarding potential analyzer using potential modulation differentiation and signal averaging. The maximum for both distributions is identical and occurs near 2.5 eV. The energy distributions of neutrals is more sharply peaked than that of the ions, presumably as a consequence of more efficient nutralization of slow escaping ions by the mobile electrons of copper. The ion-neutral ratio is compared with results from various ionization models.

  20. Negative ion based neutral beam injector for JT-60U

    NASA Astrophysics Data System (ADS)

    Okumura, Y.; Araki, M.; Hanada, M.; Inoue, T.; Kunieda, S.; Kuriyama, M.; Matsuoka, M.; Mizuno, M.; Ohara, Y.; Tanaka, M.; Watanabe, K.

    1992-10-01

    A 500 keV, 10 MW neutral beam injector is to be constructed in JT-60 Upgrade for the experiments of current drive and heating of heat density core plasmas. This is the first neutral beam injector in the world using negative ions as the primary ions. In the design, D- ion beams of 44 A, 500 keV are produced by two ion sources (22 A/each ion source) and neutralized in a long gas neutralizer. The total system efficiency is about 40%. The ion source is a cesium-seeded multicusp volume source having a three stage electrostatic accelerator. To reduce the stripping loss of D- ions in the accelerator, the ion source should be operated at a low pressure of 0.3 Pa with a current density of 13 mA/cm2. The first test of the full-size negative ion source is scheduled from middle of 1993.

  1. Identification of neutral tumor evolution across cancer types.

    PubMed

    Williams, Marc J; Werner, Benjamin; Barnes, Chris P; Graham, Trevor A; Sottoriva, Andrea

    2016-03-01

    Despite extraordinary efforts to profile cancer genomes, interpreting the vast amount of genomic data in the light of cancer evolution remains challenging. Here we demonstrate that neutral tumor evolution results in a power-law distribution of the mutant allele frequencies reported by next-generation sequencing of tumor bulk samples. We find that the neutral power law fits with high precision 323 of 904 cancers from 14 types and from different cohorts. In malignancies identified as evolving neutrally, all clonal selection seemingly occurred before the onset of cancer growth and not in later-arising subclones, resulting in numerous passenger mutations that are responsible for intratumoral heterogeneity. Reanalyzing cancer sequencing data within the neutral framework allowed the measurement, in each patient, of both the in vivo mutation rate and the order and timing of mutations. This result provides a new way to interpret existing cancer genomic data and to discriminate between functional and non-functional intratumoral heterogeneity. PMID:26780609

  2. Reactivity in ion-neutral high density media

    NASA Astrophysics Data System (ADS)

    Pérez-Ríos, J.; Greene, C. H.

    2016-03-01

    The recent development of hybrid traps technology has revolutionized the field of cold chemistry. Recently, new trap configurations have been built in order to explore more involve chemical processes, among them is the three-body recombination involving ions and neutrals. Different ion-neutral-neutral reactions at low collision energies: 0.1 mK - 10 mK, are studied by means of a very recent method for classical trajectory calculations in hyperspherical coordinates for treating three-body collisions [J. Pérez-Ríos, S. Ragole, J. Wang and C. H. Greene, J. Chem. Phys. 140, 044307 (2014)]. On the other hand a classically derived threshold law is obtained and numerically confirmed. The derived threshold law predicts molecular ions should dominate over molecular neutrals as the most products formed.

  3. Genetics Home Reference: neutral lipid storage disease with myopathy

    MedlinePlus

    ... inflammation of the pancreas (pancreatitis), reduced thyroid activity (hypothyroidism), and type 2 diabetes mellitus (the most common ... Neutral lipid storage disease with myopathy MedlinePlus Encyclopedia: Hypothyroidism MedlinePlus Encyclopedia: Type 2 Diabetes These resources from ...

  4. 29 CFR 1207.3 - Compensation of neutrals.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... where the party members of a PL Board created under Public Law 89-456 mutually agree upon a neutral... representatives are unable to agree upon the establishment and jurisdiction of a PL Board, and mutually agree...

  5. 29 CFR 1207.3 - Compensation of neutrals.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... where the party members of a PL Board created under Public Law 89-456 mutually agree upon a neutral... representatives are unable to agree upon the establishment and jurisdiction of a PL Board, and mutually agree...

  6. Calculation of neutral beam deposition accounting for excited states

    SciTech Connect

    Gianakon, T.A.

    1992-09-01

    Large-scale neutral-beam auxillary heating of plasmas has led to new plasma operational regimes which are often dominated by fast ions injected via the absorption of an energetic beam of hydrogen neutrals. An accurate simulation of the slowing down and transport of these fast ions requires an intimate knowledge of the hydrogenic neutral deposition on each flux surface of the plasma. As a refinement to the present generation of transport codes, which base their beam deposition on ground-state reaction rates, a new set of routines, based on the excited states of hydrogen, is presented as mechanism for computing the attenuation and deposition of a beam of energetic neutrals. Additionally, the numerical formulations for the underlying atomic physics for hydrogen impacting on the constiuent plasma species is developed and compiled as a numerical database. Sample results based on this excited state model are compared with the ground-state model for simple plasma configurations.

  7. Requirements for neutral beam current drive in tokamaks

    SciTech Connect

    Dory, R.A.

    1988-01-01

    This paper contains viewgraphs on the use of neutral beam current drive in future tokamaks. Current profiles, slowing down distributions, beam destabilization of alfven waves and plasma parameters are some items covered in this paper. (DWL)

  8. Nonlinear transient neutralization theory of ion beams with dissipation

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.

    1975-01-01

    An analytical theory of nonlinear neutralization waves generated by injection of electrons from a grid in the direction of a homogeneous ion beam of uniform velocity and infinite extension is presented. The electrons are assumed to interact with the ions through the self-consistent space charge field and by strong collective interactions. The associated nonlinear boundary-value problem is solved in closed form by means of a von Mises transformation. It is shown that the electron gas moves into the ion space in the form of a discontinuous neutralization wave. This periodic wave structure is damped out by intercomponent momentum transfer, i.e., after a few relaxation lengths a quasi-neutral beam results. The relaxation scale in space agrees with neutralization experiments of rarefied ion beams, if the collective momentum transfer between the electron and ion streams is assumed to be of the Buneman type.

  9. Space Charge Neutralization in the ITER Negative Ion Beams

    SciTech Connect

    Surrey, Elizabeth

    2007-08-10

    A model of the space charge neutralization of negative ion beams, developed from the model due to Holmes, is applied to the ITER heating and diagnostic beams. The Holmes model assumed that the plasma electron temperature was derived from the stripped electrons. This is shown to be incorrect for the ITER beams and the plasma electron temperature is obtained from the average creation energy upon ionization. The model shows that both ITER beams will be fully space charge compensated in the drift distance between the accelerator and the neutralizer. Inside the neutralizer, the plasma over compensates the space charge to the extent that a significant focusing force is predicted. At a certain position in the neutraliser this force balances the defocusing force due to the ions' transverse energy. Under these conditions the beam distribution function can change from Gaussian to Bennett and evidence of such a distribution observed in a multi-aperture, neutralized negative ion beam is presented.

  10. 50. VIEW OF CHEMICAL FEED PUMP HOUSE AND NEUTRALIZATION TANK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. VIEW OF CHEMICAL FEED PUMP HOUSE AND NEUTRALIZATION TANK FOR WASTE WATER TREATMENT LOOKING EAST. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  11. A Continuous Variation Study of Heats of Neutralization.

    ERIC Educational Resources Information Center

    Mahoney, Dennis W.; And Others

    1981-01-01

    Suggests that students study heats of neutralization of a 1 M solution of an unknown acid by 1 M solution of a strong base using the method continuous variation. Reviews results using several common acids. (SK)

  12. Ion engine neutralizer erosion in lab and space

    NASA Technical Reports Server (NTRS)

    Kuharski, R. A.; Mandell, M. J.; Gardner, B. M.

    2005-01-01

    In this paper we present calculations of neutralizer erosion due to both of these sources, including the difference between lab and space environments, and compare the results with laboratory test data.

