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1

Radioimmunotherapy with alpha-particle emitting radionuclides.  

PubMed

An important consideration in the development of effective strategies for radioimmunotherapy is the nature of the radiation emitted by the radionuclide. Radionuclides decaying by the emission of alpha-particles offer the possibility of matching the cell specific reactivity of monoclonal antibodies with radiation with a range of only a few cell diameters. Furthermore, alpha-particles have important biological advantages compared with external beam radiation and beta-particles including a higher biological effectiveness, which is nearly independent of oxygen concentration, dose rate and cell cycle position. In this review, the clinical settings most likely to benefit from alpha-particle radioimmunotherapy will be discussed. The current status of preclinical and clinical research with antibodies labeled with 3 promising alpha-particle emitting radionuclides - (213)Bi, (225)Ac, and (211)At - also will be summarized. PMID:15640792

Zalutsky, M R; Pozzi, O R

2004-12-01

2

Intense alpha-particle emitting crystallites in uranium mill wastes  

USGS Publications Warehouse

Nuclear emulsion microscopy has demonstrated the presence of small, intense ??-particle emitting crystallites in laboratory-produced tailings derived from the sulfuric acid milling of uranium ores. The ??-particle activity is associated with the isotope pair 210Pb 210Po, and the host mineral appears to be PbSO4 occurring as inclusions in gypsum laths. These particles represent potential inhalation hazards at uranium mill tailings disposal areas. ?? 1994.

Landa, E.R.; Stieff, L.R.; Germani, M.S.; Tanner, A.B.; Evans, J.R.

1994-01-01

3

Quality factors for alpha particles emitted in tissue  

NASA Technical Reports Server (NTRS)

A concept of a mean or dose averaged quality factor was defined in ICRP Publication 26 using relationships for quality factor as a function of LET. The concept of radiation weighting factors, wR, was introduced in ICRP Publication 60 in 1990. These are meant to be generalized factors that modify absorbed dose to reflect the risk of stochastic effects as a function of the quality of the radiation incident on the body or emitted by radioactivity within the body. The values of wr are equal to 20 for all alpha particles externally or internally emitted. This note compares the dose averaged quality factor for alpha particles originating in tissue using the old and revised recommendations for quality factor as a function of LET. The dose averaged quality factor never exceeds 20 using the old recommendations and is never less than 20 with the revised recommendations.

Borak, Thomas B.; Chatterjee, A. (Principal Investigator)

2002-01-01

4

An alpha-particle emitting antibody ([213Bi]J591) for radioimmunotherapy of prostate cancer.  

PubMed

A novel alpha-particle emitting monoclonal antibody construct targeting the external domain of prostate-specific membrane antigen (PSMA) was prepared and evaluated in vitro and in vivo. The chelating agent, N-[2-amino-3-(p-isothiocyanatophen-yl)propyl]-trans-cyclohexane-1, 2-diamine-N,N',N',N'',N''-pentaacetic acid, was appended to J591 monoclonal antibody to stably bind the 213Bi radiometal ion. Bismuth-213 is a short-lived (t 1/2 = 46 min) radionuclide that emits high energy alpha-particles with an effective range of 0.07-0.10 mm that are ideally suited to treating single-celled neoplasms and micrometastatic carcinomas. The LNCaP prostate cancer cell line had an estimated 180,000 molecules of PSMA per cell; J591 bound to PSMA with a 3-nM affinity. After binding, the radiolabeled construct-antigen complex was rapidly internalized into the cell, carrying the radiometal inside. [213Bi]J591 was specifically cytotoxic to LNCaP. The LD50 value of [213Bi]J591 was 220 nCi/ml at a specific activity of 6.4 Ci/g. The potency and specificity of [213Bi]J591 directed against LNCaP spheroids, an in vitro model for micrometastatic cancer, also was investigated. [213Bi]J591 effectively stopped growth of LNCaP spheroids relative to an equivalent dose of the irrelevant control [213Bi]HuM195 or unlabeled J591. Cytotoxicity experiments in vivo were carried out in an athymic nude mouse model with an i.m. xenograft of LNCaP cells. [213Bi]J591 was able to significantly improve (P < 0.0031) median tumor-free survival (54 days) in these experiments relative to treatment with irrelevant control [213Bi]HuM195 (33 days), or no treatment (31 days). Prostate-specific antigen (PSA) was also specifically reduced in treated animals. At day 51, mean PSA values were 104 ng/ml +/- 54 ng/ml (n = 4, untreated animals), 66 ng/ml +/- 16 ng/ml (n = 6, animals treated with [213Bi]HuM195), and 28 ng/ml +/- 22 ng/ml (n = 6, animals treated with [213Bi]J591). The reduction of PSA levels in mice treated with [213Bi]J591 relative to mice treated with [213Bi]HuM195 and untreated control animals was significant with P < 0.007 and P < 0.0136, respectively. In conclusion, a novel [213Bi]-radiolabeled J591 has been constructed that selectively delivers alpha-particles to prostate cancer cells for potent and specific killing in vitro and in vivo. PMID:11085533

McDevitt, M R; Barendswaard, E; Ma, D; Lai, L; Curcio, M J; Sgouros, G; Ballangrud, A M; Yang, W H; Finn, R D; Pellegrini, V; Geerlings, M W; Lee, M; Brechbiel, M W; Bander, N H; Cordon-Cardo, C; Scheinberg, D A

2000-11-01

5

The short-lived MAT alpha 2 transcriptional regulator is ubiquitinated in vivo.  

PubMed Central

The substrates of ubiquitin-dependent proteolytic pathways include both damaged or otherwise abnormal proteins and undamaged proteins that are naturally short-lived. Few specific examples of the latter class have been identified, however. Previous work has shown that the cell type-specific MAT alpha 2 repressor of the yeast Saccharomyces cerevisiae is an extremely short-lived protein. We now demonstrate that alpha 2 is conjugated to ubiquitin in vivo. More than one lysine residue of alpha 2 can be joined to ubiquitin, and some of the ubiquitin moieties form a Lys48-linked multiubiquitin chain. Overexpression of degradation-impaired ubiquitin variants was used to show that at least a significant fraction of alpha 2 degradation is dependent on its ubiquitination. Images PMID:1647011

Hochstrasser, M; Ellison, M J; Chau, V; Varshavsky, A

1991-01-01

6

Enhanced retention of the alpha-particle-emitting daughters of Actinium-225 by liposome carriers.  

PubMed

Targeted alpha-particle emitters hold great promise as therapeutics for micrometastatic disease. Because of their high energy deposition and short range, tumor targeted alpha-particles can result in high cancer-cell killing with minimal normal-tissue irradiation. Actinium-225 is a potential generator for alpha-particle therapy: it decays with a 10-day half-life and generates three alpha-particle-emitting daughters. Retention of (225)Ac daughters at the target increases efficacy; escape and distribution throughout the body increases toxicity. During circulation, molecular carriers conjugated to (225)Ac cannot retain any of the daughters. We previously proposed liposomal encapsulation of (225)Ac to retain the daughters, whose retention was shown to be liposome-size dependent. However, daughter retention was lower than expected: 22% of theoretical maximum decreasing to 14%, partially due to the binding of (225)Ac to the phospholipid membrane. In this study, Multivesicular liposomes (MUVELs) composed of different phospholipids were developed to increase daughter retention. MUVELs are large liposomes with entrapped smaller lipid-vesicles containing (225)Ac. PEGylated MUVELs stably retained over time 98% of encapsulated (225)Ac. Retention of (213)Bi, the last daughter, was 31% of the theoretical maximum retention of (213)Bi for the liposome sizes studied. MUVELs were conjugated to an anti-HER2/neu antibody (immunolabeled MUVELs) and were evaluated in vitro with SKOV3-NMP2 ovarian cancer cells, exhibiting significant cellular internalization (83%). This work demonstrates that immunolabeled MUVELs might be able to deliver higher fractions of generated alpha-particles per targeted (225)Ac compared to the relative fractions of alpha-particles delivered by (225)Ac-labeled molecular carriers. PMID:17935286

Sofou, Stavroula; Kappel, Barry J; Jaggi, Jaspreet S; McDevitt, Michael R; Scheinberg, David A; Sgouros, George

2007-01-01

7

Absolute determination of the energies of alpha particles emitted by 236Pu  

NASA Astrophysics Data System (ADS)

The only two previous measurements of the energies of alpha particles emitted by 236Pu were relative determinations. They were in fair agreement with each other, except for the intensity ratios of the two strong lines. We now report an absolute energy measurement which was carried out using the 180° uniform-field magnetic spectrometer at BIPM on four sources prepared at AERE, Harwell with material formed by the reaction 238U( p, 3 n) 236Npå236Npå236Pu . The alpha particles were detected with aid of Kodak LR 115 (Type 2) cellulose-nitrate films which had considerable advantages over nuclear-track plates. Etching for seven hours in dilute NaOH at 40°C produced only weak and sufficiently reproducible distortions of the films reducing uncertainties to at most 50 eV. From six spectra the following mean values of particle energy E? and relative intensity I? were obtained: E? = (5767.66±0.08) keV, I? = (69.26±0.45) %; E? = (5721000±0.10) keV, I? = (30.56±0.45) %.

Rytz, A.; Wiltshire, R. A. P.

1984-06-01

8

Thorium and actinium polyphosphonate compounds as bone-seeking alpha particle-emitting agents.  

PubMed

The present study explores the use of alpha-particle-emitting, bone-seeking agents as candidates for targeted radiotherapy. Actinium and thorium 1,4,7,10 tetraazacyclododecane N,N',N'',N''' 1,4,7,10-tetra(methylene) phosphonic acid (DOTMP) and thorium-diethylene triamine N,N',N'' penta(methylene) phosphonic acid (DTMP) were prepared and their biodistribution evaluated in conventional Balb/C mice at four hours after injection. All three bone-seeking agents showed a high uptake in bone and a low uptake in soft tissues. Among the soft tissue organs, only kidney had a relatively high uptake. The femur/kidney ratios for 227Th-DTMP, 228-Ac-DOTMP and 227Th-DOTMP were 14.2, 7.6 and 6.0, respectively. A higher liver uptake of 228Ac-DOTMP was seen than for 227Th-DTMP and 227Th-DOTMP. This suggests that some demetallation of the 228Ac-DOTMP complex had occurred. The results indicate that 225Ac-DOTMP, 227Th-DOTMP and 227Th-DTMP have promising properties as potential therapeutic bone-seeking agents. PMID:15015582

Henriksen, Gjermund; Bruland, Oyvind S; Larsen, Roy H

2004-01-01

9

Renal tubulointerstitial changes after internal irradiation with alpha-particle-emitting actinium daughters.  

PubMed

The effect of external gamma irradiation on the kidneys is well described. However, the mechanisms of radiation nephropathy as a consequence of targeted radionuclide therapies are poorly understood. The functional and morphologic changes were studied chronologically (from 10 to 40 wk) in mouse kidneys after injection with an actinium-225 (225Ac) nanogenerator, a molecular-sized, antibody-targeted, in vivo generator of alpha-particle-emitting elements. Renal irradiation from free, radioactive daughters of 225Ac led to time-dependent reduction in renal function manifesting as increase in blood urea nitrogen. The histopathologic changes corresponded with the decline in renal function. Glomerular, tubular, and endothelial cell nuclear pleomorphism and focal tubular cell injury, lysis, and karyorrhexis were observed as early as 10 wk. Progressive thinning of the cortex as a result of widespread tubulolysis, collapsed tubules, glomerular crowding, decrease in glomerular cellularity, interstitial inflammation, and an elevated juxtaglomerular cell count were noted at 20 to 30 wk after treatment. By 35 to 40 wk, regeneration of simplified tubules with tubular atrophy and loss with focal, mild interstitial fibrosis had occurred. A lower juxtaglomerular cell count with focal cytoplasmic vacuolization, suggesting increased degranulation, was also observed in this period. A focal increase in tubular and interstitial cell TGF-beta1 expression starting at 20 wk, peaking at 25 wk, and later declining in intensity with mild increase in the extracellular matrix deposition was noticed. These findings suggest that internally delivered alpha-particle irradiation-induced loss of tubular epithelial cells triggers a chain of adaptive changes that result in progressive renal parenchymal damage accompanied by a loss of renal function. These findings are dissimilar to those seen after gamma or beta irradiation of kidneys. PMID:15987754

Jaggi, Jaspreet Singh; Seshan, Surya V; McDevitt, Michael R; LaPerle, Krista; Sgouros, George; Scheinberg, David A

2005-09-01

10

Alpha-Particle Emitting 213Bi-Anti-EGFR Immunoconjugates Eradicate Tumor Cells Independent of Oxygenation  

PubMed Central

Hypoxia is a central problem in tumor treatment because hypoxic cells are less sensitive to chemo- and radiotherapy than normoxic cells. Radioresistance of hypoxic tumor cells is due to reduced sensitivity towards low Linear Energy Transfer (LET) radiation. High LET ?-emitters are thought to eradicate tumor cells independent of cellular oxygenation. Therefore, the aim of this study was to demonstrate that cell-bound ?-particle emitting 213Bi immunoconjugates kill hypoxic and normoxic CAL33 tumor cells with identical efficiency. For that purpose CAL33 cells were incubated with 213Bi-anti-EGFR-MAb or irradiated with photons with a nominal energy of 6 MeV both under hypoxic and normoxic conditions. Oxygenation of cells was checked via the hypoxia-associated marker HIF-1?. Survival of cells was analysed using the clonogenic assay. Cell viability was monitored with the WST colorimetric assay. Results were evaluated statistically using a t-test and a Generalized Linear Mixed Model (GLMM). Survival and viability of CAL33 cells decreased both after incubation with increasing 213Bi-anti-EGFR-MAb activity concentrations (9.25 kBq/ml–1.48 MBq/ml) and irradiation with increasing doses of photons (0.5–12 Gy). Following photon irradiation survival and viability of normoxic cells were significantly lower than those of hypoxic cells at all doses analysed. In contrast, cell death induced by 213Bi-anti-EGFR-MAb turned out to be independent of cellular oxygenation. These results demonstrate that ?-particle emitting 213Bi-immunoconjugates eradicate hypoxic tumor cells as effective as normoxic cells. Therefore, 213Bi-radioimmunotherapy seems to be an appropriate strategy for treatment of hypoxic tumors. PMID:23724085

Gaertner, Florian C.; Bruchertseifer, Frank; Morgenstern, Alfred; Essler, Markus; Senekowitsch-Schmidtke, Reingard

2013-01-01

11

Streptavidin in antibody pretargeting. 5. chemical modification of recombinant streptavidin for labeling with the alpha-particle-emitting radionuclides 213Bi and 211At.  

PubMed

We are investigating the use of recombinant streptavidin (rSAv) as a carrier molecule for the short-lived alpha-particle-emitting radionuclides 213Bi ( t 1/2 = 45.6 min) and 211At ( t 1/2 = 7.21 h) in cancer therapy. To utilize rSAv as a carrier, it must be modified in a manner that permits rapid chelation or bonding with these short-lived radionuclides and also modified in a manner that diminishes its natural propensity for localization in the kidney. Modification for labeling with (213)Bi was accomplished by conjugation of rSAv with the DTPA derivative p-isothiocyanato-benzyl-CHX-A'' (CHX-A''), 3a. Modification for direct labeling with 211At was accomplished by conjugation of rSAv with an isothiocyanatophenyl derivative of a nido-carborane (nCB), 3b, or an isothiocyanatophenyl-dPEG/decaborate(2-) derivative, 3c. After conjugation of the chelating or bonding moiety, rSAv was further modified by reaction with an excess (50-100 equivalents) of succinic anhydride. Succinylation of the lysine amines has previously been shown to greatly diminish kidney localization. rSAv modified by conjugation with 3a and succinylated rapidly radiolabeled with 213Bi (<5 min), providing a 72% isolated yield. 211At labeling of modified rSAv was accomplished in aqueous solution using chloramine-T as the oxidant. Astatination of rSAv conjugated with 3b and succinylated occurred very rapidly (<1 min), providing a 50% isolated radiochemical yield. Astatination of rSAv conjugated with 3c and succinylated was also very rapid (<1 min) providing 66-71% isolated radiochemical yields. Astatination of succinylated rSAv, 2a, which did not have conjugated borane cage moieties, resulted in a much lower radiolabeling yield (18%). The 213Bi or 211At-labeled modified rSAv preparations were mixed with the corresponding 125 I-labeled rSAv, and dual-label in vivo distributions were obtained in athymic mice. The in vivo data show that 213Bi-labeled succinylated rSAv [ 213Bi] 6a has tissue concentrations similar to those of 125 I-labeled modified rSAv [ 125 I] 6b, suggesting that (213)Bi is quite stable toward release from the chelate in vivo. In vivo data also indicate that the (211)At-labeled rSAv conjugated with 3b or 3c and succinylated are stable to in vivo deastatination, whereas succinylated rSAv lacking a boron cage moiety is subject to some deastatination. The modified rSAv conjugated with nido-carborane derivative 3b has a higher retention in many tissues than rSAv without the carborane conjugated. Interestingly, the rSAv conjugated with 3c, which also contains an m-dPEG 12 moiety, has significantly decreased concentrations in blood and other tissues when compared with those of direct-labeled rSAv, suggesting that it may be a good candidate for further study. In conclusion, rSAv that has been modified with CHX-A'' and succinylated (i.e., 5a) may be useful as a carrier of 213Bi. The encouraging results obtained with the PEGylated decaborate(2-) derivative 3c and succinylated (i.e., 5c) suggests that its further study as a carrier of 211At in pretargeting protocols is warranted. PMID:18072725

Wilbur, D Scott; Hamlin, Donald K; Chyan, Ming-Kuan; Brechbiel, Martin W

2008-01-01

12

Nucleon-Alpha Particle Disequilibrium and Short-Lived r-Process Radioactivities  

NASA Technical Reports Server (NTRS)

r-Process yields can be extremely sensitive to expansion parameters when a persistent disequilibrium between free nucleons and alpha particles is present. This may provide a natural scenario for understanding the variation of heavy and light r-process isotopes in different r-process events. Additional information is contained in the original extended abstract.

Meyer, B. S.; Clayton, D. D.; Chellapilla, S.; The, L.-S.

2002-01-01

13

Engineered Modular Recombinant Transporters: Application of New Platform for Targeted Radiotherapeutic Agents to {alpha}-Particle Emitting {sup 211}At  

SciTech Connect

Purpose: To generate and evaluate a modular recombinant transporter (MRT) for targeting {sup 211}At to cancer cells overexpressing the epidermal growth factor receptor (EGFR). Methods and Materials: The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[{sup 211}At]astato-5-guanidinomethylbenzoate (SAGMB), its {sup 125}I analogue SGMIB, or with {sup 131}I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines. Results: The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 10-20 times more cytotoxic than [{sup 211}At]astatide for all three cell lines. Conclusion: The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted {alpha}-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this {sup 211}At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

Rosenkranz, Andrey A. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Department of Biophysics, Biological Faculty, Moscow State University, Moscow (Russian Federation); Vaidyanathan, Ganesan; Pozzi, Oscar R. [Department of Radiology, Duke University Medical Center, Durham, NC (United States); Lunin, Vladimir G. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Gamaleya Institute of Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow (Russian Federation); Zalutsky, Michael R. [Department of Radiology, Duke University Medical Center, Durham, NC (United States)], E-mail: zalut001@mc.duke.edu; Sobolev, Alexander S. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Department of Biophysics, Biological Faculty, Moscow State University, Moscow (Russian Federation)], E-mail: sobolev@igb.ac.ru

2008-09-01

14

Production of the Alpha-Particle Emitting Radionuclide Astatine-211 at the Texas A&M Cyclotron Institute  

E-print Network

all possible particles emitted. This information is extremely useful when performing gamma-ray spectroscopy. Tables 9 ? 11 presents the output from TALYS for the Bi-209(?,x) reactions at 28 MeV. 20 Table 9. Total particle production cross...-MDM beam line of the K500 cyclotron. These calculations were corroborated using Monte Carlo simulation within the computer code SRIM (Table 12 and Table 13). The foils utilized were based on available thickness of the copper and aluminum foils along...

Bhakta, Viharkumar Satish

2011-10-21

15

Treatment of HER2-Expressing Breast Cancer and Ovarian Cancer Cells With Alpha Particle-Emitting {sup 227}Th-Trastuzumab  

SciTech Connect

Purpose: To evaluate the cytotoxic effects of low-dose-rate alpha particle-emitting radioimmunoconjugate {sup 227}Th-p-isothiocyanato-benzyl-DOTA-trastuzumab ({sup 227}Th-trastuzumab [where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]) internalized by breast and ovarian cancer cell lines in order to assess the potential of {sup 227}Th-trastuzumab as a therapeutic agent against metastatic cancers that overexpress the HER2 oncogene. Methods and Materials: Clonogenic survival and cell growth rates of breast cancer cells treated with {sup 227}Th-trastuzumab were compared with rates of cells treated with nonbinding {sup 227}Th-rituximab, cold trastuzumab, and X-radiation. Cell growth experiments were also performed with ovarian cancer cells. Cell-associated radioactivity was measured at several time points, and the mean radiation dose to cells was calculated. Results: SKBR-3 cells got 50% of the mean absorbed radiation dose from internalized activity and 50% from cell surface-bound activity, while BT-474 and SKOV-3 cells got 75% radiation dose from internalized activity and 25% from cell surface-bound activity. Incubation of breast cancer cells with 2.5 kBq/ml {sup 227}Th-trastuzumab for 1 h at 4{sup o}C, followed by washing, resulted in mean absorbed radiation doses of 2 to 2.5 Gy. A dose-dependent inhibition of cell growth and an increase in apoptosis were induced in all cell lines. Conclusions: Clinically relevant activity concentrations of {sup 227}Th-trastuzumab induced a specific cytotoxic effect in three HER2-expressing cell lines. The cytotoxic effect of {sup 227}Th-trastuzumab was higher than that of single-dose X-radiation (relative biological effectiveness = 1.2). These results warrant further studies of treatment of breast cancer and ovarian cancer with {sup 227}Th-trastuzumab.

Heyerdahl, Helen; Krogh, Cecilie [Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo (Norway); Borrebaek, Jorgen [Algeta ASA, Kjelsas, Oslo (Norway); Larsen, Asmund [Algeta ASA, Kjelsas, Oslo (Norway); Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo (Norway); Dahle, Jostein, E-mail: jostein.dahle@rr-research.n [Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo (Norway)

2011-02-01

16

Cumulative genetic damage in hematopoietic stem cells in a patient with a 40-year exposure to alpha particles emitted by thorium dioxide.  

PubMed

Thorotrast, a colloidal suspension of the long-lived radionuclide, thorium-232, was widely used as a radiographic contrast medium for several decades. Due to the poor excretion of the sol, however, Thorotrast would deposit in the liver, bone marrow and other tissue, and patients would receive alpha-particle irradiation for life. To gauge the cumulative genetic damage to hematopoietic stem cells due to chronic exposure to alpha particles, we conducted a multi-end-point evaluation in a 72-year-old man who had been administered a 32-ml bolus of Thorotrast during cerebral angiography performed over 40 years ago in 1950. Peripheral T lymphocytes were cultured to quantify the frequencies and cellular distributions of asymmetrical and symmetrical types of chromosome aberrations in first-division metaphases and micronuclei in cytokinesis-arrested interphase II cells. Aberrations were scored using classical chromosome group analysis methods and chromosome painting techniques. Assays of glycophorin-A (GPA) mutations in red blood cells were also performed to obtain a relative measurement of damage sustained by the erythroid stem cell population. Results revealed that approximately 30% of the lymphocytes in this patient contained one or more chromosome aberrations, the majority of which were of the "stable" type. About one-third of the lymphocytes with chromosome damage carried multiple aberrations, suggesting that significant numbers of stem cells survive exposures to alpha-particle radiation that induce complex genomic alterations. Increased frequencies of GPA mutations were observed, demonstrating that genomic damage is also induced in erythroid progenitors. The numbers of micronuclei in lymphocytes were only moderately increased compared to expected values for persons of comparable age, and thus this end point was not useful for quantifying exposure level. Despite the relatively severe burden of somatic cell damage induced by 40 years of internal alpha-particle irradiation, the patient remains surprisingly free of any serious illness. PMID:9254732

Littlefield, L G; Travis, L B; Sayer, A M; Voelz, G L; Jensen, R H; Boice, J D

1997-08-01

17

Short-Lived Climate Pollution  

NASA Astrophysics Data System (ADS)

Although carbon dioxide emissions are by far the most important mediator of anthropogenic climate disruption, a number of shorter-lived substances with atmospheric lifetimes of under a few decades also contribute significantly to the radiative forcing that drives climate change. In recent years, the argument that early and aggressive mitigation of the emission of these substances or their precursors forms an essential part of any climate protection strategy has gained a considerable following. There is often an implication that such control can in some way make up for the current inaction on carbon dioxide emissions. The prime targets for mitigation, known collectively as short-lived climate pollution (SLCP), are methane, hydrofluo-rocarbons, black carbon, and ozone. A re-examination of the issues shows that the benefits of early SLCP mitigation have been greatly exaggerated, largely because of inadequacies in the methodologies used to compare the climate effects of short-lived substances with those of CO2, which causes nearly irreversible climate change persisting millennia after emissions cease. Eventual mitigation of SLCP can make a useful contribution to climate protection, but there is little to be gained by implementing SLCP mitigation before stringent carbon dioxide controls are in place and have caused annual emissions to approach zero. Any earlier implementation of SLCP mitigation that substitutes to any significant extent for carbon dioxide mitigation will lead to a climate irreversibly warmer than will a strategy with delayed SLCP mitigation. SLCP mitigation does not buy time for implementation of stringent controls on CO2 emissions.

Pierrehumbert, R. T.

2014-05-01

18

Skylab short-lived event alert program  

NASA Technical Reports Server (NTRS)

During the three manned Skylab missions, the Center for Short-Lived Phenomena (CSLP) reported a total of 39 significant events to the Johnson Space Center (JSC) as part of the Skylab Short-Lived Event Alert Program. The telegraphed daily status reports included the names and locations of the events, the track number and revolution number during which the event could be observed, the time (GMT) to within plus or minus 2 sec when Skylab was closest to the event area, and the light condition (daylight or darkness) at that time and place. The messages sent to JSC during the Skylab 4 mission also included information pertaining to ground-truth studies and observations being conducted on the events. Photographic priorities were assigned for each event.

Citron, R. A.

1974-01-01

19

Counting Particles Emitted by Stratospheric Aircraft and Measuring Size of Particles Emitted by Stratospheric Aircraft  

NASA Technical Reports Server (NTRS)

There were two principal objectives of the cooperative agreement between NASA and the University of Denver. The first goal was to modify the design of the ER-2 condensation nuclei counter (CNC) so that the effective lower detection limit would be improved at high altitudes. This improvement was sought because, in the instrument used prior to 1993, diffusion losses prevented the smallest detectable particles from reaching the detection volume of the instrument during operation at low pressure. Therefore, in spite of the sensor's ability to detect particles as small as 0.008 microns in diameter, many of these particles were lost in transport to the sensing region and were not counted. Most of the particles emitted by aircraft are smaller than 0.1 micron in diameter. At the start date of this work, May 1990, continuous sizing techniques available on the ER-2 were only capable of detecting particles larger than 0.17 micron. Thus, the second objective of this work was to evaluate candidate sizing techniques in an effort to gain additional information concerning the size of particles emitted by aircraft.

Wilson, James Charles

1994-01-01

20

Short-lived radionuclides in the early Solar System  

NASA Astrophysics Data System (ADS)

Short-lived radionuclides are radioactive elements with half-lives <= 100 Myr. They have all decayed away from their initial abundances, but their presence in the early Solar System could be inferred from radiogenic excesses of daughter products in meteoritic components. A detailed understanding of the initial abundance and distribution of short-lived radionuclides can shed light on the formation condition and immediate astrophysical environment of the early Solar System.

Liu, Ming-Chang

2012-11-01

21

Study of Short-Lived Nuclear Decays by Digital Spectroscopy  

Microsoft Academic Search

A new generation of pulse processing electronics based on digital signal processing technology has been successfully tested on-line and applied for the first time in particle and gamma-ray spectroscopy experiments. Systems based on commercially available Digital Gamma Finder (DGF) modules [1] were used to study the decays of short-lived states in exotic nuclei. Since the DGFs incorporate a RTPU, they

C. R. Bingham; E. Badura; J. C. Batchelder; C. J. Gross; R. Grzywacz; Z. Janas; M. Karny; W. Krolas; C. Mazzocchi; J. W. McConnell; M. Momayezi; M. Pfützner; K. Rykaczewski; K. Schmidt

2001-01-01

22

Short-lived nuclides in the early solar system  

Microsoft Academic Search

Isotopic records in meteorites provide evidence for the presence of several short-lived nuclides in the early solar system\\u000a with half-lives varying from 105 to ?8x107 years. Most of the nuclides with longer half-life (> 107 years) are considered to be products of stellar nucleosynthesis taking place over long time scales in our galaxy. However,\\u000a for the relatively shorter-lived nuclides, two

J. N. Goswami

1998-01-01

23

First absolute mass measurements of short-lived isotopes  

NASA Astrophysics Data System (ADS)

Absolute mass measurements of short-lived isotopes have been performed at the on-line mass separator ISOLDE at CERN by determining the cyclotron frequencies of ions confined in a Penning trap. The cyclotron frequencies for77,78,85,86,88Rb and88Sr ions could be determined with a resolving power of 3×105 and an accuracy of better than 10-6, which corresponds to 100 keV for mass A=100. The shortest-lived isotope under investigation was77Rb with a half-life of 3.7 min. The resonances obtained for the isobars88Rb and88Sr were clearly resolved.

Bollen, G.; Dabkiewicz, P.; Egelhof, P.; Hilberath, T.; Kalinowsky, H.; Kern, F.; Schnatz, H.; Schweikhard, L.; Stolzenberg, H.; Moore, R. B.; Kluge, H.-J.; Temmer, G. M.; Ulm, G.

1987-12-01

24

Near-term climate mitigation by short-lived forcers  

PubMed Central

Emissions reductions focused on anthropogenic climate-forcing agents with relatively short atmospheric lifetimes, such as methane (CH4) and black carbon, have been suggested as a strategy to reduce the rate of climate change over the next several decades. We find that reductions of methane and black carbon would likely have only a modest impact on near-term global climate warming. Even with maximally feasible reductions phased in from 2015 to 2035, global mean temperatures in 2050 would be reduced by 0.16 °C, with a range of 0.04–0.35 °C because of uncertainties in carbonaceous aerosol emissions and aerosol forcing per unit of emissions. The high end of this range is only possible if total historical aerosol forcing is relatively small. More realistic emission reductions would likely provide an even smaller climate benefit. We find that the climate benefit from reductions in short-lived forcing agents are smaller than previously estimated. These near-term climate benefits of targeted reductions in short-lived forcers are not substantially different in magnitude from the benefits from a comprehensive climate policy. PMID:23940357

Smith, Steven J.; Mizrahi, Andrew

2013-01-01

25

Time-dependence in short-lived volcanic eruption plumes  

NASA Astrophysics Data System (ADS)

Establishing relationships between source conditions and plume evolution is critical for developing accurate, predictive models of volcanic plumes. Such relationships have been derived and successfully applied to field cases for long-duration eruptions with approximately constant source conditions. Similarly useful relationships exist for instantaneous releases. However, equivalent relationships have yet to be developed for time-varying and finite source conditions that drive many short-lived volcanic plumes, despite the fact that such eruptions are frequent in nature. Short-lived plumes have been observed and documented using UV, visible, and IR imaging techniques, as well as satellite and radar measurements. However, the source conditions which generate these plumes are difficult to constrain in the field. Thus, a laboratory investigation of jets and plumes generated by short-duration time-dependent sources was undertaken. Experiments were designed specifically to examine the role of time-dependent source conditions in controlling overall morphology, flow front velocity as a function of time, internal velocity and eddy structure, and entrainment characteristics. In the experimental work presented here, neutrally-buoyant turbulent jets were generated by injecting pressurized water into a tank of still water. Velocity and discharge rate with time were Gaussian-like with durations shorter than jet rise times. Flows had vent Reynolds numbers from 103 to 105 and were documented using flow visualization and particle image velocimetry. Two different flow patterns were observed: isolated vortex rings that separated from a trailing jet and head vortices connected to a trailing stem. The latter was favored as both the vent Reynolds number and the total ejected volume increased. These flows had three main phases of development - an injection phase which occurred while the source was 'on', a transition phase immediately following injection termination, and a final phase during which the flow continued to propagate although the injection had ended. The injection phase was further subdivided into two distinct sub-phases, corresponding to acceleration and deceleration at the vent. Scaling of the results indicate that individual characteristic velocities describe each of the acceleration, deceleration, and transition phases, whereas the final phase behaves like an instantaneous release of momentum, termed a puff. As such, time-dependent source conditions appear to have dominant first-order effects on flow evolution during the injection and transition phases but have little control over the dynamics during the final phase, when instead the total volume injected dominates the dynamics. These results have a number of implications for interpreting dynamics from observations of short-lived volcanic plumes. For example, estimates of vent fluxes from plume observations should be restricted to early 'source on' phases, while later stages of development should provide information about total volume erupted.

Chojnicki, K. N.; Clarke, A. B.; Phillips, J. C.; Adrian, R. J.

2011-12-01

26

Nucleosynthesis of Short-lived Radioactivities in Massive Stars  

NASA Technical Reports Server (NTRS)

A leading model for the source of many of the short-lived radioactivities in the early solar nebula is direct incorporation from a massive star [1]. A recent and promising incarnation of this model includes an injection mass cut, which is a boundary between the stellar ejecta that become incorporated into the solar cloud and those ejecta that do not [2-4]. This model also includes a delay time between ejection from the star and incorporation into early solar system solid bodies. While largely successful, this model requires further validation and comparison against data. Such evaluation becomes easier if we have a better sense of the nature of the synthesis of the various radioactivities in the star. That is the goal of this brief abstract.

Meyer, B. S.

2004-01-01

27

Near-Term Climate Mitigation by Short-Lived Forcers  

SciTech Connect

Emissions reductions focused on anthropogenic climate forcing agents with relatively short atmospheric lifetimes such as methane (CH4) and black carbon (BC) have been suggested as a strategy to reduce the rate of climate change over the next several decades. We find that reductions of methane and BC would likely have only a modest impact on near-term climate warming. Even with maximally feasible reductions phased in from 2015 to 2035, global mean temperatures in 2050 are reduced by 0.16 °C, with an uncertainty range of 0.04-0.36°C, with the high end of this range only possible if total historical aerosol forcing is small. More realistic mitigation scenarios would likely provide a smaller climate benefit. The climate benefits from targeted reductions in short-lived forcing agents are smaller than previously estimated and are not substantially different in magnitude from the benefits due to a comprehensive climate policy.

Smith, Steven J.; Mizrahi, Andrew H.

2013-08-12

28

Characterizing Background Concentrations of Short-Lived Halocarbons  

NASA Astrophysics Data System (ADS)

Some short lived halocarbons (CH3I, CH2Br2, CHBr3) are emitted to the atmosphere in large quantities from natural processes. Because these chemicals have short lifetimes (weeks to months) they supply reactive halogen to the troposphere and influence the tropospheric chemistry of ozone and mercury, for example. Additionally, the lifetimes of CH2Br2 and CHBr3 are long enough so that these chemicals contribute significant amounts of bromine to the stratosphere, which influences stratospheric ozone chemistry. The magnitudes of these contributions and their sensitivity to changes in climate are poorly quantified at present. Some of these uncertainties stem from the difficulties associated with interpreting observations of short-lived compounds at any point in space and time in terms of broader-scale mixing ratios and atmospheric impacts. We have measured these chemicals at a global network of surface stations and aircraft profiling sites for multiple years (up to 14). The results provide a unique picture of global distributions, inter-annual and seasonal variability, and vertical mixing ratio gradients at continental, marine and coastal locations. When these data are contrasted with results from the recent HIPPO campaign over the mid-Pacific Ocean basin, consistent patterns emerge over land and sea for CH2Br and CHBr3 that suggest we can quantify mean mixing ratios and their variability over large spatial scales, particularly in the free troposphere. These results provide constraints on the influence these chemicals have on atmospheric chemistry in both the troposphere and stratosphere, and they provide an important baseline for more reliably quantifying long-term concentration changes, should they occur.

Montzka, S. A.; Miller, B. R.; Siso, C.; Moore, F. L.; Hall, B. D.; Elkins, J. W.; Andrews, A. E.; Sweeney, C.; Butler, J. H.; Atlas, E. L.; Wofsy, S. C.

2012-12-01

29

Production of ?-particle emitting 211At using 45 MeV ?-beam  

NASA Astrophysics Data System (ADS)

Among the ?-particle emitting radionuclides, 211At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the decay of 211At are less than 70 µm in water with a linear energy transfer between 100 and 130 keV µm-1, which are about the maximum relative biological effectiveness for heavy ions. It is important to note that at the present time, only a few of cyclotrons routinely produce 211At. The direct production method is based on the nuclear reactions 209Bi(?,2n)211At. Production of the radionuclide 211At was carried out using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). To ensure high beam current, the ?-beam was extracted with an initial energy of 45 MeV, which was degraded to obtain the appropriate ?-beam energy. The calculations of beam energy degradation were performed utilizing the MCNPX. Alumina-baked targets were prepared by heating the bismuth metal powder onto a circular cavity in a furnace. When using an E?, av of 29.17 MeV, the very small contribution of 210At confirms the right choice of the irradiation energy to obtain a pure production of 211At isotope.

Kim, Gyehong; Chun, Kwonsoo; Park, Sung Ho; Kim, Byungil

2014-06-01

30

Production of ?-particle emitting ²¹¹At using 45 MeV ?-beam.  

PubMed

Among the ?-particle emitting radionuclides, (211)At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the decay of (211)At are less than 70 µm in water with a linear energy transfer between 100 and 130 keV µm(-1), which are about the maximum relative biological effectiveness for heavy ions. It is important to note that at the present time, only a few of cyclotrons routinely produce (211)At. The direct production method is based on the nuclear reactions (209)Bi(?,2n)(211)At. Production of the radionuclide (211)At was carried out using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). To ensure high beam current, the ?-beam was extracted with an initial energy of 45 MeV, which was degraded to obtain the appropriate ?-beam energy. The calculations of beam energy degradation were performed utilizing the MCNPX. Alumina-baked targets were prepared by heating the bismuth metal powder onto a circular cavity in a furnace. When using an E(?, av) of 29.17 MeV, the very small contribution of (210)At confirms the right choice of the irradiation energy to obtain a pure production of (211)At isotope. PMID:24819557

Kim, Gyehong; Chun, Kwonsoo; Park, Sung Ho; Kim, Byungil

2014-06-01

31

Alpha-radioimmunotherapy with At-211: Evaluations and imaging on normal tissues and tumors.  

E-print Network

??Alpha-radioimmunotherapy (alpha-RIT) is an internal conformal radiotherapy at the cellular level using alpha-particle emitting radionuclides. Alpha-particles have a very short range in tissues (<100 micrometer)… (more)

Bäck, Tom

2011-01-01

32

Convective transport of very short lived bromocarbons to the stratosphere  

NASA Astrophysics Data System (ADS)

We use the NASA Goddard Earth Observing System (GEOS) Chemistry Climate Model (GEOSCCM) to quantify the contribution of the two most important brominated very short lived substances (VSLSs), bromoform (CHBr3) and dibromomethane (CH2Br2), to stratospheric bromine and its sensitivity to convection strength. Model simulations suggest that the most active transport of VSLSs from the marine boundary layer through the tropopause occurs over the tropical Indian Ocean, the tropical western Pacific, and off the Pacific coast of Mexico. Together, convective lofting of CHBr3 and CH2Br2 and their degradation products supplies ~8 ppt total bromine to the base of the tropical tropopause layer (TTL, ~150 hPa), similar to the amount of VSLS organic bromine available in the marine boundary layer (~7.8-8.4 ppt) in the active convective lofting regions mentioned above. Of the total ~8 ppt VSLS bromine that enters the base of the TTL at ~150 hPa, half is in the form of organic source gases and half in the form of inorganic product gases. Only a small portion (<10%) of the VSLS-originated bromine is removed via wet scavenging in the TTL before reaching the lower stratosphere. On average, globally, CHBr3 and CH2Br2 together contribute ~7.7 pptv to the present-day inorganic bromine in the stratosphere. However, varying model deep-convection strength between maximum (strongest) and minimum (weakest) convection conditions can introduce a ~2.6 pptv uncertainty in the contribution of VSLSs to inorganic bromine in the stratosphere (BryVSLS). Contrary to conventional wisdom, the minimum convection condition leads to a larger BryVSLS as the reduced scavenging in soluble product gases, and thus a significant increase in product gas injection (2-3 ppt), greatly exceeds the relatively minor decrease in source gas injection (a few 10ths ppt).

Liang, Q.; Atlas, E.; Blake, D.; Dorf, M.; Pfeilsticker, K.; Schauffler, S.

2014-06-01

33

Crantor, a short-lived horseshoe companion to Uranus  

NASA Astrophysics Data System (ADS)

Context. Stable co-orbital motion with Uranus is vulnerable to planetary migration, but temporary co-orbitals may exist today. So far, only two candidates have been suggested, both moving on horseshoe orbits: 83982 Crantor (2002 GO9) and 2000 SN331. Aims: (83982) Crantor is currently classified in the group of the Centaurs by the MPC although the value of its orbital period is close to that of Uranus. Here we revisit the topic of the possible 1:1 commensurability of (83982) Crantor with Uranus, explore its dynamical past, and look into its medium-term stability and future orbital evolution. Methods: Our analysis is based on the results of N-body calculations that use the most updated ephemerides and include perturbations by the eight major planets, the Moon, the barycenter of the Pluto-Charon system, and the three largest asteroids. Results: (83982) Crantor currently moves inside Uranus' co-orbital region on a complex horseshoe orbit. The motion of this object is primarily driven by the influence of the Sun and Uranus, although Saturn plays a significant role in destabilizing its orbit. The precession of the nodes of (83982) Crantor, which is accelerated by Saturn, controls its evolution and short-term stability. Although this object follows a temporary horseshoe orbit, more stable trajectories are possible and we present 2010 EU65 as a long-term horseshoe librator candidate in urgent need of follow-up observations. Available data indicate that the candidate 2000 SN331 is not a Uranus' co-orbital. Conclusions: Our calculations confirm that (83982) Crantor is currently trapped in the 1:1 commensurability with Uranus but it is unlikely to be a primordial 1:1 librator. Although this object follows a chaotic, short-lived horseshoe orbit, longer term horseshoe stability appears to be possible. We also confirm that high-order resonances with Saturn play a major role in destabilizing the orbits of Uranus co-orbitals. Figures 2 and 6 (animations) are available in electronic form at http://www.aanda.org

de la Fuente Marcos, C.; de la Fuente Marcos, R.

2013-03-01

34

First Demonstration of Electron Scattering Using a Novel Target Developed for Short-Lived Nuclei  

SciTech Connect

We carried out a demonstrative electron scattering experiment using a novel ion-trap target exclusively developed for short-lived highly unstable nuclei. Using stable {sup 133}Cs ion as a target, this experiment completely mimicked electron scattering off short-lived nuclei. Achieving a luminosity higher than 10{sup 26} cm{sup -2} s{sup -1} with around only 10{sup 6} trapped ions on the electron beam, the angular distribution of elastic scattering was successfully measured. This experiment clearly demonstrates that electron scattering off rarely produced short-lived nuclei is practical with this target technique.

Suda, T.; Wakasugi, M.; Emoto, T.; Ito, S.; Wang, S.; Yano, Y. [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan); Ishii, K.; Kurita, K. [Department of Physics, Rikkyo University, Toshima, Tokyo 171-8501 (Japan); Kuwajima, A.; Tamae, T. [Laboratory of Nuclear Science, Tohoku University, Sendai, Miyagi 982-0826 (Japan); Noda, A.; Shirai, T.; Tongu, H. [Institute of Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)

2009-03-13

35

Age-dependent inhalation doses to members of the public from indoor short-lived radon progeny.  

PubMed

The main contribution of radiation dose to the human lungs from natural exposure originates from short-lived radon progeny. In the present work, the inhalation doses from indoor short-lived radon progeny, i.e., (218)Po, (214)Pb, (214)Bi, and (214)Po, to different age groups of members of the public were calculated. In the calculations, the age-dependent systemic biokinetic models of polonium, bismuth, and lead published by the International Commission on Radiological Protection (ICRP) were adopted. In addition, the ICRP human respiratory tract and gastrointestinal tract models were applied to determine the deposition fractions in different regions of the lungs during inhalation and exhalation, and the absorption fractions of radon progeny in the alimentary tract. Based on the calculated contribution of each progeny to equivalent dose and effective dose, the dose conversion factor was estimated, taking into account the unattached fraction of aerosols, attached aerosols in the nucleation, accumulation and coarse modes, and the potential alpha energy concentration fraction in indoor air. It turned out that for each progeny, the equivalent doses to extrathoracic airways and the lungs are greater than those to other organs. The contribution of (214)Po to effective dose is much smaller compared to that of the other short-lived radon progeny and can thus be neglected in the dose assessment. In fact, 90 % of the effective dose from short-lived radon progeny arises from (214)Pb and (214)Bi, while the rest is from (218)Po. The dose conversion factors obtained in the present study are 17 and 18 mSv per working level month (WLM) for adult female and male, respectively. This compares to values ranging from 6 to 20 mSv WLM(-1) calculated by other investigators. The dose coefficients of each radon progeny calculated in the present study can be used to estimate the radiation doses for the population, especially for small children and women, in specific regions of the world exposed to radon progeny by measuring their concentrations, aerosol sizes, and unattached fractions. PMID:24831865

Brudecki, K; Li, W B; Meisenberg, O; Tschiersch, J; Hoeschen, C; Oeh, U

2014-08-01

36

Geochemistry (Cosmochemistry) Irradiation in the early solar system and the origin of short-lived radionuclides  

Microsoft Academic Search

The origin of short-lived (T ? 1 Myr) radionuclides (SRs) in the early solar system is a matter of debate. Some short-lived radionuclides had abundances in the solar protoplanetary disk in excess compared to the expected galactic background (7Be, 10Be, 26Al, 36Cl, 41Ca and possibly 53Mn and 60Fe). These SRs thus either originated from a supernova contamination, or were produced

Matthieu Gounelle; Marc Chaussidon; Thierry Montmerle

37

Hygroscopic Behavior of Aerosol Particles Emitted from Biomass Fired Grate Boilers  

Microsoft Academic Search

This study focuses on the hygroscopic properties of submicrometer aerosol particles emitted from two small-scale district heating combustion plants (1 and 1.5 MW) burning two types of biomass fuels (moist forest residue and pellets). The hygroscopic particle diameter growth factor (Gf) was measured when taken from a dehydrated to a humidified state for particle diameters between 30–350 nm (dry size)

Jenny Rissler; Joakim Pagels; Erik Swietlicki; Aneta Wierzbicka; Michael Strand; Lena Lillieblad; Mehri Sanati; Mats Bohgard

2005-01-01

38

Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii Determination  

E-print Network

Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii along the lithium isotopic chain were determined using a combination of precise isotope shift of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field

Pachucki, Krzysztof

39

Precision mass measurements of short-lived nuclides for nuclear structure studies at TITAN  

NASA Astrophysics Data System (ADS)

TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) at TRIUMF's rare isotope beam facility ISAC is an advanced Penning trap based mass spectrometer dedicated to precise and accurate mass determinations. An overview of TITAN, the measurement technique and a highlight of recent mass measurements of the short-lived nuclides important to the nuclear structure program at TITAN are presented.

Chaudhuri, A.; Andreoiu, C.; Brunner, T.; Chowdhury, U.; Ettenauer, S.; Frekers, D.; Gallant, A. T.; Grossheim, A.; Gwinner, G.; Klawitter, R.; Kwiatkowski, A. A.; Leach, K. G.; Lennarz, A.; Lunney, D.; Macdonald, T. D.; Schultz, B. E.; Seeraji, S.; Simon, M. C.; Simon, V. V.; Dilling, J.

2014-03-01

40

Synthesis of radiopharmaceuticals containing short-lived radionuclides. Comprehensive report, March 1, 1980-February 26, 1986  

SciTech Connect

New methods for the rapid introduction of short-lived radionuclides into agents for use in diagnostic nuclear medicine are reported. Among the new syntheses reported are those for /sup 123/I-labeled fatty acids and steroids, for /sup 11/C-labeled alcohols, for /sup 13/N-labeled amines, and for /sup 15/O-labeled alcohols. 33 refs.

Kabalka, G.W.

1985-09-01

41

Synthesis of radiopharmaceuticals containing short-lived radionuclides. Progress report, March 1, 1985-February 26, 1986  

SciTech Connect

Methods for the rapid introduction of short-lived radionuclides into agents for use in diagnostic nuclear medicine are reported. Methods to synthesize radioiodinated fatty acids, lipids, and amphetamine derivatives are described. New routes for the introduction of bromine-77, chlorine-34m, and carbon-11 into agents of interest are elaborated. 46 refs.

Kabalka, G.W.