  13. PTFE-ALUMINUM films serve as neutral density filters

    NASA Technical Reports Server (NTRS)

    Burks, H. D.

    1966-01-01

    Polytetrafluoroethylene /PTFE/ films coated with aluminum films act as neutral density filters in the wavelength range 0.3 to 2.1 microns. These filters are effective in the calibration of photometric systems.

  14. Prediction of Neutral Salt Elution Profiles for Affinity Chromatography

    NASA Astrophysics Data System (ADS)

    Robinson, Jack B.; Strottmann, James M.; Stellwagen, Earle

    1981-04-01

    Neutral salts exhibit very marked differences as eluants of proteins from affinity columns. We observe: (i) that the relative potencies of neutral salts as eluants are independent of the protein or the affinity ligand in the systems studied, (ii) that the absolute salt concentration necessary to elute any given protein bound to the affinity matrix is proportional to the algebraic sum of a set of elution coefficients defined herein for the separate ions present in the solution, and (iii) that the proportionality between elution potency and elution coefficient is a function of the affinity of the protein for the immobilized ligand. Given the concentration of one neutral salt required for elution of a protein of interest from an affinity column, the elution capability of any neutral salt at any temperature can be quantitatively predicted for that protein. Accordingly, application and elution protocols for affinity chromatography can be designed to optimize the yield and fold purification of proteins.

  15. THE ROLE OF NEUTRALS IN H-MODE PEDESTAL FORMATION

    SciTech Connect

    R.J. GROEBNER; M.A. MAHDAVI; A.W. LEONARD; T.H. OSBORNE; G.D. PORTER; R.J. COLCHIN; L.W.OWEN

    2001-11-01

    An analytic model, derived from coupled continuity equations for the electron and neutral deuterium densities, is consistent with many features of edge electron density profiles in the DIII-D tokamak. For an assumed constant particle diffusion coefficient, the model shows that particle transport and neutral fueling produce electron and neutral density profiles that have the same characteristic scale lengths at the plasma edge. For systematic variations of density in H-mode discharges, the model predicts that the width of the electron density transport barrier decreases and the maximum gradient increases, as observed in the experiments. The widths computed from the model agree quantitatively with the experimental widths for conditions in which the model is valid. These results support models of transport barrier formation in which the H-mode particle barrier is driven by the edge particle flux and the width of the barrier is approximately the neutral penetration length.

  16. Empirical evaluation of neutral interactions in host-parasite networks.

    PubMed

    Canard, E F; Mouquet, N; Mouillot, D; Stanko, M; Miklisova, D; Gravel, D

    2014-04-01

    While niche-based processes have been invoked extensively to explain the structure of interaction networks, recent studies propose that neutrality could also be of great importance. Under the neutral hypothesis, network structure would simply emerge from random encounters between individuals and thus would be directly linked to species abundance. We investigated the impact of species abundance distributions on qualitative and quantitative metrics of 113 host-parasite networks. We analyzed the concordance between neutral expectations and empirical observations at interaction, species, and network levels. We found that species abundance accurately predicts network metrics at all levels. Despite host-parasite systems being constrained by physiology and immunology, our results suggest that neutrality could also explain, at least partially, their structure. We hypothesize that trait matching would determine potential interactions between species, while abundance would determine their realization. PMID:24642492

  17. Neutralization of a fast negative-ion beam

    SciTech Connect

    Schlachter, A.S.; Mowat, J.R.; Stearns, J.W.; Gohil, P.; Pyle, R.V.

    1986-01-01

    Neutralization of a fast negative-ion beam, primarily H/sup -/, is discussed in terms of competing one- and two-electron detachment processes in a variety of media: gas (vapor), plasma, liquid sheet, solid foil.

  18. Periodic oscillation for a Hopfield neural networks with neutral delays

    NASA Astrophysics Data System (ADS)

    Gui, Zhanji; Ge, Weigao; Yang, Xiao-Song

    2007-04-01

    In this Letter, a Hopfield neural networks model with neutral delay are investigated by means of an abstract continuous theorem of k-set contractive operator and some analysis technique. Sufficient conditions are obtained for the existence of periodic solutions.

  19. Neutral and charged matter in equilibrium with black holes

    NASA Astrophysics Data System (ADS)

    Bronnikov, K. A.; Zaslavskii, O. B.

    2011-10-01

    We study the conditions of a possible static equilibrium between spherically symmetric, electrically charged or neutral black holes and ambient matter. The following kinds of matter are considered: (1) neutral and charged matter with a linear equation of state pr=wρ (for neutral matter the results of our previous work are reproduced), (2) neutral and charged matter with pr˜ρm, m>1, and (3) the possible presence of a “vacuum fluid” (the cosmological constant or, more generally, anything that satisfies the equality T00=T11 at least at the horizon). We find a number of new cases of such an equilibrium, including those generalizing the well-known Majumdar-Papapetrou conditions for charged dust. It turns out, in particular, that ultraextremal black holes cannot be in equilibrium with any matter in the absence of a vacuum fluid; meanwhile, matter with w>0, if it is properly charged, can surround an extremal charged black hole.

  20. Benchmark of 3D halo neutral simulation in TRANSP and FIDASIM and application to projected neutral-beam-heated NSTX-U plasmas

    NASA Astrophysics Data System (ADS)

    Liu, D.; Medley, S. S.; Gorelenkova, M. V.; Heidbrink, W. W.; Stagner, L.

    2014-10-01

    A cloud of halo neutrals is created in the vicinity of beam footprint during the neutral beam injection and the halo neutral density can be comparable with beam neutral density. Proper modeling of halo neutrals is critical to correctly interpret neutral particle analyzers (NPA) and fast ion D-alpha (FIDA) signals since these signals strongly depend on local beam and halo neutral density. A 3D halo neutral model has been recently developed and implemented inside TRANSP code. The 3D halo neutral code uses a ``beam-in-a-box'' model that encompasses both injected beam neutrals and resulting halo neutrals. Upon deposition by charge exchange, a subset of the full, one-half and one-third beam energy components produce thermal halo neutrals that are tracked through successive halo neutral generations until an ionization event occurs or a descendant halo exits the box. A benchmark between 3D halo neural model in TRANSP and in FIDA/NPA synthetic diagnostic code FIDASIM is carried out. Detailed comparison of halo neutral density profiles from two codes will be shown. The NPA and FIDA simulations with and without 3D halos are applied to projections of plasma performance for the National Spherical Tours eXperiment-Upgrade (NSTX-U) and the effects of halo neutral density on NPA and FIDA signal amplitude and profile will be presented. Work supported by US DOE.

  1. Neutral particle dynamics in the Alcator C-Mod tokamak

    SciTech Connect

    Niemczewski, A.P.

    1995-08-01

    This thesis presents an experimental study of neutral particle dynamics in the Alcator C-Mod tokamak. The primary diagnostic used is a set of six neutral pressure gauges, including special-purpose gauges built for in situ tokamak operation. While a low main chamber neutral pressure coincides with high plasma confinement regimes, high divertor pressure is required for heat and particle flux dispersion in future devices such as ITER. Thus we examine conditions that optimize divertor compression, defined here as a divertor-to-midplane pressure ratio. We find both pressures depend primarily on the edge plasma regimes defined by the scrape-off-layer heat transport. While the maximum divertor pressure is achieved at high core plasma densities corresponding to the detached divertor state, the maximum compression is achieved in the high-recycling regime. Variations in the divertor geometry have a weaker effect on the neutral pressures. For otherwise similar plasmas the divertor pressure and compression are maximum when the strike point is at the bottom of the vertical target plate. We introduce a simple flux balance model, which allows us to explain the divertor neutral pressure across a wide range of plasma densities. In particular, high pressure sustained in the detached divertor (despite a considerable drop in the recycling source) can be explained by scattering of neutrals off the cold plasma plugging the divertor throat. Because neutrals are confined in the divertor through scattering and ionization processes (provided the mean-free-paths are much shorter than a typical escape distance) tight mechanical baffling is unnecessary. The analysis suggests that two simple structural modifications may increase the divertor compression in Alcator C-Mod by a factor of about 5. Widening the divertor throat would increase the divertor recycling source, while closing leaks in the divertor structure would eliminate a significant neutral loss mechanism. 146 refs., 82 figs., 14 tabs.

  2. A superconducting NbN detector for neutral nanoparticles

    NASA Astrophysics Data System (ADS)

    Marksteiner, Markus; Divochiy, Alexander; Sclafani, Michele; Haslinger, Philipp; Ulbricht, Hendrik; Korneev, Alexander; Semenov, Alexander; Gol'tsman, Gregory; Arndt, Markus

    2009-11-01

    We present a proof-of-principle study of superconducting single photon detectors (SSPD) for the detection of individual neutral molecules/nanoparticles at low energies. The new detector is applied to characterize a laser desorption source for biomolecules and allows retrieval of the arrival time distribution of a pulsed molecular beam containing the amino acid tryptophan, the polypeptide gramicidin as well as insulin, myoglobin and hemoglobin. We discuss the experimental evidence that the detector is actually sensitive to isolated neutral particles.

  3. The impact of exospheric neutral dynamics on ring current decay

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Liemohn, M. W.; Skoug, R. M.; Funsten, H. O.; Gruntman, M.; Bailey, J. J.; Toth, G.

    2015-12-01

    The geocorona plays an important role in the energy budget of the Earth's inner magnetosphere since charge exchange of energetic ions with exospheric neutrals makes the exosphere act as an energy sink for ring current particles. Long-term ring current decay following a magnetic storm is mainly due to these electron transfer reactions, leading to the formation energetic neutral atoms (ENAs) that leave the ring current system on ballistic trajectories. The number of ENAs emitted from a given region of space depends on several factors, such as the energy and species of the energetic ion population in that region and the density of the neutral gas with which the ions undergo charge exchange. However, the density and structure of the exosphere are strongly dependent on changes in atmospheric temperature and density as well as charge exchange with the ions of plasmaspheric origin, which depletes the geocorona (by having a neutral removed from the system). Moreover, the radiation pressure exerted by solar far-ultraviolet photons pushes the geocoronal hydrogen away from the Earth in an anti-sunward direction to form a tail of neutral hydrogen. TWINS ENA images provide a direct measurement of these ENA losses and therefore insight into the dynamics of the ring current decay through interactions with the geocorona. We assess the influence of geocoronal neutrals on ring current formation and decay by analysis of the predicted ENA emissions using 6 different geocoronal models and simulations from the HEIDI ring current model during storm time. Comparison with TWINS ENA images shows that the location of the peak ENA enhancements is highly dependent on the distribution of geocoronal hydrogen density. We show that the neutral dynamics has a strong influence on the time evolution of the ring current populations as well as on the formation of energetic neutral atoms.

  4. Beam loss by collimation in a neutralizer duct

    SciTech Connect

    Hamilton, G.W.; Willmann, P.A.

    1980-04-03

    Beam fractions lost by collimation in a neutralizer duct are computed in x-x' phase space by using three examples of slab beam distributions under a broad range of duct dimensions, beam half-widths, and beam divergences. The results can be used to design compact neutralizers and to specify beam requirements. The computer code ILOST can be used under a broad range of beam conditions to compute the fraction lost by collimation.

  5. Conceptual Design of Neutral Beam Injection System for EAST

    NASA Astrophysics Data System (ADS)

    Hu, Chundong; NBI Team

    2012-06-01

    Neutral beam injection (NBI) system with two neutral beam injections will be constructed on the Experimental Advanced Superconducting Tokamak (EAST) in two stages for high power auxiliary plasmas heating and non-inductive current drive. Each NBI can deliver 2~4 MW beam power with 50~80 keV beam energy in 10~100 s pulse length. Each elements of the NBI system are presented in this contribution.

  6. Neutral triple and quartic gauge couplings at LEP

    NASA Astrophysics Data System (ADS)

    Ofierzynski, R.

    2002-06-01

    The possible existence of neutral triple ZZZ, ZZγ and Zγγ and quartic ZZγγ gauge boson couplings is investigated. Based on data collected at LEP2 at centre-of-mass energies up to 208 GeV no evidence has been found for such couplings. Preliminary limits for neutral triple gauge couplings as obtained from the combination of the LEP experiments are presented.

  7. Neutral-beam systems for magnetic-fusion reactors

    SciTech Connect

    Fink, J. H.

    1981-08-10

    Neutral beams for magnetic fusion reactors are at an early stage of development, and require considerable effort to make them into the large, reliable, and efficient systems needed for future power plants. To optimize their performance to establish specific goals for component development, systematic analysis of the beamlines is essential. Three ion source characteristics are discussed: arc-cathode life, gas efficiency, and beam divergence, and their significance in a high-energy neutral-beam system is evaluated.

  8. Neutral current pi0 production in MiniBooNE

    SciTech Connect

    Link, J.M.; /Virginia Tech.

    2007-09-01

    This paper describes the analysis used to determine the neutral current {pi}{sup 0} production in MiniBooNE in bins of momentum. Additionally, a measurement of the relative coherent production of {pi}{sup 0}s is discussed. The coherent production rate is found to be (19.5 {+-}1.1 (stat) {+-}2.5 (sys))% of the total exclusive neutral current {pi}{sup 0} production rate.

  9. Ferroelectric Plasma Source for Heavy Ion Beam ChargeNeutralization

    SciTech Connect

    Efthimion, Philip C.; Gilson, Erik P.; Grisham, Larry; Davidson,Ronald C.; Yu, Simon; Waldron, William; Logan, B. Grant

    2005-10-01

    Plasmas are employed as a source of unbound electrons for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length {approx} 0.1-1 m would be suitable. To produce one-meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being developed. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source utilizes the ferroelectric ceramic BaTiO{sub 3} to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic, and high voltage ({approx} 1-5 kV) applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long has produced plasma densities of 5 x 10{sup 11} cm{sup -3}. The source was integrated into the previous Neutralized Transport Experiment (NTX), and successfully charge neutralized the K{sup +} ion beam. Presently, the one-meter source is being fabricated. The source is being characterized and will be integrated into NDCX for charge neutralization experiments.

  10. Interaction of a neutral cloud moving through a magnetized plasma

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.; Lu, G.

    1990-01-01

    Current collection by outgassing probes in motion relative to a magnetized plasma may be significantly affected by plasma processes that cause electron heating and cross field transport. Simulations of a neutral gas cloud moving across a static magnetic field are discussed. The authors treat a low-Beta plasma and use a 2-1/2 D electrostatic code linked with the authors' Plasma and Neutral Interaction Code (PANIC). This study emphasizes the understanding of the interface between the neutral gas cloud and the surrounding plasma where electrons are heated and can diffuse across field lines. When ionization or charge exchange collisions occur a sheath-like structure is formed at the surface of the neutral gas. In that region the crossfield component of the electric field causes the electron to E times B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating. The thermal electron current is significantly enhanced due to this heating.

  11. A microwave plasma cathode electron gun for ion beam neutralization

    NASA Astrophysics Data System (ADS)

    Fusellier, C.; Wartski, L.; Aubert, J.; Schwebel, C.; Coste, Ph.; Chabrier, A.

    1998-02-01

    It is well known that there exist two distinct types of ion beam neutralization, viz., charge and current neutralization. We have designed and studied a versatile and compact microwave plasma (MP) cathode electron gun dedicated to charge as well as current neutralization. Unlike the conventional hot cathode neutralizer, this MP cathode allows operation of the electron gun in a reactive gaseous environment when it is eventually associated with an electron cyclotron resonance (ECR) ion gun. Charge neutralization can be easily carried out by extracting from the MP cathode through a 1 mm diameter hole, a 35 mA electron beam under a 20 V voltage; the MP cathode being fed with a 75 W microwave power at 2.45 GHz. Higher beam intensities could be obtained using a multiaperture thin plate. Electron beam intensities as high as 300 mA and energies of 2 keV needed for current neutralization, e.g., when an ion beam impinges onto a thick dielectric surface, are obtained via a two-stage arrangement including an anodic chamber associated with a set of three monoaperture plates for the electron beam extraction. Transport of 200-2000 eV electron beams is ensured using focusing optics composed of three aligned tubes 6 cm in diameter and unsymmetrically polarized.