1985-09-01

42

Aging in a very short-lived nematode Michael P. Gardnera,*, David Gemsb  

E-print Network

Aging in a very short-lived nematode Michael P. Gardnera,*, David Gemsb , Mark E. Vineya a School 17 June 2004; accepted 18 June 2004 Available online 8 August 2004 Abstract Aging has been characterised in detail in relatively few animal species. Here we describe the aging process in free

Gems, David

43

Detailed modeling of the atmospheric degradation mechanism of very-short lived brominated species  

E-print Network

1 Detailed modeling of the atmospheric degradation mechanism of very-short lived brominated species brominated peroxy radicals RO2 (with R = CH2Br, CHBr2 and CBr3) for which the most likely reaction pathways to be important. The Henry's law constants of the brominated organics products have been estimated by using

Boyer, Edmond

44

Experimental Measurements of Short-Lived Fission Products from Uranium, Neptunium, Plutonium and Americium  

SciTech Connect

Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on the short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on a HPGe (high purity germanium) detector to begin counting in less than 3 minutes post irradiation. The samples were counted for various time intervals ranging from 5 minutes to 1 hour. The data was then analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.

Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.

2009-11-01

45

Time-domain magnetic resonance studies of short-lived radical pairs in liquid solution  

Microsoft Academic Search

Magnetic resonance spectra of radical-ion pairs possessing lifetimes as short as 12 ns have been obtained using a new time-resolved optically detected magnetic resonance technique. Short-lived radical pairs are produced by a laser flash. The transient optical absorbance of the radical pairs or the triplet products resulting from their collapse is monitored as a function of time in the presence

Michael R. Wasielewski; James R. Norris; Michael K. Bowman

1984-01-01

46

Emission Channeling with Short-Lived Isotopes (EC-SLI) at CERN's ISOLDE Facility  

NASA Astrophysics Data System (ADS)

We give an overview on the historical development and current program for lattice location studies at CERN's ISOLDE facility, where the EC-SLI (Emission Channeling with Short-Lived Isotopes) collaboration maintains several setups for this type of experiments. We illustrate that the three most decisive factors for the success of the technique are access to facilities producing radioactive isotopes, position-sensitive detectors for the emitted decay particles, and reliable simulation codes which allow for quantitative analysis.

Wahl, U.; Correia, J. G.; Costa, A.; David-Bosne, E.; Pereira, L. M. C.; Amorim, L. M.; Augustyns, V.; Temst, K.; Vantomme, A.; da Silva, M. R.; Silva, D. J.; Araújo, J. P.; Miranda, P.; Bharuth-Ram, K.

2015-11-01

47

Short-lived radionuclides and early solar system chronology -- A hibonite perspective  

Microsoft Academic Search

Examination of the 41 Ca- 41 K, 26 Al- 26 Mg, 10 Be- 10 B, oxygen and titanium iso-topic systems in 26 hibonite-bearing inclusions extracted from the CM meteorite Murchison provide important constraints for origins of short-lived radionuclides, early solar system chronology, and chemical evolution. Magnesium isotopic compositions divide these hibonite grains into two distinct populations which correlate perfectly with

Ming-Chang Liu

2008-01-01

48

Measurements of Short-Lived Organohalogens Over the Eastern Tropical Pacific Ocean During TORERO  

NASA Astrophysics Data System (ADS)

Short-lived halogen compounds have the ability to affect stratospheric ozone mixing ratios as well as marine boundary layer (MBL) ozone mixing ratios. Modeling studies have shown that rapid convection of short-lived halocarbons to the upper troposphere/lower stratosphere (UT/LS) can significantly impact ozone photochemistry. Recent measurements show that, indeed, the short-lived halocarbons such as CHBr3, CH2Br2, and CH3I reach the UT/LS. However, the impact of these compounds on ozone chemistry is difficult to discern due to the episodic nature of their transport to the UT/LS. Although the tropospheric budgets of these gases have been the focus of much research recently, there is still little known about the seasonal dynamics and their ambient mixing ratios. In addition, little is known about the regional distribution of sources and sinks of these compounds and their impact on MBL chemistry. TORERO (Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated volatile organic compounds) provided an opportunity to investigate the distributions of several of these species over the eastern tropical Pacific Ocean using the Trace Organic Gas Analyzer (TOGA), a fast online GC-MS instrument deployed on the NSF/NCAR G-V, and the University of York TD-GCMS, deployed on the NOAA RV Ka'imimoana and to compare these results to the CAM-chem model which has recently been extended to include tropospheric halogen chemistry.

Hornbrook, R. S.; Hills, A. J.; Andrews, S. J.; Lamarque, J.; Carpenter, L.; Apel, E. C.

2012-12-01

49

Rate of resistance evolution and polymorphism in long- and short-lived hosts.  

PubMed

Recent theoretical work has shown that long-lived hosts are expected to evolve higher equilibrium levels of disease resistance than shorter-lived hosts, but questions of how longevity affects the rate of resistance evolution and the maintenance of polymorphism remain unanswered. Conventional wisdom suggests that adaptive evolution should occur more slowly in long-lived organisms than in short-lived organisms. However, the opposite may be true for the evolution of disease-resistance traits where exposure to disease, and therefore the strength of selection for resistance increases with longevity. In a single locus model of innate resistance to a frequency-dependent, sterilizing disease, longer lived hosts evolved resistance more rapidly than short-lived hosts. Moreover, resistance in long-lived hosts could only be polymorphic for more costly and more extreme resistance levels than short-lived hosts. The increased rate of evolution occurred in spite of longer generation times because longer-lived hosts had both a longer period of exposure to disease as well as higher disease prevalence. Qualitatively similar results were found when the model was extended to mortality-inducing diseases, or to density-dependent transmission modes. Our study shows that the evolutionary dynamics of host resistance is determined by more than just levels of resistance and cost, but is highly sensitive to the life-history traits of the host. PMID:25494853

Bruns, Emily; Hood, Michael E; Antonovics, Janis

2015-02-01

50

Attached and unattached fractions of short-lived radon decay products in outdoor environments: effect on the human respiratory system.  

PubMed

The authors developed a model for determining the alpha- and beta-activities per unit volume of air due to radon ((222)Rn), thoron ((220)Rn) and their decay products attached and unattached to the aerosol in the outdoor air at the workplace in natural conditions at different locations in Morocco by using both CR-39 and LR-115 type II solid-state nuclear track detectors. In addition, the percentage of (218)Po, (214)Pb and (214)Po radionuclides attached to the aerosols and the unattached fraction fj for different values of the attachment rate were evaluated. Radon and thoron concentrations in outdoor air of the studied different locations were found to vary from 9.20±0.8 to 16.30±1.50 Bq m(-3) and 0.22±0.02 to 1.80±0.20 Bq m(-3), respectively. The committed equivalent doses due to the radon short-lived progeny (218)Po and (214)Po attached and unattached to the aerosol air were evaluated in different tissues of the respiratory tract of the members of the public from the inhalation of outdoor air. PMID:24390974

Amrane, M; Oufni, L; Misdaq, M A

2014-12-01

51

Correlation measurements of light charged particles emitted from 32S+27Al reactions at energies of 105 MeV and 215 MeV  

NASA Astrophysics Data System (ADS)

Previous work has examined light particle correlations from O+Al reactions over a range of energies within a framework of statistical emission from a composite source. The source of these light particles was assumed to be an excited composite nucleus because the excitation energy of the source was not so high that exotic processes such as fragmentation or preequilibrium emission were significant. In this Brief Report we examine correlation functions between light charged particles emitted from reactions of S+Al at 105 MeV and 215 MeV. As in previous work, the proton-proton and proton-deuteron correlations are well described by the results of Monte Carlo simulations based on statistical emission. In this Brief Report we will also compare the results of alpha-alpha and deuteron-alpha correlations to the predictions of models which include the emission of heavier unstable particles (such as 8Be and 6Li*) from the excited source. The results presented here can serve as additional validation of the correlation technique and also as tests of the statistical model.

Deyoung, P. A.; Ajitanand, N. N.; Alexander, J. M.; Datar, V.; Gelderloos, C. J.; Gilfoyle, G.; Gordon, M. S.; McGrath, R. L.; Peaslee, G. F.; Sarafa, J.

1995-12-01

52

Absence of replicative senescence in cultured cells from the short-lived killifish Nothobranchius furzeri.  

PubMed

A major challenge in age research is the absence of short-lived vertebrate model organisms. The turquoise killifish Nothobranchius furzeri has the shortest known lifespan of a vertebrate that can be bred in captivity. The short lived GRZ strain only reaches a maximum age of 3-4 months, whereas other strains (MZM) reach 6-10 months. Most importantly, the short lifespan is associated with typical signs of ageing. To find out more about possible cellular factors that might contribute to the short lifespan and to the difference in lifespan between strains, we analyzed the expression of markers for cellular senescence. Expression of Tp53, Cdkn1a and Cdkn2a/b in skin revealed no change in the short-lived GRZ but increased expression of the cell cycle inhibitors Cdkn1a and Cdkn2a/b in the long-lived MZM strain with age. This suggests that expression of distinct cell cycle inhibitors reflects rather chronological than biological age in N. furzeri. To study the relationship of organismal life span and in vitro life span of cells, we established a primary cell culture model. For both strains we demonstrate here the absence of replicative senescence as analysed by morphology, expression of Cdkn1a and Cdkn2a/b, population doubling times and ?H2AFX in long-term and short-term cultured cells. We reason this to be on account of sustained telomerase activity and maintained telomeric length. Hence, we propose that differences in maximum life span of different N. furzeri strains is not reflected by differences in proliferation speed or replicative potential of the respective cultured cells. PMID:22445733

Graf, Michael; Hartmann, Nils; Reichwald, Kathrin; Englert, Christoph

2013-01-01

53

Short-lived brominated species - observations in the source regions and the tropical tropopause layer  

NASA Astrophysics Data System (ADS)

We conducted measurements of up to the five important short-lived brominated species in the marine boundary layer (MBL) of the mid-latitudes (List/Sylt, North Sea) in June 2009 and of the tropical Western Pacific during the TransBrom ship campaign in October 2009. For the one-week time series in List mean mixing ratios of 2.0, 1.1, 0.2, 0.1 ppt were analysed for CHBr3, CH2Br2, CHBr2Cl and CH2BrCl, with maxima of 5.8 and 1.6 ppt for the two main components CHBr3 and CH2Br2. Along the cruise track in the Western Pacific (between 41° N and 13° S) mean mixing ratios of 1.0, 0.9, 0.2, 0.1 and 0.1 ppt for CHBr3, CH2Br2, CHBrCl2, CHBr2Cl and CH2BrCl were determined. Air samples with coastal influence showed considerably higher mixing ratios than the samples with open ocean origin. Correlation analyses of the two datasets yielded strong linear relationships between the mixing ratios of four of the five species (except for CH2BrCl). Using a combined dataset from the two campaigns, rough estimates of the molar emission ratios between the correlated substances were derived as follows: 9/1/0.3/0.3 for CHBr3/CH2Br2/CHBrCl2/CHBr2Cl. Additional measurements were made in the tropical tropopause layer (TTL) above Teresina (Brazil, 5.07° S, 42.87° W) in June 2008, using balloon-borne cryogenic whole air sampling technique. Near the level of zero clear-sky net radiative heating (LZRH) at 14.8 km about 2.25 ppt organic bromine was bound to the five short-lived species, making up 13 % of total organic bromine (17.82 ppt). CH2Br2 (1.45 ppt) and CHBr3 (0.56 ppt) accounted for 90 % of the budget of short-lived compounds in that region. Near the tropopause (at 17.5 km) organic bromine from short-lived substances was reduced to 1.35 ppt, with 1.07 ppt and 0.12 ppt attributed to CH2Br2 and CHBr3 respectively.

Brinckmann, S.; Engel, A.; Bönisch, H.; Quack, B.; Atlas, E.

2011-08-01

54

Mass Measurement of Short-lived Nuclei at HIRFL-CSR  

NASA Astrophysics Data System (ADS)

Four campaigns of mass measurements for short-lived nuclei have been conducted using an isochronous mass spectrometry (IMS) technique at HIRFL-CSR(Cooler Storage Ring) in Lanzhou. The radioactive nuclei were produced by projectile fragmentation and injected into the experimental storage ring CSRe. Revolution times of the ions stored in the CSRe were measured from which masses of 78Kr, 58Ni, 86Kr and 112Sn fragments have been determined with a relative uncertainty of about 10-6-10-7. The experimental results are presented and their impacts on nucleosynthesis in the rp process and nuclear structure are discussed.

Wang, M.; Xu, H. S.; Zhang, Y. H.; Tu, X. L.; Litvinov, Yu. A.

2014-03-01

55

Role of a short-lived ?* resonance in formic-acid O—H bond breaking  

NASA Astrophysics Data System (ADS)

We review briefly the recent work on dissociative electron attachment (DEA) to formic acid. Using Feshbach resonance theory we present results calculating the forces on various atoms during resonance processes that can arise at different electron impact energies. The conclusion is that DEA to formic acid happens through a short-lived ?* resonance with minimal involvement from ?-? symmetry breaking as suggested elsewhere. We conclude that rehybridization on a C atom caused by the ?-? mixing is too far from the O—H bond to detect its effect on the DEA cross section. A recent experimental confirmation is also reported.

Gallup, G. A.

2013-11-01

56

Inducible transgenic expression in the short-lived fish Nothobranchius furzeri.  

PubMed

This study demonstrates inducible transgenic expression in the exceptionally short-lived turquoise killifish Nothobranchius furzeri, which is a useful vertebrate model for ageing research. Transgenic N. furzeri bearing a green fluorescent protein (Gfp) containing construct under the control of a heat shock protein 70 promoter were generated, heat shock-induced and reversible Gfp expression was demonstrated and germline transmission of the transgene to the F1 and F2 generations was achieved. The availability of this inducible transgenic expression system will make the study of ageing-related antagonistically pleiotropic genes possible using this unique vertebrate model organism. PMID:23639168

Allard, J B; Kamei, H; Duan, C

2013-05-01

57

Accurate mass determination of short-lived isotopes by a tandem Penning-trap mass spectrometer  

NASA Astrophysics Data System (ADS)

A mass spectrometer consisting of two Penning traps has been set up for short-lived isotopes at the on-line mass separator ISOLDE at CERN. The ion beam is collected and cooled in the first trap. After delivery to the second trap, high-accuracy direct mass measurements are made by determining the cyclotron frequency of the stored ions. Measurements have been performed for 118-137Cs. A resolving power of over 106 and an accuracy of 1.4×10-7 have been achieved, corresponding to about 20 keV.

Stolzenberg, H.; Becker, St.; Bollen, G.; Kern, F.; Kluge, H.-J.; Otto, Th.; Savard, G.; Schweikhard, L.; Audi, G.; Moore, R. B.

1990-12-01

58

Short-lived and long-lived dust devil tracks in the coastal desert of southern Peru  

Microsoft Academic Search

In the coastal desert of southern Peru, sequential high-resolution satellite images document the presence of short-lived and long-lived dust devil tracks. Dust devil tracks in the study region remain visible for less than 6 months in one area and for more than 4 years in another area. Short-lived tracks are generally darker than the surrounding ground surface. The brightness of

Ralf Hesse

59

Short-lived pollutants in the Arctic: their climate impact and possible mitigation strategies  

SciTech Connect

Several short-lived pollutants known to impact Arctic climate may be contributing to the accelerated rates of warming observed in this region relative to the global annually averaged temperature increase. Here, we present a summary of the short-lived pollutants that impact Arctic climate including methane, tropospheric ozone, and tropospheric aerosols. For each pollutant, we provide a description of the major sources and the mechanism of forcing. We also provide the first seasonally averaged forcing and corresponding temperature response estimates focused specifically on the Arctic. The calculations indicate that the forcings due to black carbon, methane, and tropospheric ozone lead to a positive surface temperature response indicating the need to reduce emissions of these species within and outside the Arctic. Additional aerosol species may also lead to surface warming if the aerosol is coincident with thin, low lying clouds. We suggest strategies for reducing the warming based on current knowledge and discuss directions for future research to address the large remaining uncertainties.

Menon, Surabi; Quinn, P.K.; Bates, T.S.; Baum, E.; Doubleday, N.; Fiore, A.M.; Flanner, M.; Fridlind, A.; Garrett, T.J.; Koch, D.; Menon, S.; Shindell, D.; Stohl, A.; Warren, S.G.

2007-09-24

60

The Irradiation Origin of Beryllium Radioisotopes and Other Short-lived Radionuclides  

E-print Network

Two explanations exist for the short-lived radionuclides present in the solar system when the CAIs first formed. They originated either from the ejecta of a supernova or by the in situ irradiation of nebular dust by energetic particles. With a half-life of only 53 days, Beryllium-7 is then the key discriminant, since it can be made only by irradiation. We calculate the yield of Be-7. Within model uncertainties associated mainly with nuclear cross sections, we obtain agreement with the experimental value. Moreover, if Be-7 and Be-10 have the same origin, the irradiation time must be short. The x-wind model provides a natural astrophysical setting that gives the requisite conditions. The decoupling of the Al-26 and Be-10 observed in some rare CAIs receives a quantitative explanation when rare gradual events are considered. Finally, we show that the presence of supernova-produced Fe-60 in the solar accretion disk does not necessarily mean that other short-lived radionuclides have a stellar origin.

Matthieu Gounelle; Frank H. Shu; Hsien Shang; A. E. Glassgold; K. E. Rehm; Typhoon Lee

2005-12-21

61

Short-lived radionuclides as monitors of early crust-mantle differentiation on the terrestrial planets  

NASA Astrophysics Data System (ADS)

The kinetic energy from large impacts, the gravitational energy released by core formation, and the heat provided by the decay of short-lived radioactive isotopes all drive extensive melting and chemical differentiation of silicate planets/planetesimals during and shortly after their formation. This early differentiation is best preserved on small objects such as the parent bodies of the eucrite and angrite meteorites where silicate melts were produced within 3 million years of solar system formation. The W isotopic composition of some iron meteorites testifies to core segregation on small planetesimals within as little as one million years or less of solar system formation. On larger objects, such as the Moon, Mars and Earth, the evidence for early differentiation provided by long-lived radioisotope systems has been variably overprinted by the continuing differentiation of these objects, but a clear signature of extensive early planet-scale differentiation is preserved in a variety of short-lived radioisotope systems, particularly, I-Pu-Xe, Hf-W and 146Sm- 142Nd. All these systems suggest that global differentiation of planetesimals and the terrestrial planets occurred during the first hundred million years of solar system history. This early processing of the Moon, Mars and Earth, may have fundamentally affected the evolution of these planets and their current internal compositional structure.

Carlson, Richard W.; Boyet, Maud

2009-03-01

62

Streptavidin in Antibody Pretargeting. 5. Chemical Modification of Recombinant Streptavidin for Labeling with the ?-Particle Emitting Radionuclides 213Bi and 211At  

PubMed Central

We are investigating the use of recombinant streptavidin (rSAv) as a carrier molecule for the short-lived ?-particle emitting radionuclides 213Bi (t1/2 = 45.6 min) and 211At (t1/2 = 7.21 h) in cancer therapy. To utilize rSAv as a carrier, it must be modified in a manner that permits rapid chelation or bonding with these short-lived radionuclides, and also modified in a manner that diminishes its natural propensity for localization in kidney. Modification for labeling with 213Bi was accomplished by conjugation of rSAv with the DTPA derivative p-isothiocyanato-benzyl-CHX-A? (CHX-A?), 3a. Modification for direct labeling with 211At was accomplished by conjugation of rSAv with an isothiocyanatophenyl derivative of a nido-carborane (nCB), 3b, or an isothiocyanatophenyl-dPEG™/decaborate(2-) derivative, 3c. After conjugation of the chelating or bonding moiety, rSAv was further modified by reaction with an excess (50–100 equivalents) of succinic anhydride. Succinylation of the lysine amines has previously been shown to greatly diminish kidney localization. rSAv modified by conjugation with 3a and succinylated radiolabeled rapidly with 213Bi (< 5 min), providing a 72% isolated yield. 211At labeling of modified rSAv was accomplished in aqueous solution using chloramine-T as the oxidant. Astatination of rSAv conjugated with 3b and succinylated occurred very rapidly (<1 min), providing a 50% isolated radiochemical yield. Astatination of rSAv conjugated with 3c and succinylated was also very rapid (<1 min) providing 66–71% isolated radiochemical yields. Astatination of succinylated rSAv, 2a, which did not have conjugated borane cage moieties, resulted in much lower radiolabeling yield (18%). The 213Bi- or 211At-labeled modified rSAv preparations were mixed with the corresponding 125I-labeled rSAv, and dual-label in vivo distributions were obtained in athymic mice. The in vivo data show that 213Bi-labeled succinylated rSAv [213Bi]6a has tissue concentrations similar to 125I-labeled modified rSAv [125I]6b, suggesting that 213Bi is quite stable towards release from the chelate in vivo. In vivo data also indicate that the 211At-labeled rSAv conjugated with 3b or 3c and succinylated are stable to in vivo deastatination, whereas succinylated rSAv lacking a boron cage moiety is subject to some deastatination. The modified rSAv conjugated with nido-carborane derivative 3b has a higher retention in many tissues than rSAv without the carborane conjugated. Interestingly, the rSAv conjugated with 3c, which also contains a m-dPEG12™ moiety, has significantly decreased concentrations in blood and other tissues when compared with direct labeled rSAv, suggesting that it may be a good candidate for further study. In conclusion, rSAv that has been modified with CHX-A? and succinylated (i.e. 5a) may be useful as a carrier of 213Bi. The encouraging results obtained with the PEGylated decaborate(2-) derivative 3c and succinylated (i.e. 5c) suggests that its further study as a carrier of 211At in pretargeting protocols is warranted. PMID:18072725

Wilbur, D. Scott; Hamlin, Donald K.; Chyan, Ming-Kuan; Brechbiel, Martin W.

2008-01-01

63

Short-lived brominated hydrocarbons - observations in the source regions and the tropical tropopause layer  

NASA Astrophysics Data System (ADS)

We conducted measurements of the five important short-lived organic bromine species in the marine boundary layer (MBL). Measurements were made in the Northern Hemisphere mid-latitudes (Sylt Island, North Sea) in June 2009 and in the tropical Western Pacific during the TransBrom ship campaign in October 2009. For the one-week time series on Sylt Island, mean mixing ratios of CHBr3, CH2Br2, CHBr2Cl and CH2BrCl were 2.0, 1.1, 0.2, 0.1 ppt, respectively. We found maxima of 5.8 and 1.6 ppt for the two main components CHBr3 and CH2Br2. Along the cruise track in the Western Pacific (between 41° N and 13° S) we measured mean mixing ratios of 0.9, 0.9, 0.2, 0.1 and 0.1 ppt for CHBr3, CH2Br2, CHBrCl2, CHBr2Cl and CH2BrCl. Air samples with coastal influence showed considerably higher mixing ratios than the samples with open ocean origin. Correlation analyses of the two data sets yielded strong linear relationships between the mixing ratios of four of the five species (except for CH2BrCl). Using a combined data set from the two campaigns and a comparison with the results from two former studies, rough estimates of the molar emission ratios between the correlated substances were: 9/1/0.35/0.35 for CHBr3/CH2Br2/CHBrCl2/CHBr2Cl. Additional measurements were made in the tropical tropopause layer (TTL) above Teresina (Brazil, 5° S) in June 2008, using balloon-borne cryogenic whole air sampling technique. Near the level of zero clear-sky net radiative heating (LZRH) at 14.8 km about 2.25 ppt organic bromine was bound to the five short-lived species, making up 13% of total organic bromine (17.82 ppt). CH2Br2 (1.45 ppt) and CHBr3 (0.56 ppt) accounted for 90% of the budget of short-lived compounds in that region. Near the tropopause (at 17.5 km) organic bromine from these substances was reduced to 1.35 ppt, with 1.07 and 0.12 ppt attributed to CH2Br2 and CHBr3, respectively.

Brinckmann, S.; Engel, A.; Bönisch, H.; Quack, B.; Atlas, E.

2012-02-01

64

Counteracting the climate effects of volcanic eruptions using short-lived greenhouse gases  

NASA Astrophysics Data System (ADS)

large volcanic eruption might constitute a climate emergency, significantly altering global temperature and precipitation for several years. Major future eruptions will occur, but their size or timing cannot be predicted. We show, for the first time, that it may be possible to counteract these climate effects through deliberate emissions of short-lived greenhouse gases, dampening the abrupt impact of an eruption. We estimate an emission pathway countering a hypothetical eruption 3 times the size of Mount Pinatubo in 1991. We use a global climate model to evaluate global and regional responses to the eruption, with and without counteremissions. We then raise practical, financial, and ethical questions related to such a strategy. Unlike the more commonly discussed geoengineering to mitigate warming from long-lived greenhouse gases, designed emissions to counter temporary cooling would not have the disadvantage of needing to be sustained over long periods. Nevertheless, implementation would still face significant challenges.

Fuglestvedt, Jan S.; Samset, Bjørn H.; Shine, Keith P.

2014-12-01

65

The role of short-lived climate pollutants in meeting temperature goals  

NASA Astrophysics Data System (ADS)

Some recent high-profile publications have suggested that immediately reducing emissions of methane, black carbon and other short-lived climate pollutants (SLCPs) may contribute substantially towards the goal of limiting global warming to 2 °C above pre-industrial levels. Although this literature acknowledges that action on long-lived climate pollutants (LLCPs) such as CO2 is also required, it is not always appreciated that SLCP emissions in any given decade only have a significant impact on peak temperature under circumstances in which CO2 emissions are falling. Immediate action on SLCPs might potentially 'buy time' for adaptation by reducing near-term warming; however early SLCP reductions, compared with reductions in a future decade, do not buy time to delay reductions in CO2.

Bowerman, Niel H. A.; Frame, David J.; Huntingford, Chris; Lowe, Jason A.; Smith, Stephen M.; Allen, Myles R.

2013-12-01

66

An improved short-lived fluorescent protein transcriptional reporter for S. cerevisiae.  

PubMed Central

Ideal reporter genes for temporal transcription programs have short half-lives that restrict their detection to the window in which their transcripts are present and translated. In an effort to meet this criterion for reporters of transcription in individual living cells, we adapted the ubiquitin fusion strategy for programmable N-end rule degradation to generate an N-degron version of green fluorescent protein (GFP) with a half-life of ~7 min. The GFP variant we used here (designated GFP*) has excellent fluorescence brightness and maturation properties, which make the destabilized reporter well suited for tracking the induction and attenuation kinetics of gene expression in living cells. These attributes are illustrated by its ability to track galactose and pheromone induced transcription in S. cerevisiae. We further show that the fluorescence measurements using the short-lived N-degron GFP* reporter gene accurately predict the transient mRNA profile of the prototypical pheromone induced FUS1 gene. PMID:23172645

Houser, John R.; Ford, Eintou; Chatterjea, Sudeshna M.; Maleri, Seth; Elston, Timothy C.; Errede, Beverly

2012-01-01

67

Short-lived oxygen diffusion during hot, deep-seated meteoric alteration of anorthosite  

PubMed

Heterogeneous oxygen isotope compositions of plagioclase from the Boehls Butte anorthosite include some of the most oxygen-18-depleted values (to -16 per mil) reported for plagioclase in meta-igneous rocks and indicate high-temperature (T > 500 degrees C) isotopic exchange between plagioclase and nearly pristine meteoric fluid. Retrograde reaction-enhanced permeability assisted influx of meteoric-hydrothermal fluids into the deep-seated anorthosite. Isotopic gradients of about 14 per mil over 600 micrometers in single crystals require short-lived (about 10(4) years) diffusional exchange of oxygen and locally large effective water:rock ratios, followed by rapid loss of water and cessation of oxygen diffusion in the anorthosite. PMID:10600738

Mora; Riciputi; Cole

1999-12-17

68

Probing short-lived protein ligand interactions with single-molecule force spectroscopy  

NASA Astrophysics Data System (ADS)

Hydrogen bonding plays an important role in stabilizing biomolecular complexes. Although life time of individual bonds can be extremely short, cooperativity among many interactions increase the overall life time of the complex. To probe short-lived individual interactions, we have employed a recently developed atomic force microscopy technique that can carry out single-molecule force spectroscopy experiments on the microsecond timescale. Our loading-rate dependent measurements provide experimental evidence for an additional energy barrier in the biotin-streptavidin complex. The width of this barrier, estimated from the measurements, is both close to theoretical predictions based on steered molecular dynamics simulations and to the characteristic width of individual hydrogen bonds. We will present our experimental methodology and analysis of the results on biotin-streptavidin complex.

Sahin, Ozgur; Dong, Mingdong

2012-02-01

69

A Massive AGB Star as Source of Short-Lived Nuclei in the Early Solar System  

NASA Astrophysics Data System (ADS)

The origin of short-lived radioactive nuclei at the time of the formation of the Sun is a much debated mystery in modern astronomy. We show that abundance predictions for massive AGB stars (roughly 6 Msolar) of solar metallicity can self-consistently match the abundances of 26Al, 41Ca, 60Fe, and 107Pd in the early Solar System, as derived from meteorite analysis. On the other hand our models do not produce 182Hf, thus confirming previous results. Recent measurements of excesses in 62Ni and 96Zr, correlated to 60Fe, can be accounted for by a massive AGB source. Moreover, these stars could be an important source of 87Rb, as recently observed, and thus induce the fluctuations in the Rb/Sr ratio observed in primitive chondritic materials. Finally, we discuss recent observations of decoupling between the presence of 26Al and 60Fe in differentiated planetesimals and their implications on candidate stellar sources.

Lugaro, M.; Karakas, A. I.; van Raai, M.; García-Hernández, D. A.; Trigo-Rodríguez, J. M.

2008-04-01

70

Separation efficiency of the MASHA facility for short-lived mercury isotopes  

NASA Astrophysics Data System (ADS)

The mass-separator MASHA built to identify Super Heavy Elements by their mass-to-charge ratios is described. The results of the off- and on-line measurements of its separation efficiency are presented. In the former case four calibrated leaks of noble gases were used. In the latter the efficiency was measured via 284 MeV Ar beam and with using the hot catcher. The ECR ion source was used in both cases. The -radioactive isotopes of mercury produced in the complete fusion reaction Ar+SmHg+xn were detected at the mass-separator focal plane. The half-lives and the separation efficiency for the short-lived mercury isotopes were measured. Potentialities of the MEDIPIX detector system have been demonstrated for future use at the mass-separator MASHA.

Rodin, A. M.; Belozerov, A. V.; Chernysheva, E. V.; Dmitriev, S. N.; Gulyaev, A. V.; Gulyaeva, A. V.; Itkis, M. G.; Kliman, J.; Kondratiev, N. A.; Krupa, L.; Novoselov, A. S.; Oganessian, Yu. Ts.; Podshibyakin, A. V.; Salamatin, V. S.; Sivá?ek, I.; Stepantsov, S. V.; Vanin, D. V.; Vedeneev, V. Yu.; Yukhimchuk, S. A.; Granja, C.; Pospisil, S.

2014-06-01

71

Seeds of alpine plants are short lived: implications for long-term conservation  

PubMed Central

Background and Aims Alpine plants are considered one of the groups of species most sensitive to the direct and indirect threats to ecosystems caused by land use and climate change. Collecting and banking seeds of plant species is recognized as an effective tool for providing propagating material to re-establish wild plant populations and for habitat repair. However, seeds from cold wet environments have been shown to be relatively short lived in storage, and therefore successful long-term seed conservation for alpine plants may be difficult. Here, the life spans of 69 seed lots representing 63 related species from alpine and lowland locations from northern Italy are compared. Methods Seeds were placed into experimental storage at 45 °C and 60 % relative humidity (RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50 % (p50) was determined using probit analysis and used as a measure of relative seed longevity between seed lots. Key Results Across species, p50 at 45 °C and 60 % RH varied from 4·7 to 95·5 d. Seed lots from alpine populations/species had significantly lower p50 values compared with those from lowland populations/species; the lowland seed lots showed a slower rate of loss of germinability, higher initial seed viability, or both. Seeds were progressively longer lived with increased temperature and decreased rainfall at the collecting site. Conclusions Seeds of alpine plants are short lived in storage compared with those from lowland populations/related taxa. The lower resistance to ageing in seeds of alpine plants may arise from low selection pressure for seed resistance to ageing and/or damage incurred during seed development due to the cool wet conditions of the alpine climate. Long-term seed conservation of several alpine species using conventional seed banking methods will be problematic. PMID:21081585

Mondoni, Andrea; Probert, Robin J.; Rossi, Graziano; Vegini, Emanuele; Hay, Fiona R.

2011-01-01

72

CARIBIC observations of short-lived halocarbons and carbonyl sulphide over Asia  

NASA Astrophysics Data System (ADS)

The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container, www.caribic-atmospheric.com) aims to investigate the spatial and temporal distribution of a wide-range of compounds, including those of marine origin/influence, via ~monthly flights to collect in situ data and whole air samples aboard a commercial Lufthansa aircraft. CARIBIC measures up to an altitude of 12 km, allowing the influence of marine compounds on the upper troposphere/lower stratosphere (UTLS) to be explored. In particular, CARIBIC is a useful tool for exploring the impact of very short lived halocarbons (e.g. CH2Br2, CHBr3), whose impact on stratospheric ozone is dependent on convective uplift to the UTLS, a process which is not yet fully quantified. As part of the suite of CARIBIC measurements, whole air samples are analysed at the University of East Anglia (UEA) via gas chromatography mass spectrometry for carbonyl sulphide (OCS) and up to 40 halocarbons (accounting for virtually 100% of organic chlorine, bromine and iodine in the UTLS). Here we present an overview of short-lived halocarbons and OCS measured by CARIBIC. We focus on two regions of particular interest. (1) measurements made in 2012 over the tropical west Pacific to link with UEA measurements made during the SHIVA campaign. (2) measurements made during a collection of flights over India in 2008. Flights over India investigated the impact of monsoon circulation on the distribution of these compounds; for example, elevated concentrations of OCS were seen in CARIBIC samples taken over India during the summer monsoon (July - September). These flights, along with a wider range of flights over Asia (from Frankfurt to Guangzhou, Manila, Bangkok and Kuala Lumpur) can provide unique information on the influence of tropical convection and monsoon circulation on halocarbon and OCS transport within this region.

Leedham, E.; Wisher, A.; Oram, D.; Baker, A. K.; Brenninkmeijer, C. A.

2013-12-01

73

Muscle senescence in short-lived wild mammals, the soricine shrews Blarina brevicauda and Sorex palustris.  

PubMed

Red-toothed (soricine) shrews are consummate predators exhibiting the highest energy turnovers and shortest life spans (ca. 18 months) of any mammal, yet virtually nothing is known regarding their physiological aging. We assessed the emerging pattern of skeletal muscle senescence (contractile/connective tissue components) in sympatric species, the semi-aquatic water shrew (WS), Sorex palustris, and the terrestrial short-tailed shrew (STS), Blarina brevicauda, to determine if muscle aging occurs in wild, short-lived mammals (H(0): shrews do not survive to an age where senescence occurs), and if so, whether these alterations are species-specific. Gracilis muscles were collected from first-year (n=17) and second-year (n=17) field-caught shrews. Consistent with typical mammalian aging, collagen content (% area) increased with age in both species (S. palustris: approximately 50%; B. brevicauda: approximately 60%). Muscle was dominated by stiffer Type I collagen, and the ratio of collagen Type I:Type III more than doubled with age. The area ratio of muscle:collagen decreased with age in both species, but was considerably lower in adult STS, suggesting species-specificity of senescence. Extracellular space was age-elevated in B. brevicauda, but was preserved in S. palustris ( approximately 50 vs. 10% elevation). Though juvenile interspecific comparisons revealed no significance, adult WS myocytes had 68% larger cross-sectional area and occurred at 28% lower fibers/area than those of adult STS. We demonstrate that age-related muscle senescence does occur in wild-caught, short-lived mammals, and we therefore reject this classic aging theory tenet. Our findings moreover illustrate that differential age adjustments in contractile/connective tissue components of muscle occur in the two species of wild-caught shrews. PMID:19296507

Hindle, Allyson G; Lawler, John M; Campbell, Kevin L; Horning, Markus

2009-06-01

74

The origin of short-lived radionuclides and the astrophysical environment of solar system formation  

E-print Network

Based on early solar system abundances of short-lived radionuclides (SRs), such as $^{26}$Al (T$_{1/2} = 0.74$ Myr) and $^{60}$Fe (T$_{1/2} = 1.5$ Myr), it is often asserted that the Sun was born in a large stellar cluster, where a massive star contaminated the protoplanetary disk with freshly nucleosynthesized isotopes from its supernova (SN) explosion. To account for the inferred initial solar system abundances of short-lived radionuclides, this supernova had to be close ($\\sim$ 0.3 pc) to the young ($\\leqslant$ 1 Myr) protoplanetary disk. Here we show that massive star evolution timescales are too long, compared to typical timescales of star formation in embedded clusters, for them to explode as supernovae within the lifetimes of nearby disks. This is especially true in an Orion Nebular Cluster (ONC)-type of setting, where the most massive star will explode as a supernova $\\sim$ 5 Myr after the onset of star formation, when nearby disks will have already suffered substantial photoevaporation and/or formed large planetesimals. We quantify the probability for {\\it any} protoplanetary disk to receive SRs from a nearby supernova at the level observed in the early solar system. Key constraints on our estimate are: (1) SRs have to be injected into a newly formed ($\\leqslant$ 1 Myr) disk, (2) the disk has to survive UV photoevaporation, and (3) the protoplanetary disk must be situated in an enrichment zone permitting SR injection at the solar system level without disk disruption. The probability of protoplanetary disk contamination by a supernova ejecta is, in the most favorable case, 3 $\\times$ 10$^{-3}$.

Gounelle Meibom

2008-05-05

75

Enhanced Retention of the ?-particle Emitting Daughters of Actinium-225 by Liposome Carriers  

PubMed Central

Targeted ?-particle emitters hold great promise as therapeutics for micrometastatic disease. Because of their high energy deposition and short range, tumor targeted ?-particles can result in high cancer-cell killing with minimal normal-tissue irradiation. Actinium-225 is a potential generator for ?-particle therapy: it decays with a 10-day half-life and generates three ?-particle emitting daughters. Retention of 225Ac daughters at the target increases efficacy; escape and distribution throughout the body increases toxicity. During circulation, molecular carriers conjugated to 225Ac cannot retain any of the daughters. We previously proposed liposomal encapsulation of 225Ac to retain the daughters, whose retention was shown to be liposome-size dependent. However, daughter retention was lower than expected: 22% of theoretical maximum decreasing to 14%, partially due to binding of 225Ac to the phospholipid membrane. In this study, MUltiVEsicular Liposomes (MUVELs) composed of different phospholipids were developed to increase daughter retention. MUVELs are large liposomes with entrapped smaller lipid-vesicles containing 225Ac. PEGylated MUVELs stably retained over time 98% of encapsulated 225Ac. Retention of 213Bi, the last daughter, was 31% of the theoretical maximum retention of 213Bi for the liposome sizes studied. MUVELs were conjugated to an anti-HER2/neu antibody (immunolabeled MUVELs), and were evaluated in vitro with SKOV3-NMP2 ovarian cancer cells, exhibiting significant cellular internalization (83%). This work demonstrates that immunolabeled MUVELs could be able to deliver higher fractions of generated ?-particles per targeted 225Ac compared to the relative fractions of ?-particles delivered by 225Ac-labeled molecular carriers. PMID:17935286

Stavroula, Sofou; Kappel, Barry J.; Jaggi, Jaspreet S.; McDevitt, Michael R.; Scheinberg, David A.; Sgouros, George

2008-01-01

76

XRF-analysis of fine and ultrafine particles emitted from laser printing devices.  

PubMed

In this work, the elemental composition of fine and ultrafine particles emitted by ten different laser printing devices (LPD) is examined. The particle number concentration time series was measured as well as the particle size distributions. In parallel, emitted particles were size-selectively sampled with a cascade impactor and subsequently analyzed by the means of XRF. In order to identify potential sources for the aerosol's elemental composition, materials involved in the printing process such as toner, paper, and structural components of the printer were also analyzed. While the majority of particle emissions from laser printers are known to consist of recondensated semi volatile organic compounds, elemental analysis identifies Si, S, Cl, Ca, Ti, Cr, and Fe as well as traces of Ni and Zn in different size fractions of the aerosols. These elements can mainly be assigned to contributions from toner and paper. The detection of elements that are likely to be present in inorganic compounds is in good agreement with the measurement of nonvolatile particles. Quantitative measurements of solid particles at 400 °C resulted in residues of 1.6 × 10(9) and 1.5 × 10(10) particles per print job, representing fractions of 0.2% and 1.9% of the total number of emitted particles at room temperature. In combination with the XRF results it is concluded that solid inorganic particles contribute to LPD emissions in measurable quantities. Furthermore, for the first time Br was detected in significant concentrations in the aerosol emitted from two LPD. The analysis of several possible sources identified the plastic housings of the fuser units as main sources due to substantial Br concentrations related to brominated flame retardants. PMID:21809840

Barthel, Mathias; Pedan, Vasilisa; Hahn, Oliver; Rothhardt, Monika; Bresch, Harald; Jann, Oliver; Seeger, Stefan

2011-09-15

77

Unobservability of short-lived unstable particles and its implications for observational claims and theories in physics  

E-print Network

The physics literature contains many claims that elementary particles have been observed: such observational claims are, of course, important for the development of existential knowledge. Regarding claimed observations of short-lived unstable particles in particular, the term `observation' is not used with reference to any particular concept of observation: physicists merely use the word `observation' based on the convention in physics that the observation of a short-lived unstable particle can be claimed when its predicted decay products have been observed with a significance of 5 sigma. However, using Fox's recent concepts of direct and indirect observation, this paper shows that unstable particles with a lifetime of less than 0.01 attosecond are fundamentally unobservable. This cognitive inaccessibility of parts of the subatomic world has far-reaching implications for physics, not the least of which is that the aforementioned convention is untenable: claims that such short-lived unstable particles have bee...

Cabbolet, Marcoen J T F

2015-01-01

78

Simulation and optimization of cyclic activation analysis of short-lived isotopes with 14MeV neutron generator.  

PubMed

A program of simulation and optimization is developed for the case of cyclic activation analysis of short-lived isotopes with 14-MeV neutrons. The background line under the photopeaks of interest is simulated using Zikovsky's model. The reliability of the program is checked on real conditions with a geological reference sample "Soil 5" provided by the IAEA. Optimum experimental conditions (timing parameters, number of cycles) are determined, and corresponding detection limits calculated. A systematic study of short-lived isotopes with half-lives lower than 5 min is done for Soil 5, and the results are discussed. PMID:7710887

Khelifi, R; Idiri, Z; Tobbeche, S

1994-01-01

79

ISOLTRAP: a tandem Penning trap system for accurate on-line mass determination of short-lived isotopes  

NASA Astrophysics Data System (ADS)

The tandem Penning trap mass spectrometer ISOLTRAP has been set up at the on-line mass separator ISOLDE at CERN/Geneva for accurate mass measurements of short-lived nuclei with T {1}/{2} ? 1 s. The mass measurement is performed via the determination of the cyclotron frequency of an ion in a magnetic field. The design of the spectrometer matches the particular requirements for on-line mass measurements on short-lived isotopes. With the ISOLTRAP spectrometer masses of more than 70 radioactive nuclei have so far been determined with resolving powers exceeding one million and an accuracy of typically 10 -7.

Bollen, G.; Becker, S.; Kluge, H.-J.; König, M.; Moore, R. B.; Otto, T.; Raimbault-Hartmann, H.; Savard, G.; Schweikhard, L.; Stolzenberg, H.; Isolde Collaboration

1996-02-01

80

Distinct short-lived and long-lived antibody-producing cell populations.  

PubMed

This report analyzes the life span of Ig-containing cells (IgCC) in different sites of antibody production. The experimental approach was based upon the observations that most IgCC are derived from proliferating precursors while IgCC themselves are mainly nondividing end cells. Rats were given a continuous infusion of [3H] thymidine via an osmotic pump inserted in the peritoneal cavity. At intervals of 1, 3, 5 or 10 days after starting infusions, tissues were taken and analyzed by a combination of immunohistology and autoradiography to identify the proportions of IgCC which had gone through S phase of the cell cycle during the period of infusion. After 3 days infusion the median and (range) percent-labeled IgCC in the medullary cords of mesenteric and cervical lymph nodes and the red pulp of the spleen were, respectively, 88 (81-90), 75 (66-77) and 88 (82-93). Conversely that for IgCC in bone marrow was only 13 (11-17) and that in the lamina propria of the jejunum 47 (33-68). The rate of increase in labeling of bone marrow IgCC with length of infusion was approximately linear. Extrapolation of this slope suggests that bone marrow IgCC have a life span in excess of 3 weeks. The slopes of increase in IgCC labeled with time for lymph nodes and spleen were clearly biphasic suggesting that while most IgCC in these tissues have a life span of less than 3 days, there is also a minor population of long-lived IgCC. The lamina propria appears to have approximately equal proportions of long and short-lived IgCC. The life span of IgCC, with the exception of IgMCC, appears to be a feature of the site of antibody production rather than the Ig class produced. Almost all IgM-containing cells were found to be short lived. PMID:3490389

Ho, F; Lortan, J E; MacLennan, I C; Khan, M

1986-10-01

81

Detection and localization of particle-emitting sources with compound-eye inspired detector arrays  

NASA Astrophysics Data System (ADS)

We develop methods to detect and localize particle-emitting sources using detector arrays that are inspired by biological compound eyes. The sources of interest may be optical, nuclear, or cosmic; they emit particles such as visible photons, neutrons, protons, or charged particles. Our results may have wide applications to artificial vision, which can be important in robotics (robot vision) or medicine (e.g., artificial eyes for the blind); security, where the detection of nuclear materials is needed; or astronomy. This dissertation consists of three parts. First, we detect a far-field particle source using two directional detector arrays: cubic and spherical. We propose a mean-difference test (MDT) detector, analyze its statistical performance, and show that the MDT has a number of advantages over the generalized likelihood- ratio test (GLRT). Second, we localize the source by proposing a novel biologically inspired detector array, whose configuration generalizes the compound eye of insects. This array combines the advantages of compound eyes (e.g., large field-of-view) and human eyes (e.g., high angular resolution). Based on a statistical model of the array measurements, we analyze the array performance by computing the Cramérao bound (CRB) on the error in estimating the source direction. We also derive lower bounds on the mean-square angular error (MSAE) of the source localization and investigate the MSAE of two source- direction estimators. Numerical examples, including the optimal array design, are presented to further illustrate the array performance. Third, we derive a statistical angular resolution limit (ARL) on resolving two closely spaced point sources in a three-dimensional frame, which is applicable to various measurement models (e.g., radar, sonar, or astronomy). Using the asymptotic analysis of the GLRT, we derive the ARL with constraints on the probabilities of false alarm and detection. Our results give explicit analytical expression for the ARL that is proportional to the square root of the CRB on the angular source separation, or equivalently to the lower bound on the MSAE.

Liu, Zhi

2007-08-01

82

Modeling of carbonaceous particles emitted by boreal and temperature wildfires at northern latitudes  

NASA Astrophysics Data System (ADS)

For the first time, a spatial and monthly inventory has been constructed for carbonaceous particles emitted by boreal and temperate wildfires in forests, shrublands, and grasslands, with burned area data statistics, fuel load maps, fire characteristics, and particle emission factors. The time period considered is 1960-1997, and an important year-to-year variability was observed. On average, boreal and temperate vegetation fires represent 4% of global biomass burning, but during extreme years, their contribution may reach 12%, producing 9% and 20% of black carbon (BC) and particulate organic matter (POM), respectively, emitted by worldwide fires. The North American component of the boreal forest fires (Canada and Alaska) represents 4 to 122 Gg C yr-1 of BC and 0.07 to 2.4 Tg yr-1 of POM emitted, whereas the Eurasiatic component (Russia and northern Mongolia) may vary in the 16 to 474 Gg C yr-1 range for BC and between 0.3 and 9.4 Tg yr-1 for POM, with however great uncertainty. Temperate forests in conterminous United States and Europe have a much lower contribution with an average of 11 Gg C yr-1 of BC and 0.2 Tg yr-1 of POM. Grassland fires in Mongolia represent significant BC and POM sources which may reach 62 Gg C and 0.4 Tg, respectively. Finally, an annual average of BC emissions for shrubland fires in both the Mediterranean region and California is 20 Gg C yr-1, with average POM emissions of 0.1 Tg yr-1. These source maps obtained with a high spatial resolution (lox lo) can now be added to previous ones developed for other global carbonaceous aerosol sources (fossil fuel combustion, tropical biomass burning, agricultural and domestic fires) in order to provide global maps of particulate carbon emissions. Taking into account particle injection height in relation with each type of fire, our source map is a useful tool for studying the atmospheric transport and the impact of carbonaceous aerosols in three-dimensional transport and climate models.

Lavoué, David; Liousse, Catherine; Cachier, HéLèNe; Stocks, Brian J.; Goldammer, Johann G.

2000-11-01

83

Absolute measurement of the energies of alpha-particles emitted by sources of 252Cf and 227Ac  

NASA Astrophysics Data System (ADS)

Absolute energy measurements of ?-particles from sources of 252Cf and 227Ac by magnetic spectrometry are described. The sources were prepared at AERE, Harwell and measurements carried out using the 180° uniform-field spectrometer at BIPM followed the well-established technique applying cellulose-nitrate films (Kodak LR115) for track detection. The following values and uncertainties were obtained: 252Cf: E ? 0 = (6118.24±0.04) keV, E ? 43 = (6075.77±0.11) keV; 250Cf: E ? 0 = (6030.35±0.20) keV; 227Ac: E ? 0 = (4953.37±0.14) kev, E ? 13 = (4940.8±0.8) keV.

Rytz, A.; Wiltshire, R. A. P.; King, M.