  12. Facility for intense diagnostic neutral beam (IDNB) development

    SciTech Connect

    Kasik, R.J.; Hinckley, W.B.; Bartsch, R.R.; Rej, D.J.; Henins, I.; Greenly, J.B.

    1993-08-01

    An intense, pulsed neutral beam source is under development for use as a probe beam on hot, burning plasmas such as in the international thermonuclear experimental reactor (ITER) which is presently in the planning stage. A pulsed, neutral hydrogen beam of 10s of kilo amperes of current can have an alpha particle, charge-exchange-recombination-spectroscopy (alpha-CHERS) signal-to-noise ratio of {approximately} 10. This beam would allow the measurement, on a single pulse of a few hundred nanoseconds duration, of the local alpha particle distribution function as well as other features of the tokamak plasma such as current density profile, impurity density, and microturbulence spectrum. The cross-sections for the CHERS diagnostic dictate operation with proton energies greater than {approximately}50keV. A pulsed neutral hydrogen source of this voltage and intensity can be achieved by neutralizing the ion flux from a magnetized ion-diode. The cross-sections for attachment and stripping, when coupled with scaling from Child-Langmiur, space-charge-limited, ion-current flow imply operation below - 100keV for maximum neutral fluence. The development of a flashover-anode, ion source for forthcoming evaluation of a neutralizing section is described below. This source operates in the accelerator voltage range 70 to 100keV. Eventually, the flashover-anode, magnetized ion-diode will be replaced with a plasma-anode, magnetized ion-diode.

  13. An improved user interface for ASSESS/Neutralization

    SciTech Connect

    Paulus, W.K.; Mondragon, J.; Sedam, M.

    1993-07-01

    The ASSESS Neutralization Analysis module (Neutralization) is part of Analytic System and Software for Evaluation of Safeguards and Security, ASSESS, a vulnerability assessment tool. Neutralization models a fire fight engagement between security inspectors (SIs) and adversaries. Since version 1.0 of Neutralization was released in 1989, experience has shown that several features of the user interface should be improved. This report describes the improvements that have been implemented, which simplify operation by consolidating all capabilities under a single mode of operation, remove many restrictions on editing, and concentrate more information into fewer types of printed reports. Every adversary and SI combatant is named and described individually. Time to communicate orders is specified for each SI combatant. Adversaries and SIs can be reinforced. SI posting as well deployment destination is labeled. Scenario details can be revised without losing all completed event information. New on-screen summaries spell out characteristics, minimizing abbreviations. Neutralization will read files created by the previous version and permit the user to enter the additional labels supported in the new version. As described here, Neutralization now has an interface that handles more information, but is easier and faster to use.

  14. Testing the Neutral Theory of Biodiversity with Human Microbiome Datasets.

    PubMed

    Li, Lianwei; Ma, Zhanshan Sam

    2016-01-01

    The human microbiome project (HMP) has made it possible to test important ecological theories for arguably the most important ecosystem to human health-the human microbiome. Existing limited number of studies have reported conflicting evidence in the case of the neutral theory; the present study aims to comprehensively test the neutral theory with extensive HMP datasets covering all five major body sites inhabited by the human microbiome. Utilizing 7437 datasets of bacterial community samples, we discovered that only 49 communities (less than 1%) satisfied the neutral theory, and concluded that human microbial communities are not neutral in general. The 49 positive cases, although only a tiny minority, do demonstrate the existence of neutral processes. We realize that the traditional doctrine of microbial biogeography "Everything is everywhere, but the environment selects" first proposed by Baas-Becking resolves the apparent contradiction. The first part of Baas-Becking doctrine states that microbes are not dispersal-limited and therefore are neutral prone, and the second part reiterates that the freely dispersed microbes must endure selection by the environment. Therefore, in most cases, it is the host environment that ultimately shapes the community assembly and tip the human microbiome to niche regime. PMID:27527985

  15. Neutral beam species measurements using in situ Rutherford backscatter spectrometry

    SciTech Connect

    Kugel, H.W.; Kaita, R.; Gammel, G.; Williams, M.D.

    1984-12-01

    This work describes a new in situ method for measuring the neutral particle fractions in high power deuterium neutral beams, used to heat magnetically confined fusion plasmas. Deuterium beams, of variable energies, pulse lengths, and powers up to 47 keV, 100 msec, 1.6 MW, were Rutherford backscattered at 135/sup 0/ from TiC inner neutral beam armor of the PDX, and detected using an electrostatic analyzer with microchannel plates. Complete energy scans were made every 20 msec and data were obtained simultaneously from five different positions across the beam profile. The neutral particle fractions were measured to be D/sup 0/(E):D/sup 0/(E/2):D/sup 0/(E/3)=53:32:15. The corresponding neutral power fractions were P/sup 0/(E):P/sup 0/(E/2):P/sup 0/(E/3)=72:21:7, and the associated ionic fractions at the output of the ion source were D/sub 1//sup +/(E):D/sub 2//sup +/(E):D/sub 3//sup +/(E)=74:20:6. The measured neutral particle fractions were relatively constant over more than 70% of the beam power distribution. A decrease in the yield of the full energy component in the outer regions of the beam was observed. Other possible experimental configurations and geometries are discussed.

  16. Neutral beam dump with cathodic arc titanium gettering

    SciTech Connect

    Smirnov, A.; Korepanov, S. A.; Putvinski, S.; Krivenko, A. S.; Murakhtin, S. V.; Savkin, V. Ya.

    2011-03-15

    An incomplete neutral beam capture can degrade the plasma performance in neutral beam driven plasma machines. The beam dumps mitigating the shine-through beam recycling must entrap and retain large particle loads while maintaining the beam-exposed surfaces clean of the residual impurities. The cathodic arc gettering, which provides high evaporation rate coupled with a fast time response, is a powerful and versatile technique for depositing clean getter films in vacuum. A compact neutral beam dump utilizing the titanium arc gettering was developed for a field-reversed configuration plasma sustained by 1 MW, 20-40 keV neutral hydrogen beams. The titanium evaporator features a new improved design. The beam dump is capable of handling large pulsed gas loads, has a high sorption capacity, and is robust and reliable. With the beam particle flux density of 5 x 10{sup 17} H/(cm{sup 2}s) sustained for 3-10 ms, the beam recycling coefficient, defined as twice the ratio of the hydrogen molecular flux leaving the beam dump to the incident flux of high-energy neutral atoms, is {approx}0.7. The use of the beam dump allows us to significantly reduce the recycling of the shine-through neutral beam as well as to improve the vacuum conditions in the machine.

  17. Testing the Neutral Theory of Biodiversity with Human Microbiome Datasets

    PubMed Central

    Li, Lianwei; Ma, Zhanshan (Sam)

    2016-01-01

    The human microbiome project (HMP) has made it possible to test important ecological theories for arguably the most important ecosystem to human health—the human microbiome. Existing limited number of studies have reported conflicting evidence in the case of the neutral theory; the present study aims to comprehensively test the neutral theory with extensive HMP datasets covering all five major body sites inhabited by the human microbiome. Utilizing 7437 datasets of bacterial community samples, we discovered that only 49 communities (less than 1%) satisfied the neutral theory, and concluded that human microbial communities are not neutral in general. The 49 positive cases, although only a tiny minority, do demonstrate the existence of neutral processes. We realize that the traditional doctrine of microbial biogeography “Everything is everywhere, but the environment selects” first proposed by Baas-Becking resolves the apparent contradiction. The first part of Baas-Becking doctrine states that microbes are not dispersal-limited and therefore are neutral prone, and the second part reiterates that the freely dispersed microbes must endure selection by the environment. Therefore, in most cases, it is the host environment that ultimately shapes the community assembly and tip the human microbiome to niche regime. PMID:27527985

  18. Neutral Hydrogen in Local Group Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Grcevich, Jana

    The gas content of the faintest and lowest mass dwarf galaxies provide means to study the evolution of these unique objects. The evolutionary histories of low mass dwarf galaxies are interesting in their own right, but may also provide insight into fundamental cosmological problems. These include the nature of dark matter, the disagreement between the number of observed Local Group dwarf galaxies and that predicted by lambda cold dark matter models, and the discrepancy between the observed census of baryonic matter in the Milky Way's environment and theoretical predictions. This thesis explores these questions by studying the neutral hydrogen (HI) component of dwarf galaxies. First, limits on the HI mass of the ultra-faint dwarfs are presented, and the HI content of all Local Group dwarf galaxies is examined from an environmental standpoint. We find that those Local Group dwarfs within 270 kpc of a massive host galaxy are deficient in HI as compared to those at larger galactocentric distances. Ram-pressure arguments are invoked, which suggest halo densities greater than 2-3 x 10-4 cm-3 out to distances of at least 70 kpc, values which are consistent with theoretical models and suggest the halo may harbor a large fraction of the host galaxy's baryons. We also find that accounting for the incompleteness of the dwarf galaxy count, known dwarf galaxies whose gas has been removed could have provided at most 2.1 x 108 M⊙ of HI gas to the Milky Way. Second, we examine the possibility of discovering unknown gas-rich ultra-faint galaxies in the Local Group using HI. The GALFA-HI Survey catalog is searched for compact, isolated HI clouds which are most similar to the expected HI characteristics of low mass dwarf galaxies. Fifty-one Local Group dwarf galaxy candidates are identified through column density, brightness temperature, and kinematic selection criteria, and their properties are explored. Third, we present hydrodynamic simulations of dwarf galaxies experiencing a

  19. Imager of low energy neutral atoms (ILENA) - Imaging neutrals from the magnetosphere at energies below 20 keV

    NASA Technical Reports Server (NTRS)

    Herrero, Federico A.; Smith, Mark F.

    1992-01-01

    We describe a new imager suitable for measurements of magnetospheric neutrals with energies from about 100 eV to about 10 keV; an energy range adequate for imaging the plasmasheet neutral atoms out to about 10 R(E). The instrument, an outgrowth of a study of atom-surface collisions in support of satellite drag calculations, separates incident photons from neutral atoms by surface scattering and conversion of the neutrals to ions. Subsequently, the ions formed on the first surface are accelerated through a light rejection section which also disperses the ions according to energy. The dispersed ion beam is then allowed to impact a second surface where a start pulse is generated to obtain ion velocity and energy/charge. The second surface is chosen to give large secondary electron emission without regard to charge state of the particles reflected from it. The data supporting the proposed ILENA design is presented in the first part of the paper.

  20. Anisotropy of the neutral gas distribution of Comet Halley deduced from NGE/Vega 1 measurements. [Neutral Gas Experiment (NGE)

    NASA Technical Reports Server (NTRS)

    Hsieh, K. C.; Eip, WING-H. AFKEPPLER, E. agrichter, a. k; Eip, WING-H. AFKEPPLER, E. agrichter, a. k

    1986-01-01

    The neutral gas density profile of comet Halley measured by the Neutral Gas Experiment on Vega 1 showed an asymmetry between the inbound and the outbound legs during the fly-by on 6 March 1986. The implications of this asymmetry are discussed, and it is shown how the asymmetry detected by NGE on Vega 1 can be traced back to regions on or near the nucleus to obtain their relative gas production activities at specific times of emission.

  1. The Effects of Somatic Hypermutation on Neutralization and Binding in the PGT121 Family of Broadly Neutralizing HIV Antibodies

    PubMed Central

    Vigneault, Francois; Julien, Jean-Philippe; Briney, Bryan; Ramos, Alejandra; Saye, Karen F.; Le, Khoa; Mahan, Alison; Wang, Shenshen; Kardar, Mehran; Yaari, Gur; Walker, Laura M.; Simen, Birgitte B.; St. John, Elizabeth P.; Chan-Hui, Po-Ying; Swiderek, Kristine; Kleinstein, Stephen H.; Alter, Galit; Seaman, Michael S.; Chakraborty, Arup K.; Koller, Daphne; Wilson, Ian A.; Church, George M.; Burton, Dennis R.; Poignard, Pascal

    2013-01-01

    Broadly neutralizing HIV antibodies (bnAbs) are typically highly somatically mutated, raising doubts as to whether they can be elicited by vaccination. We used 454 sequencing and designed a novel phylogenetic method to model lineage evolution of the bnAbs PGT121–134 and found a positive correlation between the level of somatic hypermutation (SHM) and the development of neutralization breadth and potency. Strikingly, putative intermediates were characterized that show approximately half the mutation level of PGT121–134 but were still capable of neutralizing roughly 40–80% of PGT121–134 sensitive viruses in a 74-virus panel at median titers between 15- and 3-fold higher than PGT121–134. Such antibodies with lower levels of SHM may be more amenable to elicitation through vaccination while still providing noteworthy coverage. Binding characterization indicated a preference of inferred intermediates for native Env binding over monomeric gp120, suggesting that the PGT121–134 lineage may have been selected for binding to native Env at some point during maturation. Analysis of glycan-dependent neutralization for inferred intermediates identified additional adjacent glycans that comprise the epitope and suggests changes in glycan dependency or recognition over the course of affinity maturation for this lineage. Finally, patterns of neutralization of inferred bnAb intermediates suggest hypotheses as to how SHM may lead to potent and broad HIV neutralization and provide important clues for immunogen design. PMID:24278016

  2. Identification of a novel amidase motif in neutral ceramidase

    PubMed Central

    2005-01-01

    Neutral CDases (ceramidases) are newly identified enzymes with important roles in cell regulation, but little is known about their catalytic mechanisms. In the present study the full-length human neutral CDase was cloned and expressed in the yeast double-knockout strain Δypc1Δydc1, which lacks the yeast CDases YPC1p and YDC1p. Biochemical characterization of the human neutral CDase showed that the enzyme exhibited classical Michaelis–Menten kinetics, with an optimum activity at pH 7.5. Activity was enhanced by Na+ and Ca2+. Mg2+ and Mn2+ were somewhat stimulatory, but Zn2+, Cu2+ and Fe2+ inhibited the enzyme. Dithiothreitol and 2-mercaptoethanol dose-dependently inhibited neutral CDase. In order to identify which amino acids were involved in the catalytic action of neutral CDase, the purified enzyme was subjected to chemical modifications. It was observed that the serine residue modifier di-isopropyl fluorophosphate dose-dependently inhibited activity, implicating a serine residue in the catalytic action. From an alignment of the sequences of the neutral CDases from different species, all conserved serine residues were selected for site-directed mutagenesis. Of the six aligned serine residues that were mutated to alanine, only the S354A mutant lost its activity totally. Ser354 falls within a very highly conserved hexapeptide sequence GDVSPN, which itself was in the middle of a larger conserved sequence, namely NXGDVSPNXXGP/XXC. Moreover, mutations of Asp352 and Cys362 in the consensus sequence to alanine resulted in loss of activity of neutral CDase. Hence the present study identified a novel amidase sequence containing a critical serine residue that may function as a nucleophile in the hydrolytic attack on the amide bond present in ceramide. PMID:16229686

  3. Identification of a novel amidase motif in neutral ceramidase.

    PubMed

    Galadari, Sehamuddin; Wu, Bill X; Mao, Cungui; Roddy, Patrick; El Bawab, Samer; Hannun, Yusuf A

    2006-02-01

    Neutral CDases (ceramidases) are newly identified enzymes with important roles in cell regulation, but little is known about their catalytic mechanisms. In the present study the full-length human neutral CDase was cloned and expressed in the yeast double-knockout strain Dypc1Dydc1, which lacks the yeast CDases YPC1p and YDC1p. Biochemical characterization of the human neutral CDase showed that the enzyme exhibited classical Michaelis-Menten kinetics, with an optimum activity at pH 7.5. Activity was enhanced by Na+ and Ca2+. Mg2+ and Mn2+ were somewhat stimulatory, but Zn2+, Cu2+ and Fe2+ inhibited the enzyme. Dithiothreitol and 2-mercaptoethanol dose-dependently inhibited neutral CDase. In order to identify which amino acids were involved in the catalytic action of neutral CDase, the purified enzyme was subjected to chemical modifications. It was observed that the serine residue modifier di-isopropyl fluorophosphate dose-dependently inhibited activity, implicating a serine residue in the catalytic action. From an alignment of the sequences of the neutral CDases from different species, all conserved serine residues were selected for site-directed mutagenesis. Of the six aligned serine residues that were mutated to alanine, only the S354A mutant lost its activity totally. Ser354 falls within a very highly conserved hexapeptide sequence GDVSPN, which itself was in the middle of a larger conserved sequence, namely NXGDVSPNXXGP/XXC. Moreover, mutations of Asp352 and Cys362 in the consensus sequence to alanine resulted in loss of activity of neutral CDase. Hence the present study identified a novel amidase sequence containing a critical serine residue that may function as a nucleophile in the hydrolytic attack on the amide bond present in ceramide. PMID:16229686

  4. Experimental evidence of energetic neutrals production in an ion diode

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. I.; Isakova, Y. I.; Khaylov, I. P.