1986-12-01

84

Unobservability of short-lived unstable particles and its implications for observational claims and theories in physics  

E-print Network

The physics literature contains many claims that elementary particles have been observed: such observational claims are, of course, important for the development of existential knowledge. Regarding claimed observations of short-lived unstable particles in particular, the term `observation' is not used with reference to any particular concept of observation: physicists merely use the word `observation' based on the convention in physics that the observation of a short-lived unstable particle can be claimed when its predicted decay products have been observed with a significance of 5 sigma. However, using Fox's recent concepts of direct and indirect observation, this paper shows that unstable particles with a lifetime of less than 0.01 attosecond are fundamentally unobservable. This cognitive inaccessibility of parts of the subatomic world has far-reaching implications for physics, not the least of which is that the aforementioned convention is untenable: claims that such short-lived unstable particles have been observed will thus have to be retracted. The main implications are two incompleteness theorems for physics, respectively stating (i) that experiments cannot prove completeness of a physical theory predicting short-lived unstable particles, and (ii) that experiments cannot prove correctness of such a theory - one can at most test its empirical adequacy. On a general note, the conclusion is that the importance of philosophical arguments for particle physics is herewith demonstrated: it is, thus, a widespread misconception that philosophical arguments can be completely avoided.

Marcoen J. T. F. Cabbolet

2015-02-03

85

Sizes and shapes of short-lived nuclei via laser spectroscopy. Progress report, May 1, 1980-January 31, 1981  

SciTech Connect

The first stage of the program to study the sizes and shapes of short-lived nuclei through their atomic hyperfine structure is to develop a movable laser spectroscopy system. This system is now almost complete and is described in this report along with plans for measurements at Argonne National Laboratory and Brookhaven National Laboratory.

Lewis, D.A.

1981-02-01

86

Multiple, short-lived ``stellar prominences'' on O stars: the supergiant ? Cephei  

NASA Astrophysics Data System (ADS)

Many OB stars show unexplained cyclical variability in their winds and in many optical lines, which are formed at the base of the wind. For these stars no dipolar magnetic fields have been detected. We propose that these cyclical variations are caused by the presence of multiple, transient, short-lived, corotating magnetic loops, which we call ``stellar prominences''. We present a simplified model representing these prominences as corotating spherical blobs and fit the rapid variability in the Heii ?4686 line of the O supergiant ? Cep for time-resolved spectra obtained in 1989. Our conclusions are: (1) From model fits we find that the life time of the prominences varies, and is between 2-7 h. (2) The adopted inclination angle is 68° with a rotation period of ~ 4.1 d (but not well constrained). (3) The contribution of non-radial pulsations is negligible (4) Similar behavior is observed in at least 4 other O stars. We propose that prominences are a common phenomenon among O stars.

Henrichs, H. F.; Sudnik, N.

2015-01-01

87

Development of a resonant laser ionization gas cell for high-energy, short-lived nuclei  

E-print Network

A new laser ion source configuration based on resonant photoionization in a gas cell has been developed at RIBF RIKEN. This system is intended for the future PArasitic RI-beam production by Laser Ion-Source (PALIS) project which will be installed at RIKEN's fragment separator, BigRIPS. A novel implementation of differential pumping, in combination with a sextupole ion beam guide (SPIG), has been developed. A few small scroll pumps create a pressure difference from 1000 hPa - 10^-3 Pa within a geometry drastically miniaturized compared to conventional systems. This system can utilize a large exit hole for fast evacuation times, minimizing the decay loss for short-lived nuclei during extraction from a buffer gas cell, while sufficient gas cell pressure is maintained for stopping high energy RI-beams. In spite of the motion in a dense pressure gradient, the photo-ionized ions inside the gas cell are ejected with an assisting force gas jet and successfully transported to a high-vacuum region via SPIG followed by a quadrupole mass separator. Observed behaviors agree with the results of gas flow and Monte Carlo simulations.

T. Sonoda; M. Wada; H. Tomita; C. Sakamoto; T. Takatsuka; T. Furukawa; H. Iimura; Y. Ito; T. Kubo; Y. Matsuo; H. Mita; S. Naimi; S. Nakamura; T. Noto; P. Schury; T. Shinozuka; T. Wakui; H. Miyatake; S. Jeong; H. Ishiyama; Y. X. Watanabe; Y. Hirayama; K. Okada; A. Takamine

2012-10-24

88

Muonic hydrogen cascade time and lifetime of the short-lived $2S$ state  

E-print Network

Metastable ${2S}$ muonic-hydrogen atoms undergo collisional ${2S}$-quenching, with rates which depend strongly on whether the $\\mu p$ kinetic energy is above or below the ${2S}\\to {2P}$ energy threshold. Above threshold, collisional ${2S} \\to {2P}$ excitation followed by fast radiative ${2P} \\to {1S}$ deexcitation is allowed. The corresponding short-lived $\\mu p ({2S})$ component was measured at 0.6 hPa $\\mathrm{H}_2$ room temperature gas pressure, with lifetime $\\tau_{2S}^\\mathrm{short} = 165 ^{+38}_{-29}$ ns (i.e., $\\lambda_{2S}^\\mathrm{quench} = 7.9 ^{+1.8}_{-1.6} \\times 10^{12} \\mathrm{s}^{-1}$ at liquid-hydrogen density) and population $\\epsilon_{2S}^\\mathrm{short} = 1.70^{+0.80}_{-0.56}$ % (per $\\mu p$ atom). In addition, a value of the $\\mu p$ cascade time, $T_\\mathrm{cas}^{\\mu p} = (37\\pm5)$ ns, was found.

Ludhova, L; Antognini, A; Biraben, F; Cardoso, J M R; Conde, C A N; Dax, A; Dhawan, S; Dos Santos, J M F; Fernandes, L M P; Hughes, V W; Hänsch, T W; Indelicato, P J; Julien, L; Knowles, P E; Kottmann, F; Liu, Y W; Lopes, J A M; Monteiro, C M B; Mulhauser, F; Nez, F; Pohl, R; Rabinowitz, P; Schaller, L A; Schwob, C; Taqqu, D; Veloso, J F C A

2006-01-01

89

Mass spectrometric detection of short-lived drug metabolites generated in an electrochemical microfluidic chip.  

PubMed

The costs of drug development have been rising exponentially over the last six decades, making it essential to select drug candidates in the early drug discovery phases before proceeding to expensive clinical trials. Here, we present novel screening methods using an electrochemical chip coupled online to mass spectrometry (MS) or liquid chromatography (LC) and MS, to generate phase I and phase II drug metabolites and to demonstrate protein modification by reactive metabolites. The short transit time (?4.5 s) between electrochemical oxidation and mass spectrometric detection, enabled by an integrated electrospray emitter, allows us to detect a short-lived radical metabolite of chlorpromazine which is too unstable to be detected using established test routines. In addition, a fast way to screen candidate drugs is established by recording real-time mass voltammograms, which allows one to identify the drug metabolites that are expected to be formed upon oxidation by applying a linear potential sweep and simultaneously detect oxidation products. Furthermore, detoxification of electrochemically generated reactive metabolites of paracetamol was mimicked by their adduct formation with the antioxidant glutathione. Finally, the potential toxicity of reactive metabolites can be investigated by the modification of proteins, which was demonstrated by modification of carbonic anhydrase I with electrochemically generated reactive metabolites of paracetamol. With this series of experiments, we demonstrate the potential of this electrochemical chip as a complementary tool for a variety of drug metabolism studies in the early stages of drug discovery. PMID:25531627

van den Brink, Floris T G; Büter, Lars; Odijk, Mathieu; Olthuis, Wouter; Karst, Uwe; van den Berg, Albert

2015-02-01

90

Observation and modeling of short-lived oxygenated hydrocarbons in the tropical free troposphere  

NASA Astrophysics Data System (ADS)

The Tropical Ocean tRoposphere Exchange experiment TORERO (Jan/Feb 2012) probed the influence of air-sea exchange of organic carbon species and very short lived halogen species on the oxidative capacity of the tropical free troposphere over the full tropospheric air column above the eastern tropical Pacific Ocean. Organic carbon is important in the atmosphere, because it influences the reactive chemistry and lifetime of climate active gases (e.g., methane, ozone, dimethyl sulfide), and because of its relevance for the formation, composition and climate impact of aerosols. This presentation summarizes unequivocal evidence for the presence of numerous oxygenated hydrocarbons (i.e., glyoxal, formaldehyde, acetaldehyde, propanal, MVK, MEK, aliphatic aldehydes, alcohols etc.) in the remote marine boundary layer, and in the tropical free troposphere. These species were detected by means of both Differential Optical Absorption Spectroscopy (Airborne MAX-DOAS), and online GC-MS (TOGA) aboard the NSF/NCAR GV aircraft. We employ atmospheric modeling constrained by observations of gas-phase hydrocarbons, aerosols, photolysis frequencies, and meterological parameters measured aboard the plane to elucidate the formation mechanism of this as of yet unaccounted source for oxidized organic carbon, and quantify the influence on the OVOCs on hydroxyl, bromine, chlorine and iodine radical abundances.

Volkamer, Rainer; Apel, Eric

2013-04-01

91

Harvard-MIT research program in short-lived radiopharmaceuticals. Final report  

SciTech Connect

The Harvard-MIT Research Program in Short-lived Radiopharmaceuticals was established in 1977 to foster interaction among groups working in radiopharmaceutical chemistry at Harvard Medical School, the Massachusetts Institute of Technology, and the Massachusetts General Hospital. To this was added a group at The Childrens Hospital. From these collaborations and building upon the special strengths of the participating individuals, laboratories and institutions, it was hoped that original approaches would be found for the design of new, clinically useful, radiolabeled compounds. The original thrust of this proposal included: (a) examination of the coordination chemistry of technetium as a basis for rational radiopharmaceutical design, (b) development of an ultrashort-lived radionuclide generator for the diagnosis of congenital heart disease in newborns, (c) synthesis of receptor-site-directed halopharmaceuticals, (d) improved facile labeling of complex molecules with positron-emitting radionuclides. The authors` 1986 proposal was oriented toward organs and disease, emphasizing radiolabeled agents that delineate specific functions and the distribution of receptors in brain, heart, and tumors. In 1989, they further refined their purposes and focused on two major aims: (a) synthesis and utilization of neutral technetium and rhenium complexes of high specific activity, and (b) development of new approaches to the radiolabeling of proteins, peptides, immunoglobulins, and their fragments. In 1992, the authors amended this proposal to concentrate their efforts on biologically active peptides and proteins for targeted radiodiagnosis and therapy.

Adelstein, S.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Office of Sponsored Programs

1995-02-01

92

Chemistry of Very Short Lived Halogens in the Troposphere: Pre-Industrial to Present day  

NASA Astrophysics Data System (ADS)

Ozone in the troposphere is one of the most important short-lived gases contributing to greenhouse radiative forcing (IPCC, 2007) and is of central importance to the chemistry of this region of the atmosphere. Tropospheric ozone is produced by photochemical oxidation of carbon monoxide, methane and other non-methane volatile organic compounds in the presence of nitrogen oxide. A large fraction of the tropospheric ozone loss occurs within the tropical marine boundary layer via photolysis to excited oxygen atoms followed by reaction with water vapor, reactions with odd hydrogen radical, and surface deposition. In addition, inorganic halogens (i.e., chlorine, bromine, and iodine species) are known to destroy ozone through efficient catalytic reaction cycles. In this study, we use the NCAR 3D chemistry climate model (CAM-Chem), including a detailed representation of tropospheric and stratospheric chemistry. Its scope has been extended to include halogen sources, reactive halogen chemistry, and related atmospheric processes (Ordonez et al., ACP, 2012; Saiz-Lopez et al., ACP,. 2012). The purpose of this work is to contrast the pre-industrial importance of tropospheric halogen driven ozone loss to present day conditions, specifically the importance of iodine and bromine chemistry. The sensitivity to inorganic nitrogen abundance will be shown. The model results compared to the pre-industrial surface ozone measurements at Montsouris (Volz and Kley, 1988) will also be discussed.

Kinnison, Douglas; Saiz-Lopez, Alfonso; Fernandez, Rafael; Lamarque, Jean-Francois; Tilmes, Simone

2014-05-01

93

Spatial distribution of brominated very short-lived substances in the eastern Pacific  

NASA Astrophysics Data System (ADS)

Seawater concentrations and distributions of brominated very short-lived substances (BrVSLS), including bromoform (CHBr3), dibromomethane (CH2Br2), bromodichloromethane (CHBrCl2), chlorodibromomethane (CHClBr2), were measured in the upper water column (5-750 m) in the eastern Pacific. Inorganic nutrient, pigment concentrations, and picoplankton cell counts were measured to determine biogeochemical factors that affect the production and distribution of these BrVSLS. Elevated concentrations of BrVSLS were observed in coastal and tropical seawater. Concentration maxima for CHBr3, CH2Br2, and CHClBr2 were observed below the mixed layer, near the subsurface chlorophyll a maxima, which suggest BrVSLS production may be related to photosynthetic biomass production. Our results also suggest that heterotrophic bacteria may also contribute to CH2Br2 and CHBrCl2 production in the water column. The maximum CHBrCl2 concentration was observed at a depth much deeper than the euphotic zone, which suggests sources other than photosynthetic biomass. Elevated CHBrCl2 concentrations in deeper waters were coincident with elevated CHCl3 concentrations, which may be an evidence for successive chlorine substitution of CHBr3 in deeper and older water masses.

Liu, Yina; Yvon-Lewis, Shari A.; Thornton, Daniel C. O.; Campbell, Lisa; Bianchi, Thomas S.

2013-05-01

94

Short-Lived HF Molecules in Superionic Hydrogen Fluoride at Extreme Conditions  

NASA Astrophysics Data System (ADS)

The first principles molecular dynamics study enables us to elucidate the existence of short-lived HF molecules in the superionic hydrogen fluoride at an extreme high pressure and a temperature. Three fourth of the immobile fluorines constructs the molecules with lifetime of 8 fs. The ionized fluorines form weak HF bond with the proton in the nearest HF molecule of which the lifetime is 3 fs. The covalent and the Coulomb bonds between the fluorines and the protons form indirect covalent and indirect Coulomb attractions between the di-interstitial protons on the mid-fluorines. The attractions reduce the Haven's ratio of the protons. The absence of the proton dimers indicates a failure of the caterpillar diffusion model or the Frenkel–Kontorova chain model for the superionic diffusion of the protons. The incompletely ionized cations and anions reduce their Coulomb attractions which induce the sublattice melting of smaller size and smaller mass of the protons than the fluorines. The electronic states of the fluoride are intermediate between the ionic crystals and the covalent bonded molecular crystals. The superionic conductors are classified into three groups: they are molecular type, covalent metalloid type, and metallic type conductors.

Tsumuraya, Kazuo; Ohde, Yoshiyuki; Oshimi, Tadaaki

2015-02-01

95

Development of a resonant laser ionization gas cell for high-energy, short-lived nuclei  

NASA Astrophysics Data System (ADS)

A new laser ion source configuration based on resonant photoionization in a gas cell has been developed at RIBF RIKEN. This system is intended for the future PArasitic RI-beam production by Laser Ion-Source (PALIS) project which will be installed at RIKEN's fragment separator, BigRIPS. A novel implementation of differential pumping, in combination with a sextupole ion beam guide (SPIG), has been developed. A few small scroll pumps create a pressure difference from 1000 hPa-10-3 Pa within a geometry drastically miniaturized compared to conventional systems. This system can utilize a large exit hole for fast evacuation times, minimizing the decay loss for short-lived nuclei during extraction from a buffer gas cell, while sufficient gas cell pressure is maintained for stopping high energy RI-beams. In spite of the motion in a dense pressure gradient, the photo-ionized ions inside the gas cell are ejected with an assisting force gas jet and successfully transported to a high-vacuum region via SPIG followed by a quadrupole mass separator. Observed behaviors agree with the results of gas flow and Monte Carlo simulations.

Sonoda, T.; Wada, M.; Tomita, H.; Sakamoto, C.; Takatsuka, T.; Furukawa, T.; Iimura, H.; Ito, Y.; Kubo, T.; Matsuo, Y.; Mita, H.; Naimi, S.; Nakamura, S.; Noto, T.; Schury, P.; Shinozuka, T.; Wakui, T.; Miyatake, H.; Jeong, S.; Ishiyama, H.; Watanabe, Y. X.; Hirayama, Y.; Okada, K.; Takamine, A.

2013-01-01

96

Trapping of relatively short-lived radioactive {}^{146}Eu in a Paul trap  

NASA Astrophysics Data System (ADS)

A new technique has been developed wherein one of the relatively short lived isotopes of europium ({}^{146}Eu, Half life =\\;4.61 days) has been generated by decay of parent {}^{146}Gd atoms and the ions are confined in a Paul trap for spectroscopic studies. Studies of the mass dependent ion oscillation frequencies show that the ions trapped have a mass number 146 amu and this was confirmed by similar measurements carried out on trapped barium and potassium ions. From calculations of thermal ionization probabilities based on the Langmuir-Saha equation and the number of trapped ions estimated from ion response signal, the approximate number of the different isobars (of mass number 146) trapped, has been evaluated. We also present simulations of the evolution of laser-induced fluorescence photons of the trapped {}^{146}Eu ions, wherein a pulsed laser is used to excite the resonance {}^{9}S_{4} - {}^{9}P_{5} transition, which rapidly decays to the metastable {}^{9}D_{4-6} states emitting fluorescence photons.

Joshi, M. K.; Sikdar, A. K.; Rao, Pushpa M.; Bhattacharjee, T.; Das, S. K.; Das, P.

2014-08-01

97

Spin relaxation of a short-lived radical in zero magnetic field.  

PubMed

A short-lived radical containing only one I = 1/2 nucleus, the muoniated 1,2-dicarboxyvinyl radical dianion, was produced in an aqueous solution by the reaction of muonium with the dicarboxyacetylene dianion. The identity of the radical was confirmed by measuring the muon hyperfine coupling constant (hfcc) by transverse field muon spin rotation spectroscopy and comparing this value with the hfcc obtained from DFT calculations. The muon spin relaxation rate of this radical was measured as a function of temperature in zero magnetic field by the zero field muon spin relaxation technique. The results have been interpreted using the theoretical model of Fedin et al. (J. Chem. Phys., 2003, 118, 192). The muon spin polarization decreases exponentially with time after muon implantation and the temperature dependence of the spin relaxation rate indicates that the dominant relaxation mechanism is the modulation of the anisotropic hyperfine interaction due to molecular rotation. The effective radius of the radical in solution was determined to be 1.12 ± 0.04 nm from the dependence of the muon spin relaxation rate on the temperature and viscosity of the solution, and is approximately 3.6 times larger than the value obtained from DFT calculations. PMID:21079834

McKenzie, Iain

2011-01-21

98

Short-Lived Effector CD8 T Cells Induced by Genetically Attenuated Malaria Parasite Vaccination Express CD11c  

PubMed Central

Vaccination with a single dose of genetically attenuated malaria parasites can induce sterile protection against sporozoite challenge in the rodent Plasmodium yoelii model. Protection is dependent on CD8+ T cells, involves perforin and gamma interferon (IFN-?), and is correlated with the expansion of effector memory CD8+ T cells in the liver. Here, we have further characterized vaccine-induced changes in the CD8+ T cell phenotype and demonstrated significant upregulation of CD11c on CD3+ CD8b+ T cells in the liver, spleen, and peripheral blood. CD11c+ CD8+ T cells are predominantly CD11ahi CD44hi CD62L?, indicative of antigen-experienced effector cells. Following in vitro restimulation with malaria-infected hepatocytes, CD11c+ CD8+ T cells expressed inflammatory cytokines and cytotoxicity markers, including IFN-?, tumor necrosis factor alpha (TNF-?), interleukin-2 (IL-2), perforin, and CD107a. CD11c? CD8+ T cells, on the other hand, expressed negligible amounts of all inflammatory cytokines and cytotoxicity markers tested, indicating that CD11c marks multifunctional effector CD8+ T cells. Coculture of CD11c+, but not CD11c?, CD8+ T cells with sporozoite-infected primary hepatocytes significantly inhibited liver-stage parasite development. Tetramer staining for the immunodominant circumsporozoite protein (CSP)-specific CD8+ T cell epitope demonstrated that approximately two-thirds of CSP-specific cells expressed CD11c at the peak of the CD11c+ CD8+ T cell response, but CD11c expression was lost as the CD8+ T cells entered the memory phase. Further analyses showed that CD11c+ CD8+ T cells are primarily KLRG1+ CD127? terminal effectors, whereas all KLRG1? CD127+ memory precursor effector cells are CD11c? CD8+ T cells. Together, these results suggest that CD11c marks a subset of highly inflammatory, short-lived, antigen-specific effector cells, which may play an important role in eliminating infected hepatocytes. PMID:23980113

Cooney, Laura A.; Gupta, Megha; Thomas, Sunil; Mikolajczak, Sebastian; Choi, Kimberly Y.; Gibson, Claire; Jang, Ihn K.; Danziger, Sam; Aitchison, John; Gardner, Malcolm J.; Kappe, Stefan H. I.

2013-01-01

99

Proton-alpha reactions in light and heavy nuclei  

Microsoft Academic Search

Nuclear emulsion was irradiated with 45 Mev protons. and measurements ; made on the tracks of alpha-particles emitted from disintegrations of the light ; and heavy nuclei. There is a forward excess of energetic alpha-panticles in each ; case, and this can bc accounted for by direct interaction processes, for which ; several possible models are discussed. Conclusions are drawn

P. Hodgson

1958-01-01

100

A proposal for assessing study quality: Biomonitoring, Environmental Epidemiology, and Short-lived Chemicals (BEES-C) instrument  

PubMed Central

The quality of exposure assessment is a major determinant of the overall quality of any environmental epidemiology study. The use of biomonitoring as a tool for assessing exposure to ubiquitous chemicals with short physiologic half-lives began relatively recently. These chemicals present several challenges, including their presence in analytical laboratories and sampling equipment, difficulty in establishing temporal order in cross-sectional studies, short- and long-term variability in exposures and biomarker concentrations, and a paucity of information on the number of measurements required for proper exposure classification. To date, the scientific community has not developed a set of systematic guidelines for designing, implementing and interpreting studies of short-lived chemicals that use biomonitoring as the exposure metric or for evaluating the quality of this type of research for WOE assessments or for peer review of grants or publications. We describe key issues that affect epidemiology studies using biomonitoring data on short-lived chemicals and propose a systematic instrument – the Biomonitoring, Environmental Epidemiology, and Short-lived Chemicals (BEES-C) instrument – for evaluating the quality of research proposals and studies that incorporate biomonitoring data on short-lived chemicals. Quality criteria for three areas considered fundamental to the evaluation of epidemiology studies that include biological measurements of short-lived chemicals are described: 1) biomarker selection and measurement, 2) study design and execution, and 3) general epidemiological study design considerations. We recognize that the development of an evaluative tool such as BEES-C is neither simple nor non-controversial. We hope and anticipate that the instrument will initiate further discussion/debate on this topic. PMID:25137624

LaKind, Judy S.; Sobus, Jon R.; Goodman, Michael; Barr, Dana Boyd; Fürst, Peter; Albertini, Richard J.; Arbuckle, Tye E.; Schoeters, Greet; Tan, Yu-Mei; Teeguarden, Justin; Tornero-Velez, Rogelio; Weisel, Clifford P.

2015-01-01

101

Strong sensitivity of late 21st century climate to projected changes in short-lived air pollutants  

NASA Astrophysics Data System (ADS)

This study examines the impact of projected changes (A1B "marker" scenario) in emissions of four short-lived air pollutants (ozone, black carbon, organic carbon, and sulfate) on future climate. Through year 2030, simulated climate is only weakly dependent on the projected levels of short-lived air pollutants, primarily the result of a near cancellation of their global net radiative forcing. However, by year 2100, the projected decrease in sulfate aerosol (driven by a 65% reduction in global sulfur dioxide emissions) and the projected increase in black carbon aerosol (driven by a 100% increase in its global emissions) contribute a significant portion of the simulated A1B surface air warming relative to the year 2000: 0.2°C (Southern Hemisphere), 0.4°C globally, 0.6°C (Northern Hemisphere), 1.5-3°C (wintertime Arctic), and 1.5-2°C (˜40% of the total) in the summertime United States. These projected changes are also responsible for a significant decrease in central United States late summer root zone soil water and precipitation. By year 2100, changes in short-lived air pollutants produce a global average increase in radiative forcing of ˜1 W/m2; over east Asia it exceeds 5 W/m2. However, the resulting regional patterns of surface temperature warming do not follow the regional patterns of changes in short-lived species emissions, tropospheric loadings, or radiative forcing (global pattern correlation coefficient of -0.172). Rather, the regional patterns of warming from short-lived species are similar to the patterns for well-mixed greenhouse gases (global pattern correlation coefficient of 0.8) with the strongest warming occurring over the summer continental United States, Mediterranean Sea, and southern Europe and over the winter Arctic.

Levy, Hiram; Schwarzkopf, M. Daniel; Horowitz, Larry; Ramaswamy, V.; Findell, K. L.

2008-03-01

102

A proposal for assessing study quality: Biomonitoring, Environmental Epidemiology, and Short-lived Chemicals (BEES-C) instrument.  

PubMed

The quality of exposure assessment is a major determinant of the overall quality of any environmental epidemiology study. The use of biomonitoring as a tool for assessing exposure to ubiquitous chemicals with short physiologic half-lives began relatively recently. These chemicals present several challenges, including their presence in analytical laboratories and sampling equipment, difficulty in establishing temporal order in cross-sectional studies, short- and long-term variability in exposures and biomarker concentrations, and a paucity of information on the number of measurements required for proper exposure classification. To date, the scientific community has not developed a set of systematic guidelines for designing, implementing and interpreting studies of short-lived chemicals that use biomonitoring as the exposure metric or for evaluating the quality of this type of research for WOE assessments or for peer review of grants or publications. We describe key issues that affect epidemiology studies using biomonitoring data on short-lived chemicals and propose a systematic instrument--the Biomonitoring, Environmental Epidemiology, and Short-lived Chemicals (BEES-C) instrument--for evaluating the quality of research proposals and studies that incorporate biomonitoring data on short-lived chemicals. Quality criteria for three areas considered fundamental to the evaluation of epidemiology studies that include biological measurements of short-lived chemicals are described: 1) biomarker selection and measurement, 2) study design and execution, and 3) general epidemiological study design considerations. We recognize that the development of an evaluative tool such as BEES-C is neither simple nor non-controversial. We hope and anticipate that the instrument will initiate further discussion/debate on this topic. PMID:25137624

LaKind, Judy S; Sobus, Jon R; Goodman, Michael; Barr, Dana Boyd; Fürst, Peter; Albertini, Richard J; Arbuckle, Tye E; Schoeters, Greet; Tan, Yu-Mei; Teeguarden, Justin; Tornero-Velez, Rogelio; Weisel, Clifford P

2014-12-01

103

Longitudinal analysis of Plantago: adaptive benefits of iteroparity in a short-lived, herbaceous perennial.  

PubMed

Theory suggests that iteroparity may confer greater fitness than semelparity in situations in which temporal environmental variation is high and unpredictable. Variable age-specific mortality, density dependence, and other factors may also favor iteroparity over semelparity. Here, we empirically test the adaptive benefits of greater numbers of reproductive years in a study of reproductive schedules in an experimental population of a short-lived polycarpic perennial, Plantago lanceolata. A large experimental population was established that included four cohorts with similar genetic structure. Individuals were censused for mortality, size, and reproduction for seven years. Plants experienced variable numbers of reproductive years, but one or two years were most common (approximately 46.7% of the population reproduced only once). The probability of flowering at least once prior to death was determined strongly by extrinsic, environmental or intrinsic but environmentally influenced variables, including early-life size, cohort, and block, but also varied with a number of interactions involving paternal lineage. Maternal effects explained small but significant components of the variance in the number of reproductive years among individuals in each cohort, while paternal effects were significant in only two cohorts. Number of reproductive years contributed significantly to fitness in this system, more so than all other variables tested, although most of the variation in relative fitness may be attributed ultimately to environmental influences. We suggest that the high proportion of each cohort composed of plants reproducing only once may be due to environmental constraints on either growth or size. Such environmental influences, particularly on early life size, may result in small but important indirect effects on fitness. PMID:20392009

Shefferson, Richard P; Roach, Deborah A

2010-02-01

104

Disentangling the effects of CO2 and short-lived climate forcer mitigation.  

PubMed

Anthropogenic global warming is driven by emissions of a wide variety of radiative forcers ranging from very short-lived climate forcers (SLCFs), like black carbon, to very long-lived, like CO2. These species are often released from common sources and are therefore intricately linked. However, for reasons of simplification, this CO2-SLCF linkage was often disregarded in long-term projections of earlier studies. Here we explicitly account for CO2-SLCF linkages and show that the short- and long-term climate effects of many SLCF measures consistently become smaller in scenarios that keep warming to below 2 °C relative to preindustrial levels. Although long-term mitigation of methane and hydrofluorocarbons are integral parts of 2 °C scenarios, early action on these species mainly influences near-term temperatures and brings small benefits for limiting maximum warming relative to comparable reductions taking place later. Furthermore, we find that maximum 21st-century warming in 2 °C-consistent scenarios is largely unaffected by additional black-carbon-related measures because key emission sources are already phased-out through CO2 mitigation. Our study demonstrates the importance of coherently considering CO2-SLCF coevolutions. Failing to do so leads to strongly and consistently overestimating the effect of SLCF measures in climate stabilization scenarios. Our results reinforce that SLCF measures are to be considered complementary rather than a substitute for early and stringent CO2 mitigation. Near-term SLCF measures do not allow for more time for CO2 mitigation. We disentangle and resolve the distinct benefits across different species and therewith facilitate an integrated strategy for mitigating both short and long-term climate change. PMID:25368182

Rogelj, Joeri; Schaeffer, Michiel; Meinshausen, Malte; Shindell, Drew T; Hare, William; Klimont, Zbigniew; Velders, Guus J M; Amann, Markus; Schellnhuber, Hans Joachim

2014-11-18

105

Organized cell swimming motions in Bacillus subtilis colonies: patterns of short-lived whirls and jets.  

PubMed

The swimming motions of cells within Bacillus subtilis colonies, as well as the associated fluid flows, were analyzed from video films produced during colony growth and expansion on wet agar surfaces. Individual cells in very wet dense populations moved at rates between 76 and 116 microm/s. Swimming cells were organized into patterns of whirls, each approximately 1,000 microm2, and jets of about 95 by 12 microm. Whirls and jets were short-lived, lasting only about 0.25 s. Patterns within given areas constantly repeated with a periodicity of approximately 1 s. Whirls of a given direction became disorganized and then re-formed, usually into whirls moving in the opposite direction. Pattern elements were also organized with respect to one another in the colony. Neighboring whirls usually turned in opposite directions. This correlation decreased as a function of distance between whirls. Fluid flows associated with whirls and jets were measured by observing the movement of marker latex spheres added to colonies. The average velocity of markers traveling in whirls was 19 microm/s, whereas those traveling in jets moved at 27 microm/s. The paths followed by markers were aligned with the direction of cell motion, suggesting that cells create flows moving with them into whirls and along jets. When colonies became dry, swimming motions ceased except in regions close to the periphery and in isolated islands where cells traveled in slow whirls at about 4 microm/s. The addition of water resulted in immediate though transient rapid swimming (> 80 microm/s) in characteristic whirl and jet patterns. The rate of swimming decreased to 13 microm/s within 2 min, however, as the water diffused into the agar. Organized swimming patterns were nevertheless preserved throughout this period. These findings show that cell swimming in colonies is highly organized. PMID:9882676

Mendelson, N H; Bourque, A; Wilkening, K; Anderson, K R; Watkins, J C

1999-01-01

106

MIXING AND TRANSPORT OF SHORT-LIVED AND STABLE ISOTOPES AND REFRACTORY GRAINS IN PROTOPLANETARY DISKS  

SciTech Connect

Analyses of primitive meteorites and cometary samples have shown that the solar nebula must have experienced a phase of large-scale outward transport of small refractory grains as well as homogenization of initially spatially heterogeneous short-lived isotopes. The stable oxygen isotopes, however, were able to remain spatially heterogeneous at the {approx}6% level. One promising mechanism for achieving these disparate goals is the mixing and transport associated with a marginally gravitationally unstable (MGU) disk, a likely cause of FU Orionis events in young low-mass stars. Several new sets of MGU models are presented that explore mixing and transport in disks with varied masses (0.016 to 0.13 M{sub Sun }) around stars with varied masses (0.1 to 1 M{sub Sun }) and varied initial Q stability minima (1.8 to 3.1). The results show that MGU disks are able to rapidly (within {approx}10{sup 4} yr) achieve large-scale transport and homogenization of initially spatially heterogeneous distributions of disk grains or gas. In addition, the models show that while single-shot injection heterogeneity is reduced to a relatively low level ({approx}1%), as required for early solar system chronometry, continuous injection of the sort associated with the generation of stable oxygen isotope fractionations by UV photolysis leads to a sustained, relatively high level ({approx}10%) of heterogeneity, in agreement with the oxygen isotope data. These models support the suggestion that the protosun may have experienced at least one FU Orionis-like outburst, which produced several of the signatures left behind in primitive chondrites and comets.

Boss, Alan P., E-mail: boss@dtm.ciw.edu [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

2013-08-10

107

Disentangling the effects of CO2 and short-lived climate forcer mitigation  

PubMed Central

Anthropogenic global warming is driven by emissions of a wide variety of radiative forcers ranging from very short-lived climate forcers (SLCFs), like black carbon, to very long-lived, like CO2. These species are often released from common sources and are therefore intricately linked. However, for reasons of simplification, this CO2–SLCF linkage was often disregarded in long-term projections of earlier studies. Here we explicitly account for CO2–SLCF linkages and show that the short- and long-term climate effects of many SLCF measures consistently become smaller in scenarios that keep warming to below 2 °C relative to preindustrial levels. Although long-term mitigation of methane and hydrofluorocarbons are integral parts of 2 °C scenarios, early action on these species mainly influences near-term temperatures and brings small benefits for limiting maximum warming relative to comparable reductions taking place later. Furthermore, we find that maximum 21st-century warming in 2 °C-consistent scenarios is largely unaffected by additional black-carbon-related measures because key emission sources are already phased-out through CO2 mitigation. Our study demonstrates the importance of coherently considering CO2–SLCF coevolutions. Failing to do so leads to strongly and consistently overestimating the effect of SLCF measures in climate stabilization scenarios. Our results reinforce that SLCF measures are to be considered complementary rather than a substitute for early and stringent CO2 mitigation. Near-term SLCF measures do not allow for more time for CO2 mitigation. We disentangle and resolve the distinct benefits across different species and therewith facilitate an integrated strategy for mitigating both short and long-term climate change. PMID:25368182

Rogelj, Joeri; Schaeffer, Michiel; Meinshausen, Malte; Shindell, Drew T.; Hare, William; Klimont, Zbigniew; Amann, Markus; Schellnhuber, Hans Joachim

2014-01-01

108

A shallow, short-lived meso-? cyclone over the Gulf of Antalya, eastern Mediterranean  

NASA Astrophysics Data System (ADS)

The physical mechanisms of a shallow short-lived meso-? scale cyclone over the Gulf of antalya, eastern Mediterranean, are studied, with the PSU/NCAR MM4 and MM5 meso-scale models. Although the thin stratus clouds within this cyclone as observed from satellites are not resolved even by the 3 km nesting, the dynamical evolution and the 3-D structure are well captured. The small cyclone or eddy develops before sunrise following convergenceof the strong katabatic winds from the nearby steep Anatolya mountains slopes with 2 km peaks. The eddy's lifetime is of the order of 5 7 h and it quickly dissipates before noon. Based on the simulated vertical winds, vorticity, humidity as well as the IR top cloud temperatures, the depth of the eddy is estimated to be 500 800 m. It is shown that the divergence term in the vorticity equation is dominant during the eddy's generation. Lagrangian analysis for the trajectories of several air-masses that were identified as crucial for the eddy's development, reveals a sharp increase both in the PV (by 7 8 units), and in the specific humidity, 3.5 7 g/kg, as the air-parcels descend from about 840 980 hpa. This air-parcel analysis also shows that the diabatic contribution is quite important. Factor separation experiments confirm that pure topography is the major factor and the synergistic effect of sea-fluxes and topography contributes about 20% of the total vorticity. The Antalya cyclone is common during July to September morning hours and its frequency of occurrence was estimated from satellite pictures to be about 20%.

Alpert, P.; Tsidulko, M.; Itzigsohn, D.

1999-03-01

109

Convective Transport of Very-short-lived Bromocarbons to the Stratosphere  

NASA Technical Reports Server (NTRS)

We use the NASA GEOS Chemistry Climate Model (GEOSCCM) to quantify the contribution of two most important brominated very short-lived substances (VSLS), bromoform (CHBr3) and dibromomethane (CH2Br2), to stratospheric bromine and its sensitivity to convection strength. Model simulations suggest that the most active transport of VSLS from the marine boundary layer through the tropopause occurs over the tropical Indian Ocean, the Western Pacific warm pool, and off the Pacific coast of Mexico. Together, convective lofting of CHBr3 and CH2Br2 and their degradation products supplies 8 ppt total bromine to the base of the Tropical Tropopause Layer (TTL, 150 hPa), similar to the amount of VSLS organic bromine available in the marine boundary layer (7.8-8.4 ppt) in the above active convective lofting regions. Of the total 8 ppt VSLS-originated bromine that enters the base of TTL at 150 hPa, half is in the form of source gas injection (SGI) and half as product gas injection (PGI). Only a small portion (< 10%) the VSLS-originated bromine is removed via wet scavenging in the TTL before reaching the lower stratosphere. On global and annual average, CHBr3 and CH2Br2, together, contribute 7.7 pptv to the present-day inorganic bromine in the stratosphere. However, varying model deep convection strength between maximum and minimum convection conditions can introduce a 2.6 pptv uncertainty in the contribution of VSLS to inorganic bromine in the stratosphere (BryVSLS). Contrary to the conventional wisdom, minimum convection condition leads to a larger BryVSLS as the reduced scavenging in soluble product gases, thus a significant increase in PGI (2-3 ppt), greatly exceeds the relative minor decrease in SGI (a few 10ths ppt.

Liang, Qing; Atlas, Elliot Leonard; Blake, Donald Ray; Dorf, Marcel; Pfeilsticker, Klaus August; Schauffler, Sue Myhre

2014-01-01

110

Polyhalogenated Very Short Live Substances in the Atlantic Ocean, and their Linkages with Ocean Primary Production  

NASA Astrophysics Data System (ADS)

The Halocarbon Air-Sea Transect - Atlantic (HalocAST-A) cruise was conducted aboard FS Polarstern during the ANT-XXVII/1 expedition. The ship departed from Bremerhaven, Germany on October 25th and arrived in Cape Town, South Africa on November 24th in 2010. The HalocAST-A cruise was devoted to studying air-sea fluxes of a suite of halocarbon compounds. Atmospheric mixing ratios and seawater concentrations of the halocarbons were continuously measured with the gas chromatograph - mass spectrometer (GC-MS). This study focuses on the polyhalogenated very short lived substances (VSLSs) such as bromoform (CHBr3), dibromomethane (CH2Br2), chlorodibromomethane (CHClBr2), and bromodichloromethane (CHBrCl2). The goal of this study is to examine the distributions of these compounds and possible relationship between their emissions and oceanic primary production. Therefore, along with the halocarbon concentrations, parameters like dissolved organic carbon concentrations, nutrient concentrations, pigment concentrations, and picoplankton and heterotrophic bacteria counts were also determined. The observed saturation anomalies indicated these VSLSs were supersaturated for almost the entire duration of the cruise. The highest seawater concentrations for these compounds were observed near the Canary Islands. Air mixing ratios were also elevated in this region. The net fluxes for CHBr3, CH2Br2, CHClBr2, and CHBrCl2 were 13.8 nmol m-2 d-1, 4.5 nmol m-2 d-1, 4.5 nmol m-2 d-1 and 1.2 nmol m-2 d-1, respectively. During the HalocAST-A cruise, these compounds exhibit similar trends with total chlorophyll a. Contributions from selected phytoplankton group will be further assessed through the use of individual pigment biomarkers.

Liu, Y.; Yvon-Lewis, S. A.; Hu, L.; Bianchi, T. S.; Campbell, L.; Smith, R. W.

2011-12-01

111

Longitudinal analysis of Plantago: adaptive benefits of iteroparity in a short-lived, herbaceous perennial  

PubMed Central

Theory suggests that iteroparity may confer greater fitness than semelparity in situations in which temporal environmental variation is high and unpredictable. Variable age-specific mortality, density dependence, and other factors may also favor iteroparity over semelparity. Here, we empirically test the adaptive benefits of greater numbers of reproductive years in a study of reproductive schedules in an experimental population of a short-lived polycarpic perennial, Plantago lanceolata. A large experimental population was established that included four cohorts with similar genetic structure. Individuals were censused for mortality, size, and reproduction for seven years. Plants experienced variable numbers of reproductive years, but one or two years were most common (~46.7% of the population reproduced only once). The probability of flowering at least once prior to death was determined strongly by extrinsic, environmental or intrinsic but environmentally influenced variables, including early-life size, cohort, and block, but also varied with a number of interactions involving paternal lineage. Maternal effects explained small but significant components of the variance in the number of reproductive years among individuals in each cohort, while paternal effects were significant in only two cohorts. Number of reproductive years contributed significantly to fitness in this system, more so than all other variables tested, although most of the variation in relative fitness may be attributed ultimately to environmental influences. We suggest that the high proportion of each cohort composed of plants reproducing only once may be due to environmental constraints on either growth or size. Such environmental influences, particularly on early life size, may result in small but important indirect effects on fitness. PMID:20392009

Shefferson, Richard P.; Roach, Deborah A.

2010-01-01

112

First Use of High Charge States for Mass Measurements of Short-Lived Nuclides in a Penning Trap  

NASA Astrophysics Data System (ADS)

Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed ? emitter Rb74 (T1/2=65ms). The determination of its atomic mass and an improved QEC value are presented.

Ettenauer, S.; Simon, M. C.; Gallant, A. T.; Brunner, T.; Chowdhury, U.; Simon, V. V.; Brodeur, M.; Chaudhuri, A.; Mané, E.; Andreoiu, C.; Audi, G.; López-Urrutia, J. R. Crespo; Delheij, P.; Gwinner, G.; Lapierre, A.; Lunney, D.; Pearson, M. R.; Ringle, R.; Ullrich, J.; Dilling, J.

2011-12-01

113

First Use of High Charge States for Mass Measurements of Short-Lived Nuclides in a Penning Trap  

SciTech Connect

Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed {beta} emitter {sup 74}Rb (T{sub 1/2}=65 ms). The determination of its atomic mass and an improved Q{sub EC} value are presented.

Ettenauer, S.; Gallant, A. T.; Dilling, J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Simon, M. C.; Chaudhuri, A.; Mane, E.; Delheij, P.; Pearson, M. R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); Brunner, T. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); Physik Department E12, Technische Universitaet Muenchen, D-85748 Garching (Germany); Chowdhury, U. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Simon, V. V. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Ruprecht-Karls-Universitaet, Heidelberg (Germany); Brodeur, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Andreoiu, C. [Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6 (Canada); Audi, G. [CSNSM-IN2P3-CNRS, Universite Paris 11, 91405 Orsay (France); Lopez-Urrutia, J. R. Crespo; Ullrich, J. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Gwinner, G. [Dept. of Physics and Astronomy, Univ. of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Lapierre, A. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); National Superconducting Cyclotron Lab., Michigan State Univ., East Lansing, Michigan 48824 (United States); Lunney, D. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); CSNSM-IN2P3-CNRS, Univ. Paris 11, 91405 Orsay (France); Ringle, R. [National Superconducting Cyclotron Lab., Michigan State Univ., East Lansing, Michigan 48824 (United States)

2011-12-30

114

Chemical characterization of soot particles emitted by Wood-Burning Cook Stoves: A XPS and HRTEM study  

NASA Astrophysics Data System (ADS)

The morphology, microstructure, chemical composition, and electronic structure of soot particles emitted directly from biofuel cook stoves have been studied by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). In order to obtain freshly emitted soot particles, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot chain. Additionally, the morphology of soot particles was analyzed calculating the border-based fractal dimension (Df). Particles sampled on the first heating stage exhibit complex shapes with high values of Df, which are present as aggregates formed by carbon ceno-spheres. The XPS survey spectrum for soot particles shows that the main particle composition is carbon. We also observed differences in the carbon/oxygen (C/O) ratio of the particles, which probably depends on the combustion process efficiency of each cook-stove analyzed. The XPS C-1s spectra show carbon with two peaks that correspond to sp2 and sp3 hybridization. Also, real-time absorption (?a) and scattering (?s) coefficients of the particles emitted by cook stoves were measured. The trend in ?a and ?s indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

Carabali, Giovanni; Peralta, Oscar; Castro, Telma; Torres, Ricardo; Ruiz, Gerardo; Molina, Luisa; Saavedra, Isabel

2014-05-01

115

On the ecology of short-lived forbs in chalk grasslands: micro-site tolerances in relation to vegetation structure  

Microsoft Academic Search

Some aspects of vegetation structure in two chalk grasslands were studied throughout the year in relation to the occurrence of some short-lived plant species per life-cycle stage. Whereas the main growth period is in May–June, there is another relatively important growth period in less productive stands in August. When the species are arranged in the order of their tolerance for

H. J. Verkaar; A. J. Schenkeveld; J. M. Brand

1983-01-01

116

Hyperfine structure of the 6dD2 level in trapped short-lived 211,?209Ra+ ions  

NASA Astrophysics Data System (ADS)

The hyperfine structure of short-lived trapped 211,209Ra + ions was investigated by means of laser spectroscopy. The hyperfine structure constants A and B of the 6d D2 level were determined. There is a 2.2 standard deviation difference between the theoretical and the more accurate experimental value for the B coefficient of 211Ra +. These measurements provide a test for the atomic theory required for upcoming experiments on atomic parity violation and atomic clocks.

Versolato, O. O.; Giri, G. S.; van den Berg, J. E.; Böll, O.; Dammalapati, U.; van der Hoek, D. J.; Hoekstra, S.; Jungmann, K.; Kruithof, W. L.; Müller, S.; Nuñez Portela, M.; Onderwater, C. J. G.; Santra, B.; Timmermans, R. G. E.; Wansbeek, L. W.; Willmann, L.; Wilschut, H. W.

2011-08-01

117

Seasonal variation in the behaviour of a short-lived rodent  

PubMed Central

Background Short lived, iteroparous animals in seasonal environments experience variable social and environmental conditions over their lifetime. Animals can be divided into those with a “young-of-the-year” life history (YY, reproducing and dying in the summer of birth) and an “overwinter” life history (OW, overwintering in a subadult state before reproducing next spring). We investigated how behavioural patterns across the population were affected by season and sex, and whether variation in behaviour reflects the variation in life history patterns of each season. Applications of pace-of-life (POL) theory would suggest that long-lived OW animals are shyer in order to increase survival, and YY are bolder in order to increase reproduction. Therefore, we expected that in winter and spring samples, when only OW can be sampled, the animals should be shyer than in summer and autumn, when both OW and YY animals can be sampled. We studied common vole (Microtus arvalis) populations, which express typical, intra-annual density fluctuation. We captured a total of 492 voles at different months over 3 years and examined boldness and activity level with two standardised behavioural experiments. Results Behavioural variables of the two tests were correlated with each other. Boldness, measured as short latencies in both tests, was extremely high in spring compared to other seasons. Activity level was highest in spring and summer, and higher in males than in females. Conclusion Being bold in laboratory tests may translate into higher risk-taking in nature by being more mobile while seeking out partners or valuable territories. Possible explanations include asset-protection, with OW animals being rather old with low residual reproductive value in spring. Therefore, OW may take higher risks during this season. Offspring born in spring encounter a lower population density and may have higher reproductive value than offspring of later cohorts. A constant connection between life history and animal personality, as suggested by the POL theory, however, was not found. Nevertheless, correlations of traits suggest the existence of animal personalities. In conclusion, complex patterns of population dynamics, seasonal variation in life histories, and variability of behaviour due to asset-protection may cause complex seasonal behavioural dynamics in a population. PMID:24238069

2013-01-01

118

Short-lived and long-lived dust devil tracks in the coastal desert of southern Peru  

NASA Astrophysics Data System (ADS)

In the coastal desert of southern Peru, sequential high-resolution satellite images document the presence of short-lived and long-lived dust devil tracks. Dust devil tracks in the study region remain visible for less than 6 months in one area and for more than 4 years in another area. Short-lived tracks are generally darker than the surrounding ground surface. The brightness of long-lived tracks is often equal to that of their surroundings; they become visible due to a brighter edge along their margins. Different modes of formation related to ground surface properties are suggested to explain the differences in persistence and appearance. Dark, short-lived dust devil tracks are ascribed to the removal of silt-sized material from largely sand-sized surface materials. Long-lived tracks with bright margins are ascribed to coarser surface materials and the fallout of sand-sized particles along the track edges. Locating suitable areas on Earth for the study of dust devil tracks and distinguishing between different types of dust devil tracks is expected to further promote terrestrial analogue studies for Martian dust devil streaks.

Hesse, Ralf

2012-08-01

119

Short-lived and discontinuous intraplate volcanism in the South Pacific: Hot spots or extensional volcanism?  