    2015-01-01

    The paper presents several experimental proofs of the formation of energetic charge-exchange neutrals in a self-magnetically insulated ion diode with a graphite cathode. The energetic neutrals are thought to be produced as a result of charge exchange process between accelerated ions and stationary neutral molecules. The experiments have been carried out using both a diode with externally applied magnetic insulation (single-pulse mode: 100 ns, 250-300 kV) and a diode with self-magnetic insulation (double-pulse mode: 300-500 ns, 100-150 kV (negative pulse); 120 ns, 250-300 kV (positive pulse)). The motivation for looking at the neutral component of the ion beam came when we compared two independent methods to measure the energy density of the beam. A quantitative comparison of infrared measurements with signals from Faraday cups and diode voltage was made to assess the presence of neutral atoms in the ion beam. As another proof of charge-exchange effects in ion diode we present the results of statistical analysis of diode performance. It was found that the shot-to shot variation of the energy density in a set of 50-100 shots does not exceed 11%, whilst the same variation for ion current density was 20-30%; suggesting the presence of neutrals in the beam. Moreover, the pressure in the zone of ion beam energy dissipation exceeds the results stated in cited references. The difference between our experimental data and results stated by other authors we attribute to the presence of a low-energy charge-exchange neutral component in the ion beam.

  5. The Neutral Density Temporal Residual Mean overturning circulation

    NASA Astrophysics Data System (ADS)

    Stewart, A. L.; Thompson, A. F.

    2015-06-01

    Diagnosis of the ocean's overturning circulation is essential to closing global budgets of heat, salt and biogeochemical tracers. This diagnosis is sensitive to the choice of density variable used to distinguish water masses and identify transformations between them. The oceanographic community has adopted neutral density for this purpose because its isopycnal slopes are approximately aligned with neutral slopes, along which ocean flows tend to be confined. At high latitudes there are often no tenable alternatives because potential density varies non-monotonically with depth, regardless of the reference pressure. However, in many applications the use of isoneutral fluxes is impractical due to the high computational cost of calculating neutral density. Consequently neutral density-related diagnostics are typically not available as output from ocean models. In this article the authors derive a modified Temporal Residual Mean (TRM) approximation to the isoneutral mass fluxes, referred to as the Neutral Density Temporal Residual Mean (NDTRM). The NDTRM may be calculated using quantities that are routinely offered as diagnostic output from ocean models, making it several orders of magnitude faster than explicitly computing isoneutral mass fluxes. The NDTRM is assessed using a process model of the Antarctic continental shelf and slope. The onshore transport of warm Circumpolar Deep Water in the model ocean interior approximately doubles when diagnosed using neutral density, rather than potential density. The NDTRM closely approximates these explicitly-computed isoneutral mass fluxes. The NDTRM also exhibits a much smaller error than the traditional TRM in regions of large isoneutral temperature and salinity gradients, where nonlinearities in the equation of state diabatically modify the neutral density.

  6. Io's neutral clouds: From the atmosphere to the plasma torus

    NASA Astrophysics Data System (ADS)

    Burger, Matthew Howard

    2003-10-01

    Since the discovery of sodium thirty years ago, observations of Io's neutral features have provided essential insight into understanding the relationship between the Io's atmosphere and the Io torus, a ring of plasma encircling Jupiter. In this thesis I use observations and models of lo's corona, extended neutral clouds, and fast sodium jet to probe the interactions between the atmosphere, torus, and neutral clouds. A corona and neutral cloud model, based on the model of Wilson and Schneider (1999), has been developed to study neutral loss from Io. Neutrals are ejected from Io's exobase and their trajectories followed under the influence of gravity until lost into the plasma torus. I also developed description of the plasma torus based on Voyager and ground-based observations to accurately determine neutral lifetimes. Mutual eclipsing events between Galilean satellites were used to measure the shape of lo's sodium corona, revealing a corona that is only approximately spherically symmetric around Io. I discovered a previously undetected asymmetry: the sub-Jupiter corona is denser than the anti-Jupiter corona. Modeling implies that sodium source from the sub-Jupiter hemisphere must be twice as large as from the anti-Jupiter hemisphere. The Galileo spacecraft has imaged a remarkable atmospheric escape process occurring in Io's ionosphere. Electrodynamic consequences of Io's motion through Jupiter's magnetosphere drive mega-amp currents through lo's ionosphere; some sodium ions carrying this current are neutralized as they leave the atmosphere. The Galileo images show that the resulting fast sodium jet removes ˜5 × 1025 atoms sec-1 from Io's atmosphere. The source region of the jet is much smaller than Io itself implying that the ionosphere is densest near Io's equator. A model-based comparison of the neutral oxygen and sodium clouds details differences in the morphologies and spatial extent of each: sodium extends only 1/4 the way around Jupiter while oxygen forms a

  7. Integral Transport Analysis of Ions Flowing Through Neutral Gas

    NASA Astrophysics Data System (ADS)

    Emmert, Gilbert; Santarius, John; Alderson, Eric

    2011-10-01

    A computational model for the flow of energetic ions through a background neutral gas is being developed. Its essence is to consider reactions as creating a new source of ions or neutrals if the energy or charge state of the resulting particle is changed. For a given source boundary condition, the creation and annihilation of the various species is formulated as a 1-D Volterra integral equation that can quickly be solved numerically by finite differences. The current work focuses on radially converging, multiple-pass, 1-D ion flow through neutral gas and a nearly transparent, concentric anode and cathode pair in spherical geometry. This has been implemented as a computer code for atomic (3He, 3He+) and molecular (D, D2, D-, D+, D2+, D3+) ion and neutral species, and applied to modeling inertial-electrostatic confinement (IEC) devices. The inclusion of negative ions is a recent development. The code yields detailed energy spectra of the various ions and energetic neutral species. Comparisons with experimental data for a University of Wisconsin IEC device will be presented. Research supported by US Dept of Energy, grant DE-FG02-04ER54745, and by the Grainger Foundation.

  8. Seeking to Improve Low Energy Neutral Atom Detection in Space

    NASA Technical Reports Server (NTRS)

    Shappirio, M.; Coplan, M.; Chornay, D.; Collier, M.; Herrero, F.; Ogilvie, K.; Williams, E.

    2007-01-01

    The detection of energetic neutral atoms allows for the remote examination of the interactions between plasmas and neutral populations in space. Before these neutral atoms can be measured, they must first be converted to ions. For the low energy end of this spectrum, interaction with a conversion surface is often the most efficient method to convert neutrals into ions. It is generally thought that the most efficient surfaces are low work functions materials. However, by their very nature, these surfaces are highly reactive and unstable, and therefore are not suitable for space missions where conditions cannot be controlled as they are in a laboratory. We therefore are looking to optimize a stable surface for conversion efficiency. Conversion efficiency can be increased either by changing the incident angle of the neutral particles to be grazing incidence and using stable surfaces with high conversion efficiencies. We have examined how to increase the angle of incidence from -80 degrees to -89 degrees, while maintaining or improving the total active conversion surface area without increasing the overall volume of the instrument. We are developing a method to micro-machine silicon, which will reduce the volume to surface area ratio by a factor of 60. We have also examined the material properties that affect the conversion efficiency of the surface for stable surfaces. Some of the parameters we have examined are work function, smoothness, and bond structure. We find that for stable surfaces, the most important property is the smoothness of the surface.