NASA Astrophysics Data System (ADS)

South Pacific intraplate volcanoes have been active since the Early Cretaceous. Their HIMU-EMI-EMII mantle sources can be traced back into the West Pacific Seamount Province (WPSP) using plate tectonic reconstructions, implying that these distinctive components are enduring features within the Earth's mantle for, at least, the last 120 Myr. These correlations are eminent on the scale of the WPSP and the South Pacific Thermal and Isotopic Anomaly (SOPITA), but the evolution of single hot spots emerges notably more complicated. Hot spots in the WPSP and SOPITA mantle regions typically display intermittent volcanic activity, longevities shorter than 40 Myr, superposition of hot spot volcanism, and motion relative to other hot spots. In this review, we use 40Ar/39Ar seamount ages and Sr-Nd-Pb isotopic signatures to map out Cretaceous volcanism in the WPSP and to characterize its evolution with respect to the currently active hot spots in the SOPITA region. Our plate tectonic reconstructions indicate cessation of volcanism during the Cretaceous for the Typhoon and Japanese hot spots; whereas the currently active Samoan, Society, Pitcairn and Marquesas hot spots lack long-lived counterparts in the WPSP. These hot spots may have become active during the last 20 Myr only. The other WPSP seamount trails can be only "indirectly" reconciled with hot spots in the SOPITA region. Complex age distributions in the Magellan, Anewetak, Ralik and Ratak seamount trails would necessitate the superposition of multiple volcanic trails generated by the Macdonald, Rurutu and Rarotonga hot spots during the Cretaceous; whereas HIMU-type seamounts in the Southern Wake seamount trail would require 350-500 km of hot spot motion over the last 100 Myr following its origination along the Mangaia-Rurutu "hotline" in the Cook-Austral Islands. These observations, however, violate all assumptions of the classical Wilson-Morgan hot spot hypothesis, indicating that long-lived, deep and fixed mantle plumes cannot explain the intraplate volcanism of the South Pacific region. We argue that the observed short-lived and discontinuous intraplate volcanism has been produced by another type of hot spot-related volcanism, as opposed to the strong and continuous Hawaiian-type hot spots. Our results also indicate that other geological processes (plate tension, hotlines, faulting, wetspots, self-propagating volcanoes) may act in conjunction with hot spot volcanism in the South Pacific. In all these scenarios, intraplate volcanism has to be controlled by "broad-scale" events giving rise to multiple closely-spaced mantle plumelets, each with a distinct isotopic signature, but only briefly active and stable over geological time. It seems most likely that these plumelets originate and dissipate at very shallow mantle depths, where they may shoot off as thin plumes from the top of a "superplume" that is present in the South Pacific mantle. The absence of clear age progressions in most seamount trails and periodic flare-ups of massive intraplate volcanism in the South Pacific (such as the one in the Cretaceous and one starting 30 Myr ago) show that regional extension (caused by changes in the global plate circuit and/or the rise-and-fall of an oscillating superplume) may be driving the waxing and waning of intraplate volcanism in the South Pacific.

Koppers, Anthony A. P.; Staudigel, Hubert; Pringle, Malcolm S.; Wijbrans, Jan R.

2003-10-01

120

Detailed modeling of the atmospheric degradation mechanism of very-short lived brominated species  

NASA Astrophysics Data System (ADS)

Detailed chemical reaction schemes for the atmospheric degradations of the very short-lived species (VSLS) bromoform (CHBr3) and dibromomethane (CH2Br2) have been established. These degradation schemes have been implemented in the meteorological/tracer transport model CATT-BRAMS used in the present case as pseudo one-dimensional model with chemistry of CH4, CO, HOx, NOx, NOy and Ox. They include the main possible reactions of the intermediate brominated peroxy radicals RO2 (with R = CH2Br, CHBr2 and CBr3) for which the most likely reaction pathways with HO2 have been found using ab initio computational calculations. The full degradation schemes have been run for two well-defined realistic scenarios, “clean” atmosphere and “moderately” NOy-polluted atmosphere, as representative of a tropical coastal region where these VSLS natural emissions are expected to be important. The Henry's law constants of the brominated organics products have been estimated by using the Bond Contribution Method (BCM; Meylan and Howard, 1991) or the Molecular Connectivity Index (MCI; Nirmalakhandan and Speece, 1988). Using these constants, the least soluble species formed from the VSLS degradation are found to be CBr2O, CHBrO, CBr3O2NO2, CHBr2O2NO2, BrO, BrONO2 and HOBr, which leads those to be potentially transported into the tropical tropopause layer (TTL) in case of deep convection and contribute to stratospheric bromine additionally to the original substances. For bromoform and dibromomethane degradation, the moderate NOy pollution increases the production of the least soluble species and thus approximately doubles the bromine quantity potentially able to reach the TTL (from 22.5% to 43% for CHBr3 and from 8.8% to 20.2% for CH2Br2). The influence of the reactions of the RO2 radicals with HO2, CH3O2 and NO2 on the nature and abundance of the stable intermediate and end-products has been tested for CHBr3 degradation. As a result, the reactions of the RO2 radicals with NO2 have no impact. Taking into account the reaction between RO2 and CH3O2 and modifying the branching ratios of the reaction between RO2 and HO2 lead to a small impact on the bromoform degradation by slightly decreasing (by 10%) the bromine quantity potentially able to reach the TTL. As a final point, in contrast to CHBr3, CH2Br2 degradation produces negligible quantities of organics species and the effects of pollution increase only the inorganic species production. By taking into account the results of these tests, new simplified degradation schemes for CHBr3 and CH2Br2 are proposed.

Krysztofiak, G.; Catoire, V.; Poulet, G.; Marécal, V.; Pirre, M.; Louis, F.; Canneaux, S.; Josse, B.

2012-11-01

121

In vitro immunotoxic and genotoxic activities of particles emitted from two different small-scale wood combustion appliances  

NASA Astrophysics Data System (ADS)

Residential wood combustion appliances emit large quantities of fine particles which are suspected to cause a substantial health burden worldwide. Wood combustion particles contain several potential health-damaging metals and carbon compounds such as polycyclic aromatic hydrocarbons (PAH), which may determine the toxic properties of the emitted particles. The aim of the present study was to characterize in vitro immunotoxicological and chemical properties of PM 1 ( Dp ? 1 ?m) emitted from a pellet boiler and a conventional masonry heater. Mouse RAW264.7 macrophages were exposed for 24 h to different doses of the emission particles. Cytotoxicity, production of the proinflammatory cytokine TNF-? and the chemokine MIP-2, apoptosis and phases of the cell cycle as well as genotoxic activity were measured after the exposure. The type of wood combustion appliance had a significant effect on emissions and chemical composition of the particles. All the studied PM 1 samples induced cytotoxic, genotoxic and inflammatory responses in a dose-dependent manner. The particles emitted from the conventional masonry heater were 3-fold more potent inducers of programmed cell death and DNA damage than those emitted from the pellet boiler. Furthermore, the particulate samples that induced extensive DNA damage contained also large amounts of PAH compounds. Instead, significant differences between the studied appliances were not detected in measurements of inflammatory mediators, although the chemical composition of the combustion particles differed considerably from each other. In conclusion, the present results show that appliances representing different combustion technology have remarkable effects on physicochemical and associated toxicological and properties of wood combustion particles. The present data indicate that the particles emitted from incomplete combustion are toxicologically more potent than those emitted from more complete combustion processes.

Tapanainen, Maija; Jalava, Pasi I.; Mäki-Paakkanen, Jorma; Hakulinen, Pasi; Happo, Mikko S.; Lamberg, Heikki; Ruusunen, Jarno; Tissari, Jarkko; Nuutinen, Kati; Yli-Pirilä, Pasi; Hillamo, Risto; Salonen, Raimo O.; Jokiniemi, Jorma; Hirvonen, Maija-Riitta

2011-12-01

122

Studies of images of short-lived events using ERTS data. [forest fires, oil spills, vegetation damage, volcanoes, storm ridges, earthquakes, and floods  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Detection of short-lived events has continued. Forest fires, oil spills, vegetation damage, volcanoes, storm ridges, earthquakes, and floods have been detected and analyzed.

Deutschman, W. A. (principal investigator)

1973-01-01

123

Production of Short-lived Radionuclides by Protons and Neutrons in Fe and Ni Targets: Cross Sections Needed for Cosmic Ray Studies  

NASA Technical Reports Server (NTRS)

New neutron and proton cross sections for short-lived radionuclides produced in Fe and Ni are presented. These cross sections are essential to understand cosmic ray interactions with meteorites and the lunar surface.

Sisterson, J. M.; Vincent, J.; Jones, D. T. L.; Binns, P. J.; Langen, K.; Schroeder, I.; Buthelezi, Z.; Brooks, F. D.; Buffler, A.; Allie, M. S.

2000-01-01

124

Vibronic emission from short-lived core-hole states: Theory and applications for the water molecule  

NASA Astrophysics Data System (ADS)

Vibronic cross sections for x-ray and Auger decay from short-lived core-hole states in molecules are derived starting from Åberg's description of atomic x-ray and Auger decay as multichannel-scattering processes [Åberg, Phys. Scr. 21, 495 (1980)]. The derivation includes a scattering-matrix formulation in which intra- and interchannel interactions as well as nonadiabatic corrections are introduced. Computable expressions for x-ray and Auger vibronic spectra are derived assuming the harmonic approximation for multidimensional nuclear motions. Applications for water are carried out using truly ab initio values for all energy and lifetime-related parameters.

Cesar, Amary; Ågren, Hans; Carravetta, Vincenzo

1989-07-01

125

Incidence of leukaemia and other malignant diseases following injections of the short-lived ?-emitter 224 Ra into man  

Microsoft Academic Search

We performed an epidemiological study on 1,471 ankylosing spondylitis patients treated with repeated intravenous injections\\u000a of the short lived ?-emitter 224Ra (excluding radiation therapy with X-rays) between 1948 and 1975. These patients have been followed together with a control\\u000a group of 1,324 ankylosing spondylitis patients treated neither with radioactive drugs nor with X-rays. The mean follow-up\\u000a time was 26.3 years in

Roland R. Wick; M. J. Atkinson; E. A. Nekolla

2009-01-01

126

VLA Observations Confirm Origin of Gamma Ray Bursts in Short-Lived Stars  

NASA Astrophysics Data System (ADS)

Radio telescope studies of the fiery afterglow of a Gamma Ray Burst have provided astronomers with the best clues yet about the origins of these tremendous cosmic cataclysms since their discovery more than 30 years ago. Observations with the National Science Foundation's (NSF) Very Large Array (VLA) radio telescope confirm that a blast seen to occur on March 29 had its origin in a star-forming region in a distant galaxy. "There are two leading theories for the causes of Gamma Ray Bursts," said Dale Frail of the NSF National Radio Astronomy Observatory (NRAO) in Socorro, NM. "According to one theory, the blasts occur in the death throes of pairs of old stars. The other requires them to arise from exploding, massive, short-lived stars that still reside within the star-forming gas and dust from which they formed. The VLA studies of the burst show that at least this one almost certainly occurred within a star-forming region. This result also explains why half of the Gamma Ray Burst afterglows are not detected by optical telescopes." Frail heads a VLA observing team including Greg Taylor, also of NRAO, and Shri Kulkarni of Caltech, that reported its findings to the American Astronomical Society meeting in San Diego, CA. The March 29 burst was seen clearly by radio telescopes (the accompanying image is GRB 980329 as seen by the VLA) but only very faintly with optical instruments. "That is extremely important," said Taylor. "This burst was very faint at visible wavelengths, brighter at infrared wavelengths and brighter still at radio wavelengths. This is a clear indication that the exploding object was surrounded by dust. Dust is most commonly found in star-forming regions." This strongly favors one of the two leading theories about Gamma Ray Bursts over the other. One explanation for these tremendously energetic fireballs is that a pair of superdense neutron stars collides. The other is that a single, very massive star explodes in a "hypernova," more powerful than a supernova, at the end of its normal life. The hypernova explosion, scientists believe, would come only a few million years after the giant star was formed, while it is still within the cloud of gas and dust from which it formed. Neutron stars, on the other hand, are formed by supernova explosions that give a "kick" to the resulting neutron star, propelling it at high speeds. An orbiting pair of neutron stars, astronomers think, would collide only after hundreds of millions of years of orbital decay, by which time they would be far away from the gas and dust of their birthplace. "The observations already have provided crucial insight; we intend to continue observing the relic of the March 29 burst with the VLA, and in the coming months, we will gain new information that will help further refine our ideas about these fireballs," Frail said. "We're going to learn about the size and expansion rate of the fireball and test predictions made by the models." "These observations indicate the extraordinary importance of radio astronomy for providing information that can be gained in no other way about one of the major frontier areas of astrophysics," said Hugh Van Horn, Director of the NSF's Division of Astronomical Sciences. The March 29 burst (GRB 980329) was the second such blast to have its afterglow detected at radio wavelengths. Last year, the VLA made the first radio detection of a GRB afterglow, finding radio emission coming from the location of a Gamma Ray Burst on May 8, 1997 (GRB 970508). "Of the world's radio telescopes, only the VLA has the sensitivity and resolving power to quickly detect these radio afterglows of Gamma Ray Bursts and study them in detail over extended periods of time," Taylor said. "Even so, we only see the brightest one-third of them. With upgraded capabilities at the VLA, as planned by NRAO, we will see them all." The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agr

1998-06-01

127

Overview of the methods for the measurement and interpretation of short-lived radioisotopes and their limits  

NASA Astrophysics Data System (ADS)

The daughter products of the uranium and thorium series consist of several radioactive isotopes with half-lives varying from less than a second to 105 years. Combining their half-live with their geochemical behaviour some of these radioisotopes could be used as tracers and/or chronometers of sedimentary processes. For example, thorium isotopes, and to a lesser extent polonium isotopes are characterized by very low solubility and very high affinity for the surface of particles. Consequently, thorium isotopes can be used to document scavenging and adsorption processes. On the other hand, radium isotopes tend to remain in solution and can be used to document diffusion processes. In the following, we present the analytical methods for the measurement and analysis of the most common short-lived isotopes and throughout their utility in studying sedimentary processes will be illustrated by a few examples of applications. These examples will focus essentially on the applications of short lived thorium isotopes (notably 234Th) and the use of 210Pb as chronometer for recent sedimentary accumulation.

Ghaleb, B.

2009-01-01

128

Size distribution, chemical composition, and hygroscopicity of fine particles emitted from an oil-fired heating plant.  

PubMed

Heavy fuel oil (HFO) is a commonly used fuel in industrial heating and power generation and for large marine vessels. In this study, the fine particle emissions of a 47 MW oil-fired boiler were studied at 30 MW power and with three different fuels. The studied fuels were HFO, water emulsion of HFO, and water emulsion of HFO mixed with light fuel oil (LFO). With all the fuels, the boiler emitted considerable amounts of particles smaller than 200 nm in diameter. Further, these small particles were quite hygroscopic even as fresh and, in the case of HFO+LFO emulsion, the hygroscopic growth of the particles was dependent on particle size. The use of emulsions and the addition of LFO to the fuel had a reducing effect on the hygroscopic growth of particles. The use of emulsions lowered the sulfate content of the smallest particles but did not affect significantly the sulfate content of particles larger than 42 nm and, further, the addition of LFO considerably increased the black carbon content of particulate matter. The results indicate that even the fine particles emitted from HFO based combustion can have a significant effect on cloud formation, visibility, and air quality. PMID:24245691

Happonen, Matti; Mylläri, Fanni; Karjalainen, Panu; Frey, Anna; Saarikoski, Sanna; Carbone, Samara; Hillamo, Risto; Pirjola, Liisa; Häyrinen, Anna; Kytömäki, Jorma; Niemi, Jarkko V; Keskinen, Jorma; Rönkkö, Topi

2013-12-17

129

Time-separated oscillatory fields for high-precision mass measurements on short-lived Al and Ca nuclides  

E-print Network

High-precision Penning trap mass measurements on the stable nuclide 27Al as well as on the short-lived radionuclides 26Al and 38,39Ca have been performed by use of radiofrequency excitation with time-separated oscillatory fields, i.e. Ramsey's method, as recently introduced for the excitation of the ion motion in a Penning trap, was applied. A comparison with the conventional method of a single continuous excitation demonstrates its advantage of up to ten times shorter measurements. The new mass values of 26,27Al clarify conflicting data in this specific mass region. In addition, the resulting mass values of the superallowed beta-emitter 38Ca as well as of the groundstate of the beta-emitter 26Al m confirm previous measurements and corresponding theoretical corrections of the ft-values.

S. George; G. Audi; B. Blank; K. Blaum; M. Breitenfeldt; U. Hager; F. Herfurth; A. Herlert; A. Kellerbauer; H. -J. Kluge; M. Kretzschmar; D. Lunney; R. Savreux; S. Schwarz; L. Schweikhard; C. Yazidjian

2008-01-17

130

Cooling of short-lived, radioactive, highly charged ions with the TITAN cooler Penning trap. Status and perspectives  

NASA Astrophysics Data System (ADS)

TITAN is an on-line facility dedicated to precision experiments with short-lived radioactive isotopes, in particular mass measurements. The achievable resolution on mass measurement, which depends on the excitation time, is limited by the half life of the radioactive ion. One way to bypass this is by increasing the charge state of the ion of interest. TITAN has the unique capability of charge-breeding radioactive ions using an electron-beam ion trap (EBIT) in combination with Penning trap mass spectrometry. However, the breeding process leads to an increase in energy spread, ? E, which in turn negatively influences the mass uncertainty. We report on the development of a cooler Penning trap which aims at reducing the energy spread of the highly charged ions prior to injection into the precision mass measurement trap. Electron and proton cooling will be tested as possible routes. Mass selective cooling techniques are also envisioned.

Simon, V. V.; Delheij, P.; Dilling, J.; Ke, Z.; Shi, W.; Gwinner, G.

2011-07-01

131

Clinical applications of a pressurized xenon wire chamber gamma camera utilizing the short lived agent 178Ta  

NASA Astrophysics Data System (ADS)

A pressurized xenon wire chamber camera has been developed for applications in nuclear medicine. The device employs a high speed delay-line readout and digital processing system providing a peak count rate of 850 000 cps, spatial resolution of 2.5 mm and highly uniform imaging characteristics. A short-lived generator produced radionuclide, 178Ta, having an emission energy of 55-65 keV has also been developed. It provides greatly reduced radiation dosimetry compared with any commercial isotope in current use and is imaged very effectively with the wire chamber camera. Performance of this camera and isotope for first-pass radionuclide assessment of cardiac function compares favorably with the accepted standard of this technique, the multicrystal gamma camera and 99mTc. Currently ongoing studies in exercise cardiac assessment, bedside imaging in myocardial infarction patients and pediatric cardiac imaging, point the way to unique applications of this technology in cardiology.

Lacy, J. L.; Verani, M. S.; Ball, M. E.; Roberts, R.

1988-06-01

132

Prompt gamma activation analysis (PGAA) and short-lived neutron activation analysis (NAA) applied to the characterization of legacy materials  

SciTech Connect

Without quality historical records that provide the composition of legacy materials, the elemental and/or chemical characterization of such materials requires a manual analytical strategy that may expose the analyst to unknown toxicological hazards. In addition, much of the existing legacy inventory also incorporates radioactivity, and, although radiological composition may be determined by various nuclear-analytical methods, most importantly, gamma-spectroscopy, current methods of chemical characterization still require direct sample manipulation, thereby presenting special problems with broad implications for both the analyst and the environment. Alternately, prompt gamma activation analysis (PGAA) provides a'single-shot' in-situ, non-destructive method that provides a complete assay of all major entrained elemental constituents.1-3. Additionally, neutron activation analysis (NAA) using short-lived activation products complements PGAA and is especially useful when NAA activation surpasses the PGAA in elemental sensitivity.

Firestone, Richard B; English, G.A.; Firestone, R.B.; Perry, D.L.; Reijonen, J.P.; Leung, Ka-Ngo; Garabedian, G.F.; Molnar, G.L.; Revay, Zs.

2008-02-13

133

Identifying and quantifying short-lived fission products from thermal fission of HEU using portable HPGe detectors  

SciTech Connect

Due to the emerging potential for trafficking of special nuclear material, research programs are investigating current capabilities of commercially available portable gamma ray detection systems. Presented in this paper are the results of three different portable high-purity germanium (HPGe) detectors used to identify short-lived fission products generated from thermal neutron interrogation of small samples of highly enriched uranium. Samples were irradiated at the Washington State University (WSU) Nuclear Radiation Center’s 1MW TRIGA reactor. The three portable, HPGe detectors used were the ORTEC MicroDetective, the ORTEC Detective, and the Canberra Falcon. Canberra’s GENIE-2000 software was used to analyze the spectral data collected from each detector. Ultimately, these three portable detectors were able to identify a large range of fission products showing potential for material discrimination.

Pierson, Bruce D.; Finn, Erin C.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Kephart, Rosara F.; Metz, Lori A.

2013-03-01

134

Actinium-225 in targeted alpha-particle therapeutic applications.  

PubMed

Alpha particle-emitting isotopes are being investigated in radioimmunotherapeutic applications because of their unparalleled cytotoxicity when targeted to cancer and their relative lack of toxicity towards untargeted normal tissue. Actinium- 225 has been developed into potent targeting drug constructs and is in clinical use against acute myelogenous leukemia. The key properties of the alpha particles generated by 225Ac are the following: i) limited range in tissue of a few cell diameters; ii) high linear energy transfer leading to dense radiation damage along each alpha track; iii) a 10 day halflife; and iv) four net alpha particles emitted per decay. Targeting 225Ac-drug constructs have potential in the treatment of cancer. PMID:22202153

Scheinberg, David A; McDevitt, Michael R

2011-10-01

135

Direct high-resolution alpha spectrometry from nuclear fuel particles in an outdoor air sample.  

PubMed

The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are 242Cm, 239Pu and 240Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra. PMID:17951235

Pöllänen, R; Siiskonen, T

2008-01-01

136

Thyroid cancer in the Marshallese: relative risk of short-lived internal emitters and external radiation exposure  

SciTech Connect

In a study of the comparative effects of internal versus external irradiation of the thyroid in young people, we determined that the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times less thyroid cancer than did the same dose of radiation given externally. We determined this finding for a group of 85 Marshall Islands children, who were less than 10 years of age at the time of exposure and who were accidentially exposed to internal and external thyroid radiation at an average level of 1400 rad. The external risk coefficient ranged between 2.5 and 4.9 cancers per million person-rad-years at risk, and thus, from our computations, the internal risk coefficient for the Marshallese children was estimated to range between 1.0 and 1.4 cancers per million person-rad-years at risk. In contrast, for individual more than 10 years of age at the time of exposure, the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times more thyroid cancer than did the same dose of radiation given externally. The external risk coefficients for the older age groups were reported in the literature to be in the range of 1.0 to 3.3 cancers per million person-rad-years-at risk. We computed internal risk coefficients of 3.3 to 8.1 cancers per million person-rad-years at risk for adolescent and adult groups. This higher sensitivity to cancer induction in the exposed adolescents and adults, is different from that seen in other exposed groups. 14 refs., 8 tabs.

Lessard, E.T.; Brill, A.B.; Adams, W.H.

1985-01-01

137

Effects of fragment size and isolation on the occurrence of four short-lived plants in semi-natural grasslands  

NASA Astrophysics Data System (ADS)

Habitat fragmentation is predicted to lead to an area-related reduction in population size and a decreasing colonisation rate due to isolation. A reduction in grassland size may promote a "run-away-decline process" leading to reduced individual fitness and viability of the populations originally inhabiting the grassland. To circumvent the problems of time-lags associated with the slow response of long-lived plants to semi-natural grassland fragmentation, four short-lived grassland species were studied. During three years, data on population sizes were gathered for Carum carvi, Rhinanthus minor, Trifolium arvense and Viola tricolor in Swedish semi-natural grasslands varying in size and degree of isolation. A seed-sowing experiment was conducted to assess dispersal and seed limitation at a local and regional scale, respectively. Overall, the presence/absence of species was not related to fragment size and isolation (connectivity). However, for the fragments where the species were present, positive relationships between grassland size and population size were detected for three species. No significant relationships between isolation and population size were detected for any species. This study thus demonstrates that short-lived plant species, confined to semi-natural grasslands, respond to decreases in fragment size by forming smaller populations. Seed sowing indicated that the species are both dispersal and seed limited in the study area, and that disturbances are important for establishment. In order to maintain characteristic grassland species in fragmented (isolated) semi-natural grasslands, it may therefore be of interest to preserve large intact fragments instead of several small ones.

Kiviniemi, Katariina

2008-01-01

138

Development and Application of A Membrane-Based Thermodenuder for Measurement of Volatile Particles Emitted by A Jet Turbine Engine  

SciTech Connect

Measurement of volatile particles emitted by modern jet engines is a daunting task. Besides the complexity in sampling jet aircraft exhaust, the main difficulty lies at how to faithfully capture the phase-partition dynamics of volatile particles as they travel downstream from the engine exhaust nozzle. As a result, the physico-chemical properties of the exhaust are also transformed. We have developed a sampling instrument that aims at enabling study of the phase-partition dynamics. The objective of this research project was to design and evaluate a new thermodenuder for performing phase separation of the engine-emitted volatile particles. The backbone of the new thermodenuder is a thin metallic membrane. The membrane enables extraction of molecules that can be thermally desorbed from the condensed particulate phases and collected for subsequent chemical analysis. Toward realization of the technique in the future field aircraft emissions measurement we tested this new thermo-denuding device using laboratory-generated particles that were made of non-volatile or semi-volatile chemicals. The particle penetration efficiency, a measure of the device performance, of this thermodenuder was found to be better than 99%. Results obtained from the tests executed at a number of operating temperature conditions show reasonably good thermal separation. We have scheduled to apply this new device to characterize emissions from a T63 turboshaft engine in the spring of 2010 and are expecting to show the engine results at the conference. The test results based on the laboratory-generated particles were encouraging for the intended application. With excellent particle transmission efficiency and an ability to simultaneously measure the composition in the gas and particle phases of the engine particles, we believe the new technology will make a great contribution to measurement research of engine emissions.

Cheng, Mengdawn [ORNL

2010-01-01

139

Chemical Composition of Aerosol Particles Emitted by a Passenger Car Engine Fueled by Ethanol/Gasoline Mixtures  

NASA Astrophysics Data System (ADS)

With concerns of national security, climate change, and human health, many people have called for oil independence for the United States and for the creation of alternative fuels. Ethanol has been widely praised as a viable alternative to petroleum-based fuels, due to the fact that it can be produced locally. A great deal of work has been done to characterize the energy balance of ethanol production versus consumption, but there have been fewer studies of the environmental and health impacts of emissions from combustion of ethanol/gasoline mixtures such as those burned in the modern vehicle fleet. To study the particulate emissions from such fuels, different ethanol/gasoline fuel mixtures with 0, 20, 40, and 85% ethanol were burned in a dynamometer-mounted automobile engine. The engine exhaust was diluted and sampled with two aerosol Time-of-Flight Mass Spectrometers (TSI 3800 ATOFMS), sampling different particle size ranges (50-500 nm and 150-3000 nm, respectively), to measure size and composition of the emitted aerosol particles. A variety of other aerosol characterization techniques were also employed to determine the size distribution of the aerosol particles, the mass emission rate from the engine, and the concentration of polycyclic aromatic hydrocarbons (PAHs) and elemental carbon (EC) in the particle emissions. Here we will focus on results from the ATOFMS, which provides us with a particle size and mass spectra - for both negative and positive ions - for each particle that is sampled. Particles being emitted were found to contain primarily PAHs, elemental carbon (EC), nitrates, and sulfates. Particles were analyzed to investigate trends in particle composition as a function of fuel ethanol content, particle size, and for the types of particles emitted. A trend in particle type as a function of fuel ethanol content was evident in smaller particles, and trends in composition as a function of particle size were visible across the entire size range sampled.

Medrano, J. M.; Gross, D. S.; Dutcher, D. D.; Drayton, M.; Kittelson, D.; McMurry, P.

2007-12-01

140

Treatment of HER2 Positive Breast Carcinomatous Meningitis with Intrathecal Administration of ?-Particle Emitting 211At-labeled Trastuzumab?  

PubMed Central

Introduction Carcinomatous meningitis (CM) is a devastating disease characterized by the dissemination of malignant tumor cells into the subarachnoid space along the brain and spine. Systemic treatment with monoclonal antibody (mAb) trastuzumab can be effective against HER2-positive systemic breast carcinoma but like other therapies, is ineffective against CM. The goal of this study was to evaluate the therapeutic effect of ?-particle emitting 211At-labeled trastuzumab following intrathecal administration in a rat model of breast carcinoma CM. Methods Athymic rats were injected intrathecally with MCF-7/HER2-18 breast carcinoma cells through a surgically-implanted indwelling intrathecal catheter. In Experiment 1, animals received 33 or 66 µCi 211At-labeled trastuzumab, cold trastuzumab, or saline. In Experiment 2, animals were inoculated with a lower tumor burden and received 46 or 92 µCi 211At-labeled trastuzumab, or saline. In Experiment 3, animals received 28 µCi 211At-labeled trastuzumab, 30 µCi 211At-labeled TPS3.2 control mAb or saline. Histopathological analysis of the neuroaxis was performed at the end of the study. Results In Experiment 1, median survival increased from 21 days for the saline and cold trastuzumab groups to 45 and 48 days for 33 and 66 µCi 211At-labeled trastuzumab, respectively. In Experiment 2, median survival increased from 23 days for saline controls to 68 and 92 days for 46 and 92 µCi 211At-labeled trastuzumab, respectively. In Experiment 3, median survival increased from 20 days to 29 and 36 days for animals treated with 211At-labeled TPS3.2 and 211At-labeled trastuzumab, respectively. Long-term survivors were observed exclusively in the 211At-trastuzumab-treated groups. Conclusion Intrathecal 211At-labeled trastuzumab shows promise as a treatment for patients with HER2-positive breast CM. PMID:19647172

Boskovitz, Abraham; McLendon, Roger E.; Okamura, Tatsunori; Sampson, John H.; Bigner, Darell D.; Zalutsky, Michael R.

2009-01-01

141

ENGINEERED MODULAR RECOMBINANT TRANSPORTERS: APPLICATION OF NEW PLATFORM FOR TARGETED RADIOTHERAPEUTIC AGENTS TO ?-PARTICLE EMITTING 211At  

PubMed Central

Purpose To generate and evaluate a modular recombinant transporter (MRT) for targeting 211At to cancer cells overexpressing the epidermal growth factor receptor (EGFR). Methods and Materials The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[211At]astato-5-guanidinomethylbenzoate (SAGMB), its 125I analogue SGMIB, or with 131I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines. Results The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 10–20 times more cytotoxic than [211At]astatide for all three cell lines. Conclusion The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted ?-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this 211At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor. PMID:18722270

Rosenkranz, Andrey A.; Vaidyanathan, Ganesan; Pozzi, Oscar R.; Lunin, Vladimir G.; Zalutsky, Michael R.; Sobolev, Alexander S.

2010-01-01

142

Effects of East Asian Short-lived Anthropogenic Air Pollutants on the Northern Hemispheric Air Quality and Climate  

NASA Astrophysics Data System (ADS)

Short-lived anthropogenic pollutants (such as ozone and aerosols) not only degrade ambient air quality and influence human health, but also play an important role in scattering/absorbing atmospheric radiation and disturbing regional climate. Due to the rapid industrialization, anthropogenic emissions from East Asia (EA) have increased substantially during the past decades. At the same time, EA has experienced a changing climate in terms of surface temperature and precipitation. In order to understand to what extent that EA short-lived anthropogenic emissions could influence domestic and downwind air quality (e.g. surface O3 and PM2.5), and explore the potential linkage between hemispheric-scale climate perturbation and regional anthropogenic forcing, we simulate global climate and chemical compositions during 1981-2000 based on the coupled general circulation model CM3 for atmosphere (with interactive tropospheric and stratospheric chemistry), oceans, land and sea ice, recently developed at Geophysical Fluid Dynamics Laboratory (GFDL/NOAA). We also conduct a parallel sensitivity simulation which is identical to the base simulation but with all anthropogenic emissions over EA turned off. The difference between the base and sensitivity simulations represents the short-term response of the Northern Hemispheric climate system and atmospheric composition to the perturbation of regional anthropogenic forcing. We find that East Asian short-lived anthropogenic emissions exert significant adverse impacts on local air quality during 1981-2000, accounting for 10-30ppbV daily-averaged O3 over Eastern China in JJA. In particular, EA anthropogenic emissions elevate the summertime daily maximum 8-hour average ozone (MDA8 O3) by 30-40ppbV over the North China Plain, where the typical background MDA8 ozone ranges 30 to 45ppbV. In addition, the surface PM2.5 concentrations peak at the same season and over the same region, with a seasonal mean of 10-30ug/m3, mostly contributed from local anthropogenic sources. In terms of long-range transport, anthropogenic pollutants from EA generally account for 2-5ppbv surface ozone from east to west mid-latitude North Pacific, but with distinct seasonal variability. During spring, EA anthropogenic emissions enhance nearly 2ppbV ozone over the west coast of California, USA, which increases the number of days when MADA8 exceeds 75ppbV by 2~5days/season in JJA. We find that the high aerosol loadings over EA significantly elevate aerosol optical depth (AOD) over Eastern China (0.2-0.4 in DJF and 0.3-0.5 in JJA), which warms up the atmosphere (15~20 Watts/m2) at the expense of cooling the surface (-30~-20 Watts/m2), potentially reducing the local surface temperature by -0.5K ~ -2K. Moreover, our model results also show that EA anthropogenic pollutants significantly depress local precipitation rate (up to 1.5 mm/day) and rain frequency (4-10 days/season), particularly over South and Southwestern China. This may partly explain the change of seasonal precipitation patterns over EA during the past decades.

Liu, J.; Horowitz, L. W.; Lau, N.; Fan, S.; Tao, S.; Mauzerall, D. L.; Levy, H.

2012-12-01

143

Short-lived charge-transfer-to-solvent-states and multiple electronic relaxations following femtosecond excitation of aqueous chloride ion  

NASA Astrophysics Data System (ADS)

Early charge transfer processes triggered by the photoexcitation of an aqueous sodium chloride solution (molar ratio H 2O/NaCl = 55) at 294 K have been investigated by using femtosecond absorption UV-IR spectroscopy. The initial UV energy deposition proceeding by one- (4 eV) and/or two-photon (2 × 4 eV) absorption results in the formation of multiple short-lived electronic states which have been discriminated within the spectral range 360-1250 nm (3.44-0.99 eV). Two well-separated spectral signatures involving UV and infrared transitions have been discriminated and assigned to different excited CTTS states (charge transfer to solvent) as recently suggested by quantum simulations of an aqueous halide I - [Sheu and Rossky, Chem. Phys. Letters 202 (1993) 186; 213 (1993) 233]. A short-lived ultraviolet component appearing within the UV pump pulse and exhibiting a monoexponential relaxation time of 190 ± 20 fs would correspond to a lo excited CTTS state of the chloride ion (CTTS ?). The other ultrashort-lived band peaking above 0.99 eV (1250 nm) and characterized by a high deactivation rate (?2 × 10 13s -1) is tentatively assigned to a high excited CTTS state (CTTS ??) triggered by a two-photon absorption process (8 eV). This transient state precedes the ap pearance of a well-defined infrared component peaking around 1250 nm and due to the (p-like) excited hydrated electron (e prehyd-). The relaxation of this infrared electron occurs with a time constant of 300 fs and leads to the formation of the ground state of the hydrated electron (e hyd-). Near-infrared spectroscopic investigations performed in the energy range 1.51-1.24 eV (820-1000 nm) have permitted to clearly identify the existence of additional absorption bands peaking around 880 nm. It is the first time that near-infrared bands are directly observed in an aqueous solution of halide ions. These spectral contributions are assigned to inhomogeneous populations of electron-atom pairs ({e -:Cl nH 2O A,B}). The involved photochemical channel can compete wit electron hydration channel for which a pre-hydrated state (e prehyd-) has been identified. The existence of these near-infrared states would be due to local solvent effects which assist or impede an electron localization outside the first hydration shells of the atomic core (Cl). The electronic population absorbing in the near infrared exhibits a dual behavior whose characteristic times are 330 fs ({e -:Cl nH 2O A}) and 750 fs (e -: Cl nH 2O B) respectivley. The faster relaxation channel due to contribute to the early geminate recombination between the ground state of the hydrated electron and the chlorine atom. The slower deactivation channel (1.29 × 10 12s -1) would be due to an electronic state ({e -:Cl nH f2 0 B}) whose interconversion with a ground state of a hydrated electron has been identified in the present study. This electron photodetachment pathway leads to a delayed formation of hydrated electrons (e hyd-') and can be seen as a specific solvent cage effect in the vicinity of the counterion (Na +). The direct characterization of short-lived semi-ionized states by near-infrared spectroscopy provides new informations on solvent cage effects during ultrafast electron transfer reactions in ionic solutions. These complex photochemical data obtained with aqueous sodium chloride are discussed at the microscopic level considering recent quantum theories on semi-ionized or metastable states in ionic solutions.

Gauduel, Y.; Gelabert, H.; Ashokkumar, M.

1995-08-01

144

Realizing the potential of the Actinium-225 radionuclide generator in targeted alpha-particle therapy applications  

PubMed Central

Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225Ac to potently and specifically affect cancer. PMID:18514364

Miederer, Matthias; Scheinberg, David A.; McDevitt, Michael R.

2013-01-01

145

Realizing the potential of the Actinium-225 radionuclide generator in targeted alpha particle therapy applications.  

PubMed

Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225 Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209 Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225 Ac to potently and specifically affect cancer. PMID:18514364

Miederer, Matthias; Scheinberg, David A; McDevitt, Michael R

2008-09-01

146

Mechanism and Rate of Long-Range alpha-Particle Emission in Fission  

Microsoft Academic Search

The statistical theory of fission has been used in previous works to calculate the energy and angular distributions of the long-range alpha particle emitted in fission. It is now applied to calculate the probability of long-range alpha-particle-accompanied fission relative to binary fission. For thermal-neutron fission of U235 the calculated rate is 1 alpha-particle-accompanied fission in 461 binary fissions, which agrees

Peter Fong

1971-01-01

147

Ozone Destruction in the Upper Troposphere/Lower Stratosphere from Short-Lived Halogens and Climate Impacts  

NASA Astrophysics Data System (ADS)

Halogens released from very short-lived substances (VSLS) can deplete ozone in the upper-troposphere and lower stratosphere where the perturbation can exert a large climate impact. In addition to the known ozone loss from natural biogenic bromine VSLS, such as bromoform (CHBr3), using a global atmospheric model we show that anthropogenic chlorine VSLS such as dichloromethane (CH2Cl2) - not regulated by the Montreal Protocol - also contribute. Although this impact is small compared to bromine VSLS at present, CH2Cl2 has industrial sources and observations show its atmospheric loading is increasing rapidly. We estimate a significant radiative effect of the bromine and chlorine VSLS-driven lower stratospheric ozone destruction of -0.11 Wm-2. The largest impact comes from ozone loss at high latitudes, where column ozone decreases due to VSLS are up to 6%. The trend in anthropogenic chlorine VSLS could cause a significant radiative forcing, especially if augmented by any trend in natural bromine VSLS. We also used the model to study the impact of iodine-containing VSLS such as methyl iodide (CH3I). Of the three halogens iodine has the largest leverage to destroy lower stratospheric ozone, but current limits based on IO observations indicate only a minor impact at present.

Hossaini, Ryan; Chipperfield, Martyn; Montzka, Stephen; Rap, Alex; Dhomse, Sandip; Feng, Wuhu

2014-05-01

148

Iodine-131: a potential short-lived, wastewater-specific particle tracer in an urbanized estuarine system.  

PubMed

The short-lived, fission-produced radioisotope, 131I (t1/2 = 8.04 days), was detected in wastewater, surficial sediment, and suspended particulate matter (SPM) samples collected from New York Harbor (NYH) between 2001 and 2002. lodine-131 is used as a radiopharmaceutical for medical imaging, diagnostics, and treatments for conditions of the thyroid. It is introduced into the municipal waste stream by medical facilities and patients and is subsequently released into the estuary via wastewater effluent. Measured 131I activities in surface sediments were correlated with those of 7Be (t1/2 = 53.2 days), a naturally occurring radioisotope that is widely used to quantify particle dynamics, sediment focusing, and short-term sediment deposition and accumulation in aquatic systems. Surficial sediment 131I activities were also compared with measured trace metal (Cu, Pb) and organic carbon (OC(sed)) concentrations which can be linked to wastewater inputs. These preliminary results from NYH introduce 131I as a potentially valuable source-specific, shortlived biogeochemical tracer (timescales < 1 month) for particles, sediments, and wastewater-sourced contaminants in urbanized aquatic systems. PMID:18754457

Smith, Joseph P; Oktay, Sarah I; Kada, John; Olsen, Curtis R

2008-08-01

149

Reaction dynamics. Extremely short-lived reaction resonances in Cl + HD (v = 1) ? DCl + H due to chemical bond softening.  

PubMed

The Cl + H2 reaction is an important benchmark system in the study of chemical reaction dynamics that has always appeared to proceed via a direct abstraction mechanism, with no clear signature of reaction resonances. Here we report a high-resolution crossed-molecular beam study on the Cl + HD (v = 1, j = 0) ? DCl + H reaction (where v is the vibrational quantum number and j is the rotational quantum number). Very few forward scattered products were observed. However, two distinctive peaks at collision energies of 2.4 and 4.3 kilocalories per mole for the DCl (v' = 1) product were detected in the backward scattering direction. Detailed quantum dynamics calculations on a highly accurate potential energy surface suggested that these features originate from two very short-lived dynamical resonances trapped in the peculiar H-DCl (v' = 2) vibrational adiabatic potential wells that result from chemical bond softening. We anticipate that dynamical resonances trapped in such wells exist in many reactions involving vibrationally excited molecules. PMID:25554783

Yang, Tiangang; Chen, Jun; Huang, Long; Wang, Tao; Xiao, Chunlei; Sun, Zhigang; Dai, Dongxu; Yang, Xueming; Zhang, Dong H

2015-01-01

150

Short-lived charge-transfer excitons in organic photovoltaic cells studied by high-field magneto-photocurrent  

NASA Astrophysics Data System (ADS)

The main route of charge photogeneration in efficient organic photovoltaic cells based on bulk hetero-junction donor-acceptor blends involves short-lived charge-transfer excitons at the donor-acceptor interfaces. The cell efficiency is critically affected by the charge-transfer exciton recombination and dissociation processes. By measuring the magneto-photocurrent under ambient conditions at room temperature, we show here that magnetic field-induced spin-mixing among the charge-transfer exciton spin sublevels occurs in fields up to at least 8.5?Tesla. The resulting magneto-photocurrent increases at high fields showing non-saturating behaviour up to the highest applied field. We attribute the observed high-field spin-mixing mechanism to the difference in the donor-acceptor g-factors. The non-saturating magneto-photocurrent response at high field indicates that there exist charge-transfer excitons with lifetime in the sub-nanosecond time domain. The non-Lorentzian high-field magneto-photocurrent response indicates a dispersive decay mechanism that originates due to a broad distribution of charge-transfer exciton lifetimes.

Devir-Wolfman, Ayeleth H.; Khachatryan, Bagrat; Gautam, Bhoj R.; Tzabary, Lior; Keren, Amit; Tessler, Nir; Vardeny, Z. Valy; Ehrenfreund, Eitan

2014-07-01

151

Very Short-lived Bromomethanes in the Upper Troposphere/Lower Stratosphere during CARIBIC May 2009 to May 2011  

NASA Astrophysics Data System (ADS)

Reactive halogenated compounds including brominated very short-lived substances (VSLS) play an important role both in the stratosphere, where they impact on stratospheric ozone, and in the troposphere, where they participate in catalytic ozone destruction and aerosol formation. According to the latest WMO figures, brominated VSLS could be responsible for 1-8 ppt contribution to the stratospheric bromine burden. However, observations of brominated VSLS in the upper troposphere/lower stratosphere are relatively sparse. In this study we present measurements made during the CARIBIC project from May 2009 to May 2011 using a negative ion chemical ionisation (NICI) mass spectrometer instrument. NICI is a "soft" ionisation technique that gives enhanced detection limits for electronegative species such as halocarbons. The CARIBIC project deploys a large range of automated instruments in an airfreight container aboard a Lufthansa A340-600 passenger aircraft. The container system also houses two automated bottle samplers which are analysed for various compounds. As part of the project we measure a range of halogenated compounds in the bottle samples. We will present profiles of bromoform (CHBr3), dibromomethane (CH2Br2), dibromochloromethane (CHBr2Cl), bromodichloromethane (CHBrCl2) and bromochloromethane (CH2BrCl) and compare results with previous measurements of brominated VSLS.

Wisher, Adam; Oram, Dave; Laube, Johannes; van Velthoven, Peter; Brenninkmeijer, Carl

2013-04-01

152

Age-specific, density-dependent and environment-based mortality of a short-lived perennial herb.  

PubMed

Density-independent and density-dependent processes affect plant mortality. Although less well understood, age-specific mortality can also play an important role in plant mortality. The goal of this study was to analyse several factors accounting for mortality in the Mediterranean short-lived perennial herb Lobularia maritima. We followed three cohorts of plants (from emergence to death) during 4 years in field conditions. We collected data on plant mortality of the effect of biotic agents (moth larvae and mycoplasma-like organisms, MLOs) and environmental variables. We also estimated density-dependent relationships affecting the fate of seedlings and adults. Results show that cohorts differed in their survival curves and ageing significantly increased mortality risk. Seedling mortality was density-dependent whereas adult mortality was not affected by density. MLO infection led to higher plant mortality whereas moth larvae attack did not affect plant mortality. In general, seedlings and adult plants experienced the highest mortality events in summer. We found, however, weak relationships between weather records and plant mortality. Age and size structures were not correlated. Overall, this study provides a comprehensive review of age-specific, density-dependent and density-independent factors that account for mortality of L. maritima plants throughout their life cycle in field conditions, highlighting the fact that age is an important factor in determining plant population dynamics. PMID:18426484

Picó, F X; Retana, J

2008-05-01

153

Injection of Short-Lived Radionuclides into the Early Solar System from a Faint Supernova with Mixing-Fallback  

E-print Network

Several short-lived radionuclides (SLRs) were present in the early solar system, some of which should have formed just prior to or soon after the solar system formation. Stellar nucleosynthesis has been proposed as the mechanism for production of SLRs in the solar system, but no appropriate stellar source has been found to explain the abundances of all solar system SLRs. In this study, we propose a faint supernova with mixing and fallback as a stellar source of SLRs with mean lives of solar system. In such a supernova, the inner region of the exploding star experiences mixing, a small fraction of mixed materials is ejected, and the rest undergoes fallback onto the core. The modeled SLR abundances agree well with their solar system abundances if mixing-fallback occurs within the C/O-burning layer. In some cases, the initial solar system abundances of the SLRs can be reproduced within a factor of 2. The dilution factor of supernova ejecta to the solar system materials is ~10E-4 and the time interval between the supernova explosion and the formation of oldest solid materials in the solar system is ~1 Myr. If the dilution occurred due to spherically symmetric expansion, a faint supernova should have occurred nearby the solar system forming region in a star cluster.

A. Takigawa; J. Miki; S. Tachibana; G. R. Huss; N. Tominaga; H. Umeda; K. Nomoto

2008-08-11

154

Short-lived Radium Isotopes in the Hawaiian Margin: Evidence for Large Fluid Fluxes Through the Puna Ridge  

NASA Astrophysics Data System (ADS)

Techniques to sample and measure short-lived radium isotopes have significantly advanced understanding of groundwater-seawater exchange in coastal areas. The established sampling protocol utilizes traditional wire-line samplers from surface vessels to recover large (200 L) seawater samples. These samples are subsequently passed through Mn-fiber columns at a slow rate (100 L per hour) to assure high radium stripping efficiency. But, sampling near-bottom waters in areas of complicated bathymetry represents a technical challenge for traditional wire-line water sampling equipment. For MBARI's 2001 Hawaii expedition, we built a simple sampler to extract Ra from seawater surrounding the ROV Tiburon. The system uses a variable-flow electric pump to provide 1-2 L/min flow through one of 12 Mn-fiber-filled Ra-stripping canisters mounted on the ROV Tiburon. Values allow the flow to be directed to specific canisters. A flow meter allows the operator to control the flow and compute the volume sampled. The fibers are counted shipboard shortly after vehicle recovery. The ROV proved to be an ideal platform for Ra-sampling because it is able to slowly pump considerable volumes of seawater through the Ra-stripping columns while maintaining close contact with the bottom. Because the manifold was mounted on the ROV's side arm, its interference with other research objectives was minimal. Most of our sampling in Hawaii was conducted as a piggyback effort. We were able to collect 167 radium samples on 37 ROV dives with an average of 206 liters of seawater passing through the stripping canisters. Moreover, we are confident that the sampled waters come from 1-3 above the bottom. We measured significant activities of short-lived radium isotopes, 223Ra (half-life = 11 days) and 224Ra (half-life = 3.7 days), around the margins of the Hawaiian Islands to depths of 3100 m. These measurements suggest numerous groundwater or pore fluid inputs to the surrounding ocean. In general 223Ra activities were considerably greater than 224Ra in spite of the expected higher production rate of 224Ra from basalt. 223Ra was not supported by dissolved 227Ac. The highest enrichments of 223Ra were measured over the Puna Ridge (2100 m depth) east of Hawaii. Here 223Ra activities reached 2 dpm/100L, similar to activities measured near sites of active submarine groundwater discharge in the South Atlantic Bight. The high 223Ra values were not associated with significant thermal anomalies. To explain the high activities of 223Ra unaccompanied by 224Ra, we postulate that thermally-driven circulation of sea water through the Puna Ridge deposits 231Pa on basalt surfaces. With time the 231Pa produces 227Ac and 223Ra, which desorbs into circulating fluids. These fluids then transport 223Ra into the overlying ocean. Based on the inventory of 223Ra above the Puna Ridge, we estimate the flow of fluids through the ridge to be on the order of 40cm3cm-2day-1. In less than 100 years the incoming seawater could provide enough 231Pa to basalt surfaces to balance the inventory of 223Ra above the ridge if all of the 223Ra was transported to the overlying water. These observations have significant implications for quantifying fluid fluxes from the flanks of the mid ocean ridge. By mapping 223Ra inventories in the ocean above ridge flanks and the activity of 223Ra in the emerging fluids, the fluid flux can be obtained. These measurements could help resolve the debate of the relative importance of high and low temperature venting from the ridge.

Moore, W. S.; Paull, C. K.; Ussler, W.

2001-12-01

155

How sensitive is the recovery of stratospheric ozone to changes in concentrations of very short lived bromocarbons?  

NASA Astrophysics Data System (ADS)

Naturally produced very short-lived substances (VSLS), like bromocarbons, account for almost a quarter of the current stratospheric inorganic bromine, Bry. Following VSLS oxidation, bromine radicals (Br and BrO) can catalytically destroy ozone. The extent to which possible increases in surface emissions or transport of these VSLS bromocarbons to the stratosphere could counteract the effect of halogen reductions under the Montreal Protocol is an important policy question. Here by using a chemistry-climate model, UM-UKCA, we investigate the impact of a hypothetical increase in VSLS on ozone and how that impact depends on the background concentrations of chlorine and bromine. Our model experiments indicate that for a ~5 ppt increase in Bry from VSLS, the local ozone loss in the lowermost stratosphere of the Southern Hemisphere (SH) may reach up to 10% in the annual mean; the ozone loss in the Northern Hemisphere (NH) is smaller (4-6%). There is more ozone loss following an increase in VSLS burden under a high stratospheric chlorine background than under a low chlorine background indicating the importance of the inter-halogen reactions. For example, the rate of decline of the stratospheric ozone concentration as a function of Bry is higher by about 30-40% when stratospheric Cly is ~3 ppb (present day) compared with Cly of ~0.8 ppb (apre-industrial or projected future situation). Although bromine plays an important role in destroying ozone, inorganic chlorine is the dominant halogen compound. Even if bromine levels from natural VSLS were to increase significantly later this century, changes in the concentration of ozone will be dominated by the recovery of anthropogenic chlorine. Our calculation suggests that for a 5 ppt increase in Bry from VSLS, the Antarctic ozone hole recover date could be delayed by approximately 7 years.

Yang, X.; Abraham, N. L.; Archibald, A. T.; Braesicke, P.; Keeble, J.; Telford, P.; Warwick, N. J.; Pyle, J. A.

2014-04-01

156

From mantle to ash cloud: quantifying magma generation, ascent, and degassing rates at Kilauea during short-lived explosive episodes using short-lived U-series radionuclide disequilibria  

NASA Astrophysics Data System (ADS)

We analyzed for 238U-series isotopes lava, scoria and ash samples erupted from Kilauea volcano, Hawai'i between 1982 and 2008, in order to investigate processes and timescales of magma generation in the mantle, magma ascent through the crust, and eruption. Timescales of degassing during steady-state lava flow activity occurring in Kilauea East Rift Zone and short-lived explosive episodes that occurred in both the East Rift Zone (Pu'u 'O'o vent opening in 1983 and episode 54 at N?pau crater in January 1997) and on the summit (Halema'uma'u crater eruptions in March 2008) are compared and contrasted. All samples were found to have small but variable 230Th and 226Ra activity excesses over 238U and 230Th, respectively, with (230Th/238U) ratios ranging from 1.00 to 1.13 and (226Ra/230Th) ratios ranging from 1.03 to 1.17. These two variable isotopic disequilibria may reflect local heterogeneities in the mantle underneath Kilauea, with sources in relatively primitive mantle with (238U)-(230Th)-(226Ra) in secular equilibrium and in recently (< 8000 years) depleted mantle with (230Th) and (226Ra) deficits over parent nuclides. In this model, both types of mantle melt to generate Kilauea magmas and subsequently mix in variable proportions. Samples from the brief explosive episodes span the entire composition range, suggesting that they were fed by heterogeneous magma batches which did not homogenize during ascent from the mantle. (210Pb/226Ra) ratios range from 0.75 to 1.00. The lack of correlation between (210Pb/226Ra) and (226Ra/230Th) or (230Th/238U), and the rapid return to secular equilibrium of 210Pb (< 100 years) suggest a fractionation process distinct from and subsequent to the Ra-Th-U fractionation inherited from mantle melting. We hypothesize that 210Pb deficits originate from 222Rn degassing during magma ascent, and estimate magma ascent from lower crust to surface to take place in a maximum of ~ 7 years for the lava flow samples. Products from the explosive episodes have ratios from ~ 0.75 to near equilibrium, suggesting that they comprise of a mix of young melts and degassed magmas which were stored in the shallow volcanic edifice for a few decades, in agreement with existing petrologic models.

Girard, G.; Reagan, M. K.; Sims, K. W.; Garcia, M. O.; Pietruszka, A. J.; Thornber, C. R.

2012-12-01

157

ESTIMATION OF THE CONTRIBUTION OF SHORT-LIVED RADIOIODINES TO THE THYROID DOSE FOR THE PUBLIC IN CASE OF INHALATION INTAKE FOLLOWING THE FUKUSHIMA ACCIDENT.  

PubMed

The purpose of this paper is to present (1) the method of assessing the contribution of short-lived radioiodines to the thyroid for members of the public in Fukushima and neighbouring prefectures based on available data and (2) the results of a realistic assessment of such a contribution. The estimates of that contribution for the inhalation intake that occurred on the day of the main fallout (15 March 2011) are within 15 % of the dose to the thyroid from (131)I. The contribution to the thyroid dose from intake of (132)Te is higher than that from the intake of (133)I by a factor of ?3. The contribution of short-lived radioiodines to the thyroid dose for the public in the case of inhalation intake occurring as early as March 12 might be as great as 30-40 %. PMID:25394649

Shinkarev, S M; Kotenko, K V; Granovskaya, E O; Yatsenko, V N; Imanaka, T; Hoshi, M

2014-11-13

158

SProtP: A Web Server to Recognize Those Short-Lived Proteins Based on Sequence-Derived Features in Human Cells  

Microsoft Academic Search

Protein turnover metabolism plays important roles in cell cycle progression, signal transduction, and differentiation. Those proteins with short half-lives are involved in various regulatory processes. To better understand the regulation of cell process, it is important to study the key sequence-derived factors affecting short-lived protein degradation. Until now, most of protein half-lives are still unknown due to the difficulties of

Xiaofeng Song; Tao Zhou; Hao Jia; Xuejiang Guo; Xiaobai Zhang; Ping Han; Jiahao Sha

2011-01-01

159

On the Relation between Stratospheric Chlorine/Bromine Loading and Short-Lived Tropospheric Source Gases. Appendix D  

NASA Technical Reports Server (NTRS)

Current methods for estimating the concentrations of inorganic chlorine/bromine species Cl(y)/Br(y) in the stratosphere due to decomposition of tropospheric source gases assume that the Cl(y)/Br(y) concentration in the stratosphere is determined mainly by the balance between production from in situ oxidation of the source gases in the stratosphere and removal by transport of Cl(y)/Br(y) out of the stratosphere. The rationale being that for source gases whose lifetimes are of the order of several months or longer the concentration of Cl(y)/Br(y) in the troposphere is small because they are produced at a relatively slow rate and also removed efficiently by washout processes. As a result of the small concentration, the rate at which Cl(y)/Br(y) is transported to the stratosphere is expected to be small compared to the in situ stratospheric production. Thus the transport of Cl(y)/Br(y) from the troposphere contributes little to the stratospheric concentration. In contrast, the origin of stratospheric Cl(y)/Br(y) from reactive source gases with tropospheric lifetimes comparable to the washout lifetime of Cl(y)/Br(y) (of the order of 10-30 days) in the troposphere is distinctly different. The in situ source in the stratosphere is expected to be significantly smaller because only a small portion of the source gas is expected to survive the troposphere to be transported into this region. At the same time these short-lived source gases produce appreciable amounts of Cl(y)/Br(y) in the troposphere such that transport to the stratosphere offers a larger source for stratospheric Cl(y)/Br(y) than in situ production. Thus, for reactive source species, simple methods of estimating the concentration of stratospheric Cl(y)/Br(y) that ignore the tropospheric contribution will seriously underestimate the loading. Therefore estimation of the stratospheric Cl(y)/Br(y) loading requires not only measurements of tropospheric source gases but also measurements of Cl(y)/Br(y) at the tropopause. This paper illustrates the mechanism by using results from a two-dimensional chemistry-transport model. However, in view of the importance of tropospheric transport on stratospheric loading the detailed values should be further evaluated using a three-dimensional model with appropriate treatment of convective transport.

Ko, Malcolm K. W.; Sze, Nien-Dak; Scott, Courtney J.; Weisenstein, Debra K.

1997-01-01

160

Short-lived tectonic switch mechanism for long-term pulses of volcanic activity after mega-thrust earthquakes  

NASA Astrophysics Data System (ADS)

Eruptive rates in volcanic arcs increase significantly after mega-thrust earthquakes in subduction zones. Over short to intermediate time periods the link between mega-thrust earthquakes and arc response can be attributed to dynamic triggering processes or static stress changes, but a fundamental mechanism that controls long-term pulses of volcanic activity after mega-thrust earthquakes has not been proposed yet. Using geomechanical, geological, and geophysical arguments, we propose that increased eruption rates over longer timescales are due to the relaxation of the compressional regime that accompanies mega-thrust subduction zone earthquakes. More specifically, the reduction of the horizontal stress ?h promotes the occurrence of short-lived strike-slip kinematics rather than reverse faulting in the volcanic arc. The relaxation of the pre-earthquake compressional regime facilitates magma mobilization by providing a short-circuit pathway to shallow depths by significantly increasing the hydraulic properties of the system. The timescale for the onset of strike-slip faulting depends on the degree of shear stress accumulated in the arc during inter-seismic periods, which in turn is connected to the degree of strain-partitioning at convergent margins. We performed Coulomb stress transfer analysis to determine the order of magnitude of the stress perturbations in present-day volcanic arcs in response to five actual mega-thrust earthquakes; the 2005 M8.6, 2007 M8.5, and 2007 M7.9 Sumatra earthquakes; the 2010 M8.8 Maule, Chile earthquake; and the 2011 M9.0 Tohoku, Japan earthquake. We find that all, but one, the shallow earthquakes that occurred in the arcs of Sumatra, Chile and Japan show a marked lateral component. Our hypothesis suggests that the long-term response of volcanic arcs to subduction zone mega-thrust earthquakes will be manifested as predominantly strike-slip seismic events, and that these future earthquakes will be followed closely by seismic swarms, inflation, and other indications of a rising magma source.

Lupi, M.; Miller, S. A.

2013-06-01

161

Short-lived tectonic switch mechanism for long-term pulses of volcanic activity after mega-thrust earthquakes  

NASA Astrophysics Data System (ADS)

Eruptive rates in volcanic arcs increase significantly after subduction mega-thrust earthquakes. Over short to intermediate time periods the link between mega-thrust earthquakes and arc response can be attributed to dynamic triggering processes or static stress changes, but a fundamental mechanism that controls long-term pulses of volcanic activity after mega-thrust earthquakes has not been proposed yet. Using geomechanical, geological, and geophysical arguments, we propose that increased eruption rates over longer timescales are due to the relaxation of the compressional regime that accompanies mega-thrust subduction zone earthquakes. More specifically, the reduction of the horizontal stress ?h promotes the occurrence of short-lived strike-slip kinematics rather than reverse faulting in the volcanic arc. The relaxation of the pre-earthquake compressional regime facilitates magma mobilisation by providing a short-circuit pathway to shallow depths by significantly increasing the hydraulic properties of the system. The timescale for the onset of strike-slip faulting depends on the degree of shear stress accumulated in the arc during inter-seismic periods, which in turn is connected to the degree of strain-partitioning at convergent margins. We performed Coulomb stress transfer analysis to determine the order of magnitude of the stress perturbations in present-day volcanic arcs in response to five recent mega-thrust earthquakes; the 2005 M8.6, 2007 M8.5, and 2007 M7.9 Sumatra earthquakes; the 2010 M8.8 Maule, Chile earthquake; and the 2011 M9.0 Tohoku, Japan earthquake. We find that all but one the shallow earthquakes that occurred in the arcs of Sumatra, Chile and Japan show a marked lateral component. We suggests that the long-term response of volcanic arcs to subduction zone mega-thrust earthquakes will be manifested as predominantly strike-slip seismic events, and that these future earthquakes may be followed closely by indications of rising magma to shallower depths, e.g. surface inflation and seismic swarms.

Lupi, M.; Miller, S. A.

2014-01-01

162

Asymptotic Giant Branch stars as a source of short-lived radioactive nuclei in the solar nebula  

NASA Astrophysics Data System (ADS)

We carried out a theoretical evaluation of the contribution of Asymptotic Giant Branch (AGB) stars to some short-lived (106 less than or equal to Tau-bar less than or equal to 2 x 107 yr) isotopes in the Interstellar Medium (ISM) and in the early solar system using stellar model calculations for thermally pulsing evolutionary phases of low-mass stars. The yields of s-process nuclei in the convective He-shell for different neutron exposures tau0 were obtained, and AGB stars were shown to produce several radioactive nuclei (especially Pd-107, Pb-205, Fe-60, Zr-93, Tc-99, Cs-135, and Hf-182) in diferent amounts. Assuming either contamination of the solar nebula from a single AGB star or models for continuous injection and mixing from many stars into the ISM, we calculate the ratios of radioactive to stable nuclei at the epoch of the Sun's formation. The dilution factor between the AGB ejecta and the early solar system matter is obtained by matching the observed Pd-107/Pd-108 and depends on the value of tau0. It is found that small masses MHe of He-shell material (10-4-10-7 solar mass) enriched in s-process nuclei are sufficient to contaminate 1 solar mass of the ISM to produce the Pd-107 found in the early solar system. Predictions are made for all of the other radioactive isotopes. The optimal model to explain several observed radioactive species at different states of the proto-solar nebula involves a single AGB star with a low neutron exposure (tau0 = 0.03 mbarn-1) which contaminated the cloud with a dilution factor of MHe/solar mass approximately 1.5 x 10-4. This will also contribute newly synthesized stable s-process nuclei in the amount of approximately 10-4 of their abundances already present in the proto-solar cloud. Variations in the degree of homogenization (approximately 30%) of the injected material may account for some of the small general isotopic anomalies found in meteorites. It is also found that Fe-60 is produced in small but significant quantities that may be sufficient to explain the observations if the time elapsed delta from the contamination of the ISM to the formation of protoplanetary bodies is not higher than delta = 5 x 106 yr. If delta is longer, up to 10 x 106 yr, this would require the single AGB star to experience enhanced neutron densities (nn approximately 3 x 109n/cu cm) in the s-processing zone in order to compensate for the branching at Fe-59. The alternative model of long-term continuous ejection of matter from many AGB stars does not appear to match the observations. We also estimate the Al-26 production from the H-shell and find that the Al-26 abundance in the early solar system may be readily explained in a self-consistent manner. Moreover, Al-26 from AGB stars may contribute substantially to the galactic Al-26 gamma-source, while no significant gamma-flux from Co-60 (deriving from Fe-60 decay) is to be expected.

Wasserburg, G. J.; Busso, M.; Gallino, R.; Raiteri, C. M.

1994-03-01

163

A High-Throughput Screen for Alpha Particle Radiation Protectants  

PubMed Central

Abstract Alpha-particle-emitting elements are of increasing importance as environmental and occupational carcinogens, toxic components of radiation dispersal devices and accidents, and potent therapeutics in oncology. Alpha particle radiation differs from radiations of lower linear energy transfer in that it predominantly damages DNA via direct action. Because of this, radical scavengers effective for other radiations have had only limited effect in mitigating alpha particle toxicity. We describe here a simple assay and a pilot screen of 3,119 compounds in a high-throughput screen (HTS), using the alpha-particle-emitting isotope, 225Ac, for the discovery of compounds that might protect mammalian cells from alpha particles through novel mechanisms. The assay, which monitored the viability of a myeloid leukemic cell line upon alpha particle exposure, was robust and reproducible, yielding a Z' factor of 0.66 and a signal-to-noise ratio of nearly 10 to 1. Surprisingly, 1 compound emerged from this screen, epoxy-4,5-?-dihydroxysantonin (EDHS), that showed considerable protective activity. While the value of EDHS remains to be determined, its discovery is a proof of concept and validation of the utility of this HTS methodology. Further application of the described assay could yield compounds useful in minimizing the toxicity and carcinogenesis associated with alpha particle exposure. PMID:20658946

Seideman, Jonathan H.; Shum, David; Djaballah, Hakim

2010-01-01

164

Alpha particle emitters in medicine  

SciTech Connect

Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 ({sup 211}At) and natural bismuth-212 ({sup 212}Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ({sup 223}Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs.

Fisher, D.R.

1989-09-01

165

Changes in oxidative stress parameters in relation to age, growth and reproduction in the short-lived catarina scallop Argopecten ventricosus reared in its natural environment.  

PubMed

Increase in oxidative damage and decrease in cellular maintenance is often associated with aging, but, in marine ectotherms, both processes are also strongly influenced by somatic growth, maturation and reproduction. In this study, we used a single cohort of the short-lived catarina scallop Argopecten ventricosus, to investigate the effects of somatic growth, reproduction and aging on oxidative damage parameters (protein carbonyls, TBARS and lipofuscin) and cellular maintenance mechanisms (antioxidant activity and apoptosis) in scallops, caged in their natural environment. The concentrations of protein carbonyls and TBARS increased steeply during the early period of fast growth and during reproduction in one-year-old scallops. However, oxidative damage was transient, and apoptotic cell death played a pivotal role in eliminating damage in gill, mantle and muscle tissues of young scallops. Animals were able to reproduce again in the second year, but the reduced intensity of apoptosis impaired subsequent removal of damaged cells. In late survivors low antioxidant capacity and apoptotic activity together with a fast accumulation of the age pigment lipofuscin was observed. Rates of oxygen consumption and oxidative stress markers were strongly dependent on somatic growth and reproductive state but not on temperature. Compared to longer-lived bivalves, A. ventricosus seems more susceptible to oxidative stress with higher tissue-specific protein carbonyl levels and fast accumulation of lipofuscin in animals surviving the second spawning. Superoxide dismutase activity and apoptotic cell death intensity were however higher in this short-lived scallop than in longer-lived bivalves. The life strategy of this short-lived and intensely predated scallop supports rapid somatic growth and fitness as well as early maturation at young age at the cost of fast cellular degradation in second year scallops. PMID:22561662

Guerra, C; Zenteno-Savín, T; Maeda-Martínez, A N; Philipp, E E R; Abele, D

2012-08-01

166

182Hf–182W age dating of a 26Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System  

PubMed Central

Refractory inclusions [calcium–aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., 26Al, 41Ca, and 182Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of 26Al corresponding to 26Al/27Al of ?5 × 10?5, rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and 26Al/27Al of <5 × 10?6, possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the 182Hf–182W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with 26Al/27Al of ?3 × 10?6. The decoupling between 182Hf and 26Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for 182Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for 26Al. Admixing of stellar-derived 26Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the 26Al–26Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support 182Hf homogeneity and chronological significance of the 182Hf–182W clock. PMID:23671077

Holst, Jesper C.; Olsen, Mia B.; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K.; Connelly, James N.; Jørgensen, Jes K.; Krot, Alexander N.; Nordlund, Åke; Bizzarro, Martin

2013-01-01

167

182Hf-182W age dating of a 26Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.  

PubMed

Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (26)Al, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (26)Al corresponding to (26)Al/(27)Al of ?5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (26)Al/(27)Al of <5 × 10(-6), possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (26)Al/(27)Al of ?3 × 10(-6). The decoupling between (182)Hf and (26)Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (26)Al. Admixing of stellar-derived (26)Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (26)Al-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock. PMID:23671077

Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin

2013-05-28

168

Sister chromatid exchange induced by short-lived monoadducts produced by the bifunctional agents mitomycin C and 8-methoxypsoralen. [CHO cells  

SciTech Connect

To see if DNA crosslinks are involved in the induction of sister chromated exchange (SCE), Chinese hamster ovary cells were exposed to two bifunctional alkylating agents,mitomycin C and 8-methoxypsoralen, and their monofunctional derivatives, decarbamoyl mitomycin C and angelicin. The data indicates that monoadducts, rather than crosslinks, are responsible for SCE formation. Furthermore, all agents but angelicin produced short-lived lesions that led to SCEs in the first period of DNA replication after treatment (twin SCEs). In contrast, angelicin, like methyl methanesulfonate and N-acetoxyacetylaminofluorene, produced lesions that lasted more than one cycle, indicating that several different types of DNA lesions are capable of SCE induction.

Linnainmaa, K.; Wolff, S.

1982-01-01

169

Measurement of the Internal Magnetic Field of Plasmas using an Alpha Particle Source  

SciTech Connect

The internal magnetic fields of plasmas can be measured under certain conditions from the integrated v x B deflection of MeV alpha particles emitted by a small radioactive source. This alpha source and large-area alpha particle detector would be located inside the vacuum vessel but outside the plasma. Alphas with a typical energy of 5.5 MeV (241Am) can reach the center of almost all laboratory plasmas and magnetic fusion devices, so this method can potentially determine the q(r) profile of tokamaks or STs. Orbit calculations, background evaluations, and conceptual designs for such a vxB (or ''AVB'') detector are described.

S.J. Zweben; D.S. Darrow; P.W. Ross; J.L. Lowrance; G. Renda

2004-05-13

170

Alpha-band Suppression in the Visual Word Form Area as a Functional Bottleneck to Consciousness  

E-print Network

1 Alpha-band Suppression in the Visual Word Form Area as a Functional Bottleneck to Consciousness. Abstract The current state of empirical investigations refers to consciousness as an all-or-none phenomenon and full) of conscious perception. In the well-studied case of single-word reading, short-lived exposure

Boyer, Edmond

171

Development of a system for real-time measurements of metabolite transport in plants using short-lived positron-emitting radiotracers  

NASA Astrophysics Data System (ADS)

Over the past 200 years, the Earth's atmospheric carbon dioxide (CO 2) concentration has increased by more than 35%, and climate experts predict that CO2 levels may double by the end of this century. Understanding the mechanisms of resource management in plants is fundamental for predicting how plants will respond to the increase in atmospheric CO 2. Plant productivity sustains life on Earth and is a principal component of the planet's system that regulates atmospheric CO2 concentration. As such, one of the central goals of plant science is to understand the regulatory mechanisms of plant growth in a changing environment. Short-lived positron-emitting radiotracer techniques provide time-dependent data that are critical for developing models of metabolite transport and resource distribution in plants and their microenvironments. To better understand the effects of environmental changes on resource transport and allocation in plants, we have developed a system for real-time measurements of rnetabolite transport in plants using short-lived positron-emitting radio-tracers. This thesis project includes the design, construction, and demonstration of the capabilities of this system for performing real-time measurements of metabolite transport in plants. The short-lived radiotracer system described in this dissertation takes advantage of the combined capabilities and close proximity of two research facilities at. Duke University: the Triangle Universities Nuclear Laboratory (TUNL) and the Duke University Phytotron, which are separated by approximately 100 meters. The short-lived positron-emitting radioisotopes are generated using the 10-MV tandem Van de Graaff accelerator located in the main TUNL building, which provides the capability of producing short-lived positron-emitting isotopes such as carbon-11 (11C: 20 minute half-life), nitrogen-13 (13N; 10 minute half-life), fluorine-18 (18F; 110 minute half-life), and oxygen-15 (15O; 2 minute half-life). The radioisotopes may be introduced to plants as biologically active molecules such as 11CO2, N13O-3, 18F--[H2O], and H152O . Plants for these studies are grown in controlled-environment chambers at the Phytotron. The chambers offer an array of control for temperature, humidity, atmospheric CO2 concentration, and light intensity. Additionally, the Phytotron houses one large reach-in growth chamber that is dedicated to this project for radioisotope labeling measurements. There are several important properties of short-lived positron-emitting radio-tracers that make them well suited for use in investigating metabolite transport in plants. First, because the molecular mass of a radioisotope-tagged compound is only minutely different from the corresponding stable compound, radiotracer substances should be metabolized and transported in plants the same as their non-radioactive counterparts. Second, because the relatively high energy gamma rays emitted from electron-positron annihilation are attenuated very little by plant tissue, the real-time distribution of a radiotracer can be measured in vivo in plants. Finally, the short radioactive half-lives of these isotopes allow for repeat measurements on the same plant in a short period of time. For example, in studies of short-term environmental changes on plant metabolite dynamics, a single plant can be labeled multiple times to measure its responses to different, environmental conditions. Also, different short-lived radiotracers can be applied to the same plant over a short period of time to investigate the transport and allocation of various metabolites. This newly developed system provides the capabilities for production of 11CO2 at TUNL, transfer of the 11CO 2 gas from the target area at TUNL to a radiation-shielded cryogenic trap at the Phytotron, labeling of photoassimilates with 11C, and in vivo gamma-ray detection for real-time measurements of the radiotracer distribution in small plants. The experimental techniques and instrumentation that enabled the quantitative biological studies reported in this thesis were developed through a

Kiser, Matthew R.

172

Time-dependent isospin composition of particles emitted in fission events following Ar40+Au197 at 35 MeV/u  

NASA Astrophysics Data System (ADS)

Fission fragments resulting from the fission of target-like nuclei produced in the Ar40+Au197 reaction at 35 MeV/u are measured in coincidence with the emitted light charged particles (LCPs). Comparison of the N /Z composition of the LCPs at middle and large angles in the laboratory frame shows that particles emitted at smaller angles, which contain a larger contribution from dynamical emission, are more neutron rich. A moving-source model is used to fit the energy spectra of the hydrogen isotopes. A hierarchy from proton to deuteron and triton is observed in the multiplicity ratio between the intermediate velocity source and the compound nucleus source. This ratio is sensitive to the dynamical emission at early stages of the reaction and to statistical emission lasting up to the scission point. Calculations with the improved quantum molecular dynamics (ImQMD) transport-model qualitatively support the picture that more free and bound neutrons are emitted during the early stage, showing a clear dependence of N /Z on the parametrization of the symmetry energy. The time-dependent isospin composition of the emitted particles thus may be used to probe the symmetry energy at subsaturation densities.

Wang, R. S.; Zhang, Y.; Xiao, Z. G.; Tian, J. L.; Zhang, Y. X.; Wu, Q. H.; Duan, L. M.; Jin, G. M.; Hu, R. J.; Wang, S. F.; Li, Z. Y.; Wang, H. W.; Zhang, Z.; Yi, H.; Li, H. J.; Cheng, W. J.; Huang, Y.; Lü, L. M.

2014-06-01

173

First Results Using a New Technology for Measuring Masses of Very Short-Lived Nuclides with Very High Accuracy: the MISTRAL Program at ISOLDE  

SciTech Connect

MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na{clubsuit}, Mg, Al{clubsuit}, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

C. Monsanglant; C. Toader; G. Audi; G. Bollen; C. Borcea; G. Conreur; R. Cousin; H. Doubre; M. Duma; M. Jacotin; S. Henry; J.-F. Kepinski; H.-J. Kluge; G. Lebee; G. Le Scornet; D. Lunney; M. de Saint Simon; C. Scheidenberger; C. Thibault

1999-12-31

174

Charge and frequency resolved isochronous mass spectrometry in storage rings: First direct mass measurement of the short-lived neutron-deficient $^{51}$Co nuclide  

E-print Network

Revolution frequency measurements of individual ions in storage rings require sophisticated timing detectors. One of common approaches for such detectors is the detection of secondary electrons released from a thin foil due to penetration of the stored ions. A new method based on the analysis of intensities of secondary electrons was developed which enables determination of the charge of each ion simultaneously with the measurement of its revolution frequency. Although the mass-over-charge ratios of $^{51}$Co$^{27+}$ and $^{34}$Ar$^{18+}$ ions are almost identical, and therefore, the ions can not be resolved in a storage ring, by applying the new method the mass excess of the short-lived $^{51}$Co is determined for the first time to be ME($^{51}$Co)=-27342(48) keV. Shell-model calculations in the $fp$-shell nuclei compared to the new data indicate the need to include isospin-nonconserving forces.

P. Shuai; H. S. Xu; X. L. Tu; Y. H. Zhang; B. H. Sun; Yu. A. Litvinov; X. L. Yan; K. Blaum; M. Wang; X. H. Zhou; J. J. He; Y. Sun; K. Kaneko; Y. J. Yuan; J. W. Xia; J. C. Yang; G. Audi; X. C. Chen; G. B. Jia; Z. G. Hu; X. W. Ma; R. S. Mao; B. Mei; Z. Y. Sun; S. T. Wang; G. Q. Xiao; X. Xu; T. Yamaguchi; Y. Yamaguchi; Y. D. Zang; H. W. Zhao; T. C. Zhao; W. Zhang; W. L. Zhan

2014-04-08

175

Short-Lived Infected Cells Support Virus Replication in Sooty Mangabeys Naturally Infected with Simian Immunodeficiency Virus: Implications for AIDS Pathogenesis?  

PubMed Central

Sooty mangabeys (SMs) naturally infected with simian immunodeficiency virus (SIV) do not develop AIDS despite high levels of virus replication. At present, the mechanisms underlying this disease resistance are poorly understood. Here we tested the hypothesis that SIV-infected SMs avoid immunodeficiency as a result of virus replication occurring in infected cells that live significantly longer than human immunodeficiency virus (HIV)-infected human cells. To this end, we treated six SIV-infected SMs with potent antiretroviral therapy (ART) and longitudinally measured the decline in plasma viremia. We applied the same mathematical models used in HIV-infected individuals and observed that SMs naturally infected with SIV also present a two-phase decay of viremia following ART, with the bulk (92 to 99%) of virus replication sustained by short-lived cells (average life span, 1.06 days), and only 1 to 8% occurring in longer-lived cells. In addition, we observed that ART had a limited impact on CD4+ T cells and the prevailing level of T-cell activation and proliferation in SIV-infected SMs. Collectively, these results suggest that in SIV-infected SMs, similar to HIV type 1-infected humans, short-lived activated CD4+ T cells, rather than macrophages, are the main source of virus production. These findings indicate that a short in vivo life span of infected cells is a common feature of both pathogenic and nonpathogenic primate lentivirus infections and support a model for AIDS pathogenesis whereby the direct killing of infected cells by HIV is not the main determinant of disease progression. PMID:18216113

Gordon, Shari N.; Dunham, Richard M.; Engram, Jessica C.; Estes, Jacob; Wang, Zichun; Klatt, Nichole R.; Paiardini, Mirko; Pandrea, Ivona V.; Apetrei, Cristian; Sodora, Donald L.; Lee, Ha Youn; Haase, Ashley T.; Miller, Michael D.; Kaur, Amitinder; Staprans, Silvija I.; Perelson, Alan S.; Feinberg, Mark B.; Silvestri, Guido

2008-01-01

176

Emission of Long-Range Alpha Particles in the Fission of U238 with 17.5MeV Protons  

Microsoft Academic Search

The angular distribution of long-range alpha particles from ternary fission induced by 17.5-MeV protons incident on U238 has been measured with respect to both the fission-fragment axis and the beam direction. For alpha particles emitted perpendicularly to the fragment direction, the distributions are found to be independent of the azimuthal angle about the fission-fragment separation axis and independent of the

R. A. Atneosen; T. D. Thomas; G. T. Garvey

1965-01-01

177

Modifications in Dynamic Contrast-Enhanced Magnetic Resonance Imaging Parameters After ?-Particle-Emitting {sup 227}Th-trastuzumab Therapy of HER2-Expressing Ovarian Cancer Xenografts  

SciTech Connect

Purpose: The purpose of this study was to investigate the effect of ?-particle-emitting {sup 227}Th-trastuzumab radioimmunotherapy on tumor vasculature to increase the knowledge about the mechanisms of action of {sup 227}Th-trastuzumab. Methods and Materials: Human HER2-expressing SKOV-3 ovarian cancer xenografts were grown bilaterally in athymic nude mice. Mice with tumor volumes 253 ± 36 mm{sup 3} (mean ± SEM) were treated with a single injection of either {sup 227}Th-trastuzumab at a dose of 1000 kBq/kg body weight (treated group, n=14 tumors) or 0.9% NaCl (control group, n=10 tumors). Dynamic T1-weighted contrast-enhanced magnetic resonance imaging (DCEMRI) was used to study the effect of {sup 227}Th-trastuzumab on tumor vasculature. DCEMRI was performed before treatment and 1, 2, and 3 weeks after therapy. Tumor contrast-enhancement curves were extracted voxel by voxel and fitted to the Brix pharmacokinetic model. Pharmacokinetic parameters for the tumors that underwent radioimmunotherapy were compared with the corresponding parameters of control tumors. Results: Significant increases of k{sub ep}, the rate constant of diffusion from the extravascular extracellular space to the plasma (P<.05), and k{sub el,} the rate of clearance of contrast agent from the plasma (P<.01), were seen in the radioimmunotherapy group 2 and 3 weeks after injection, compared with the control group. The product of k{sub ep} and the amplitude parameter A, associated with increased vessel permeability and perfusion, was also significantly increased in the radioimmunotherapy group 2 and 3 weeks after injection (P<.01). Conclusions: Pharmacokinetic modeling of MRI contrast-enhancement curves evidenced significant alterations in parameters associated with increased tumor vessel permeability and tumor perfusion after {sup 227}Th-trastuzumab treatment of HER2-expressing ovarian cancer xenografts.

Heyerdahl, Helen, E-mail: Helen.Heyerdahl@rr-research.no [Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital - The Norwegian Radium Hospital, Oslo (Norway); Røe, Kathrine [Department of Oncology, Division of Medicine, Akershus University Hospital, Lørenskog (Norway); Brevik, Ellen Mengshoel [Department of Research and Development, Algeta ASA, Oslo (Norway); Dahle, Jostein [Nordic Nanovector AS, Oslo (Norway)

2013-09-01

178

How Many Airborne Particles Emitted from a Nurse will Reach the Breathing Zone\\/Body Surface of the Patient in ISO Class5 Single-Bed Hospital Protective Environments?—A Numerical Analysis  

Microsoft Academic Search

We conducted a numerical simulation to quantify the number of particles emitted from a nurse that will enter the breathing zone or reach the body surface of a patient during patient care in an ISO Class-5 single-bed protective environment. Nurses may be the most likely source of infection for patients in this environment as they are typically single-bed rooms and

Bin Zhao; Caiqing Yang; Chun Chen; Chao Feng; Xudong Yang; Luchun Sun; Wei Gong; Li Yu

2009-01-01

179

Short Lived Climate Pollutants cause a Long Lived Effect on Sea-level Rise: Analyzing climate metrics for sea-level rise  

NASA Astrophysics Data System (ADS)

Climate change depends on the increase of several different atmospheric pollutants. While long term global warming will be determined mainly by carbon dioxide, warming in the next few decades will depend to a large extent on short lived climate pollutants (SLCP). Reducing emissions of SLCPs could contribute to lower the global mean surface temperature by 0.5 °C already by 2050 (Shindell et al. 2012). Furthermore, the warming effect of one of the most potent SLCPs, black carbon (BC), may have been underestimated in the past. Bond et al. (2013) presents a new best estimate of the total BC radiative forcing (RF) of 1.1 W/m2 (90 % uncertainty bounds of 0.17 to 2.1 W/m2) since the beginning of the industrial era. BC is however never emitted alone and cooling aerosols from the same sources offset a majority of this RF. In the wake of calls for mitigation of SLCPs it is important to study other aspects of the climate effect of SLCPs. One key impact of climate change is sea-level rise (SLR). In a recent study, the effect of SLCP mitigation scenarios on SLR is examined. Hu et al (2013) find a substantial effect on SLR from mitigating SLCPs sharply, reducing SLR by 22-42% by 2100. We choose a different approach focusing on emission pulses and analyse a metric based on sea level rise so as to further enlighten the SLR consequences of SLCPs. We want in particular to understand the time dynamics of SLR impacts caused by SLCPs compared to other greenhouse gases. The most commonly used physical based metrics are GWP and GTP. We propose and evaluate an additional metric: The global sea-level rise potential (GSP). The GSP is defined as the sea level rise after a time horizon caused by an emissions pulse of a forcer to the sea level rise after a time horizon caused by an emissions pulse of a CO2. GSP is evaluated and compared to GWP and GTP using a set of climate forcers chosen to cover the whole scale of atmospheric perturbation life times (BC, CH4, N2O, CO2 and SF6). The study utilizes an upwelling diffusion energy balance model and focuses on the thermosteric part of sea-level rise. Example GSP results are 244, 15 and 278 for BC, CH4 and N2O for a time horizon of 100 years. Compare GWP and GTP values of 405, 24 and 288 as well as 62, 4.5 and 252. The main result of the study is that no climate forcer is in any absolute sense short lived when it comes to Sea Level impacts. All of the examined climate forcers have considerable influence on the thermosteric SLR, and the closely linked ocean heat content, on the time scale of centuries. The reason for this is that heat, once it has been induced by the climate drivers and warmed the surface ocean, is transported down into the slowly mixing oceans. References: Shindell, D. et al. Simultaneously mitigating near-term climate change and improving human health and food security. Science 335, 183-189 (2012). Bond, T. C. et al. Bounding the role of black carbon in the climate system: A scientific assessment. Journal of Geophysical Research: Atmospheres 118 5380-5552 (2013). Hu, A., Xu, Y., Tebaldi, C., Washington, W. M. & Ramanathan, V. Mitigation of short-lived climate pollutants slows sea-level rise. Nature Climate Change 3, 730-734 (2013).

Sterner, E.; Johansson, D. J.

2013-12-01

180

Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and South-East Asia during 2009-2013  

NASA Astrophysics Data System (ADS)

Short-lived organic brominated compounds make up a significant part (~20%) of the organic bromine budget in the atmosphere. Emissions of these compounds are highly variable and there are limited measurements, particularly in the extra-tropical upper troposphere/lower stratosphere and tropical troposphere. Measurements of five short-lived bromomethanes (VSLB) were made in air samples collected on the CARIBIC project aircraft over three flight routes; Germany to Venezuela/Columbia during 2009-2011, Germany to South Africa during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during 2012 and 2013. In the tropical troposphere, as the most important entrance region to the stratosphere, we observe a total mean organic bromine derived from these compounds across all flights at 10-12 km altitude of 3.4 ± 1.5 ppt. Individual mean tropical tropospheric mixing ratios across all flights were 0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The highest levels of VSLS-derived bromine (4.20 ± 0.56 ppt) were observed in flights between Bangkok and Kuala Lumpur indicating that the South China Sea is an important source region for these compounds. Across all routes, CHBr3 and CH2Br2 accounted for 34% (4.7-71) and 48% (14-73) respectively of total bromine derived from the analysed VSLB in the tropical mid-upper troposphere totalling 82% (54-89). In samples collected between Germany and Venezuela/Columbia, we find decreasing mean mixing ratios with increasing potential temperature in the extra-tropics. Tropical mean mixing ratios are higher than extra-tropical values between 340-350 K indicating that rapid uplift is important in determining mixing ratios in the lower tropical tropopause layer in the West Atlantic tropics. O3 was used as a tracer for stratospherically influenced air and we detect rapidly decreasing mixing ratios for all VSLB above ~100 ppb O3 corresponding to the extra-tropical tropopause layer.

Wisher, A.; Oram, D. E.; Laube, J. C.; Mills, G. P.; van Velthoven, P.; Zahn, A.; Brenninkmeijer, C. A. M.

2013-11-01

181

Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and Southeast Asia during 2009-2013  

NASA Astrophysics Data System (ADS)

Short-lived organic brominated compounds make up a significant part of the organic bromine budget in the atmosphere. Emissions of these compounds are highly variable and there are limited measurements, particularly in the extra-tropical upper troposphere/lower stratosphere and tropical troposphere. Measurements of five very short-lived bromomethanes (VSLB) were made in air samples collected on the CARIBIC project aircraft over three flight routes; Germany to Venezuela/Columbia during 2009-2011, Germany to South Africa during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during 2012 and 2013. In the tropical troposphere, as the most important entrance region to the stratosphere, we observe a total mean organic bromine derived from these compounds across all flights at 10-12 km altitude of 3.4 ± 1.5 ppt. Individual mean tropical tropospheric mixing ratios across all flights were 0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The highest levels of VSLB-derived bromine (4.20 ± 0.56 ppt) were observed in flights between Bangkok and Kuala Lumpur indicating that the South China Sea is an important source region for these compounds. Across all routes, CHBr3 and CH2Br2 accounted for 34% (4.7-71) and 48% (14-73) respectively of total bromine derived from the analysed VSLB in the tropical mid-upper troposphere totalling 82% (54-89). In samples collected between Germany and Venezuela/Columbia, we find decreasing mean mixing ratios with increasing potential temperature in the extra-tropics. Tropical mean mixing ratios are higher than extra-tropical values between 340-350 K indicating that rapid uplift is important in determining mixing ratios in the lower tropical tropopause layer in the West Atlantic tropics. O3 was used as a tracer for stratospherically influenced air and we detect rapidly decreasing mixing ratios for all VSLB above ∼100 ppb O3 corresponding to the extra-tropical tropopause layer.

Wisher, A.; Oram, D. E.; Laube, J. C.; Mills, G. P.; van Velthoven, P.; Zahn, A.; Brenninkmeijer, C. A. M.

2014-04-01

182

Composition and Trends of Short-Lived Trace Gases in the UT/LS over Europe Observed by the CARIBIC Aircraft  

NASA Astrophysics Data System (ADS)

The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) involves the monthly deployment of an instrument container equipped to make atmospheric measurements from aboard a commercial airliner, and has operated since 2005 from aboard a Lufthansa Airbus 340-600 . Measurements from the container include in-situ trace gas and aerosol analyses and the collection of aerosol and whole air samples for post-flight laboratory analysis. Measurements made from the sampling flasks include greenhouse gas (GHG), halocarbon and nonmethane hydrocarbon (NMHC) analysis. CARIBIC flights originate in Frankfurt, Germany with routes to India, East Asia, South America, North America and Africa, and typical aircraft cruising altitudes of 10-12km allow for the monitoring of the upper troposphere/lower stratosphere (UT/LS) along these routes. Data collected during the aircraft’s departure from and return to Frankfurt provide a 4 year time series of near-monthly measurements of the composition of the UT/LS above Europe. Here we present a discussion of the composition of short-lived trace gases in the whole air samples collected above Europe during CARIBIC flights. Over 150 air samples were collected between May 2005 and July 2009, or about 4 samples per month. Of the whole air samples collected, about 45% showed influence by stratospheric air (i.e. very low values of GHG, NMHC and halocarbons, elevated O3, high potential vorticity). The remaining samples were representative of the upper troposphere; back trajectories for these samples indicate that a little over half were collected in air masses that had been in the boundary layer within the previous 8 days. The predominant source regions for these samples were the Gulf of Mexico and continental North America. Owing to their wide range of chemical lifetimes and the varying composition of emissions, short-lived trace gases transported to the UT/LS can be useful indicators of source region, photochemical processing and transport timescales of an air mass. Seasonal and longer-term trends in trace gases and trace gas composition are discussed, as well as composition of air masses having different origins. Additionally, we apply relationships between the different species, particularly the NMHC, to gain a qualitative understanding of photochemical processes occurring during transport from the boundary layer to the upper troposphere over Europe.

Baker, A. K.; Brenninkmeijer, C. A.; Oram, D. E.; O'Sullivan, D. A.; Slemr, F.; Schuck, T. J.

2009-12-01

183

An alternative approach to comparing long- and short-lived emissions in light of the 2&amp;deg;C global temperature limit  

NASA Astrophysics Data System (ADS)

International climate policy has defined its goal in terms of limiting global average temperature, specifically to 2°C above pre-industrial levels. Emissions of several different greenhouse gases (GHGs) are currently aggregated and traded in terms of their carbon dioxide equivalent. The metric used for aggregating and trading is the 100-year Global Warming Potential (GWP100). Importantly though, the GWP100 does not measure temperature and so does clearly indicate the relative value of different emissions in the context of a global temperature limit. Recent developments in climate research have led to two different, potentially conflicting, perspectives on priorities in reducing emissions. First, a clear link has been demonstrated between cumulative emissions of carbon dioxide and peak temperature. This emphasises the need for carbon dioxide emissions to fall to near zero and provides a conceptually neat way to frame policy, but says little about the role of other GHGs. Second, other studies have shown that emissions of short-lived climate pollutants (SLCPs), many of which currently lie outside climate policy, have a substantial near-term effect on climate. It has been suggested that immediate SLCP reductions will therefore increase the chance of staying below 2°C and may even "buy time" for carbon dioxide reductions. This presentation summarises two recent papers which clarify the roles of SLCPs and long-lived GHGs in determining peak global temperature, and propose new emission metrics to reflect these. SLCP emissions reductions in a given decade have a significant impact on peak temperature only if carbon dioxide emissions are already falling. Immediate action on SLCPs might potentially "buy time" for adaptation by reducing near-term warming, but it does not buy time to delay reductions in carbon dioxide compared with delayed SLCP reductions. Peak temperature is ultimately constrained by cumulative emissions of several long-lived gases (including carbon dioxide) and sustained emission rates of a separate basket of shorter-lived species (including methane and other SLCPs). For these two baskets we develop an emissions-equivalence metric which allows trading within, but not between, each basket. The 2°C limit could therefore be met by setting a limit to cumulative long-lived emissions while setting a maximum future rate for short-lived emissions.

Smith, Stephen; Bowerman, Niel; Lowe, Jason; Huntingford, Chris; Frame, Dave; Allen, Myles; Gohar, Laila; Millar, Richard

2014-05-01

184

Increased Concentrations of Short-Lived Decay-Series Radionuclides in Groundwaters Underneath the Nopal I Uranium Deposit at Pena Blanca, Mexico  

NASA Astrophysics Data System (ADS)

The Nopal I uranium ore deposit at Pena Blanca, Mexico, located at > 200 meters above the groundwater table, provides an ideal natural analog for quantifying the effectiveness of geological barrier for isolation of radioactive waste nuclides from reaching the human environments through ground water transport. To fulfill such natural analog studies, three wells (PB1, PB2, and PB3 respectively) were drilled at the site from the land surface down to the saturated groundwater zone and ground waters were collected from each of these wells through large- volume sampling/in-situ Mn-filter filtration for analyses of short-lived uranium/thorium-series radionuclides. Our measurements from PB1 show that the groundwater standing in the hole has much lower 222Rn activity than the freshly pumped groundwater. From this change in 222Rn activity, we estimate the residence time of groundwater in PB1 to be about 20 days. Our measurements also show that the activities of short-lived radioisotopes of Th (234Th), Ra (228Ra, 224Ra, 223Ra), Rn (222Rn), Pb (210Pb), and Po (210Po) in PB1, PB2, and PB3 are all significantly higher than those from the other wells near the Nopal I site. These high activities provide evidence for the enrichment of long-lived U and Ra isotopes in the groundwater as well as in the associated adsorbed phases on the fractured aquifer rocks underneath the ore deposit. Such enrichment suggests a rapid dissolution of U and Ra isotopes from the uranium ore deposit in the vadose zone and the subsequent migration to the groundwater underneath. A reactive transport model can be established to characterize the in-situ transport of radionuclides at the site. The observed change of 222Rn activity at PB1 also suggests that the measured high radioactivityies in ground waters from the site isare not an artifact of drilling operations. However, further studies are needed to assess if or to what extent the radionuclide migration is affected by the previous mining activities at the site.

Luo, S.; Ku, T.; Todd, V.; Murrell, M. T.; Dinsmoor, J. C.

2007-05-01

185

Detection of the short-lived cation radical intermediate in the electrochemical oxidation of n,n-dimethylaniline by scanning electrochemical microscopy.  