  9. Neutralizing antibodies decrease the envelope fluidity of HIV-1

    SciTech Connect

    Harada, Shinji Monde, Kazuaki; Tanaka, Yuetsu; Kimura, Tetsuya; Maeda, Yosuke; Yusa, Keisuke

    2008-01-05

    For successful penetration of HIV-1, the formation of a fusion pore may be required in order to accumulate critical numbers of fusion-activated gp41 with the help of fluidization of the plasma membrane and viral envelope. An increase in temperature to 40 {sup o}C after viral adsorption at 25 {sup o}C enhanced the infectivity by 1.4-fold. The enhanced infectivity was inhibited by an anti-CXCR4 peptide, T140, and anti-V3 monoclonal antibodies (0.5{beta} and 694/98-D) by post-attachment neutralization, but not by non-neutralizing antibodies (670-30D and 246-D) specific for the C5 of gp120 and cluster I of gp41, respectively. Anti-HLA-II and an anti-HTLV-I gp46 antibody, LAT27, neutralized the molecule-carrying HIV-1{sub C-2(MT-2)}. The anti-V3 antibodies suppressed the fluidity of the HIV-1{sub C-2} envelope, whereas the non-neutralizing antibodies did not. The anti-HLA-II antibody decreased the envelope fluidity of HIV-1{sub C-2(MT-2)}, but not that of HIV-1{sub C-2}. Therefore, fluidity suppression by these antibodies represents an important neutralization mechanism, in addition to inhibition of viral attachment.

  10. Neutral particle analyzer diagnostics on the TCV tokamak

    SciTech Connect

    Karpushov, Alexander N.; Duval, Basil P.; Schlatter, Christian; Afanasyev, Valery I.; Chernyshev, Fedor V.

    2006-03-15

    Experimental apparatus and data analysis techniques used in neutral particle analyzer (NPA) diagnostics on the Tokamak a Configuration Variable (TCV) are described. Two NPAs are used on TCV to measure the energy spectrum of neutral particle fluxes from the plasma. The 'five-channel energy analyzer of atomic particles' used in double electrical analysis mode with fast voltage sweeping detect particles without atomic mass discrimination in the energy range of 0.6-8.0 keV with a time resolution of 0.5-2.0 ms and an energy resolution of 7%-20%. The 28-channel ''compact neutral particle analyzer'' (CNPA) is an EIIB spectrometer with mass and energy separations designed for medium sized fusion machines featuring a carbon neutral stripping foil, a permanent magnet for dispersion, and channel-electron multiplier detectors. The CNPA simultaneously detects two mass species [hydrogen (H) and deuterium (D) or D and helium (He)] in the 0.5-50 keV energy range with a resolution of 60%-10% and a time resolution of 0.5-4.0 ms. The CNPA views the plasma across the path of the diagnostic neutral beam and can perform active charge-exchange NPA measurement. Data analysis procedures and numerical algorithms developed for NPA measurement are routinely used on TCV to obtain information on the plasma ion temperature, ion energy distribution function, plasma isotope ratios, and other plasma characteristics.

  11. Observation of neutral modes in the fractional quantum Hall regime.

    PubMed

    Bid, Aveek; Ofek, N; Inoue, H; Heiblum, M; Kane, C L; Umansky, V; Mahalu, D

    2010-07-29

    The quantum Hall effect takes place in a two-dimensional electron gas under a strong magnetic field and involves current flow along the edges of the sample. For some particle-hole conjugate states of the fractional regime (for example, with fillings between 1/2 and 1 of the lowest Landau level), early predictions suggested the presence of counter-propagating edge currents in addition to the expected ones. When this did not agree with the measured conductance, it was suggested that disorder and interactions will lead to counter-propagating modes that carry only energy--the so called neutral modes. In addition, a neutral upstream mode (the Majorana mode) was expected for selected wavefunctions proposed for the even-denominator filling 5/2. Here we report the direct observation of counter-propagating neutral modes for fillings of 2/3, 3/5 and 5/2. The basis of our approach is that, if such modes impinge on a narrow constriction, the neutral quasiparticles will be partly reflected and fragmented into charge carriers, which can be detected through shot noise measurements. We find that the resultant shot noise is proportional to the injected current. Moreover, when we simultaneously inject a charge mode, the presence of the neutral mode was found to significantly affect the Fano factor and the temperature of the backscattered charge mode. In particular, such observations for filling 5/2 may single out the non-Abelian wavefunctions for the state. PMID:20671702

  12. Physics Opportunities with the Neutral Particle Spectrometer in Hall C

    NASA Astrophysics Data System (ADS)

    Horn, Tanja; NPS Collaboration

    2015-10-01

    The two-arm combination of neutral-particle detection and a high-resolution magnetic spectrometer offers unique scientific capabilities to push the energy scale for studies of the transverse spatial and momentum structure of the nucleon through reactions with neutral particles requiring precision and high luminosity. It enables precision measurements of the deeply-virtual Compton scattering cross section at different beam energies to extract the real part of the Compton form factor without any assumptions. It allows measurements to push the energy scale of real Compton scattering, the process of choice to explore factorization in a whole class of wide-angle processes, and its extension to neutral pion photo-production. It further makes possible measurements of the basic semi-inclusive neutral-pion cross section in a kinematic region where the QCD factorization scheme is expected to hold, which is crucial to validate the foundation of this cornerstone of 3D transverse momentum imaging. Adding the option of polarized targets to such a setup, allows for exploration of further scientific directions, e.g., timelike Compton scattering. We describe the unique science program as enabled by the Neutral-Particle Spectrometer and the magnetic spectrometer pair in Hall C at JLab. Supported in part by NSF Grants PHY-1530874 and PHY-1306227.

  13. The impact of neutral impurity concentration on charge drift mobility

    NASA Astrophysics Data System (ADS)

    Mei, Hao; Wang, Guojian; Mei, Dongming; Yang, Gang; Guan, Yutong

    High-purity germanium crystals are being grown using the Czochralski technique at the University of South Dakota. The carrier concentration, mobility and resistivity are measured by Hall Effect system. Many factors contribute to the overall mobility. We investigated the impact of neutral impurity concentration on charge drift mobility. Several samples with measured mobility lager than 35000 cm2/Vs from the grown crystals were used for this investigation. With the measured mobility and the ionized impurity concentration, we were able to calculate the neutral impurity concentration by the Matthiessen's rule. The correlations between the neutral impurity concentrations with the radius of the crystals were studied. We report that the concentration of neutral impurity constrains charge draft mobility for high-purity germanium crystals and the non-uniform distribution of neutral impurity could result in an anisotropy of draft time distribution in a given germanium detector. This work is supported by DOE Grant DE-FG02-10ER46709 and the state of South Dakota.

  14. Midplane neutral density profiles in the National Spherical Torus Experiment

    DOE PAGESBeta

    Stotler, D. P.; Scotti, F.; Bell, R. E.; Diallo, A.; LeBlanc, B. P.; Podesta, M.; Roquemore, A. L.; Ross, P. W.