PubMed

The short-lived intermediate N,N-dimethylaniline (DMA) cation radical, DMA(•+), was detected during the oxidation of DMA in MeCN with 0.1 M tetra-n-butylammonium hexafluorophosphate. The detection was accomplished at steady state by scanning electrochemical microscopy (SECM) with ultramicroelectrodes using the tip generation/substrate collection mode. Cyclic voltammetry (CV) with a 2 mm Pt electrode indicates that DMA oxidation in acetonitrile is followed by a dimerization and two electrochemical reactions, which is consistent with previous results. The DMA(•+) intermediate is detected by SECM, where the DMA(•+) generated at the ca. 500 nm radius Pt tip is collected on a 5 ?m radius Pt substrate when the gap between the tip and the substrate is a few hundred nanometers. Almost all of the DMA(•+) is reduced at the substrate when the gap is 200 nm or less, yielding a dimerization rate constant of 2.5 × 10(8) M(-1)·s(-1) based on a simulation. This is roughly 3 orders of magnitude larger than the value estimated by fast-scan CV. We attribute this discrepancy to the effects of double-layer capacitance charging and adsorbed species in the high scan rate CV. PMID:25478724

Cao, Fahe; Kim, Jiyeon; Bard, Allen J

2014-12-31

186

Naturally acquired inhibitory antibodies to Plasmodium vivax Duffy binding protein are short-lived and allele-specific following a single malaria infection  

PubMed Central

The Duffy binding protein of Plasmodium vivax (DBP) is a critical adhesion ligand that participates in merozoite invasion of human Duffy-positive erythrocytes. A small outbreak of P. vivax malaria, in a village located in a non-malarious area of Brazil, offered us an opportunity to investigate the DBP immune responses among individuals who had their first and brief exposure to malaria. Thirty-three individuals participated in the five cross-sectional surveys, 15 with confirmed P. vivax infection while residing in the outbreak area (cases) and 18 who had not experienced malaria (non-cases). In the present study, we found that only 20% (three of 15) of the individuals who experienced their first P. vivax infection developed an antibody response to DBP; a secondary boosting can be achieved with a recurrent P. vivax infection. DNA sequences from primary/recurrent P. vivax samples identified a single dbp allele among the samples from the outbreak area. To investigate inhibitory antibodies to the ligand domain of the DBP (cysteine-rich region II, DBPII), we performed in vitro assays with mammalian cells expressing DBPII sequences which were homologous or not to those from the outbreak isolate. In non-immune individuals, the results of a 12-month follow-up period provided evidence that naturally acquired inhibitory antibodies to DBPII are short-lived and biased towards a specific allele. PMID:19438604

Ceravolo, I P; Sanchez, B A M; Sousa, T N; Guerra, B M; Soares, I S; Braga, E M; McHenry, A M; Adams, J H; Brito, C F A; Carvalho, L H

2009-01-01

187

Transport of short-lived climate forcers/pollutants (SLCF/P) to the Himalayas during the South Asian summer monsoon onset  

NASA Astrophysics Data System (ADS)

Over the course of six years (2006-2011), equivalent black carbon (eqBC), coarse aerosol mass (PM1-10), and surface ozone (O3), observed during the monsoon onset period at the Nepal Climate Observatory-Pyramid WMO/GAW Global Station (NCO-P, 5079 m a.s.l.), were analyzed to investigate events characterized by a significant increase in these short-lived climate forcers/pollutants (SLCF/P). These events occurred during periods characterized by low (or nearly absent) rain precipitation in the central Himalayas, and they appeared to be related to weakening stages (or ‘breaking’) of the South Asian summer monsoon system. As revealed by the combined analysis of atmospheric circulation, air-mass three-dimensional back trajectories, and satellite measurements of atmospheric aerosol loading, surface open fire, and tropospheric NO x , the large amount of SLCF/P reaching the NCO-P appeared to be related to natural (mineral dust) and anthropogenic emissions occurring within the PBL of central Pakistan (i.e., Thar Desert), the Northwestern Indo-Gangetic plain, and the Himalayan foothills. The systematic occurrence of these events appeared to represent the most important source of SLCF/P inputs into the central Himalayas during the summer monsoon onset period, with possible important implications for the regional climate and for hydrological cycles.

Cristofanelli, P.; Putero, D.; Adhikary, B.; Landi, T. C.; Marinoni, A.; Duchi, R.; Calzolari, F.; Laj, P.; Stocchi, P.; Verza, G.; Vuillermoz, E.; Kang, S.; Ming, J.; Bonasoni, P.

2014-08-01

188

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer  

NASA Astrophysics Data System (ADS)

Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a by-product of the very oxidation chemistry it largely initiates. Much effort is focussed on the reduction of surface levels of ozone owing to its health impacts but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve due to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate-change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner.

Monks, P. S.; Archibald, A. T.; Colette, A.; Cooper, O.; Coyle, M.; Derwent, R.; Fowler, D.; Granier, C.; Law, K. S.; Stevenson, D. S.; Tarasova, O.; Thouret, V.; von Schneidemesser, E.; Sommariva, R.; Wild, O.; Williams, M. L.

2014-12-01

189

Climate Impacts of Short-Lived Climate Forcers versus CO2 from Biodiesel: A Case of the EU on-Road Sector.  

PubMed

Biofuels are proposed to play an important role in several mitigation strategies to meet future CO2 emission targets for the transport sector but remain controversial due to significant uncertainties in net impacts on environment, society, and climate. A switch to biofuels can also affect short-lived climate forcers (SLCFs), which provide significant contributions to the net climate impact of transportation. We quantify the radiative forcing (RF) and global-mean temperature response over time to EU on-road fossil diesel SLCFs and the impact of 20% (B20) and 100% (B100) replacement of fossil diesel by biodiesel. SLCFs are compared to impacts of on-road CO2 using different approaches from existing literature to account for biodiesel CO2. Given the best estimates for changes in emissions when replacing fossil diesel with biodiesel, the net positive RF from EU on-road fossil diesel SLCFs of 3.4 mW/m(2) is reduced by 15% and 80% in B20 and B100, respectively. Over time the warming of SLCFs is likely small compared to biodiesel CO2 impacts. However, SLCFs may be relatively more important for the total warming than in the fossil fuel case if biodiesel from feedstock with very short rotation periods and low land-use-change impacts replaces a high fraction of fossil diesel. PMID:25405926

Lund, Marianne T; Berntsen, Terje K; Fuglestvedt, Jan S

2014-12-16

190

Diurnal variation climatology of short-lived at atmospheric compositions (ClO, BrO, HO2 and HOCl) derived from SMILES NICT data  

NASA Astrophysics Data System (ADS)

We present a diurnal variation climatology for short-lived at atmospheric compositions, such as ClO, BrO, HO2 and HOCl, as well as for longer life time species, like O3 and HCl from observations of unprecedented sensitivity with the Superconducting SubMIllimeter wave Limb-Emission Sounder (SMILES), which is installed on the Japanese Experiment Module (JEM) at the International Space Station (ISS). With its non sun synchronous orbit, SMILES measurements comprise observations at all local times. The target altitude range is between lower stratosphere and mesopause. Differences in diurnal variation chemistry of strato-, and mesospheric BrO and ClO of the diurnal climatology are presented. The data employed is produced by the SMILES level 2 retrieval algorithm version 2.1.5 at the National Institute of Information and Communications Technology (NICT). The SMILES climatology data sets are available via the SMILES data distribution homepage in NICT at https://smiles-p6.nict.go.jp/products/research_latitude-longitude.jsf

Kreyling, Daniel; Sagawa, Hideo; Kasai, Yasuko

2013-04-01

191

Simultaneous Triggered Collapse of the Presolar Dense Cloud Core and Injection of Short-Lived Radioisotopes by a Supernova Shock Wave  

E-print Network

Cosmochemical evidence for the existence of short-lived radioisotopes (SLRI) such as $^{26}$Al and $^{60}$Fe at the time of the formation of primitive meteorites requires that these isotopes were synthesized in a massive star and then incorporated into chondrites within $\\sim 10^6$ yr. A supernova shock wave has long been hypothesized to have transported the SLRI to the presolar dense cloud core, triggered cloud collapse, and injected the isotopes. Previous numerical calculations have shown that this scenario is plausible when the shock wave and dense cloud core are assumed to be isothermal at $\\sim 10$ K, but not when compressional heating to $\\sim 1000$ K is assumed. We show here for the first time that when calculated with the FLASH2.5 adaptive mesh refinement (AMR) hydrodynamics code, a 20 km/sec shock wave can indeed trigger the collapse of a 1 $M_\\odot$ cloud while simultaneously injecting shock wave isotopes into the collapsing cloud, provided that cooling by molecular species such as H$_2$O, CO$_2$, and H$_2$ is included. These calculations imply that the supernova trigger hypothesis is the most likely mechanism for delivering the SLRI present during the formation of the solar system.

Alan P. Boss; Sergei I. Ipatov; Sandra A. Keiser; Elizabeth A. Myhill; Harri A. T. Vanhala

2008-09-18

192

Immune responses in newly developed short-lived SAM mice. Selectively impaired T-helper cell activity in in vitro antibody response.  

PubMed

New short-lived strains of mice (SAM-P), which have been developed by Takeda et al. (1981), shows a defective antibody response to T dependent (TD) antigen in vitro, as demonstrated in the accompanying paper (see page 419). In the present study, we investigated the cellular site of the defect, using a cell culture system. In this paper, it is demonstrated that T-helper (Th) cell activity for the antibody response to TD antigen is impaired, while other cellular immune responses, e.g. mixed leucocyte reaction, cytotoxic T-lymphocyte response, and delayed-type hypersensitivity reaction, are normal. These results suggest that the defect in T-helper subset is limited in helper function for the antibody response, and that the helper function for the cell-mediated immune responses is intact. These two functions of the T-helper subset are apparently regulated in a different manner. The SAM-P strains of mice may thus serve as an appropriate model for studying functional heterogeneity in T-helper/inducer cell subsets. PMID:2959613

Hosokawa, T; Hosono, M; Hanada, K; Aoike, A; Kawai, K; Takeda, T

1987-11-01

193

Immune responses in newly developed short-lived SAM mice. Selectively impaired T-helper cell activity in in vitro antibody response.  

PubMed Central

New short-lived strains of mice (SAM-P), which have been developed by Takeda et al. (1981), shows a defective antibody response to T dependent (TD) antigen in vitro, as demonstrated in the accompanying paper (see page 419). In the present study, we investigated the cellular site of the defect, using a cell culture system. In this paper, it is demonstrated that T-helper (Th) cell activity for the antibody response to TD antigen is impaired, while other cellular immune responses, e.g. mixed leucocyte reaction, cytotoxic T-lymphocyte response, and delayed-type hypersensitivity reaction, are normal. These results suggest that the defect in T-helper subset is limited in helper function for the antibody response, and that the helper function for the cell-mediated immune responses is intact. These two functions of the T-helper subset are apparently regulated in a different manner. The SAM-P strains of mice may thus serve as an appropriate model for studying functional heterogeneity in T-helper/inducer cell subsets. PMID:2959613

Hosokawa, T; Hosono, M; Hanada, K; Aoike, A; Kawai, K; Takeda, T

1987-01-01

194

Immune responses in newly developed short-lived SAM mice. I. Age-associated early decline in immune activities of cultured spleen cells.  

PubMed Central

Using a cell culture system, age-associated changes in immune activities were investigated in newly developed, short-lived mouse strains. These SAM-P strains of mice (H-2k), which have a remarkably short life span (around 9 months) under conventional breeding conditions, showed an age-associated early decline in several immune functions, as compared to ordinary strains of AKR/J (H-2k) and C3H/He (H-2k) mice. Their antibody-forming capacity to T-independent antigen, DNP-Ficoll, and natural killer (NK) cell activity showed a markedly early onset of regression and a sharp decline from the level of control mice at 2 months of age. SAM-P strains of mice have a profound defect in antibody response to a T-dependent (TD) antigen, such as sheep red blood cells (SRBC), thus there was only a feeble antibody response to SRBC as early as the age of 2 months, and a negligible response at a later age. In contrast, the allo-specific cytotoxic T lymphocyte (CTL) response of the mice was as high as that of control mouse strains at 2 months of age and declined little until at least 6 months of age. The early age-related functional decline in the immune system of SAM-P mice suggests that these new inbred strains are appropriate models for investigating the age-related appearance of immune dysfunctions. PMID:3499380

Hosokawa, T; Hosono, M; Higuchi, K; Aoike, A; Kawai, K; Takeda, T

1987-01-01

195

Immune responses in newly developed short-lived SAM mice. I. Age-associated early decline in immune activities of cultured spleen cells.  

PubMed

Using a cell culture system, age-associated changes in immune activities were investigated in newly developed, short-lived mouse strains. These SAM-P strains of mice (H-2k), which have a remarkably short life span (around 9 months) under conventional breeding conditions, showed an age-associated early decline in several immune functions, as compared to ordinary strains of AKR/J (H-2k) and C3H/He (H-2k) mice. Their antibody-forming capacity to T-independent antigen, DNP-Ficoll, and natural killer (NK) cell activity showed a markedly early onset of regression and a sharp decline from the level of control mice at 2 months of age. SAM-P strains of mice have a profound defect in antibody response to a T-dependent (TD) antigen, such as sheep red blood cells (SRBC), thus there was only a feeble antibody response to SRBC as early as the age of 2 months, and a negligible response at a later age. In contrast, the allo-specific cytotoxic T lymphocyte (CTL) response of the mice was as high as that of control mouse strains at 2 months of age and declined little until at least 6 months of age. The early age-related functional decline in the immune system of SAM-P mice suggests that these new inbred strains are appropriate models for investigating the age-related appearance of immune dysfunctions. PMID:3499380

Hosokawa, T; Hosono, M; Higuchi, K; Aoike, A; Kawai, K; Takeda, T

1987-11-01

196

Alpha Thalassemia  

MedlinePLUS

Alpha Thalassemia ? Physicians often mistake alpha thalassemia trait for iron deficiency anemia and incorrectly prescribe iron supplements that have no effect on the anemia. Normal alpha globin genes ...

197

Lyman alpha radiation in external galaxies  

NASA Technical Reports Server (NTRS)

The Ly alpha line of atomic hydrogen is often a luminous component of the radiation emitted by distant galaxies. Except for those galaxies which have a substantial central source of non-stellar ionizing radiation, most of the Ly alpha radiation emitted by galaxies is generated within regions of the interstellar medium which are photoionized by starlight. Conversely, much of the energy radiated by photoionized regions is carried by the Ly alpha line. Only hot, massive stars are capable of ionizing hydrogen in the interstellar medium which surrounds them, and because such stars are necessarily short-lived, Ly alpha emission traces regions of active star formation. Researchers argue that the strength of the Ly alpha emission observed from external galaxies may be used to estimate quantitatively the dust content of the emitting region, while the Ly alpha line profile is sensitive to the presence of shock waves. Interstellar dust particles and shock waves are intimately associated with the process of star formation in two senses. First, both dust particles and shock waves owe their existence to stellar activity; second, they may both serve as agents which facilitate the formation of stars, shocks by triggering gravitational instabilities in the interstellar gas that they compress, and dust by shielding star-forming molecular clouds from the ionizing and dissociative effects of external UV radiation. By using Ly alpha observations as a probe of the dust content in diffuse gas at high redshift, we might hope to learn about the earliest epochs of star formation.

Neufeld, David A.; Mckee, Christopher F.

1990-01-01

198

Formation of the Short-lived Radionuclide 36Cl in the Protoplanetary Disk During Late-stage Irradiation of a Volatile-rich Reservoir  

NASA Astrophysics Data System (ADS)

Short-lived radionuclides (SLRs) in the early solar system provide fundamental insight into protoplanetary disk evolution. We measured the 36Cl-36S-isotope abundance in wadalite (<15 ?m), a secondary chlorine-bearing mineral found in calcium-aluminum-rich inclusions (CAIs) in the Allende CV chondrite, to decipher the origin of the SLR 36Cl (? 1/2 ~ 3 × 105 yr) in the early solar system. Its presence, initial abundance, and the noticeable decoupling from 26Al raise serious questions about the origin of SLRs. The inferred initial 36Cl abundance for wadalite, corresponding to a 36Cl/35Cl ratio of (1.81 ± 0.13) × 10-5, is the highest 36Cl abundance ever reported in any early solar system material. The high level of 36Cl in wadalite and the absence of 26Al (26Al/27Al <= 3.9 × 10-6) in co-existing grossular (1) unequivocally support the production of 36Cl by late-stage solar energetic particle irradiation in the protoplanetary disk and (2) indicates that the production of 36Cl, recorded by wadalite, is unrelated to the origin of 26Al and other SLRs (10Be, 53Mn) recorded by primary minerals of CAIs and chondrules. We infer that 36Cl was largely produced by irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the region in which the CV chondrite parent asteroid accreted while the Sun was a weak T Tauri star. Subsequently, 36Cl accreted into the Allende CV chondrite together with condensed water ices.

Jacobsen, Benjamin; Matzel, Jennifer; Hutcheon, Ian D.; Krot, Alexander N.; Yin, Qing-Zhu; Nagashima, Kazuhide; Ramon, Erick C.; Weber, Peter K.; Ishii, Hope A.; Ciesla, Fred J.

2011-04-01

199

Concentrated fish oil (Lovaza®) extends lifespan and attenuates kidney disease in lupus-prone short-lived (NZBxNZW)F1 mice  

PubMed Central

A growing number of reports indicate that anti-inflammatory actions of fish oil (FO) are beneficial against systemic lupus erythematosus (SLE). However, the majority of pre-clinical studies were performed using 5–20% FO, which is higher than the clinically relevant dose for lupus patients. The present study was performed in order to determine the effective low dose of FDA-approved concentrated FO (Lovaza®) compared to the commonly used FO-18/12 (18-Eicosapentaenoic acid [EPA]/12-Docosahexaenoic acid [DHA]). We examined the dose-dependent response of Lovaza® (1% and 4%) on an SLE mouse strain (NZB×NZW)F1 and compared the same with 1% and 4% placebo, as well as 4% FO-18/12, maintaining standard chow as the control. Results show for the first time that 1% Lovaza® extends maximal lifespan (517 d) and 4% Lovaza® significantly extends both the median (502 d) and maximal (600 d) life span of (NZB×NZW)F1 mice. In contrast, FO-18/12 extends only median lifespan (410 d) compared to standard chow diet (301 d). Additionally, 4% Lovaza® significantly decreased anti-dsDNA antibodies, reduced glomerulonephritis and attenuated lipopolysaccharide-induced pro-inflammatory cytokines (IL-1?, IL-6, TNF-?) in splenocytes compared to placebo. 4% Lovaza® was also shown to reduce the expression of inflammatory cytokines, including IL-1?, IL-6 and TNF-?, while increasing renal anti-oxidant enzymes in comparison to placebo. Notably, NF?B activation and p65 nuclear translocation were lowered by 4% Lovaza® compared to placebo. These data indicate that 1% Lovaza® is beneficial, but 4% Lovaza® is more effective in suppressing glomerulonephritis and extending life span of SLE-prone short-lived mice, possibly via reducing inflammation signaling and modulating oxidative stress. PMID:23918873

Halade, Ganesh V; Williams, Paul J; Veigas, Jyothi M; Barnes, Jeffrey L; Fernandes, Gabriel

2014-01-01

200

TRIGGERING COLLAPSE OF THE PRESOLAR DENSE CLOUD CORE AND INJECTING SHORT-LIVED RADIOISOTOPES WITH A SHOCK WAVE. I. VARIED SHOCK SPEEDS  

SciTech Connect

The discovery of decay products of a short-lived radioisotope (SLRI) in the Allende meteorite led to the hypothesis that a supernova shock wave transported freshly synthesized SLRI to the presolar dense cloud core, triggered its self-gravitational collapse, and injected the SLRI into the core. Previous multidimensional numerical calculations of the shock-cloud collision process showed that this hypothesis is plausible when the shock wave and dense cloud core are assumed to remain isothermal at approx10 K, but not when compressional heating to approx1000 K is assumed. Our two-dimensional models with the FLASH2.5 adaptive mesh refinement hydrodynamics code have shown that a 20 km s{sup -1} shock front can simultaneously trigger collapse of a 1 M{sub sun} core and inject shock wave material, provided that cooling by molecular species such as H{sub 2}O, CO, and H{sub 2} is included. Here, we present the results for similar calculations with shock speeds ranging from 1 km s{sup -1} to 100 km s{sup -1}. We find that shock speeds in the range from 5 km s{sup -1} to 70 km s{sup -1} are able to trigger the collapse of a 2.2 M{sub sun} cloud while simultaneously injecting shock wave material: lower speed shocks do not achieve injection, while higher speed shocks do not trigger sustained collapse. The calculations continue to support the shock-wave trigger hypothesis for the formation of the solar system, though the injection efficiencies in the present models are lower than desired.

Boss, Alan P.; Keiser, Sandra A.; Ipatov, Sergei I.; Myhill, Elizabeth A.; Vanhala, Harri A. T., E-mail: boss@dtm.ciw.ed, E-mail: keiser@dtm.ciw.ed, E-mail: siipatov@hotmail.co, E-mail: elizabeth.myhill@marymount.ed, E-mail: HarriVanhala@ncesse.or [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

2010-01-10

201

IL-2 induction of Blimp-1 is a key in vivo signal for CD8+ short-lived effector T cell differentiation.  

PubMed

During infection or vaccination, only a small proportion of CD8(+) T cells differentiate into memory cells. The mechanisms underlying the differentiation of CD8(+) T cells into short-lived effector cells (SLECs) or memory precursor effector cells are poorly defined. It was recently shown in infectious models that the transcriptional repressor B lymphocyte-induced maturation protein 1 (Blimp-1) enhances the formation of SLECs. The factors controlling Blimp-1 expression leading to the in vivo formation of SLECs are still not known. However, it has been shown that cytokines such as IL-2 induce Blimp-1 expression in vitro. In this study, we took advantage of the low-inflammation model of dendritic cell immunization to study the role of the IL-2/Blimp-1 axis in SLEC differentiation as well as the importance of Blimp-1 expression in memory precursor effector cells for proper CD8(+) memory generation. Our results show that Blimp-1 deficiency affects effector differentiation and function in the absence of inflammation. Unexpectedly, memory generation was not affected in Blimp-1-deficient OT-I cells responding to vaccination. In addition, modulation of the bioavailability of IL-2 by injection either of a blocking Ab or of the cytokine, demonstrates a link between IL-2, Blimp-1 induction, and SLEC formation in wild-type cells. Conversely, injection of IL-2 had less effect on Blimp-1-deficient CD8(+) T cells, indicating that the effect of IL-2 on in vivo SLEC differentiation is mediated by Blimp-1. In conclusion, IL-2 induction of Blimp-1 expression is a key regulator of SLEC differentiation in vivo. PMID:25015830

Boulet, Salix; Daudelin, Jean-François; Labrecque, Nathalie

2014-08-15

202

Triptolide is an inhibitor of RNA polymerase I and II-dependent transcription leading predominantly to down-regulation of short-lived mRNA.  

PubMed

Triptolide, a natural product extracted from the Chinese plant Tripterygium wilfordii, possesses antitumor properties. Despite numerous reports showing the proapoptotic capacity and the inhibition of NF-kappaB-mediated transcription by triptolide, the identity of its cellular target is still unknown. To clarify its mechanism of action, we further investigated the effect of triptolide on RNA synthesis in the human non-small cell lung cancer cell line A549. Triptolide inhibited both total RNA and mRNA de novo synthesis, with the primary action being on the latter pool. We used 44K human pan-genomic DNA microarrays and identified the genes primarily affected by a short treatment with triptolide. Among the modulated genes, up to 98% are down-regulated, encompassing a large array of oncogenes including transcription factors and cell cycle regulators. We next observed that triptolide induced a rapid depletion of RPB1, the RNA polymerase II main subunit that is considered a hallmark of a transcription elongation blockage. However, we also show that triptolide does not directly interact with the RNA polymerase II complex nor does it damage DNA. We thus conclude that triptolide is an original pharmacologic inhibitor of RNA polymerase activity, affecting indirectly the transcription machinery, leading to a rapid depletion of short-lived mRNA, including transcription factors, cell cycle regulators such as CDC25A, and the oncogenes MYC and Src. Overall, the data shed light on the effect of triptolide on transcription, along with its novel potential applications in cancers, including acute myeloid leukemia, which is in part driven by the aforementioned oncogenic factors. PMID:19808979

Vispé, Stéphane; DeVries, Luc; Créancier, Laurent; Besse, Jérome; Bréand, Sophie; Hobson, David J; Svejstrup, Jesper Q; Annereau, Jean-Philippe; Cussac, Didier; Dumontet, Charles; Guilbaud, Nicolas; Barret, Jean-Marc; Bailly, Christian

2009-10-01

203

TRIGGERING COLLAPSE OF THE PRESOLAR DENSE CLOUD CORE AND INJECTING SHORT-LIVED RADIOISOTOPES WITH A SHOCK WAVE. II. VARIED SHOCK WAVE AND CLOUD CORE PARAMETERS  

SciTech Connect

A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest solar system solids, including Type II supernovae (SNe), asymptotic giant branch (AGB) and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin SN shocks may be uniquely suited for the task. However, recent meteoritical studies have weakened the case for a direct SN injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that SN shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet (WR) star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave, by as much as a factor of {approx}10. The amount of gas and dust accreted from the post-shock wind can exceed that injected from the shock wave, with implications for the isotopic abundances expected for a SN source.

Boss, Alan P.; Keiser, Sandra A., E-mail: boss@dtm.ciw.edu, E-mail: keiser@dtm.ciw.edu [Department of Terrestrial Magnetism, Carnegie Institution, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

2013-06-10

204

RNA-seq of the aging brain in the short-lived fish N. furzeri – conserved pathways and novel genes associated with neurogenesis  

PubMed Central

The brains of teleost fish show extensive adult neurogenesis and neuronal regeneration. The patterns of gene regulation during fish brain aging are unknown. The short-lived teleost fish Nothobranchius furzeri shows markers of brain aging including reduced learning performances, gliosis, and reduced adult neurogenesis. We used RNA-seq to quantify genome-wide transcript regulation and sampled five different time points to characterize whole-genome transcript regulation during brain aging of N. furzeri. Comparison with human datasets revealed conserved up-regulation of ribosome, lysosome, and complement activation and conserved down-regulation of synapse, mitochondrion, proteasome, and spliceosome. Down-regulated genes differ in their temporal profiles: neurogenesis and extracellular matrix genes showed rapid decay, synaptic and axonal genes a progressive decay. A substantial proportion of differentially expressed genes (?40%) showed inversion of their temporal profiles in the last time point: spliceosome and proteasome showed initial down-regulation and stress-response genes initial up-regulation. Extensive regulation was detected for chromatin remodelers of the DNMT and CBX families as well as members of the polycomb complex and was mirrored by an up-regulation of the H3K27me3 epigenetic mark. Network analysis showed extensive coregulation of cell cycle/DNA synthesis genes with the uncharacterized zinc-finger protein ZNF367 as central hub. In situ hybridization showed that ZNF367 is expressed in neuronal stem cell niches of both embryonic zebrafish and adult N. furzeri. Other genes down-regulated with age, not previously associated with adult neurogenesis and with similar patterns of expression are AGR2, DNMT3A, KRCP, MEX3A, SCML4, and CBX1. CBX7, on the other hand, was up-regulated with age. PMID:25059688

Baumgart, Mario; Groth, Marco; Priebe, Steffen; Savino, Aurora; Testa, Giovanna; Dix, Andreas; Ripa, Roberto; Spallotta, Francesco; Gaetano, Carlo; Ori, Michela; Terzibasi Tozzini, Eva; Guthke, Reinhard; Platzer, Matthias; Cellerino, Alessandro

2014-01-01

205

Immune responses in newly developed short-lived SAM mice. IV. Chromosomal location of a gene controlling defective helper T-cell activity.  

PubMed Central

Short-lived SAMP-P/1 mice are low responders in in vitro antibody responses because of a selectively impaired helper T(Th)-cell activity. After crossing with high responders (B10.BR mice), about 12% of (B10.BR x SAM-P/1) (BRP)F2 mice showed low responsiveness, as did SAM-P/1 mice, against two T-dependent antigens, sheep and horse red blood cells (RBC), both of which were not cross-reactive to each other at helper T- and B-cell levels. The immune activities against the two antigens in individual BRPF2 mice showed a good correlation (r = 0.81), thereby suggesting that SAM-P/1 mice have an antigen non-specific Th cell dysfunction. Based on the incidence of the low responders in F2 generation and statistical analyses, the hypo-responsiveness was postulated to be controlled by two genes. To survey the location of these genes, linkage analyses were performed in the F2 mice using a large set of genetic markers. Low responders in the F2 generation showed a significantly higher incidence of SAM-P/1 genotype at the Gpi-1 as well as c locus on chromosome 7 (Chr.7). However, no linkage of low responsiveness to the Hbb locus was evident, an area present at a more distal site to the centromere on the same chromosome. These results suggest that one of the genes controlling the hypo-responsiveness of SAM-P/1 mice is linked to both Gpi-1 and c loci and that it locates at a more proximal site on Chr.7. PMID:1834548

Hanada, K; Katoh, H; Hosokawa, T; Hosono, M; Takeda, T

1991-01-01

206

Immune responses in newly developed short-lived SAM mice. III. Genetic control of defective helper T-cell activity in in vitro primary antibody response.  

PubMed Central

Immune activities of newly developed, short-lived SAM-P/1 mice declined sharply after a few months of age. As early as 2 months of age, the activity of T-helper (Th) cells ('Th2'-like) in the in vitro primary antibody response was profoundly impaired, in contrast to normal activity of Th cells ('Th1'-like) engaged in cell-mediated immune responses. Thus, young SAM-P/1 mice show a functional heterogeneity of Th cells. To determine how such a 'Th2' abnormality is inherited in SAM-P/1 mice, immune activities of their hybrids and backcrosses between MHC-identical, high responder B10.BR mice were statistically assessed. The distribution of responses did not support the Mendelian single-gene determination for low responsiveness. Moreover, involvement of a single gene which exhibits incomplete dominance was ruled out because of a continuous distribution pattern of antibody response in the F2 generation. Such an analysis strongly suggests that the impaired 'Th2'-like activity of SAM-P/1 mice is under control of two genes, based on the proportion of low responders in F2 hybrids (29 out of 267, 10.8%) and on calculation according to Wright's formula (n = 1.72). Further linkage analyses suggest that one of the genes is closely linked to albino coat-colour (c) locus on chromosome 7. The putative two genes are likely to control 'differentiation' or 'maturation' of Th2-like cells defectively, but the defect is not refractory, because in vivo-primed Th cells function in vitro as do those in ordinary strains of mice. Possible mechanisms and biological significance in relation to loss of immune activity with ageing are discussed. PMID:2532621

Hanada, K; Hosono, M; Hosokawa, T; Chen, W E; Tsuboyama, T; Takeda, T

1989-01-01

207

Chronic Parasitic Infection Maintains High Frequencies of Short-Lived Ly6C+CD4+ Effector T Cells That Are Required for Protection against Re-infection  

PubMed Central

In contrast to the ability of long-lived CD8+ memory T cells to mediate protection against systemic viral infections, the relationship between CD4+ T cell memory and acquired resistance against infectious pathogens remains poorly defined. This is especially true for T helper 1 (Th1) concomitant immunity, in which protection against reinfection coincides with a persisting primary infection. In these situations, pre-existing effector CD4 T cells generated by ongoing chronic infection, not memory cells, may be essential for protection against reinfection. We present a systematic study of the tissue homing properties, functionality, and life span of subsets of memory and effector CD4 T cells activated in the setting of chronic Leishmania major infection in resistant C57Bl/6 mice. We found that pre-existing, CD44+CD62L?T-bet+Ly6C+ effector (TEFF) cells that are short-lived in the absence of infection and are not derived from memory cells reactivated by secondary challenge, mediate concomitant immunity. Upon adoptive transfer and challenge, non-dividing Ly6C+ TEFF cells preferentially homed to the skin, released IFN-?, and conferred protection as compared to CD44+CD62L?Ly6C? effector memory or CD44+CD62L+Ly6C? central memory cells. During chronic infection, Ly6C+ TEFF cells were maintained at high frequencies via reactivation of TCM and the TEFF themselves. The lack of effective vaccines for many chronic diseases may be because protection against infectious challenge requires the maintenance of pre-existing TEFF cells, and is therefore not amenable to conventional, memory inducing, vaccination strategies. PMID:25473946

Peters, Nathan C.; Pagán, Antonio J.; Lawyer, Phillip G.; Hand, Timothy W.; Henrique Roma, Eric; Stamper, Lisa W.; Romano, Audrey; Sacks, David L.

2014-01-01

208

In vitro cell irradiation systems based on 210Po alpha source: construction and characterisation.  

PubMed

One way of studying the risk to human health of low-level radiation exposure is to make biological experiments on living cell cultures. Two 210Po alpha-particle emitting devices, with 0.5 and 100 MBq activity, were designed and constructed to perform such experiments irradiating monolayers of cells. Estimates of dose rate at the cell surface were obtained from measurements by a PIPS alpha-particle spectrometer and from calculations by the SRIM 2000, Monte Carlo charged particle transport code. Particle fluence area distributions were measured by solid state nuclear track detectors. The design and dosimetric characterisation of the devices are discussed. PMID:12455514

Szabo, J; Feher, I; Palfalvi, J; Balashazy, I; Dam, A M; Polonyi, I; Bogdandi, E N

2002-12-01

209

Alpha-Particle Angular Distributions of At and Rn Isotopes and Their Relation to Nuclear Structure  

SciTech Connect

We report on an extensive on-line nuclear orientation study of the angular distribution of {alpha} particles emitted in the favored decay of neutron deficient At and Rn nuclei near the {ital N}=126 shell closure. Surprisingly large anisotropies were observed, showing pronounced changes from one isotope to another. Comparing these data with several theoretical models shows that anisotropic {alpha} emission in favored decays from near-spherical nuclei can well be explained within the shell model, implying that it is mainly determined by the structure of the decaying nucleus. {copyright} {ital 1996 The American Physical Society.}

NICOLE Collaboration and ISOLDE Collaboration

1996-12-01

210

Apparatus for detecting alpha radiation in difficult access areas  

DOEpatents

An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure is disclosed. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure. 4 figs.

Steadman, P.; MacArthur, D.W.

1997-09-02

211

Apparatus for detecting alpha radiation in difficult access areas  

DOEpatents

An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure.

Steadman, Peter (Santa Fe, NM); MacArthur, Duncan W. (Los Alamos, NM)

1997-09-02

212

Oxygen isotopic and geochemical evidence for a short-lived, high-temperature hydrothermal event in the Chegem caldera, Caucasus Mountains, Russia  

USGS Publications Warehouse

Within the 2.8 Ma Chegem ash-flow caldera (11 ?? 15 km), a single cooling unit of rhyolitic to dacitic welded tuff more than 2 km thick is exposed in deep valleys incised during recent rapid uplift of the Caucasus Mountains. The intracaldera tuff is mineralogically fresh and unaltered, and is overlain by andesite lavas and cut by a resurgent granodiorite intrusion. Major- and trace-element compositions for a 1405-m stratigraphic section of intracaldera tuff display trends of upwardly increasing Na2O, CaO, Al2O3, total Fe, MgO, TiO2, Sr and Zr and decreasing SiO2, K2O and Rb. This mafic-upward zoning (from 76.1 to 69.9% SiO2) reflects an inverted view of the upper part of the source magma chamber. Oxygen isotope studies of 35 samples from this 1405-m section define a striking profile with "normal" igneous ??18O values (+7.0 to +8.5) in the lower 600 m of tuff, much lower ??18O values (-4.0 to +4.3) in a 700-m zone above that and a shift to high ??18O values (+4.4 to -10.9) in the upper 100 m of caldera-fill exposure. Data from two other partial stratigraphic sections indicate that these oxygen isotope systematics are probably a caldera-wide phenomenon. Quartz and feldspar phenocrysts everywhere have "normal" igneous ??18O values of about +8.5 and +7.5, respectively, whereas groundmass and glass ??18O values range from -7.7 to +12.3. Consequently, the ??18O values of coexisting feldspar, groundmass and glass form a steep array in a plot of ??feldspar vs. ??groundmass/glass. Such pronounced disequilibrium between coexisting feldspar and groundmass or glass has never before been observed on this scale. It requires a hydrothermal event involving large amounts of low-18O H2O at sufficiently high temperatures and short enough time (tens of years or less) that glass exchanges thoroughly but feldspar does not. The most likely process responsible for the O depletions at Chegem is a very high temperature (500-600??C), short-lived, vigorous meteoric-hydrothermal event that was focused within the upper 750 m of intracaldera tuff. Mass balance calculations indicate fluid fluxes of = 6 ?? 10-6 mol cm-2 s-1. We believe that the closest historical analogue to this Chegem hydrothermal event is the situation observed in the Valley of Ten Thousand Smokes (Alaska, USA), where hundreds of steam fumaroles with measured temperatures as high as 645??C persisted for 10 to 15 years in the much smaller welded ash-flow tuff sheet (??? 200 m thick) produced by the 1912 Katmai eruption.

Gazis, C.; Taylor, H.P., Jr.; Hon, K.; Tsvetkov, A.

1996-01-01

213

Linking early Earth magma ocean crystallization and overturn with observed large low-shear-velocity provinces (LLSVPs) and short-lived radioisotopic measurements in Archean rocks  

NASA Astrophysics Data System (ADS)

Motivated by the well-characterized discrepancy between measurements of 142Nd in chondrites and those in Earth rocks (e.g.,[1][2]) in addition to recent measurements of Archean rocks with anomalous 142Nd and 182W (e.g.,[3][4][5]), we model the crystallization and overturn of a terrestrial chondritic magma ocean, and track the isotopic reservoirs that may result. Following magma ocean solidification, solid-state overturn occurs because solidification produces a gravitationally unstable configuration where the last cumulates to solidify are densest and also enriched in incompatible elements. As suggested by [1][2], these originally shallow cumulates that, following overturn, would now reside near the core-mantle boundary are tantalizing targets for the hypothesized hidden reservoir(s) of incompatible elements. These last, dense, enriched cumulates may have evolved negative 142Nd and 182W isotopic anomalies, while cumulates that form earlier and deeper in the magma ocean would likely be poor in incompatible elements and have evolved complementary positive isotopic anomalies. Because crystal - liquid partition coefficients of Sm, Nd, Hf, and W in nucleating mantle phases are poorly constrained and vary over orders of magnitude, we use a Monte Carlo approach to cover the parameter space of reported partition coefficients. Although data are limited, Archean rocks appear to show a non-linear trend between age and 142Nd and 182W, suggesting inefficient heterogeneous mixing of some of the early enriched reservoir (EER or late stage cumulates) back into the early depleted reservoir (EDR or deeper cumulates) during or after overturn, also first suggested by [1][2]. To account for this, we model various mixing scenarios using post-overturn mantle stratigraphy. Additionally, because 142Nd and 182W are decay products of short-lived radioisotopes, the timing of magma ocean crystallization is critical to producing a modern day mantle consistent with measured compositions. We therefore iterate through time to determine the statistically most likely time of the last major mantle-melting event. Consistent with [2], we argue that the EER is not hidden but is instead the seismologically observed large low-shear-velocity provinces (LLSVPs), or the D'' region, and the ultra low velocity zones (ULVZs) are dense, iron-rich silicon-poor melts of the LLSVPs. Given this, the isotopic reservoirs produced by our models must mix such that the EER remaining after mixing is the same volume as the LLSVPs, or 2% of the mantle (e.g., [6][7]). Approximately two-thirds our run results are "successful" given known partition coefficients, and so our results suggest that this model is viable: magma ocean fractional solidification can produce mantle reservoirs consistent with isotopic compositions observed in some rocks, and can produce a dense lower mantle layer consistent in longevity and volume to the LLSVPs. [1]Boyet and Carlson,2005,Science,309(5743),576-81.[2]Carlson and Boyet,2008,Phil. Trans. R. Soc. A,366(1883),4077-103. [3]Willbold et al.,2011,Nature,477(7363), 195-8. [4]Touboul et al.,2012,Science,335(6072),1065-9. [5]Rizo et al.,Nature,491(7422),96-100. [6]Burke et al.,2008,EPSL,265(1-2),49-60. [7]Hernlund and Houser,2008,EPSL,265(3-4),423-37.

Brown, S. M.; Elkins-Tanton, L. T.; Walker, R. J.

2013-12-01

214

Nuclear clusters studied with alpha resonant scatterings using RI beams at CRIB  

NASA Astrophysics Data System (ADS)

Alpha resonant scattering is a simple and promising method to study ?-cluster structure in nuclei. It has several good features which enable us to perform measurements with short-lived and relatively low-intense RI beams. Several measurements on alpha resonant scattering have been carried out at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. Recent ? resonant scattering studies at CRIB, using 7Li, 7Be and 10Be beams with a helium gas target, are discussed.

Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. N.; Kubono, S.; Suhara, T.; Kanada-En'yo, Y.; Moon, J. Y.; Kim, A.; Iwasa, N.; Lee, P. S.; Chae, K. Y.; Cha, S. M.; Gwak, M. S.; Kim, D. H.; Milman, E.

2014-12-01

215

{alpha} decay of the new isotope {sup 206}Ac  

SciTech Connect

The new neutron-deficient nuclide {sup 206}Ac was produced by bombarding a {sup 175}Lu target with 5.5 MeV/nucleon {sup 36}Ar ions. The evaporation residues were separated in flight by a gas-filled separator and subsequently identified by the {alpha}-{alpha} position and time correlation method. {sup 206}Ac was found to have two {alpha} particle emitting isomeric levels with half-lives of (22{sub {minus}5}{sup +9}) ms and (33{sub {minus}9}{sup +22}) ms, and with {alpha} particle energies of (7790{plus_minus}30) keV and (7750{plus_minus}20) keV, respectively. The former isomer is tentatively assigned to a J{sup {pi}}=3{sup +} level and the latter to a J{sup {pi}}=10{sup {minus}} level, both of which are also seen in the daughter and granddaughter nuclides {sup 202}Fr and {sup 198}At. Improved values of (27{sub {minus}6}{sup +11}) ms and (7693{plus_minus}25) keV for the half-life and {alpha} particle energy of {sup 207}Ac are also reported. {copyright} {ital 1998} {ital The American Physical Society}

Eskola, K. [Department of Physics, University of Helsinki, FIN-00014 Helsinki (Finland)] [Department of Physics, University of Helsinki, FIN-00014 Helsinki (Finland); Kuusiniemi, P.; Leino, M.; Cocks, J.F.; Enqvist, T.; Hurskanen, S.; Kettunen, H.; Trzaska, W.H.; Uusitalo, J. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40351 Jyvaeskylae (Finland)] [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40351 Jyvaeskylae (Finland); Allatt, R.G.; Greenlees, P.T.; Page, R.D. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom)] [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

1998-01-01

216

Alpha decay of neutron deficient polonium and bismuth isotopes  

SciTech Connect

Neutron deficient isotopes of polonium and bismuth have been produced in the reactions /sup 56/Fe+/sup n/atCe and /sup 56/Fe+/sup 141/Pr, separated from the primary beam by our gas-filled on-line mass separator. The half-lives have been determined by measuring the lifetimes of individual nuclei. The new isotope /sup 192/Po(T/sub 1/2/ = 34 +- 3 ms, E/sub ..cap alpha../ = 7.17 MeV) and a short-lived isomeric state in /sup 191/Bi (T/sub 1/2/ = 150 +- 15 ms, E/sub ..cap alpha../ = 6.86 MeV) have been identified.

Leino, M.E.; Yashita, S.; Ghiorso, A.

1981-11-01

217

Direct mass measurements of short-lived A=2Z-1 nuclides (63)Ge, (65)As, (67)Se, and (71)Kr and their impact on nucleosynthesis in the rp process.  

PubMed

Mass excesses of short-lived A=2Z-1 nuclei (63)Ge, (65)As, (67)Se, and (71)Kr have been directly measured to be -46,921(37), -46,937(85), -46,580(67), and -46,320(141)??keV, respectively. The deduced proton separation energy of -90(85)??keV for (65)As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of (65)As suggest that the majority of the reaction flow passes through (64)Ge via proton capture, indicating that (64)Ge is not a significant rp-process waiting point. PMID:21469858

Tu, X L; Xu, H S; Wang, M; Zhang, Y H; Litvinov, Yu A; Sun, Y; Schatz, H; Zhou, X H; Yuan, Y J; Xia, J W; Audi, G; Blaum, K; Du, C M; Geng, P; Hu, Z G; Huang, W X; Jin, S L; Liu, L X; Liu, Y; Ma, X; Mao, R S; Mei, B; Shuai, P; Sun, Z Y; Suzuki, H; Tang, S W; Wang, J S; Wang, S T; Xiao, G Q; Xu, X; Yamaguchi, T; Yamaguchi, Y; Yan, X L; Yang, J C; Ye, R P; Zang, Y D; Zhao, H W; Zhao, T C; Zhang, X Y; Zhan, W L

2011-03-18

218

In vitro cell irradiation systems based on 210Po alpha source: construction and characterisation  

NASA Technical Reports Server (NTRS)

One way of studying the risk to human health of low-level radiation exposure is to make biological experiments on living cell cultures. Two 210Po alpha-particle emitting devices, with 0.5 and 100 MBq activity, were designed and constructed to perform such experiments irradiating monolayers of cells. Estimates of dose rate at the cell surface were obtained from measurements by a PIPS alpha-particle spectrometer and from calculations by the SRIM 2000, Monte Carlo charged particle transport code. Particle fluence area distributions were measured by solid state nuclear track detectors. The design and dosimetric characterisation of the devices are discussed. c2002 Elsevier Science Ltd. All rights reserved.

Szabo, J.; Feher, I.; Palfalvi, J.; Balashazy, I.; Dam, A. M.; Polonyi, I.; Bogdandi, E. N.

2002-01-01

219

Targeted alpha-particle radiotherapy with 211At-labeled monoclonal antibodies.  

PubMed

An attractive feature of targeted radionuclide therapy is the ability to select radionuclides and targeting vehicles with characteristics that are best suited for a particular clinical application. One combination that has been receiving increasing attention is the use of monoclonal antibodies (mAbs) specifically reactive to receptors and antigens that are expressed in tumor cells to selectively deliver the alpha-particle-emitting radiohalogen astatine-211 (211At) to malignant cell populations. Promising results have been obtained in preclinical models with multiple 211At-labeled mAbs; however, translation of the concept to the clinic has been slow. Impediments to this process include limited radionuclide availability, the need for suitable radiochemistry methods operant at high activity levels and lack of data concerning the toxicity of alpha-particle emitters in humans. Nonetheless, two clinical trials have been initiated to date with 211At-labeled mAbs, and others are planned for the near future. PMID:17921029

Zalutsky, Michael R; Reardon, David A; Pozzi, Oscar R; Vaidyanathan, Ganesan; Bigner, Darell D

2007-10-01

220

Examining the mechanisms responsible for lower ROS release rates in liver mitochondria from the long-lived house sparrow (Passer domesticus) and big brown bat (Eptesicus fuscus) compared to the short-lived mouse (Mus musculus).  

PubMed

Lower ROS release rate in long-lived species is likely caused by decreased reduction of electron transport chain (ETC) complexes, but how this is achieved remains largely unknown. We compared liver mitochondrial H(2)O(2) release rates among endotherms of comparable size and metabolic rate: house sparrow and big brown bat (both long-lived) and house mouse (short-lived). We hypothesized that low ROS release rates in long-lived species result from (i) lower mitochondrial respiration rate, (ii) increased mitochondrial proton conductance ('uncoupling to survive'), and/or (iii) increased ETC oxidative capacity ('spare oxidative capacity'). H(2)O(2) release rate was 70% lower in bats than mice despite similar respiration rates. Consistent with 'uncoupling to survive', proton leakiness was 3-fold higher in bats at membrane potentials above 130mV. Basal H(2)O(2) release rate and respiration rates were 2-fold higher in sparrows than mice. Consistent with 'spare oxidative capacity', subsaturating succinate decreased H(2)O(2) release rate in sparrows but not mice. Moreover, succinate:Cytochrome c oxidoreductase activity was 3-fold higher in sparrows, and ETC inhibitors increased ROS release rate 20-27-fold in sparrows (with glutamate or subsaturating succinate) but only 4-5-fold in mice. Taken together these data suggest that complexes I and III are less reduced under physiological conditions in sparrows. We conclude that different long-lived species may use distinct mechanisms to lower mitochondrial ROS release rate. PMID:19464314

Brown, Jason C L; McClelland, Grant B; Faure, Paul A; Klaiman, Jordan M; Staples, James F

2009-08-01

221

DIFFERENCES AND SIMILARITIES IN ANDRA'S ASSESSMENT OF ACTIVITIES CARRIED OUT BY RADIOACTIVE WASTE GENERATORS AND AFFECTING THE QUALITY OF IL-LL SHORT-LIVED WASTE PACKAGES AND HL-IL LONG-LIVED WASTE PACKAGES  

SciTech Connect

In both cases of packages for either low-level and intermediate-level short-lived (LL-IL/SL) or high-level and intermediate-level long-lived (HL-IL/LL) radioactive waste, Andra has defined a quality reference system, manages it, follows up its appropriate implementation in production plants and verifies its effectiveness in production. The purpose of such a reference system is to ensure, in the first case, that waste packages comply with the Centre de l'Aube's acceptance criteria and, in the second case, that the characteristics submitted by the waste generators to Andra as input data for the deep geological repository project reflect the actual production conditions. In that context, the three management steps of the quality reference system include differences due to the fact that HL-IL/SL packages have not been submitted yet to any technical acceptance criterion. Compliance with any such criterion should be the subject of a characterization report during the qualification phase and of a examination during the verification phase. The management of the quality reference system also involves similarities that facilitate the joint work carried out by Andra with the waste generators, especially in the facilities where both package types are produced.

Trentesaux, C.; Cairon, P.; Dumont, J.-N.; Felix, B.; Losada, F.

2003-02-27

222

Alpha detection in pipes using an inverting membrane scintillator  

SciTech Connect

Characterization of surface alpha emitting contamination inside enclosed spaces such as piping systems presents an interesting radiological measurement challenge. Detection of these alpha particles from the exterior of the pipe is impossible since the alpha particles are completely absorbed by the pipe wall. Traditional survey techniques, using hand-held instruments, simply can not be used effectively inside pipes. Science and Engineering Associates, Inc. is currently developing an enhancement to its Pipe Explorer{trademark} system that will address this challenge. The Pipe Explorer{trademark} uses a unique sensor deployment method where an inverted tubular membrane is propagated through complex pipe runs via air pressure. The inversion process causes the membrane to fold out against the pipe wall, such that no part of the membrane drags along the pipe wall. This deployment methodology has been successfully demonstrated at several DOE sites to transport specially designed beta and gamma scintillation detectors into pipes ranging in length up to 250 ft. The measurement methodology under development overcomes the limitations associated with conventional hand-held survey instruments by remotely emplacing an alpha scintillator in direct contact with the interior pipe surface over the entire length to be characterized. This is accomplished by incorporating a suitable scintillator into the otherwise clear membrane material. Alpha particles emitted from the interior pipe surface will intersect the membrane, resulting in the emission of light pulses from the scintillator. A photodetector, towed by the inverting membrane, is used to count these light pulses as a function of distance into the pipe, thereby producing a log of the surface alpha contamination levels. It is anticipated that the resulting system will be able to perform measurements in pipes as small as two inches in diameter, and several hundred feet in length.