    2015-08-13

    Atomic and molecular density data in the outer midplane of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] are inferred from tangential camera data via a forward modeling procedure using the DEGAS 2 Monte Carlo neutral transport code. The observed Balmer-β light emission data from 17 shots during the 2010 NSTX campaign display no obvious trends with discharge parameters such as the divertor Balmer-α emission level or edge deuterium ion density. Simulations of 12 time slices in 7 of these discharges produce molecular densities near the vacuum vessel wall of 2–8 × 1017 m–3 and atomic densities ranging frommore » 1 to 7 ×1016 m–3; neither has a clear correlation with other parameters. Validation of the technique, begun in an earlier publication, is continued with an assessment of the sensitivity of the simulated camera image and neutral densities to uncertainties in the data input to the model. The simulated camera image is sensitive to the plasma profiles and virtually nothing else. The neutral densities at the vessel wall depend most strongly on the spatial distribution of the source; simulations with a localized neutral source yield densities within a factor of two of the baseline, uniform source, case. Furthermore, the uncertainties in the neutral densities associated with other model inputs and assumptions are ≤ 50%.« less

  15. Human-like antibodies neutralizing Western equine encephalitis virus

    PubMed Central

    Hülseweh, Birgit; Rülker, Torsten; Pelat, Thibaut; Langermann, Claudia; Frenzel, Andrè; Schirrmann, Thomas; Dübel, Stefan; Thullier, Philippe; Hust, Michael

    2014-01-01

    This study describes the development of the first neutralizing antibodies against Western equine encephalitis virus (WEEV), a member of the genus Alphavirus. WEEV is transmitted by mosquitoes and can spread to the human central nervous system, causing symptoms ranging from mild febrile reactions to life-threatening encephalitis. WEEV has been classified as a biological warfare agent by the US Centers for Disease Control and Prevention. No anti-WEEV drugs are currently commercially available. Neutralizing antibodies are useful for the pre- and post-exposure treatment of WEEV infections. In this study, two immune antibody gene libraries were constructed from two macaques immunized with inactivated WEEV. Four antibodies were selected from these libraries and recloned as scFv-Fc, with a human Fc part. These antibodies bound WEEV specifically in ELISA with little or no cross-reaction with other alphaviruses. They were further analyzed by immunohistochemistry. All binders were suitable for the intracellular detection of WEEV particles. Neutralizing activity was determined in vitro. Three of the four antibodies were found to be neutralizing; about 1 ng/mL of the best antibody (ToR69–3A2) neutralized 50% of 5x104 TCID50/mL. Due to its human-like nature with a germinality index of 89% (VH) and 91% (VL), the ToR69–3A2 antibody is a promising candidate for future passive vaccine development. PMID:24518197

  16. Studies on Neutral Beam Injection into the SSPX Spheromak Plasma

    SciTech Connect

    Jayakumar, R; Pearlstein, L D; Casper, T A; Fowler, T K; Hill, D N; Hudson, B; McLean, H; Moller, J

    2007-10-19

    In the Sustained Spheromak Physics Experiment, (SSPX) ['Improved operation of the SSPX spheromak', R.D. Wood, D.N. Hill, E.B. Hooper, S. Woodruff1, H.S. McLean and B.W. Stallard, Nucl. Fusion 45 1582-1588 (2005)], plasmas with core electron temperatures reaching up to 500 eV at densities of 10{sup 20}/m{sup 3} have been sustained for several milliseconds, making them suitable as targets for neutral beam injection. High performance and further progress in understanding Spheromak plasma physics are expected if neutral beams are injected into the plasma. This paper presents the results of numerical 1.5 D modeling of the plasma to calculate neutral beam current drive and ion and electron heating. The results are presented for varying initial conditions of density, temperatures and profiles and beam energy, injection angle and power. Current drive efficiency (Ampere/Watt of absorbed power) of up to 0.08 can be achieved with best performance SSPX shots as target. Analyses of neutral beam heating indicate that ion temperatures of up to 1.5 keV and electron temperatures of up to 750 eV can be obtained with injection of about 1 MW of neutral beam for 5-10 ms and with diffusivities typically observed in SSPX. Injection targeting near the magnetic axis appears to be the best for heating and current drive. Effect of the current drive and evolution of SSPX equilibrium are discussed.

  17. Biological neutralization of chlor-alkali industry wastewater.

    PubMed

    Jain, Rakeshkumar M; Mody, Kalpana H; Keshri, Jitendra; Jha, Bhavanath

    2011-11-01

    The present work reports biological neutralization of chlor-alkali industrial effluent by an alkaliphilic bacterium, isolated from the Gujarat coast, which was identified as Enterococcus faecium strain R-5 on the basis of morphological, biochemical and partial 16S rRNA gene sequencing. The isolate was capable of bringing down the pH of waste water from 12.0 to 7.0 within 3 h in the presence of carbon and nitrogen sources, with simultaneous reduction in total dissolved solutes (TDS) up to 19-22%. This bacterium produced carboxylic acid, as revealed by FT-IR analysis, which facilitated neutralization of alkaline effluent. The presence of unconventional raw materials viz. Madhuca indica flowers or sugar cane bagasse as carbon and nitrogen sources could effectively neutralize alkaline effluent and thus making the bioremediation process economically viable. The time required for neutralization varied with size of inoculum. To the best of our knowledge, this is the first report on biological neutralization of a chlor-alkali industrial effluent. PMID:21944194

  18. Neutral dynamics and ion energy transport in MST plasma

    NASA Astrophysics Data System (ADS)

    Xing, Zichuan; Nornberg, Mark; den Hartog, Daniel; Kumar, Santosh; Anderson, Jay

    2015-11-01

    Neutral dynamics can have a significant effect on ion energy transport through charge exchange collisions. Whereas previously charge exchange was considered a direct loss mechanism in MST plasmas, new analysis indicates that significant thermal charge exchange neutrals are reionized. Further, the temperatures of the neutral species in the core of the plasma are suspected to be much higher than room temperature, which has a large effect on ion energy losses due to charge exchange. The DEGAS2 Monte Carlo simulation code is applied to the MST reversed field pinch experiment to estimate the density and temperature profile of the neutral species. The result is then used to further examine the effect of the neutral species on ion energy transport in improved confinement plasmas. This enables the development of a model that accounts for collisional equilibration between species, classical convective and conductive energy transport, and energy loss due to charge exchange collisions. The goal is to quantify classical, stochastic, and anomalous ion heating and transport in RFP plasmas. Work supported by the US DOE. DEGAS2 is provided by PPPL and STRAHL is provided by Ralph Dux of the Max-Planck-Institut fur Plasmaphysik.

  19. Neutral transport in the ALT-I limiter

    SciTech Connect

    Boley, C.D.; Heifetz, D.B.; Post, D.E.; Malinowski, M.E.

    1983-10-01

    The behavior of neutral atoms and molecules in the TEXTOR pump limiter ALT-I has been investigated with the aid of the 2-D Monte Carlo neutral transport code DEGAS. The code incorporates the full set of relevant collision processes (atomic and molecular), and it has a standard wall model which includes fast-neutral reflection and molecular desorption. The limiter was modeled with a 2-D geometry, which included corrections for 3-D effects. Among the quantities predicted by the code which are directly relevant to experiment include the neutral pressure within the plenum and along the duct leading into the plenum, the gettering rates, and the heat flux to the walls of the duct. These have been calculated for a variety of plasma parameters in the inlet, and the behavior with respect to variations of the duct widths has been studied. Because of the presence of the long duct separating the entrance chamber from the plenum, a high probability of ionization generally results, suggesting that a calculation allowing the plasma to adjust to the neutral sources might show a large amount of recycling.

  20. Midplane neutral density profiles in the National Spherical Torus Experiment

    SciTech Connect

    Stotler, D. P.; Scotti, F.; Bell, R. E.; Diallo, A.; LeBlanc, B. P.; Podesta, M.; Roquemore, A. L.; Ross, P. W.

    2015-08-13

    Atomic and molecular density data in the outer midplane of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] are inferred from tangential camera data via a forward modeling procedure using the DEGAS 2 Monte Carlo neutral transport code. The observed Balmer-β light emission data from 17 shots during the 2010 NSTX campaign display no obvious trends with discharge parameters such as the divertor Balmer-α emission level or edge deuterium ion density. Simulations of 12 time slices in 7 of these discharges produce molecular densities near the vacuum vessel wall of 2–8 × 1017 m–3 and atomic densities ranging from 1 to 7 ×1016 m–3; neither has a clear correlation with other parameters. Validation of the technique, begun in an earlier publication, is continued with an assessment of the sensitivity of the simulated camera image and neutral densities to uncertainties in the data input to the model. The simulated camera image is sensitive to the plasma profiles and virtually nothing else. The neutral densities at the vessel wall depend most strongly on the spatial distribution of the source; simulations with a localized neutral source yield densities within a factor of two of the baseline, uniform source, case. Furthermore, the uncertainties in the neutral densities associated with other model inputs and assumptions are ≤ 50%.