Kendrick, D.T.; Cremer, C.D.; Lowry, W.; Cramer, E.

1995-12-31

223

Astronuclear Physics with Short-Lived Isotopes  

E-print Network

A revolution in nuclear physics is underway. If you know hadron physics you also know that it will last long, as most past developments in nuclear physics have shown. It will take many decades of dedicated efforts of theorists and experimentalists to give astronomers, cosmologists and stellar modelers what they need for the accuracy required in the description and modeling of many cosmic phenomena of interest. In this contribution I review a small number of examples of the utmost relevance for the nuclear in the astro and in particular the humongous importance of the new area of astronuclear physics studied in radioactive beam facilities.

C. A. Bertulani

2014-03-31

224

RAPID DETERMINATION OF ACTINIDES IN URINE BY INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY: A HYBRID APPROACH  

SciTech Connect

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. 239Pu, 242Pu, 237Np, 243Am, 234U, 235U and 238U were measured by ICP-MS, while 236Pu, 238Pu, 239Pu, 241Am, 243Am and 244Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead. Multiple vacuum box locations may be set-up to supply several ICP-MS units with purified sample fractions such that a high sample throughput may be achieved, while still allowing for rapid measurement of short-lived actinides by alpha spectrometry.

Maxwell, S.; Jones, V.

2009-05-27

225

Alpha-1 Antitrypsin Deficiency  

MedlinePLUS

... Liver > Liver Disease Information > Alpha-1 Antitrypsin Deficiency Alpha-1 Antitrypsin Deficiency Explore this section to learn more about alpha-1 antitrypsin deficiency, including a description of the ...

226

EVOLUTION OF THE SOLAR NEBULA. IX. GRADIENTS IN THE SPATIAL HETEROGENEITY OF THE SHORT-LIVED RADIOISOTOPES {sup 60}Fe AND {sup 26}Al AND THE STABLE OXYGEN ISOTOPES  

SciTech Connect

Short-lived radioisotopes (SLRIs) such as {sup 60}Fe and {sup 26}Al were likely injected into the solar nebula in a spatially and temporally heterogeneous manner. Marginally gravitationally unstable (MGU) disks, of the type required to form gas giant planets, are capable of rapid homogenization of isotopic heterogeneity as well as of rapid radial transport of dust grains and gases throughout a protoplanetary disk. Two different types of new models of an MGU disk in orbit around a solar-mass protostar are presented. The first set has variations in the number of terms in the spherical harmonic solution for the gravitational potential, effectively studying the effect of varying the spatial resolution of the gravitational torques responsible for MGU disk evolution. The second set explores the effects of varying the initial minimum value of the Toomre Q stability parameter, from values of 1.4 to 2.5, i.e., toward increasingly less unstable disks. The new models show that the basic results are largely independent of both sets of variations. MGU disk models robustly result in rapid mixing of initially highly heterogeneous distributions of SLRIs to levels of {approx}10% in both the inner (<5 AU) and outer (>10 AU) disk regions, and to even lower levels ({approx}2%) in intermediate regions, where gravitational torques are most effective at mixing. These gradients should have cosmochemical implications for the distribution of SLRIs and stable oxygen isotopes contained in planetesimals (e.g., comets) formed in the giant planet region ({approx}5 to {approx}10 AU) compared to those formed elsewhere.

Boss, Alan P., E-mail: boss@dtm.ciw.edu [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

2011-10-01

227

Accelerator Production of 225Ac For Alpha-Immunotherapy  

NASA Astrophysics Data System (ADS)

225Ac has tremendous potential for the treatment of metastatic cancer due to the four alpha-particles emitted during its decay to stable 209Bi. Additionally, it is one of the few alpha-emitters being considered for clinical trials. The anticipated 225Ac demand for these trials is expected to far exceed the annual worldwide supply of approximately 1,000 mCi/yr. Consequently, the DOE Office of Science has funded investigations into accelerator-based production of 225Ac. Existing 232Th(p,x)225Ac cross section data indicate that up to 480 mCi/day of 225Ac could be created by bombarding a thick target of natural thorium with 100 MeV protons at the Los Alamos Isotope Production Facility. To verify these predictions, experiments are underway at the Los Alamos Neutron Science Center to measure the 232Th(p,x)225Ac production cross sections for protons in the energy range 40-200 MeV, and at 800 MeV. For 800 MeV protons, preliminary results indicate that the 225Ac production cross section is 12.4±0.6 mb and the 225Ra production cross section is 3.2±0.2 mb. Moreover, preliminary results suggest that the 227Ac production cross section is 16±1 mb. Experiments to measure these same cross sections at proton energies below 200 MeV are planned for the last half of calendar year 2010.

Weidner, J. W.; Nortier, F. M.; Bach, H. T.; John, K. D.; Couture, A.; Ullmann, J. L.; Fassbender, M. E.; Goff, G. S.; Taylor, W.; Valdez, F.; Wolfsberg, L. E.; Cisneros, M.; Dry, D.; Gallegos, M.; Gritzo, R.; Bitteker, L. J.; Wender, S.; Baty, R. S.

2011-06-01

228

Counting particles emitted by stratospheric aircraft and measuring size of particles emitted by stratospheric aircraft  

NASA Technical Reports Server (NTRS)

The ER-2 condensation nuclei counter (CNC) has been modified to reduce the diffusive losses of particles within the instrument. These changes have been successful in improving the counting efficiency of small particles at low pressures. Two techniques for measuring the size distributions of particles with diameters less than 0.17 micrometers have been evaluated. Both of these methods, the differential mobility analyzer (DMA) and the diffusion battery, have fundamental problems that limit their usefulness for stratospheric applications. We cannot recommend either for this application. Newly developed, alternative methods for measuring small particles include inertial separation with a low-loss critical orifice and thin-plate impactor device. This technique is now used to collect particles in the multisample aerosol collector housed in the ER-2 CNC-2, and shows some promise for particle size measurements when coupled with a CNC as a counting device. The modified focused-cavity aerosol spectrometer (FCAS) can determine the size distribution of particles with ambient diameters as small as about 0.07 micrometers. Data from this instrument indicates the presence of a nuclei mode when CNC-2 indicates high concentrations of particles, but cannot resolve important parameters of the distribution.

Wilson, James Charles

1994-01-01

229

ALPHA OMEGA ALPHA National Honor Medical Society  

E-print Network

12/6/2012 1 ALPHA OMEGA ALPHA National Honor Medical Society www.alphaomegaalpha.org AA and Leadership The Alpha Omega Alpha honor medical society was organized in 1902 to "recognize and perpetuate Enter into a contract with patients and society Build a foundation of medical professionalism Define

230

Study of short-lived climate forcers atmospheric variability at Kathmandu and at the WMO/GAW Global Station "Nepal Climate Observatory-Pyramid" (5079 m a.s.l.) in the Himalayas  

NASA Astrophysics Data System (ADS)

Aerosols and tropospheric ozone play a key role in the climate system, since they are short-lived climate forcers (SLCFs). South Asia represents a "hot-spot" in terms of climate change, since a vast region extending from the Indian Ocean to the Himalayas appears to be affected by large amounts of aerosols and pollutant gases (the so-called Atmospheric Brown Cloud). In the framework of the SusKat - ABC field campaign, a new measurement station has been installed in Pakanajol, Kathmandu (Nepal) on January 2013. This station is representative of the severe polluted conditions of the Kathmandu valley. Continuous measurements of equivalent black carbon (eqBC), surface ozone (O3), aerosol number concentration and size distribution, on-line PM10-PM1, as well as meteorological parameters, are carried out at this sampling site. In the high Himalayas (150 km north-east from Kathmandu), continuous atmospheric composition measurements are performed at the WMO/GAW Global Station Nepal Climate Observatory-Pyramid (NCO-P, 5079 m a.s.l.) in the Southern Himalayas. This measurement site is representative of the background conditions of the Himalayan ridge and measurements of eqBC, O3, aerosol number size distribution and meteorological parameters are continuously carried out since March 2006. The aim of this work is to compare the variability of atmospheric composition between the two sampling sites, with a particular emphasis on SLCFs, thus providing two complementary perspectives about the Atmospheric Brown Cloud phenomenon. Moreover, hints about the possible role of vertical air-mass transport of SLCFs from the foothills to the high Himalayas will be provided. The seasonal trend of eqBC at Pakanajol is characterized by a decreasing behavior from winter to monsoon, while at NCO-P it is characterized by a clear pre-monsoon maximum. On the other hand, at both sampling sites, O3 and particle number (accumulation and coarse) showed highest values during the pre-monsoon (April-May), even if at NCO-P significantly lower levels of eqBC and aerosol particle number (ratio 7% for eqBC, 29% for accumulation and 12% for coarse particles) were observed in respect to Kathmandu. Moreover, case studies concerning simultaneous events of eqBC and O3 increases in Kathmandu and in the high Himalayas will be investigated.

Putero, Davide; Cristofanelli, Paolo; Adhikary, Bhupesh; Marinoni, Angela; Duchi, Rocco; Calzolari, Francescopiero; Landi, Tony Christian; Pietro Verza, Gian; Alborghetti, Marcello; Vuillermoz, Elisa; Rupakheti, Maheswar; Lawrence, Mark; Bonasoni, Paolo

2014-05-01

231

Microbicidal Power of Alpha Radiation in Sterilizing Germinating Bacillus anthracis Spores  

PubMed Central

Radioimmunotherapy (RIT) takes advantage of the specificity and affinity of the antigen-antibody interaction to deliver microbicidal radioactive nuclides to a site of infection. In this study, we investigated the microbicidal properties of an alpha particle-emitting 213Bi-labeled monoclonal antibody (MAb), EA2-1 (213Bi-EA2-1), that binds to the immunodominant antigen on Bacillus anthracis spores. Our results showed that dormant spores were resistant to 213Bi-EA2-1. Significant spore killing was observed following treatment with EA2-1 labeled with 300 ?Ci 213Bi; however, this effect was not dependent on the MAb. In contrast, when spores were germinating, 213Bi-EA2-1 mediated MAb-specific killing in a dose-dependent manner. Dormant spores are very resistant to RIT, and RIT should focus on targeting vegetative cells and germinating spores. PMID:24379209

Morgenstern, Alfred; Bruchertseifer, Frank; Kearney, John F.; Turnbough, Charles L.; Dadachova, Ekaterina; Casadevall, Arturo

2014-01-01

232

Traversal of cells by radiation and absorbed fraction estimates for electrons and alpha particles  

SciTech Connect

Consideration of the pathlength which radiation traverses in a cell is central to algorithms for estimating energy deposition on a cellular level. Distinct pathlength distributions occur for radionuclides: (1) uniformly distributed in space about the cell (referred to as -randomness); (2) uniformly distributed on the surface of the cell (S-randomness); and (3) uniformly distributed within the cell volume (I-randomness). For a spherical cell of diameter d, the mean pathlengths are 2/3d, 1/2d, and 3/4d, respectively, for these distributions. Algorithms for simulating the path of radiation through a cell are presented and the absorbed fraction in the cell and its nucleus are tabulated for low energy electrons and alpha particles emitted on the surface of spherical cells. The algorithms and absorbed fraction data should be of interest to those concerned with the dosimetry of radionuclide-labeled monoclonal antibodies. 8 refs., 3 figs., 2 tabs.

Eckerman, K.F.; Ryman, J.C.; Taner, A.C.; Kerr, G.D.

1985-01-01

233

Sterically stabilized liposomes as a carrier for alpha-emitting radium and actinium radionuclides.  

PubMed

The alpha-particle emitting radionuclides (223)Ra (t(1/2) = 11.4 d), (224)Ra (t(1/2) = 3.6 d), and (225)Ac(t(1/2) = 10.0 d) may have a broad application in targeted radiotherapy provided that they could be linked to vehicles with tumor affinity. The potential usefulness of liposomes as carriers was studied in the present work. Radium and actinium radionuclides could be loaded in good yields into sterically stabilized liposomes. Subsequent coating of the liposomes with a folate-F(ab')(2) construct yielded a product with affinity towards tumor cells expressing folate receptors. Radionuclide loaded liposomes showed excellent stability in serum in vitro. PMID:15093814

Henriksen, Gjermund; Schoultz, B W; Michaelsen, T E; Bruland, Ø S; Larsen, R H

2004-05-01

234

Local Control of Lung Derived Tumors by Diffusing Alpha-Emitting Atoms Released From Intratumoral Wires Loaded With Radium-224  

SciTech Connect

Purpose: Diffusing alpha-emitters radiation therapy (DART) is a new form of brachytherapy enabling the treatment of solid tumors with alpha radiation. The present study examines the antitumoral effects resulting from the release of alpha emitting radioisotopes into solid lung carcinoma (LL2, A427, and NCI-H520). Methods and Materials: An in vitro setup tested the dose-dependent killing of tumor cells exposed to alpha particles. In in vivo studies, radioactive wires (0.3 mm diameter, 5 mm long) with {sup 224}Ra activities in the range of 21-38 kBq were inserted into LL/2 tumors in C57BL/6 mice and into human-derived A427 or NCI-H520 tumors in athymic mice. The efficacy of the short-lived daughters of {sup 224}Ra to produce tumor growth retardation and prolong life was assessed, and the spread of radioisotopes inside tumors was measured using autoradiography. Results: The insertion of a single DART wire into the center of 6- to 7-mm tumors had a pronounced retardation effect on tumor growth, leading to a significant inhibition of 49% (LL2) and 93% (A427) in tumor development and prolongations of 48% (LL2) in life expectancy. In the human model, more than 80% of the treated tumors disappeared or shrunk. Autoradiographic analysis of the treated sectioned tissue revealed the intratumoral distribution of the radioisotopes, and histological analysis showed corresponding areas of necrosis. In vitro experiments demonstrated a dose-dependent killing of tumors cells exposed to alpha particles. Conclusions: Short-lived diffusing alpha-emitters produced tumor growth retardation and increased survival in mice bearing lung tumor implants. These results justify further investigations with improved dose distributions.

Cooks, Tomer [Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); Schmidt, Michael [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv (Israel); Bittan, Hadas; Lazarov, Elinor [Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv (Israel); Arazi, Lior; Kelson, Itzhak [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv (Israel); Althera Medical Ltd., Tel Aviv (Israel); Keisari, Yona [Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel)], E-mail: ykeisari@post.tau.ac.il

2009-07-01

235

Alpha-1 Antitrypsin Deficiency  

MedlinePLUS

... page from the NHLBI on Twitter. What Is Alpha-1 Antitrypsin Deficiency? Alpha-1 antitrypsin (an-tee-TRIP-sin) deficiency, or ... deficiency as it relates to lung disease. Overview Alpha-1 antitrypsin, also called AAT, is a protein ...

236

Liver and Alpha-1  

MedlinePLUS

... Resources CSL Behring Grifols The mission of the Alpha-1 Foundation is to provide the leadership and ... more information, visit: www.alpha-1foundation.org. The Alpha-1 Association is the leading national patient membership ...

237

Alpha One Foundation  

MedlinePLUS

What is Alpha-1? A lpha-1 Antitrypsin Deficiency (Alpha-1) is a genetic (inherited) condition – it is passed from parents to their children through their genes. Alpha-1 may result in serious lung disease in ...

238

Effects of alpha-particles on survival and chromosomal aberrations in human mammary epithelial cells  

NASA Technical Reports Server (NTRS)

We have studied the radiation responses of a human mammary epithelial cell line, H184B5 F5-1 M/10. This cell line was derived from primary mammary cells after treatment with chemicals and heavy ions. The F5-1 M/10 cells are immortal, density-inhibited in growth, and non-tumorigenic in athymic nude mice and represent an in vitro model of the human epithelium for radiation studies. Because epithelial cells are the target of alpha-particles emitted from radon daughters, we concentrated our studies on the efficiency of alpha-particles. Confluent cultures of M/10 cells were exposed to accelerated alpha-particles [beam energy incident at the cell monolayer = 3.85 MeV, incident linear energy transfer (LET) in cell = 109 keV/microns] and, for comparison, to 80 kVp x-rays. The following endpoints were studied: (1) survival, (2) chromosome aberrations at the first postirradiation mitosis, and (3) chromosome alterations at later passages following irradiation. The survival curve was exponential for alpha-particles (D0 = 0.73 +/- 0.04 Gy), while a shoulder was observed for x-rays (alpha/beta = 2.9 Gy; D0 = 2.5 Gy, extrapolation number 1.6). The relative biological effectiveness (RBE) of high-LET alpha-particles for human epithelial cell killing was 3.3 at 37% survival. Dose-response curves for the induction of chromosome aberrations were linear for alpha-particles and linearquadratic for x-rays. The RBE for the induction of chromosome aberrations varied with the type of aberration scored and was high (about 5) for chromosome breaks and low (about 2) for chromosome exchanges.(ABSTRACT TRUNCATED AT 250 WORDS).

Durante, M.; Grossi, G. F.; Gialanella, G.; Pugliese, M.; Nappo, M.; Yang, T. C.

1995-01-01

239

Cancer Stem Cell Targeting Using the Alpha-Particle Emitter, 213Bi: Mathematical Modeling and Feasibility Analysis  

PubMed Central

There is increasing recognition that treatment failure in cancer may be associated with the failure to sterilize a small subpopulation of tumor cells that have been characterized as tumor stem cells. Defined as cells that are able to self-renew and also to replenish a phenotypically diverse tumor-cell population, such cells are also considered resistant to chemotherapy. These characteristics are optimal for targeting by using alpha-particle-emitting radionuclides. Because of their high-energy deposition density per track, alpha-particles are capable of targeting single cells or small clusters of cells with minimal normal organ toxicity. The DNA damage induced by alpha-particles is largely irreparable and, therefore, alpha-particle-induced damage is minimally susceptible to resistance mechanisms. In this work, theoretical modeling was performed to examine the potential of alpha-emitter targeting of such small clusters of cancer stem cells. Critical parameters influencing efficacy and toxicity were identified and their relationship elucidated. The results identify specific activity, antigen site density, and number of target cells as critical parameters for effective cell killing and demonstrate substantial efficacy gains by targeting a smaller number of stem cells, as opposed to the entire tumor-cell population. PMID:18298331

Sgouros, George; Song, Hong

2010-01-01

240

Experimental Identification of Spin-Parities and Single-Particle Configurations in {sup 257}No and Its {alpha}-Decay Daughter {sup 253}Fm  

SciTech Connect

{alpha}-{gamma} and {alpha}-electron coincidence spectroscopy for a short-lived heavy actinide nucleus {sup 257}No (T{sub 1/2}=24.5 s) has been performed using a gas-jet transport system and an on-line isotope separator. Spin-parities of excited states in {sup 253}Fm fed by the {alpha} decay of {sup 257}No have been identified on the basis of the measured internal conversion coefficients. The {nu}3/2{sup +}[622] configuration has been assigned to the ground state of {sup 257}No as well as to the 124.1 keV level in {sup 253}Fm. It was found that the ground-state configuration of {sup 257}No is different from that of lighter N=155 isotones.

Asai, M.; Tsukada, K.; Ichikawa, S.; Nagame, Y.; Nishinaka, I.; Akiyama, K. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Sakama, M. [Department of Radiologic Science and Engineering, The University of Tokushima, Tokushima 770-8509 (Japan); Ishii, T.; Osa, A. [Department of Materials Science, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Oura, Y. [Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan); Sueki, K. [Department of Chemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan); Shibata, M. [Radioisotope Research Center, Nagoya University, Nagoya 464-8602 (Japan)

2005-09-02

241

Accelerator Production of {sup 225}Ac For Alpha-Immunotherapy  

SciTech Connect

{sup 225}Ac has tremendous potential for the treatment of metastatic cancer due to the four alpha-particles emitted during its decay to stable {sup 209}Bi. Additionally, it is one of the few alpha-emitters being considered for clinical trials. The anticipated {sup 225}Ac demand for these trials is expected to far exceed the annual worldwide supply of approximately 1,000 mCi/yr. Consequently, the DOE Office of Science has funded investigations into accelerator-based production of {sup 225}Ac. Existing {sup 232}Th(p,x){sup 225}Ac cross section data indicate that up to 480 mCi/day of {sup 225}Ac could be created by bombarding a thick target of natural thorium with 100 MeV protons at the Los Alamos Isotope Production Facility. To verify these predictions, experiments are underway at the Los Alamos Neutron Science Center to measure the {sup 232}Th(p,x){sup 225}Ac production cross sections for protons in the energy range 40-200 MeV, and at 800 MeV. For 800 MeV protons, preliminary results indicate that the {sup 225}Ac production cross section is 12.4{+-}0.6 mb and the {sup 225}Ra production cross section is 3.2{+-}0.2 mb. Moreover, preliminary results suggest that the {sup 227}Ac production cross section is 16{+-}1 mb. Experiments to measure these same cross sections at proton energies below 200 MeV are planned for the last half of calendar year 2010.

Weidner, J. W.; Nortier, F. M.; Bach, H. T.; John, K. D.; Couture, A.; Ullmann, J. L.; Fassbender, M. E.; Goff, G. S.; Taylor, W.; Valdez, F.; Wolfsberg, L. E.; Cisneros, M.; Dry, D.; Gallegos, M.; Gritzo, R.; Bitteker, L. J.; Wender, S.; Baty, R. S. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

2011-06-01

242

Alpha-1 Antitrypsin Test  

MedlinePLUS

... 1 Antitrypsin; ?1-antitrypsin Related tests: Protein Electrophoresis ; Total Protein ; Blood Gases ; Liver Panel At a Glance Test ... Alpha-1 antitrypsin measures the level of the protein AAT in blood. Alpha-1 antitrypsin ... antitrypsin genotype testing ( DNA testing) can ...

243

Emphysema and Alpha-1  

MedlinePLUS

... be carriers of the defective gene that causes Alpha-1. About 100,000 people in the U.S. ... of people with COPD may actually have undiagnosed Alpha-1 deficiency. © 2015 American Association for Respiratory Care

244

Alpha-1 antitrypsin deficiency  

MedlinePLUS

Alpha-1 antitrypsin (AAT) deficiency is a condition in which the body does not make enough of a protein ... Alpha-1 antitrypsin (AAT) is a type of protein called a protease inhibitor. AAT is made in the liver ...

245

Personal alpha dosimetry and measurement of exposure to radon and thoron progeny and long-lived radioactive dust  

SciTech Connect

Personal alpha dosimeters are used in Canadian uranium mines and mills to monitor workers for exposure to radon and thoron progeny and Long-Lived Radioactive Dust (LLRD). Personal alpha dosimeters commonly used in Canadian uranium mines consist of a solid-state nuclear track detector (SSNTD) mounted in a battery operated air pumping system. The SSNTD system utilizes LR 115 Type II film as a detector which provides a permanent record of the exposure. The film is mounted inside a specially designed non-electronic spectrometer which consists of a collection filter, and a series of collimators fitted with energy absorbing materials of precise thicknesses. The spectrometer isolates the alpha particles emitted by radon and thoron progeny into separate and readily identifiable irradiated regions on the LR 115 film. After chemically etching the film to enlarge the tracks made by alpha radiation, the concentrations of radon and thoron progeny can be computed directly by optically counting the number of tracks created on the film. The lower limit of detection for the personal alpha dosimeter is between 4 and 5 mWLM and is based on a one month operation period at a nominal air flow rate of 4 L h{sup -1} through the SSNTD. LLRD measurements are obtained by performing standard gross alpha counts of the collection filter inside the SSNTD. The Minimum Detectable Amount (MDA) for the personal alpha dosimeter was calculated to be between 0.04 and 0.06 Bq m{sup -3} depending on the counting period. Comparative studies of the SSNTD measurement of radon and thoron progeny have been carried out at the United States Environmental Measurements Laboratory (EML) in New York, at the LANMET Radon/Thoron Chamber in Elliot Lake, Ontario, Canada, and at the CAIRS Radon/Thoron Calibration Chamber in Saskatoon, Saskatchewan, Canada.

Bjorndal, B.; Cubbon, G.; Moridi, R. [Canadian Inst. for Radiation Safety, Saskatchewan (Canada)

1996-06-01

246

Targeted alpha therapy: evidence for potential efficacy of alpha-immunoconjugates in the management of micrometastatic cancer.  

PubMed

There can be little doubt that one of the most important problems in the management of cancer is control of metastatic disease. This objective must be achieved ideally with a systemic therapeutic modality that targets cancer cells and gives minimal collateral damage to critical normal cells. The efficacy of targeted cancer therapy relies on the ability of a toxin to be located in the target cancer cell. The ideal toxin is one that is active only in the cancer cell, and not in critical normal cells. Failing this, the next best approach is a toxin with a short effective lifetime to target early stage micrometastatic disease. This rules out chemical toxins, given that they remain effective until excreted from the body, and localization of dose to the cancer cell rules out beta-emitting radio-isotopes (RI). Alpha-emitting RI, however, are much more appropriate toxins because they are short-lived and because their cytotoxicity is the result of their high rate of energy loss and short range of the alpha particles. These radionuclides have properties that are particularly suited for the elimination of single cells in transit or small nests of cancer cells. In vitro and in vivo experiments with alpha RI show dramatic superiority over beta RI. Only a few nuclear hits are needed to kill cells, and the formation of metastatic lung lesions and subcutaneous lesions in mice can be inhibited by systemic administration of alpha emitters. But alpha RI have not been able to control solid tumours, for which beta RI are better suited. A small number of alpha-emitting radionuclides are currently under investigation. These are terbium (Tb)-149, astatine (At)-211, bismuth (Bi)-212 and Bi-213. Terbium-149 and At-211 both require accelerators in close proximity to the place of application. The Bi isotopes are produced by long-lived parents and, as such, can be obtained from generators. The first phase-1 dose escalation trial with Bi-213 radioimmunoconjugate (RIC) commenced in New York in 1997, and other trials are planned with At-211 RIC and At-211 methylene blue for melanoma. Actinium (Ac)-225 is obtained from the decay of thorium (Th)-229, which is a waste product in the enrichment of fissile Th-233. Alternative accelerator production routes are being investigated, beginning with the European Centre for Nuclear Research (CERN) GeV proton spallation source. The ready and low-cost availability of the Ac:Bi generator is an important element in the implementation of clinical trials for patients with poor prognoses but without evidence of metastatic disease. PMID:10901964

Allen, B J

1999-11-01

247

Observation of lunar radon emanation with the Apollo 15 alpha particle spectrometer.  

NASA Technical Reports Server (NTRS)

The alpha particle spectrometer, a component of the orbital Sim Bay group of 'geochemistry' experiments on Apollo 15, was designed to detect alpha particles emitted during the decay of isotopes of radon gas and her daughter products. The purpose was to measure the gross activity of radon on the lunar surface and to find possible regions of increased local activity. Results are presented from a partial analysis of Apollo 15 data. For the moon as a whole, Rn220 was not observed and the upper limit on its decay rate above the lunar surface is 0.00038 disintegrations/sq cm-sec. Rn222 was marginally observed. Possible variations of radon activity on the lunar surface are being investigated. Po210 (a daughter product of Rn222) has been detected in a broad region from west of Mare Crisium to the Van de Graaff-Orlov region. The observed count rate is (4.6 plus or minus 1.4) x 0.001 disintegrations/sq cm-sec. The observed level of Po210 activity is in excess of the amount that would be in equilibrium with Rn222 by about an order of magnitude. This implies that larger levels of radon emanation have occurred on the moon within a time scale of 10 to 100 years.

Gorenstein, P.; Bjorkholm, P.

1972-01-01

248

Preferential leaching and the age of radiation damage from alpha decay in minerals  

NASA Astrophysics Data System (ADS)

Preferential release into solution of radionuclides that result from alpha decay is a contributor to natural isotopic disequilibrium. Such release is critical to geochemical understanding of alpha-decay products and would be an undesirable characteristic of solidified nuclear waste in deep geological formations. Spontaneous annealing of the radiation damage that is responsible for the preferential release is shown to diminish the effect in thorianite and uraninite which we have found to be 550 to 1000 M.y. old, respectively. Leaching experiments and measurements of the thorium and uranium isotopes show that there is strongly enhanced release of short-lived 228Th relative to 232Th, but only slight enhancement of long-lived 234U and 230Th relative to 238U and 232Th. These results are interpreted in terms of natural annealing of damage occurring on a time scale between the ~10 and 10 5 years of the alpha-decay products. With a simple assumption actual times for the survival of the enhanced leaching in these minerals are ~ 15,000 years.

Eyal, Yehuda; Fleischer, Robert L.

1985-05-01

249

Postmortem diagnosis of diabetic metabolic derangement: elevated alpha 1-antitrypsin and haptoglobin glycosylation levels as an index of antemortem hyperglycemia.  

PubMed

Fatal diabetic metabolic derangement is difficult to diagnose postmortem because of the paucity of characteristic morphologic findings. Hyperglycemia is an indicator of diabetic derangement. Conventional biochemical parameters for postmortem diagnosis of antemortem hyperglycemic states are not sufficiently resistant to antemortem and postmortem non-diabetic influences or are suited only for long and medium-term assessment of diabetes control. In the search for other, more reliable, indices of immediately antemortem blood glucose levels, we investigated the value of glycosylation levels of serum proteins with very brief biologic half-lives: a) In vitro studies were performed on the glycosylation course of the short-lived serum proteins alpha 1-antitrypsin (alpha 1-AT) and haptoglobin (HP). b) Glycosylation levels were measured after purification of alpha 1-AT and HP from sera of living and deceased non-diabetics and diabetics. c) The resistance of alpha 1-AT and HP glycosylation levels to autolysis was investigated. Our studies revealed the following: 1) alpha 1-AT and HP glycosylate considerably more rapidly than either albumin or hemoglobin. This rapid glycosylation, combined with the rapid turnover of both proteins; facilitates detection of short-term changes in glycemia. 2) alpha 1-AT and HP glycosylation levels are autolysis-stable and can be assessed even after advanced hemolysis. 3) alpha 1-AT and HP glycosylation levels appear to allow reliable ante- and postmortem discrimination between normoglycemic and hyperglycemic metabolic states. As a tool in the postmortem diagnosis of antemortem hyperglycemic states, alpha 1-AT and HP glycosylation levels combine the advantages of a short-term parameter with resistance to non-diabetic influences. PMID:8934703

Ritz, S; Mehlan, G; Martz, W

1996-01-01

250

Rossi Alpha Method  

SciTech Connect

The Rossi Alpha Method has proved to be valuable for the determination of prompt neutron lifetimes in fissile assemblies having known reproduction numbers at or near delayed critical. This workshop report emphasizes the pioneering applications of the method by Dr. John D. Orndoff to fast-neutron critical assemblies at Los Alamos. The value of the method appears to disappear for subcritical systems where the Rossi-..alpha.. is no longer an ..alpha..-eigenvalue.

Hansen, G.E.

1985-01-01

251

Alpha-1 Health Tips  

MedlinePLUS

... risk factors. The biggest risk factor for lung disease is cigarette smoking. Any Alpha who smokes must stop! It is also important to avoid second-hand smoke and avoid inhaling irritants at ... available for Alphas with lung disease, this is only one part of the management ...

252

Alpha-1 Panniculitis  

MedlinePLUS

... of serum levels of alpha-1 antitrypsin (typically PI*ZZ) and others with only mild deficiency (typically PI*MZ). In one reported series of 26 patients with panniculitis and Alpha-1, 62 percent were PI*ZZ; 15 percent were PI*MZ; 8 percent ...

253

Event counting alpha detector  

DOEpatents

An electrostatic detector is disclosed for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure. 6 figs.

Bolton, R.D.; MacArthur, D.W.

1996-08-27

254

Event counting alpha detector  

DOEpatents

An electrostatic detector for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure.

Bolton, Richard D. (Los Alamos, NM); MacArthur, Duncan W. (Los Alamos, NM)

1996-01-01

255

Imaging alpha particle detector  

DOEpatents

A method and apparatus for detecting and imaging alpha particles sources is described. A conducting coated high voltage electrode (1) and a tungsten wire grid (2) constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source (3) to be quantitatively or qualitatively analyzed. A thin polyester film window (4) allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

Anderson, David F. (Los Alamos, NM)

1985-01-01

256

ELEMENTAL COMPOSITION OF SIZED PARTICLES EMITTED FROM STATIONARY SOURCES  

EPA Science Inventory

This paper discusses several approaches for obtaining the elemental and, in a few cases, inorganic compound identification in sized particles. The elemental analyses are done by wavelength dispersion x-ray fluorescence (WXRF). Fourier Transform infrared is being used for inorgani...

257

SURFACE ANALYSIS OF PARTICLES EMITTED TO THE ATMOSPHERE (JOURNAL VERSION)  

EPA Science Inventory

A number of potentially toxic trace metal and organic species have been shown to be preferentially enriched on the surfaces of most types of anthropogenic particles which are emitted to the atmosphere. The use of several surface analytical techniques including ion microprobe mass...

258

Reexamination of the {alpha}-{alpha}''fishbone'' potential  

SciTech Connect

The fishbone potential of composite particles simulates the Pauli effect by nonlocal terms. We determine the {alpha}-{alpha} fishbone potential by simultaneously fitting to two-{alpha} resonance energies, experimental phase shifts, and three-{alpha} binding energies. We found that, essentially, a simple Gaussian can provide a good description of two-{alpha} and three-{alpha} experimental data without invoking three-body potentials.

Day, J. P.; McEwen, J. E.; Elhanafy, M.; Smith, E.; Woodhouse, R.; Papp, Z. [Department of Physics and Astronomy, California State University Long Beach, Long Beach, California (United States)

2011-09-15

259

Genetics Home Reference: Alpha thalassemia  

MedlinePLUS

... PubMed Recent literature OMIM Genetic disorder catalog Conditions > Alpha thalassemia On this page: Description Genetic changes Inheritance ... names Glossary definitions Reviewed August 2009 What is alpha thalassemia? Alpha thalassemia is a blood disorder that ...

260

Alpha Thalassemia (For Parents)  

MedlinePLUS

... of alpha thalassemia trait may want to seek genetic counseling if they're considering having children. If your ... For Parents MORE ON THIS TOPIC Genetic Testing Genetic Counseling All About Genetics Blood Blood Test: Hemoglobin Electrophoresis ...

261

Alpha Particle Diagnostic  

SciTech Connect

The study of burning plasmas is the next frontier in fusion energy research, and will be a major objective of the U.S. fusion program through U.S. collaboration with our international partners on the ITER Project. For DT magnetic fusion to be useful for energy production, it is essential that the energetic alpha particles produced by the fusion reactions be confined long enough to deposit a significant fraction of their initial ~3.5 MeV energy in the plasma before they are lost. Development of diagnostics to study the behavior of energetic confined alpha particles is a very important if not essential part of burning plasma research. Despite the clear need for these measurements, development of diagnostics to study confined the fast confined alphas to date has proven extremely difficult, and the available techniques remain for the most part unproven and with significant uncertainties. Research under this grant had the goal of developing diagnostics of fast confined alphas, primarily based on measurements of the neutron and ion tails resulting from alpha particle knock-on collisions with the plasma deuterium and tritium fuel ions. One of the strengths of this approach is the ability to measure the alphas in the hot plasma core where the interesting ignition physics will occur.

Fisher, Ray, K.

2009-05-13

262

On Al-26 and other short-lived interstellar radioactivity  

NASA Technical Reports Server (NTRS)

Several authors have shown that massive stars exploding at a rate of about three per century can account for a large portion, if not all, of the observed interstellar Al-26. In a separate argument using models of Galactic chemical evolution, Clayton (1984) showed that the Al-26/Al-27 production ratio was not large enough to maintain enough Al-26 in the Galactic disk gas of about 10 exp 10 solar masses having solar composition. We present a resolution of those conflicting arguments. A past history of Galactic infall growing the Galactic disk so dilutes the stable Al-27 concentration that the two approaches can be brought into near agreement. If massive stars dominate the production of Al-26, we suggest that the apparent shortfall of their Al-26/Al-27 yield ratio is to be interpreted as evidence for significant growth of the Galactic disk. We also discuss the implications of these arguments for other extinct radioactivities in meteorites, using I-129 and Sm-146 as examples.

Clayton, Donald D.; Hartmann, Dieter H.; Leising, Mark D.

1993-01-01

263

Short-Lived Radioactivities and Recent Star Formation  

NASA Astrophysics Data System (ADS)

We follow the time evolution of isotopes in a multi-dimensional molecular cloud model. Solar systems that form with low 60Fe show 26Al well below the canonical value, as expected. Some solar systems show interesting levels of 182Hf and 129I.

Meyer, B. S.; Bojazi, M. J.

2014-09-01

264

Cosmic crystallography using short-lived objects - Active Galactic Nuclei  

Microsoft Academic Search

Cosmic crystallography is based on the principle that peaks in the pair separation histogram (PSH) of objects in a catalogue should be induced by the high number of topologically lensed pairs that are separated by Clifford translations, in excess to ``random'' pairs of objects. Here we present modifications of this method that successively improve the signal-to-noise ratio by removing a

Andrzej Marecki; B. F. Roukema; Stanislaw Bajtlik

2005-01-01

265

Harvard-MIT research program in short-lived radiopharmaceuticals  

SciTech Connect

This report presents research on radiopharmaceuticals. The following topics are discussed: antibody labeling with positron-emitting radionuclides; antibody modification for radioimmune imaging; labeling antibodies; evaluation of technetium acetlyacetonates as potential cerebral blood flow agents; and studies in technetium chemistry. (CBS)

Adelstein, S.J.

1991-01-01

266

Short-lived Rn-222 daughters in cryogenic liquids  

SciTech Connect

In this paper a detection method of ? emitters from {sup 222}Rn decay chain, present in cryogenic liquids, using bare Si-PIN diodes immersed in the liquids is presented. Properties of ionized {sup 222}Rn daughters deduced from conducted measurements are outlined. Life-time of positive ions was found to be of the order of 10 s, and nonzero content of electronegative ions was observed.

Pelczar, Krzysztof; Frodyma, Nikodem; Wójcik, Marcin [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków (Poland)] [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków (Poland)

2013-08-08

267

Crantor, a short-lived horseshoe companion to Uranus  

E-print Network

Stable co-orbital motion with Uranus is vulnerable to planetary migration but temporary co-orbitals may exist today. So far only two candidates have been suggested, both moving on horseshoe orbits: 83982 Crantor (2002 GO9) and 2000 SN331. (83982) Crantor is currently classified in the group of the Centaurs by the MPC although the value of its orbital period is close to that of Uranus. Here we revisit the topic of the possible 1:1 commensurability of (83982) Crantor with Uranus and also explore its dynamical past and look into its medium-term stability and future orbital evolution. (83982) Crantor currently moves inside Uranus' co-orbital region on a complex horseshoe orbit. The motion of this object is primarily driven by the influence of the Sun and Uranus, although Saturn plays a significant role in destabilizing its orbit. The precession of the nodes of (83982) Crantor, which is accelerated by Saturn, controls its evolution and short-term stability. Although this object follows a temporary horseshoe orbit,...

Marcos, C de la Fuente

2013-01-01

268

Life Extension in the Short-Lived Fish Nothobranchius furzeri  

Microsoft Academic Search

\\u000a Genetic and pharmacological research on aging is hampered by the life span of available vertebrate models. We recently initiated\\u000a studies on Nothobranchius furzeri, a species with a maximum life expectancy in captivity of just 3 months, the shortest documented captive life span for a vertebrate.\\u000a Further research on N. furzeri has demonstrated the following:\\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a Short life span correlates with

Alessandro Cellerino

269

Tropospheric Ozone as a Short-lived Chemical Climate Forcer  

NASA Technical Reports Server (NTRS)

Tropospheric ozone is the third most important greenhouse gas according to the most recent IPCC assessment. However, tropospheric ozone is highly variable in both space and time. Ozone that is located in the vicinity of the tropopause has the greatest effect on climate forcing. Nitrogen oxides (NOx) are the most important precursors for ozone In most of the troposphere. Therefore, pollution that is lofted upward in thunderstorm updrafts or NOx produced by lightning leads to efficient ozone production in the upper troposphere, where ozone is most important climatically. Global and regional model estimates of the impact of North American pollution and lightning on ozone radiative forcing will be presented. It will be shown that in the Northern Hemisphere summer, the lightning effect on ozone radiative forcing can dominate over that of pollution, and that the radiative forcing signal from North America extends well into Europe and North Africa. An algorithm for predicting lightning flash rates and estimating lightning NOx emissions is being incorporated into the NASA GEOS-5 Chemistry and Climate Model. Changes in flash rates and emissions over an ENSO cycle and in future climates will be assessed, along with the resulting changes in upper tropospheric ozone. Other research on the production of NOx per lightning flash and its distribution in the vertical based on cloud-resolving modeling and satellite observations will be presented. Distributions of NO2 and O3 over the Middle East from the OMI instrument on NASA's Aura satellite will also be shown.

Pickering, Kenneth E.

2012-01-01

270

Production of a short-lived filament by a surge  

NASA Technical Reports Server (NTRS)

A large surge was observed on September 17, 1971 part of which, after travelling 200,000 km across the surface, returned to the surface to form a filament. The filament lasted about 30 minutes, then rose up and returned to the source of the surge. This was interpreted as the filling of a semi-stable magnetic trap. Analysis of the microwave radio burst showed it to have been produced by a source optically thick at 8,800 MHz, with area 4 (arc min)squared and T approximately 275,000 deg, N squared sub eV approximately 7 x 10 to the 48th power. The soft x-ray burst showed a component at 12 x 1,00.000 deg with N squared sub eV approximately 3 x 10 to the 48th power.

Zirin, H.

1976-01-01

271

RAPID DETERMINATION OF 237 NP AND PU ISOTOPES IN WATER BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY  

SciTech Connect

A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of {sup 237}Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry; a hybrid approach. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4 to 6 hours, and can also be used for emergency response. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu, {sup 238}Pu, and {sup 239}Pu were measured by alpha spectrometry.

Maxwell, S.; Jones, V.; Culligan, B.; Nichols, S.; Noyes, G.

2010-06-23

272

AlphaGalileo  

NSDL National Science Digital Library

AlphaGalileo is designed for science journalists, but anyone with an itch for breaking academic news will enjoy this research-rich site. Readers may browse by region, including Africa, Asia, Caribbean, Europe, Latin America, Middle East, North America, Oceania, and this Scout EditorâÂÂs favorite: Extraterrestrial. Next, try trawling the site by Science, Health, Society, Humanities, Arts, Applied Science, and Business for the latest illuminating research in each of these fields. AlphaGalileo also issues News Releases, usually five or six paragraphs long, that cover particularly interesting research findings. Best of all, since the Scout Report previously covered AlphaGalileo back in 2007, the site has dropped its membership requirements and visitors can browse more freely than ever.

273

Mitigation of radiation nephropathy after internal {alpha}-particle irradiation of kidneys  

SciTech Connect

Purpose: Internal irradiation of kidneys as a consequence of radioimmunotherapy, radiation accidents, or nuclear terrorism can result in radiation nephropathy. We attempted to modify pharmacologically, the functional and morphologic changes in mouse kidneys after injection with the actinium ({sup 225}Ac) nanogenerator, an in vivo generator of {alpha}- and {beta}-particle emitting elements. Methods and Materials: The animals were injected with 0.35 {mu}Ci of the {sup 225}Ac nanogenerator, which delivers a dose of 27.6 Gy to the kidneys. Then, they were randomized to receive captopril (angiotensin-converting enzyme inhibitor), L-158,809 (angiotensin II receptor-1 blocker), spironolactone (aldosterone receptor antagonist), or a placebo. Results: Forty weeks after the {sup 225}Ac injection, the placebo-control mice showed a significant increase in blood urea nitrogen (BUN) (87.6 {+-} 6.9 mg/dL), dilated Bowman spaces, and tubulolysis with basement membrane thickening. Captopril treatment accentuated the functional (BUN 119.0 {+-} 4.0 mg/dL; p <0.01 vs. placebo controls) and histopathologic damage. In contrast, L-158,809 offered moderate protection (BUN 66.6 {+-} 3.9 mg/dL; p = 0.02 vs. placebo controls). Spironolactone treatment, however, significantly prevented the development of histopathologic and functional changes (BUN 31.2 {+-} 2.5 mg/dL; p <0.001 vs. placebo controls). Conclusions: Low-dose spironolactone and, to a lesser extent, angiotensin receptor-1 blockade can offer renal protection in a mouse model of internal {alpha}-particle irradiation.

Jaggi, Jaspreet Singh [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Seshan, Surya V. [Department of Pathology, Cornell University Weill Medical College, New York, NY (United States); McDevitt, Michael R. [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Sgouros, George [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD (United States); Hyjek, Elizabeth [Department of Pathology, Cornell University Weill Medical College, New York, NY (United States); Scheinberg, David A. [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States) and Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)]. E-mail: d-scheinberg@ski.mskcc.org

2006-04-01

274

[alpha]-Oxocarboxylic Acids  

ERIC Educational Resources Information Center

Several [alpha]-oxocarboxylic acids play key roles in metabolism in plants and animals. However, there are inconsistencies between the structures as commonly portrayed and the reported acid ionization constants, which result because the acids are predominantly hydrated in aqueous solution; that is, the predominant form is RC(OH)[subscript 2]COOH…

Kerber, Robert C.; Fernando, Marian S.

2010-01-01

275

[alpha-Neurotoxins and alpha-conotoxins--nicotinic cholinoreceptor blockers].  

PubMed

The review is devoted to the competitive blockers of different nicotinic acetylcholine receptors, alpha-neurotoxins from snake venoms, and alpha-conotoxins from marine snails of the Conidae family. The relationship between the structure and function of these toxins is discussed. Recent data on the mechanism of alpha-neurotoxin and alpha-conotoxin interaction with the nicotinic acetylcholine receptor are presented. PMID:10645484

Utkin, Iu N; Kasheverov, I E; Tsetlin, V I

1999-11-01

276

ChemTeacher: Alpha Decay  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Alpha Decay page includes resources for teaching students about the discovery and applications of alpha decay.

2011-01-01

277

Ethanol inhibits palmitoylation of G protein G alpha(s).  

PubMed

Neurobiological actions of ethanol have been linked to perturbations in cyclic AMP (cAMP)-dependent signaling processes. Chronic ethanol exposure leads to desensitization of cAMP production in response to physiological ligands (heterologous desensitization). Ethanol-induced alterations in neuronal expression of G proteins G(s) and G(i) have been invoked as a cause of heterologous desensitization. However, effects of ethanol on G protein expression vary considerably among different experimental protocols, various brain regions and diverse neuronal cell types. Dynamic palmitoylation of G protein alpha subunits is critical for membrane localization and protein-protein interactions, and represents a regulatory feature of G protein function. We studied the effect of ethanol on G alpha(s) palmitoylation. In NG108-15 rat neuroblastoma x glioma hybrid cells, acute exposure to pharmacologically relevant concentrations of ethanol (25-100 mm) inhibited basal and prostaglandin E1-stimulated incorporation of palmitate into G alpha(s). Exposure of NG108-15 cells to ethanol for 72 h induced a shift in G alpha(s) to its non-palmitoylated state, coincident with an inhibition of prostaglandin E1-induced cAMP production. Both parameters were restored following 24 h of ethanol withdrawal. Chronic ethanol exposure also induced the depalmitoylation of G alpha(s) in human embryonic kidney (HEK)293 cells that overexpress wild-type G alpha(s) and caused heterologous desensitization of adenylyl cyclase. By contrast, HEK293 cells that express a non-palmitoylated mutant of G alpha(s) were insensitive to heterologous desensitization after chronic ethanol exposure. In summary, the findings identify a novel effect of ethanol on post-translational lipid modification of G alpha(s), and represent a mechanism by which ethanol might affect adenylyl cyclase activity. PMID:15140191

Hallak, Hazem; Rubin, Raphael

2004-05-01

278

The alpha 21264 microprocessor  

Microsoft Academic Search

The third generation Alpha microprocessor from Compaq Computer Corporation (formerly Digital Equipment) is the 21264. This microprocessor can execute 2.0-2.4 billion instructions per second with a 500-600 MHz cycle time in a 0.35 um CMOS process, resulting in the industry-leading performance of 30+ SPECint95 and 58+ SPECfp95 in early system offerings. This paper focuses on the overall 21264 architecture, as

Richard E. Kessler

1999-01-01

279

Stellar Helium Burning: a Further Measurement of the Beta-Delayed Alpha-Particle Emission of (16)N  

NASA Astrophysics Data System (ADS)

The 12C(?,?)16O reaction is of critical importance for understanding stellar evolution. During helium burning this reaction competes with the triple-alpha reaction that forms carbon. The final carbon/oxygen ratio at the end of this burning stage largely determines the final stages of the star. The beta-delayed alpha-emission of 16N (i.e. prompt alpha-particles emitted from excited states of 16O populated by the slow beta-decay of 16N) has been predicted to provide a constraint on the cross section of this reaction, but requires a high sensitivity (B.R. ~ 10-9) measurement. The low energy portion of the alpha-particle spectrum has been predicted to provide a sensitive means to deduce the reduced alpha-particle width of the bound 1- state in 16O. In the past few years three attempts have been made to constrain the p-wave component of this cross section using the beta-delayed alpha-particle emission of 16N. In this work we have made a high statistics measurement of this spectrum as a continuation of our earlier low statistics Yale-UConn experiment. We have improved the statistics by a factor of more than 5, the energy resolution by 20%, and we demonstrate an understanding of our line shape from known and measured quantities. Our newly measured spectrum is compared to the three previous high statistics experiments and found to be consistent with the experimental results from Mainz and Seattle and inconsistent with those from TRIUMF. Our discrepancy with the TRIUMF results is in the width of the primary peak, with the largest differences (nearly a factor of two) near the region of the interference minimum. This region of the spectrum determines the size of the f-wave contribution to the low energy secondary maximum. This is crucial as the magnitude of the p-wave contribution only is of importance to astrophysics due to the low energy (~300 keV) that stellar helium burning occurs in massive stars. We conclude that with the current data sets the p-wave S-factor of the 12C(?,?)16O reaction cannot be determined at this stage with the accuracy (15-20%) required for the stellar evolution models developed by Woosley and Weaver.

France, Ralph Hayward, III

1997-11-01

280

Background canceling surface alpha detector  

DOEpatents

A background canceling long range alpha detector which is capable of providing output proportional to both the alpha radiation emitted from a surface and to radioactive gas emanating from the surface. The detector operates by using an electrical field between first and second signal planes, an enclosure and the surface or substance to be monitored for alpha radiation. The first and second signal planes are maintained at the same voltage with respect to the electrically conductive enclosure, reducing leakage currents. In the presence of alpha radiation and radioactive gas decay, the signal from the first signal plane is proportional to both the surface alpha radiation and to the airborne radioactive gas, while the signal from the second signal plane is proportional only to the airborne radioactive gas. The difference between these two signals is proportional to the surface alpha radiation alone.

MacArthur, Duncan W. (Los Alamos, NM); Allander, Krag S. (Ojo Caliente, NM); Bounds, John A. (Los Alamos, NM)

1996-01-01

281

Long range alpha particle detector  

DOEpatents

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

MacArthur, D.W.; Wolf, M.A.; McAtee, J.L.; Unruh, W.P.; Cucchiara, A.L.; Huchton, R.L.

1993-02-02

282

Long range alpha particle detector  

DOEpatents

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

MacArthur, Duncan W. (Los Alamos, NM); Wolf, Michael A. (Los Alamos, NM); McAtee, James L. (Los Alamos, NM); Unruh, Wesley P. (Los Alamos, NM); Cucchiara, Alfred L. (Los Alamos, NM); Huchton, Roger L. (Los Alamos, NM)

1993-01-01

283

Alpha particle confinement in tokamaks  

SciTech Connect

An assessment of diffusive tokamak transport mechanisms of concern for alpha particles indicates that the ''stochastic regime'' is the only one which appears to pose a real danger for adequate alpha confinement. This fact, in conjunction with the threshold character of that mechanism, allows one to decide whether an alpha born at a given location will be lost or confined, according to a very simple criterion. Implementing this criterion numerically results in a new code for the assessment of alpha confinement, which is orders of magnitude faster than earlier codes used for this purpose. 13 refs., 3 figs., 1 tab.

White, R.B.; Mynick, H.E.

1988-11-01

284

Live! From 2-Alpha  

NSDL National Science Digital Library

This activity is one of several in which students are required to access and analyze actual data from NASA missions, including video "interviews" with real NASA scientists, to solve a mystery. In this mystery, students learn about the force of gravity and how scientists analyze data by studying the properties of different objects in space. Live! From 2-Alpha can be used to support instruction about forces and motion, origin and evolution of the universe, and the interaction of energy and matter. This activity is one of several in "Space Mysteries," a series of inquiry-driven, interactive Web explorations. Each Mystery in "Space Mysteries" is designed to teach at least one physical science concept (e.g. interactions of energy and matter, structures and properties of matter, energy, motion, or forces), and is accompanied by materials to be used by classroom teachers.

285

DFT CONFORMATIONAL STUDIES OF ALPHA-MALTOTRIOSE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent DFT optimization studies on alpha-maltose improved our understanding of the preferred conformations of alpha-maltose and the present study extends these studies to alpha-maltotriose with three alpha-D-glucopyranose residues linked by two alpha-[1-4] bridges, denoted herein as DP-3's. Combina...

286

Efficacy of astatine-211-labeled monoclonal antibody in treatment of murine T-cell lymphoma  

SciTech Connect

The short-lived isotope /sup 211/At (half-life, 7.2 hr), an alpha particle-emitting halogen, has been attached to a monoclonal antibody (anti-thy 1.1, IgG1, OX7) and used in mice in the treatment of a thy 1.1 T-cell lymphoma (A120). Forty-eight hours after receiving an iv injection of 10(3) or 10(5) A120 cells, mice were treated with phosphate-buffered saline, /sup 211/At-, antibody alone, or /sup 211/At conjugated to OX7. Treatment with the /sup 211/At-labeled OX7 conjugate increased the median survival time of mice and probably cured (survival at 200 days) 6 of the 15 mice given 10(5) cells and 21 of the 27 mice given 10(3) cells.

Harrison, A.; Royle, L.

1987-01-01

287

EEG Alpha Power and Intelligence.  

ERIC Educational Resources Information Center

Tested whether alpha power in different sub-bands is selectively related to intelligence. For 74 Austrian subjects, the EEG was recorded during a resting session and 2 different intelligence tests were performed. Findings show a strong positive correlation between intelligence and alpha power. (SLD)

Doppelmayr, M.; Klimesch, W.; Stadler, W.; Pollhuber, D.; Heine, C.

2002-01-01

288

Determination of alpha_s from the QCD static energy  

E-print Network

We compare lattice data for the short-distance part of the static energy in 2+1 flavor quantum chromodynamics (QCD) with perturbative calculations, up to next-to-next-to-next-to leading-logarithmic accuracy. We show that perturbation theory describes very well the lattice data at short distances, and exploit this fact to obtain a determination of the product of the lattice scale r_0 with the QCD scale Lambda_{MS}. With the input of the value of r_0, this provides a determination of the strong coupling alpha_s at the typical distance scale of the lattice data. We obtain alpha_s(1.5 GeV)=0.326\\pm0.019, which provides a novel determination of alpha_s at low energy and with three-loop accuracy (including resummation of the leading ultrasoft logarithms). When this value is evolved to the Z-mass scale M_Z, it corresponds to alpha_s(M_Z)=0.1156^{+0.0021}_{-0.0022}.

Alexei Bazavov; Nora Brambilla; Xavier Garcia i Tormo; Peter Petreczky; Joan Soto; Antonio Vairo

2012-12-18

289

Learning about Alpha-1 Antitrypsin Deficiency (AATD)  

MedlinePLUS

... disease in children and adults. Alpha-1 Association Genetic Counseling Service [alpha1.org] The Alpha-1 Association Genetic Counseling Center provides toll-free, confidential genetic counseling to ...

290

Triplicated alpha-globin loci in humans.  

PubMed Central

We have identified 12 individuals who are heterozygous for a chromosome with three alpha-globin genes. We determined the presence of the third alpha-globin locus by restriction endonuclease digestion and hybridization with alpha-globin cDNA probes. The three alpha-globin loci resided in an elongated fragment on digestion with EcoRI, BamHI, and Xba I, and the third locus was present in an additional 3.7-kilobase fragment on digestion with Hpa I, Sac I, and Bgl II. The locations of the restriction sites are compatible with a nonhomologous crossover mechanism producing the triple alpha loci. The frequency of the triple alpha loci was 0.0036 in American blacks and less than 0.004 in Sardinians, but was higher in Greek Crypriots (0.05). Individuals with five alpha-globin genes (alpha alpha/alpha alpha alpha) apparently showed no clinical or hematologic abnormalities. Images PMID:6928643

Goossens, M; Dozy, A M; Embury, S H; Zachariades, Z; Hadjiminas, M G; Stamatoyannopoulos, G; Kan, Y W

1980-01-01

291

21 CFR 882.1610 - Alpha monitor.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 2011-04-01 false Alpha monitor. 882.1610 Section 882.1610...Neurological Diagnostic Devices § 882.1610 Alpha monitor. (a) Identification. An alpha monitor is a device with electrodes...

2011-04-01

292

Alpha-1 Antitrypsin Deficiency (Inherited Emphysema)  

MedlinePLUS

Alpha-1 Antitrypsin Deficiency Chronic obstructive pulmonary disease or COPD for short is a lung disease that ... disease. The inherited form of emphysema is called Alpha-1 Antitrypsin Deficiency or " Alpha-1 " for short. ...

293

How Is Alpha-1 Antitrypsin Deficiency Diagnosed?  

MedlinePLUS

... page from the NHLBI on Twitter. How Is Alpha-1 Antitrypsin Deficiency Diagnosed? Alpha-1 antitrypsin (AAT) deficiency usually is diagnosed after ... is. Rate This Content: Next >> October 11, 2011 Alpha-1 Antitrypsin Deficiency Clinical Trials Clinical trials are ...

294

Genetics Home Reference: Alpha-mannosidosis  

MedlinePLUS

... PubMed Recent literature OMIM Genetic disorder catalog Conditions > Alpha-mannosidosis On this page: Description Genetic changes Inheritance ... names Glossary definitions Reviewed May 2014 What is alpha-mannosidosis? Alpha-mannosidosis is a rare inherited disorder ...

295

How Is Alpha-1 Antitrypsin Deficiency Treated?  

MedlinePLUS

... page from the NHLBI on Twitter. How Is Alpha-1 Antitrypsin Deficiency Treated? Alpha-1 antitrypsin (AAT) deficiency has no cure, but ... deficiency. Rate This Content: Next >> October 11, 2011 Alpha-1 Antitrypsin Deficiency Clinical Trials Clinical trials are ...

296

What Is Alpha-1 Antitrypsin Deficiency?  

MedlinePLUS

... obstruction) to the ?ow of air. What causes Alpha-1? Alpha-1 is an inherited condition. Every ... two abnormal genes. Does everyone with two abnormal Alpha-1 genes develop disease? Not everyone who inherits ...

297

What Causes Alpha-1 Antitrypsin Deficiency?  

MedlinePLUS

... page from the NHLBI on Twitter. What Causes Alpha-1 Antitrypsin Deficiency? Alpha-1 antitrypsin (AAT) deficiency is an inherited disease. " ... deficiency. Rate This Content: Next >> October 11, 2011 Alpha-1 Antitrypsin Deficiency Clinical Trials Clinical trials are ...

298

Genetics Home Reference: 5-alpha reductase deficiency  

MedlinePLUS

... Recent literature OMIM Genetic disorder catalog Conditions > 5-alpha reductase deficiency On this page: Description Genetic changes ... Glossary definitions Reviewed April 2008 What is 5-alpha reductase deficiency? 5-alpha reductase deficiency is a ...

299

Genetics Home Reference: Alpha-1 antitrypsin deficiency  

MedlinePLUS

... PubMed Recent literature OMIM Genetic disorder catalog Conditions > Alpha-1 antitrypsin deficiency On this page: Description Genetic ... names Glossary definitions Reviewed January 2013 What is alpha-1 antitrypsin deficiency? Alpha-1 antitrypsin deficiency is ...

300

21 CFR 882.1610 - Alpha monitor.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Alpha monitor. 882.1610 Section 882.1610...Neurological Diagnostic Devices § 882.1610 Alpha monitor. (a) Identification. An alpha monitor is a device with electrodes...

2010-04-01

301

[Alpha-1-antitrypsin deficiency].  

PubMed

Alpha-1-antitrypsin (?1AT) deficiency is a genetic disorder that manifests as pulmonary emphysema and liver cirrhosis. ?1AT deficiency is the most common genetic cause of liver disease in children and also an underappreciated cause of liver disease in adults. The prevalence in the general population in Western Europe is approximately 1 in 2,000. The most common and severe deficiency allele is the Z variant (two alleles mutated). This variant is characterized by the accumulation of Z-?1AT polymers in the endoplasmic reticulum of hepatocytes leading to cell death and to a severe reduction of ?1AT in the serum. The latter results in a loss of its antiprotease activity and its ability to protect lung tissue. Thus far, there are only very limited therapeutic options in ?1AT deficiency. A more detailed understanding of the biology governing ?1AT biogenesis is required in order to identify new pharmacological agents and biomarkers. This review will present current knowledge on ?1AT deficiency and focus on recent discoveries and new strategies in the treatment of this disease. PMID:25311024

Bouchecareilh, Marion

2014-10-01

302

Measurement of $\\alpha_{s}$ with Radiative Hadronic Events  

E-print Network

Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass of the Z0 boson with the OPAL detector at LEP. The strong coupling alpha S is extracted by comparing data and QCD predictions for event shape observables at average reduced centre-of-mass energies ranging from 24 GeV to 78 GeV, and the energy dependence of alpha S is studied. Our results are consistent with the running of alpha S as predicted by QCD and show that within the uncertainties of our analysis event shapes in hadronic Z0 decays with hard and isolated photon radiation can be described by QCD at reduced centre-of-mass energies. Combining all values from different event shape observables and energies gives alpha S (Mz)=0.1182 pm 0.0015(stat.) pm 0.0101(syst.).

Abbiendi, G; Åkesson, P F; Alexander, G; Anagnostou, G; Anderson, K J; Asai, S; Axen, D; Bailey, I; Barberio, E; Barillari, T; Barlow, R J; Batley, R J; Bechtle, P; Behnke, T; Bell, K W; Bell, P J; Bella, G; Bellerive, A; Benelli, G; Bethke, S; Biebel, O; Boeriu, O; Bock, P; Boutemeur, M; Braibant, S; Brown, R M; Burckhart, H J; Campana, S; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Ciocca, C; Csilling, A; Cuffiani, M; Dado, S; Dallavalle, M; de Roeck, A; De Wolf, E A; Desch, K; Dienes, B; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Etzion, E; Fabbri, F; Ferrari, P; Fiedler, F; Fleck, I; Ford, M; Frey, A; Gagnon, P; Gary, J W; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Giunta, M; Goldberg, J; Gross, E; Grunhaus, J; Gruwé, M; Sen-Gupta, A; Hajdu, C; Hamann, M; Hanson, G G; Harel, A; Hauschild, M; Hawkes, C M; Hawkings, R; Herten, G; Heuer, R D; Hill, J C; Horváth, D; Igo-Kemenes, P; Ishii, K; Jeremie, H; Jovanovic, P; Junk, T R; Kanzaki, J; Karlen, D; Kawagoe, K; Kawamoto, T; Keeler, R K; Kellogg, R G; Kennedy, B W; Kluth, S; Kobayashi, T; Kobel, M; Komamiya, S; Kramer, T; Krasznahorkays, A Jr; Krieger, P; Von Krogh, J; Kühl, T; Kupper, M; Lafferty, G D; Landsman, H; Lanske, D; Lellouch, D; Letts, J; Levinson, L; Lillich, J; Lloyd, S L; Loebinger, F K; Lü, J; Ludwig, A; Ludwig, J; Mader, W; Marcellini, S; Martin, A J; Mashimo, T; Mättig, P; McKenna, J; McPherson, R A; Meijers, F; Menges, W; Merritt, F S; Mes, H; Meyer, N; Michelini, A; Mihara, S; Mikenberg, G; Miller, D J; Mohr, W; Mori, T; Mutter, A; Nagai, K; Nakamura, I; Nanjo, H; Neal, H A; O'Neale, S W; Oh, A; Oreglia, M J; Orito, S; Pahl, C; Pásztor, G; Pater, J R; Pilcher, J E; Pinfold, J L; Plane, D E; Pooth, O; Przybycien, M; Quadt, A; Rabbertz, K; Rembser, C; Renkel, P; Roney, J M; Rossi, A M; Rozen, Y; Runge, K; Sachs, K; Saeki, T; Sarkisyan-Grinbaum, E; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schiecks, J; Schörner-Sadenius, T; Schröder, M; Schumacher, M; Seuster, R; Shears, T G; Shen, B C; Sherwood, P; Skuja, A; Smith, A M; Sobie, R J; Söldner-Rembold, S; Spanó, F; Stahl, A; Strom, D; Ströhmer, R; Tarem, S; Tasevsky, M; Teuscher, R; Thomson, M A; Torrence, E; Toya, D; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Ujvári, B; Vollmer, C F; Vannerem, P; Vertesi, R; Verzocchi, M; Voss, H; Vossebeld, J; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wengler, T; Wermes, N; Wilson, G W; Wilson, J A; Wolf, G; Wyatt, T R; Yamashita, S; Zer-Zion, D; Zivkovic, L

2008-01-01

303

I. Excluded Volume Effects in Ising Cluster Distributions and Nuclear Multifragmentation II. Multiple-Chance Effects in Alpha-Particle Evaporation  

SciTech Connect

In Part 1, geometric clusters of the Ising model are studied as possible model clusters for nuclear multifragmentation. These clusters may not be considered as non-interacting (ideal gas) due to excluded volume effect which predominantly is the artifact of the cluster's finite size. Interaction significantly complicates the use of clusters in the analysis of thermodynamic systems. Stillinger's theory is used as a basis for the analysis, which within the RFL (Reiss, Frisch, Lebowitz) fluid-of-spheres approximation produces a prediction for cluster concentrations well obeyed by geometric clusters of the Ising model. If thermodynamic condition of phase coexistence is met, these concentrations can be incorporated into a differential equation procedure of moderate complexity to elucidate the liquid-vapor phase diagram of the system with cluster interaction included. The drawback of increased complexity is outweighted by the reward of greater accuracy of the phase diagram, as it is demonstrated by the Ising model. A novel nuclear-cluster analysis procedure is developed by modifying Fisher's model to contain cluster interaction and employing the differential equation procedure to obtain thermodynamic variables. With this procedure applied to geometric clusters, the guidelines are developed to look for excluded volume effect in nuclear multifragmentation. In part 2, an explanation is offered for the recently observed oscillations in the energy spectra of {alpha}-particles emitted from hot compound nuclei. Contrary to what was previously expected, the oscillations are assumed to be caused by the multiple-chance nature of {alpha}-evaporation. In a semi-empirical fashion this assumption is successfully confirmed by a technique of two-spectra decomposition which treats experimental {alpha}-spectra has having contributions from at least two independent emitters. Building upon the success of the multiple-chance explanation of the oscillations, Moretto's single-chance evaporation theory is augmented to include multiple-chance emission and tested on experimental data to yield positive results.

Breus, Dimitry E.

2005-05-16

304

Treatment of recurrent genital herpes with interferon alpha-2alpha.  

PubMed

The purpose of the present study was to evaluate the efficacy and safety of parenteral administration of interferon alpha-2alpha in the treatment of recurrent herpes genitalis. A total of 97 patients (66 males, 31 females, mean age 34.86 +/-16.74 years), who had at least five recurrences of genital herpes during the previous 12 months, participated in a prospective open study on the effects of treatment with interferon alpha-2alpha (Roferon-A; Roche). The patients were treated with interferon alpha-2alpha (3 x 10(6) IU) by subcutaneous injection, three times weekly for 4 weeks, and the same schedule was repeated after 3 and 6 months. All patients were asymptomatic at the start of the study. After initiation of treatment, all patients reported to the clinic every 3 months for 2 years (the males were submitted to peoscopy and the females to Pap test and colposcopy) at the time of their recurrences. Comparison was made of the number of recurrences, duration of lesions, duration and severity of pain, and itching and burning. Prophylactic administration of interferon alpha-2alpha prevented recurrences of genital herpes virus infection in 51 patients (20 males and 31 females). Interferon administration shortened the healing time from 8.5 days before treatment to 2.5 days after treatment (p < 0.001). There was a significant reduction in the number of recurrences during the study period, from 7.46 before treatment to 2.64 after treatment (p < 0.001). On the basis of the overall efficacy and adverse effects, this regimen may be of value in the routine treatment of recurrent herpes. PMID:9692344

Cardamakis, E; Relakis, K; Kotoulas, I G; Michopoulos, J; Metallinos, K; Mantouvalos, H; Tzingounis, V

1998-01-01

305

A very young, compact bipolar H$_2$O maser outflow in the intermediate-mass star-forming LkH$\\alpha$ 234 region  

E-print Network

We report multi-epoch VLBI H$_2$O maser observations towards the compact cluster of YSOs close to the Herbig Be star LkH$\\alpha$ 234. This cluster includes LkH$\\alpha$ 234 and at least nine more YSOs that are formed within projected distances of $\\sim$10 arcsec ($\\sim$9,000 au). We detect H$_2$O maser emission towards four of these YSOs. In particular, our VLBI observations (including proper motion measurements) reveal a remarkable very compact ($\\sim$0.2 arcsec = $\\sim$180 au), bipolar H$_2$O maser outflow emerging from the embedded YSO VLA 2. We estimate a kinematic age of $\\sim$40 yr for this bipolar outflow, with expanding velocities of $\\sim$20 km s$^{-1}$ and momentum rate $\\dot M_w V_w$ $\\simeq$ $10^{-4}-10^{-3}$ M$_{\\odot}$ yr$^{-1}$ km s$^{-1}$$\\times (\\Omega$/$4\\pi)$, powered by a YSO of a few solar masses. We propose that the outflow is produced by recurrent episodic jet ejections associated with the formation of this YSO. Short-lived episodic ejection events have previously been found towards high...

Torrelles, J M; Estalella, R; Anglada, G; Gómez, J F; Cantó, J; Patel, N A; Trinidad, M A; Girart, J M; Carrasco-González, C; Rodríguez, L F

2014-01-01

306

Alpha Ori - Evidence for pulsation  

NASA Technical Reports Server (NTRS)

The study deals with a periodic modulation of the UV continuum and Mg II emission-line fluxes shown by the bright cool supergiant Alpha Orionis; this pulsation is identified with the supergiant's atmosphere. UV brightness is shown to occur near the time of maximum outflow velocity of the photosphere, while local minima in the UV continuum occur near the time of maximum infall velocity. Visible and UV observations of Alpha Ori since the beginning of the monitoring program with IUE are discussed.

Dupree, A. K.; Baliunas, S. L.; Hartmann, L.; Guinan, E. F.; Sonneborn, G.

1990-01-01

307

A Ly{alpha} EMITTER WITH AN EXTREMELY LARGE REST-FRAME EQUIVALENT WIDTH OF {approx}900 A AT z = 6.5: A CANDIDATE POPULATION III-DOMINATED GALAXY?  

SciTech Connect

We have identified a very interesting Ly{alpha} emitter (LAE), whose Ly{alpha} emission line has an extremely large observed equivalent width of EW{sub 0} = 436{sup +422}{sub -{sub 149}} A, which corresponds to an extraordinarily large intrinsic rest-frame equivalent width of EW{sup int}{sub 0} = 872{sup +844}{sub -{sub 298}} A after the average intergalactic absorption correction. The object was spectroscopically confirmed to be a real LAE by its apparent asymmetric Ly{alpha} line profile detected at z = 6.538. The continuum emission of the object was definitely detected in our deep z'-band image; thus, its EW{sub 0} was reliably determined. Follow-up deep near-infrared spectroscopy revealed emission lines of neither He II {lambda}1640 as an apparent signature of Population III (Pop III) nor C IV {lambda}1549 as proof of an active nucleus. No detection of the short-lived He II {lambda}1640 line is not necessarily inconsistent with the interpretation that the underlying stellar population of the object is dominated by Pop III. We found that the observed extremely large EW{sub 0} of the Ly{alpha} emission and the upper limit on the EW{sub 0} of the He II {lambda}1640 emission can be explained by population synthesis models favoring a very young age less than 2-4 Myr and massive metal-poor (Z < 10{sup -5}) or even metal-free stars. The observed large EW{sub 0} of Ly{alpha} is insufficiently explained by Population I/II synthesis models with Z {>=} 10{sup -3}. However, we cannot conclusively rule out the possibility that this object is composed of a normal stellar population with a clumpy dust distribution, which could enhance the Ly{alpha} EW{sub 0}, though its significance is still unclear.

Kashikawa, Nobunari; Hayashi, Masao; Iye, Masanori [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Nagao, Tohru; Ota, Kazuaki [Department of Astronomy, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Toshikawa, Jun; Ishizaki, Yoshifumi; Shibuya, Takatoshi [Department of Astronomy, School of Science, Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588 (Japan); Egami, Eiichi; Jiang, Linhua [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Ly, Chun [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Matsuda, Yuichi [Radio Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Shimasaku, Kazuhiro [Department of Astronomy, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Taniguchi, Yoshiaki; Shioya, Yasuhiro, E-mail: n.kashikawa@nao.ac.jp [Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan)

2012-12-20

308

Selective binding of collagen subtypes by integrin alpha 1I, alpha 2I, and alpha 10I domains.  

PubMed

Four integrins, namely alpha(1)beta(1), alpha(2)beta(1), alpha(10)beta(1), and alpha(11)beta(1), form a special subclass of cell adhesion receptors. They are all collagen receptors, and they recognize their ligands with an inserted domain (I domain) in their alpha subunit. We have produced the human integrin alpha(10)I domain as a recombinant protein to reveal its ligand binding specificity. In general, alpha(10)I did recognize collagen types I-VI and laminin-1 in a Mg(2+)-dependent manner, whereas its binding to tenascin was only slightly better than to albumin. When alpha(10)I was tested together with the alpha(1)I and alpha(2)I domains, all three I domains seemed to have their own collagen binding preferences. The integrin alpha(2)I domain bound much better to fibrillar collagens (I-III) than to basement membrane type IV collagen or to beaded filament-forming type VI collagen. Integrin alpha(1)I had the opposite binding pattern. The integrin alpha(10)I domain was similar to the alpha(1)I domain in that it bound very well to collagen types IV and VI. Based on the previously published atomic structures of the alpha(1)I and alpha(2)I domains, we modeled the structure of the alpha(10)I domain. The comparison of the three I domains revealed similarities and differences that could potentially explain their functional differences. Mutations were introduced into the alphaI domains, and their binding to types I, IV, and VI collagen was tested. In the alpha(2)I domain, Asp-219 is one of the amino acids previously suggested to interact directly with type I collagen. The corresponding amino acid in both the alpha(1)I and alpha(10)I domains is oppositely charged (Arg-218). The mutation D219R in the alpha(2)I domain changed the ligand binding pattern to resemble that of the alpha(1)I and alpha(10)I domains and, vice versa, the R218D mutation in the alpha(1)I and alpha(10)I domains created an alpha(2)I domain-like ligand binding pattern. Thus, all three collagen receptors appear to differ in their ability to recognize distinct collagen subtypes. The relatively small structural differences on their collagen binding surfaces may explain the functional specifics. PMID:11572855

Tulla, M; Pentikäinen, O T; Viitasalo, T; Käpylä, J; Impola, U; Nykvist, P; Nissinen, L; Johnson, M S; Heino, J

2001-12-21

309

Container structure of alpha alpha Lambda clusters in $_?^9$Be  

E-print Network

New concept of clustering is discussed in $\\Lambda$ hypernuclei using a new-type microscopic cluster model wave function, which has a structure that constituent clusters are confined in a container, whose size is a variational parameter and which we refer to as Hyper-Tohsaki-Horiuchi-Schuck-R\\"opke (Hyper-THSR) wave function. By using the Hyper-THSR wave function, $2\\alpha + \\Lambda$ cluster structure in ${^{9}_\\Lambda{\\rm Be}}$ is investigated. We show that full microscopic solutions in the $2\\alpha + \\Lambda$ cluster system, which are given as $2\\alpha + \\Lambda$ Brink-GCM wave functions, are almost perfectly reproduced by the single configurations of the Hyper-THSR wave function. The squared overlaps between the both wave functions are calculated to be $99.5$%, $99.4$%, and $97.7$% for $J^\\pi=0^+$, $2^+$, and $4^+$ states, respectively. We also simulate the structural change by adding the $\\Lambda$ particle, by varying the $\\Lambda N$ interaction artificially. As the increase of the $\\Lambda N$ interaction, the $\\Lambda$ particle gets to move more deeply inside the core and invokes strongly the spatial core shrinkage, and accordingly distinct localized $2\\alpha$ clusters appear in the nucleonic intrinsic density, though in ${^{8}{\\rm Be}}$ rather gaslike $2\\alpha$-cluster structure is shown. The origin of the localization is associated with the strong effect of Pauli principle. We conclude that the container picture of the $2\\alpha$ and $\\Lambda$ clusters is essential in understanding the cluster structure in ${^{9}_\\Lambda{\\rm Be}}$, in which the very compact spatial localization of clusters is shown in the density distribution.

Y. Funaki; T. Yamada; E. Hiyama; B. Zhou; K. Ikeda

2014-05-23

310

Workshop on Precision Measurements of $\\alpha_s$  

SciTech Connect

These are the proceedings of the Workshop on Precision Measurements of {alpha}{sub s} held at the Max-Planck-Institute for Physics, Munich, February 9-11, 2011. The workshop explored in depth the determination of {alpha}{sub s}(m{sub Z}) in the {ovr MS} scheme from the key categories where high precision measurements are currently being made, including DIS and global PDF fits, {tau}-decays, electro-weak precision observables and Z-decays, event-shapes, and lattice QCD. These proceedings contain a short summary contribution from the speakers, as well as the lists of authors, conveners, participants, and talks.

Bethke, Siegfried; /Munich, Max Planck Inst.; Hoang, Andre H.; /Vienna U.; Kluth, Stefan; /Munich, Max Planck Inst.; Schieck, Jochen; /Munich U.; Stewart, Iain W.; Aoki, S.; Beneke, M.; Bethke, S.; Blumlein, J.; Brambilla, N.; Brodsky, S.; /MIT, LNS

2011-10-01

311

The Cycles of Alpha Centauri  

NASA Astrophysics Data System (ADS)

The main AB pair of the nearby Alpha Centauri triple system has an extensive X-ray history, covering three decades. Alpha Cen A (G2V) is a near twin of the Sun, with a similarly soft (1-2 MK) corona. Alpha Cen B (K1V) is more active than the Sun, with a generally harder X-ray spectrum. Here, spatially resolved measurements from ROSAT, XMM-Newton, and Chandra are compared on a common basis. In the combined time series, Alpha Cen B shows a distinct X-ray modulation with a period of about eight years and a factor of 5 cycle depth (the latter is similar to the Sun's). Alpha Cen A showed minimal variability 1995-2000, a decrease in the initial XMM epoch 2003-2005, and nearly constant behavior in the subsequent Chandra segment (late-2005 to present), although down a factor of 2 from the mid-1990's level. A remarkable ``smoking gun'' LETGS spectrum in mid-2007 emphasized that much of the coronal luminosity of solar-activity objects falls at longer wavelengths than recorded efficiently by contemporary instruments. This makes cycle depth strongly dependent on the energy bandpass of the measurement (here 0.2-2 keV), and complicates assessments of coronal heating requirements.

Ayres, Thomas

2009-09-01

312

Space Station alpha joint bearing  

NASA Technical Reports Server (NTRS)

Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

1987-01-01

313

Bremsstrahlung in {alpha} Decay Reexamined  

SciTech Connect

A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed, which allows us to follow the photon spectra up to energies of {approx}500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the {alpha} particle and the emitted photon.

Boie, H.; Scheit, H.; Jentschura, U. D.; Koeck, F.; Lauer, M.; Schwalm, D. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Milstein, A. I.; Terekhov, I. S. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation)

2007-07-13

314

NACA Physicist Studying Alpha Rays  

NASA Technical Reports Server (NTRS)

NACA Physicits studying Alpha Rays in a continuous cloud chamber. A cloud chamber is used by Lewis scientists to obtain information aimed at minimizing undesirable effects of radiation on nuclear-powered aircraft components. Here, alpha particles from a polonium source emit in a flower-like pattern at the cloud chamber's center. The particles are made visible by means of alcohol vapor diffusing from an area at room temperature to an area at minus -78 deg. Centigrade. Nuclear-powered aircraft were never developed and aircraft nuclear propulsion systems were canceled in the early 1960s.

1957-01-01

315

Simulating the Lyman Alpha Forest  

E-print Network

In this paper we review the importance of the Lyman alpha forest as a probe of structure formation in the universe. We first discuss the statistics used to describe the Lyman alpha forest and the numerical techniques used to produce simulated spectra of the forest from a given cosmological model. We then discuss the physical picture of the absorbing structures that emerges from these numerical simulations. Finally, we comment on how two of the statistics, the slope of the column density distribution and the b parameter distribution, may be used to constrain competing cosmologies.

Marie E. Machacek; Greg L. Bryan; Peter Anninos; Avery Meiksin; Michael L. Norman

1998-08-04

316

alpha_s From the Lattice and Hadronic Tau Decays  

E-print Network

Until recently, determinations of alpha_s(M_Z) from hadronic tau decays and the analysis of short-distance-sensitive lattice observables yielded results which, though precise, were not in good agreement. I review new analyses that bring these into good agreement and provide some details on the source of the main changes in the tau decay analysis.

Kim Maltman

2009-06-26

317

Evaluation of internal alpha-particle radiation exposure and subsequent fertility among a cohort of women formerly employed in the radium dial industry  

SciTech Connect

This study examined the effect of internal exposure to {alpha}-particle radiation on subsequent fertility among women employed in radium dial industry prior to 1930, when appreciable amounts of radium were often ingested through the practice of pointing the paint brush with the lips. The analysis was limited to women for whom a radium body burden measurement had been obtained and who were married prior to age 45 (n = 603). Internal radiation dose to the ovary was calculated based on initial intakes of radium-226 and radium-228, average ovarian mass, number and energy of {alpha} particles emitted, fraction of energy absorbed within the ovary, effective retention integrals and estimated photon irradiation. Time between marriage and pregnancy, number of pregnancies and number of live births served as surrogates for fertility. Radiation appeared to have no effect on fertility at estimated cumulative ovarian dose equivalents below 5 Sv; above this dose, however, statistically significant declines in both number of pregnancies and live births were observed. These trends persisted after multivariable adjustment for potential confounding variables and after exclusion of subjects contributing a potential classification or selection bias to the study. Additionally, the high-dose group experienced fewer live births than would have been expected based on population rates. There were no differences in time to first pregnancy between high- and low-dose groups. These results are consistent with earlier studies of {gamma}-ray exposures and suggest that exposure to high doses of radiation from internally deposited radium reduces fertility rather than inducing sterility. 42 refs., 5 tabs.

Schieve, L.A.; Davis, F.; Freels, S. [Univ. of Illinois, Chicago, IL (United States)] [and others

1997-02-01

318

Evaluation of internal alpha radiation exposure and subsequent infertility among a cohort of women formerly employed in the radium dial industry.  

SciTech Connect

This study examined the effect of internal exposure to {alpha}-particle radiation on subsequent fertility among women employed in the radium dial industry prior to 1930, when appreciable amounts of radium were often ingested through the practice of pointing the paint brush with the lips. The analysis was limited to women for whom a radium body burden measurement had been obtained and who were married prior to age 45 (n=603). Internal radiation dose to the ovary was calculated based on initial intakes of radium-226 and radium-228, average ovarian mass, number and energy of {alpha} particles emitted, fraction of energy absorbed with in the ovary, effective retention integrals and estimated photon irradiation. Time between marriage and pregnancy, number of pregnancies and number of live births served as surrogates for fertility. Radiation appeared to have no effect on fertility at estimated cumulative ovarian dose equivalents below 5 Sv; above this dose, however, statistically significant declines in both number of pregnancies and live births were observed. These trends persisted after multivariable adjustment for potential confounding variables and after exclusion of subjects contributing a potential classification or selection bias to the study. Additionally, the high-dose group experienced fewer live births than would have been expected based on population rates. There were no differences in time to first pregnancy between high- and low-dose groups. These results are consistent with earlier studies of {gamma}-ray exposures and suggest that exposure to high doses of radiation from internally deposited radium reduces fertility rather than inducing sterility.

Schieve, L. A.; Davis, F.; Roeske, J.; Handler, A.; Freels, S.; Stinchcomb, T.; Keane, A.; Environmental Research; Univ. of Illinois at Chicago; Univ. of Chicago; DePaul Univ.

1997-02-01

319

Intratumour injection of immunoglobulins labelled with the alpha-particle emitter 211At: analyses of tumour retention, microdistribution and growth delay.  

PubMed Central

To determine the effects of 211At-labelled antibodies in solid tumour tissue, nude mice carrying OHS human osteosarcoma xenografts received intratumour injections at dosages of 1, 2 or 4 MBq (-1) tumour. The radioisotope was conjugated to either the osteosarcoma-specific monoclonal antibody TP-3 or the non-specific polyclonal antibody hlgGkappa. Tumour retention of injected radioimmunoconjugate (RIC), measured as the percentage of injected activity dosage per gram, was significantly higher for the [211At]TP-3 (203 +/- 93 at 24.1 h post injection) compared with the [211At]hlgGkappa (57 +/- 22 at 23.2 h post injection). The radioactive count rates in body (measured at neck and abdomen) were significantly lower with the TP-3 than with the hlgGkappa. Microautoradiography of the tumour radionuclide distribution was different for the two RICs, i.e. the [211At]TP-3 was to a larger extent concentrated near the injection site, whereas the [211At]hlgGkappa was more evenly distributed all over the tumour. The tumour growth was significantly delayed as a function of the injected activity dosage but without significant difference between the specific and the non-specific RIC. According to this study, it is possible to deliver highly selective radiation doses to solid tumours using intratumour injection of alpha-particle-emitting RICs. Improved tumour retention caused by antigen binding indicates that reduced normal tissue exposure can be obtained with antigen-specific antibodies. The heterogeneous tumour dose distribution observed is, however, a major impediment to the use of alpha-particle emitters against solid tumours. Images Figure 2 Figure 3 PMID:9569048

Larsen, R. H.; Bruland, O. S.

1998-01-01

320

Scattering of alpha particles by 22Ne  

Microsoft Academic Search

Differential cross sections at a few angles for 22Ne(alpha,alphai)22Ne are reported for alphai=alpha0, alpha1, and alpha2 mainly in 10 keV steps for 22alpha,alpha), 13.4<=Ealpha (MeV)<=20,8, elastic and inelastic (2+, 1.27 MeV and 4+, 3.36 MeV). Measured sigma(theta,Ealpha) at one or two angles.

C. A. Davis

1981-01-01

321

Meet the Alpha-Pets.  

ERIC Educational Resources Information Center

"Alpha-Pets" are the focal point of an integrated, multidisciplinary curriculum. Each pet is featured for a week in a vocabulary-rich story and introduces related activities beginning with the featured letter, such as the four food groups during Freddie Fish's week or universe during Ulysses Unicorn's week. (MT)

Zitlaw, Jo Ann Bruce; Frank, Cheryl Standish

1985-01-01

322

Alpha Testing Escape from Diab  

Technology Transfer Automated Retrieval System (TEKTRAN)

Alpha testing was conducted of sessions 2 and 3 from Diab to assess whether the activities worked as expected, and whether children in the target ages enjoyed it. Data include both RA observations of child performance while playing the games and cognitive interview responses from the players after t...

323

Alpha proton x ray spectrometer  

NASA Technical Reports Server (NTRS)

Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N, and O at levels above typically 1 percent.

Rieder, Rudi; Waeke, H.; Economou, T.

1994-01-01

324

A New Population of High-z, Dusty Lyman-alpha Emitters and Blobs Discovered by WISE: Feedback Caught in the Act?  

NASA Technical Reports Server (NTRS)

By combining data from the NASA Wide-field Infrared Survey Explorer (WISE) mission with optical spectroscopy from the W. M. Keck telescope, we discover a mid-IR color criterion that yields a 78% success rate in identifying rare, typically radio-quiet, 1.6 approx. < z approx. < 4.6 dusty Ly-alpha emitters (LAEs). Of these, at least 37% have emission extended on scales of 30-100 kpc and are considered Ly-alpha "blobs" (LABs). The objects have a surface density of only approx.. 0.1 deg(exp -2), making them rare enough that they have been largely missed in deep, small area surveys. We measured spectroscopic redshifts for 92 of these galaxies, and find that the LAEs (LABs) have a median redshift of 2.3 (2.5). The WISE photometry coupled with data from Herschel (Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA) reveals that these galaxies are in the Hyper Luminous IR galaxy regime (L(sub IR) approx. > 10(exp 13)-10(exp 14) Solar L) and have warm colors. They are typically more luminous and warmer than other dusty, z approx.. 2 populations such as submillimeter-selected galaxies and dust-obscured galaxies. These traits are commonly associated with the dust being illuminated by intense active galactic nucleus activity. We hypothesize that the combination of spatially extended Ly-alpha, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing brief, intense "feedback" transforming them from an extreme dusty starburst/QSO into a mature galaxy.

Bridge, Carrie R.; Blain, Andrew; Borys, Colin J. K.; Petty, Sara; Benford, Dominic; Eisenhardt, Peter; Farrah, Duncan; Griffith, Roger, L.; Jarrett, Tom; Lonsdale, Carol; Stanford. Spencer A.; Stern, Daniel; Tsai, Chao-Wei; Wright, Edward L.; Wu, Jingwen

2013-01-01

325

A NEW POPULATION OF HIGH-z, DUSTY Ly{alpha} EMITTERS AND BLOBS DISCOVERED BY WISE: FEEDBACK CAUGHT IN THE ACT?  

SciTech Connect

By combining data from the NASA Wide-field Infrared Survey Explorer (WISE) mission with optical spectroscopy from the W. M. Keck telescope, we discover a mid-IR color criterion that yields a 78% success rate in identifying rare, typically radio-quiet, 1.6 {approx}< z {approx}< 4.6 dusty Ly{alpha} emitters (LAEs). Of these, at least 37% have emission extended on scales of 30-100 kpc and are considered Ly{alpha} ''blobs'' (LABs). The objects have a surface density of only {approx}0.1 deg{sup -2}, making them rare enough that they have been largely missed in deep, small area surveys. We measured spectroscopic redshifts for 92 of these galaxies, and find that the LAEs (LABs) have a median redshift of 2.3 (2.5). The WISE photometry coupled with data from Herschel (Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA) reveals that these galaxies are in the Hyper Luminous IR galaxy regime (L{sub IR} {approx}> 10{sup 13}-10{sup 14} L{sub Sun }) and have warm colors. They are typically more luminous and warmer than other dusty, z {approx} 2 populations such as submillimeter-selected galaxies and dust-obscured galaxies. These traits are commonly associated with the dust being illuminated by intense active galactic nucleus activity. We hypothesize that the combination of spatially extended Ly{alpha}, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing brief, intense ''feedback'' transforming them from an extreme dusty starburst/QSO into a mature galaxy.

Bridge, Carrie R. [California Institute of Technology, MS249-17, Pasadena, CA 91125 (United States); Blain, Andrew [Department of Physics and Astronomy, University of Leicester, LE1 7RH Leicester (United Kingdom); Borys, Colin J. K.; Griffith, Roger L.; Tsai, Chao-Wei [Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States); Petty, Sara; Farrah, Duncan [Department of Physics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Benford, Dominic [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Eisenhardt, Peter; Stern, Daniel; Wu Jingwen [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109 (United States); Jarrett, Tom [Astronomy Department, University of Cape Town, Rondebosch 7701 (South Africa); Lonsdale, Carol [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Stanford, Spencer A. [Department of Physics, University of California Davis, One Shields Ave., Davis, CA 95616 (United States); Wright, Edward L., E-mail: bridge@astro.caltech.edu [Astronomy Department, University of California Los Angeles, Los Angeles, CA 90095 (United States)

2013-06-01

326

Coexistence of {alpha}+{alpha}+n+n and {alpha}+t+t cluster structures in {sup 10}Be  

SciTech Connect

The coexistence of the {alpha}+{alpha}+n+n and {alpha}+t+t cluster structures in the excited states of {sup 10}Be has been discussed. In the previous analysis, all the low-lying states of {sup 10}Be were found to be well described by the motion of the two valence neutrons around two {alpha} clusters. However, the {alpha}+t+t cluster structure was found to coexist with the {alpha}+{alpha}+n+n structure around E{sub x}=15 MeV, close to the corresponding threshold. We have introduced a microscopic model to solve the coupling effect between these two configurations. The K=0 and K=1 states are generated from the {alpha}+t+t configurations due to the spin coupling of two triton clusters. The present case of {sup 10}Be is one of the few examples in which completely different configurations of triton-type ({alpha}+t+t three-center) and {alpha}-type ({alpha}+{alpha}+n+n two-center) clusters coexist in a single nucleus in the same energy region.

Itagaki, N. [Department of Physics, University of Tokyo, Hongo, 113-0033 Tokyo (Japan); Ito, M. [RIKEN Nishina Center, Wako, 351-0198 Saitama (Japan); Milin, M. [Department of Physics, University of Zagreb, HR-10000 Zagreb (Croatia); Hashimoto, T.; Ishiyama, H.; Miyatake, H. [Tokai Radioactive Ion Accelerator Complex, High Energy Accelerator Research Organization (KEK), Tokai, 319-1105 Ibaraki (Japan)

2008-06-15

327

Aversive Situational Effects on Alpha Feedback Training  

ERIC Educational Resources Information Center

Anticipation of electric shock did not depress alpha activity in a feedback situation. Contrary to previous reports, a reduction in alpha activity is not a necessary consequence of apprehension or heightened arousal. (Author)

Orne, Martin T.; Paskeqitz, David A.

1974-01-01

328

Q (Alpha) Function and Squeezing Effect  

NASA Technical Reports Server (NTRS)

The relation of squeezing and Q(alpha) function is discussed in this paper. By means of Q function, the squeezing of field with gaussian Q(alpha) function or negative P(a)function is also discussed in detail.

Yunjie, Xia; Xianghe, Kong; Kezhu, Yan; Wanping, Chen

1996-01-01

329

Association of actin with alpha crystallins  

NASA Technical Reports Server (NTRS)

The alpha crystallins are cytosolic proteins that co-localize and co-purify with actin-containing microfilaments. Affinity column chromatography employing both covalently-coupled actin or alpha crystallin was used to demonstrate specific and saturable binding of actin with alpha crystallin. This conclusion was confirmed by direct visualization of alpha aggregates bound to actin polymerized in vitro. The significance of this interaction in relation to the functional properties of these two polypeptides will be discussed.

Gopalakrishnan, S.; Boyle, D.; Takemoto, L.; Spooner, B. S. (Principal Investigator)

1993-01-01

330

AlphaSort: A RISC Machine Sort  

Microsoft Academic Search

A new sort algorithm, called AlphaSort, demonstrates that commodity processors and disks can handle commercial batch workloads. Using Alpha AXP processors, commodi~ memory, and arrays of SCSI disks, AlphaSort runs the industry-standard sort benchmark in seven seconds. This beats the best published record on a 32-cpu 32-disk Hypercube by 8:1. On another benchmark, AlphaSort sorted more than a gigabyte in

Chris Nyberg; Tom Barclay; Zarka Cvetanovic; Jim Gray; David B. Lomet

1994-01-01

331

Unfolding domains of recombinant fusion alpha alpha-tropomyosin.  

PubMed Central

The thermal unfolding of the coiled-coil alpha-helix of recombinant alpha alpha-tropomyosin from rat striated muscle containing an additional 80-residue peptide of influenza virus NS1 protein at the N-terminus (fusion-tropomyosin) was studied with circular dichroism and fluorescence techniques. Fusion-tropomyosin unfolded in four cooperative transitions: (1) a pretransition starting at 35 degrees C involving the middle of the molecule; (2) a major transition at 46 degrees C involving no more than 36% of the helix from the C-terminus; (3) a major transition at 56 degrees C involving about 46% of the helix from the N-terminus; and (4) a transition from the nonhelical fusion domain at about 70 degrees C. Rabbit skeletal muscle tropomyosin, which lacks the fusion peptide but has the same tropomyosin sequence, does not exhibit the 56 degrees C or 70 degrees C transition. The very stable fusion unfolding domain of fusion-tropomyosin, which appears in electron micrographs as a globular structural domain at one end of the tropomyosin rod, acts as a cross-link to stabilize the adjacent N-terminal domain. The least stable middle of the molecule, when unfolded, acts as a boundary to allow the independent unfolding of the C-terminal domain at 46 degrees C from the stabilized N-terminal unfolding domain at 56 degrees C. Thus, strong localized interchain interactions in coiled-coil molecules can increase the stability of neighboring domains. PMID:1303750

Ishii, Y.; Hitchcock-DeGregori, S.; Mabuchi, K.; Lehrer, S. S.

1992-01-01

332

Analogs of alpha-conotoxin MII are selective for alpha6-containing nicotinic acetylcholine receptors.  

PubMed

Neuronal nicotinic acetylcholine receptors (nAChRs) both mediate direct cholinergic synaptic transmission and modulate synaptic transmission by other neurotransmitters. Novel ligands are needed as probes to discriminate among structurally related nAChR subtypes. Alpha-conotoxin MII, a selective ligand that discriminates among a variety of nAChR subtypes, fails to discriminate well between some subtypes containing the closely related alpha3 and alpha6 subunits. Structure-function analysis of alpha-conotoxin MII was performed in an attempt to generate analogs with preference for alpha6-containing [alpha6(*) (asterisks indicate the possible presence of additional subunits)] nAChRs. Alanine substitution resulted in several analogs with decreased activity at alpha3(*) versus alpha6(*) nAChRs heterologously expressed in Xenopus laevis oocytes. From the initial analogs, a series of mutations with two alanine substitutions was synthesized. Substitution at His9 and Leu15 (MII[H9A;L15A]) resulted in a 29-fold lower IC(50) at alpha6beta4 versus alpha3beta4 nAChRs. The peptide had a 590-fold lower IC(50) for alpha6/alpha3beta2 versus alpha3beta2 and a 2020-fold lower IC(50) for alpha6/alpha3beta2beta3 versus alpha3beta2 nAChRs. MII[H9A;L15A] had little or no activity at alpha2beta2, alpha2beta4, alpha3beta4, alpha4beta2, alpha4beta4, and alpha7 nAChRs. Functional block by MII[H9A;L15A] of rat alpha6/alpha3beta2beta3 nAChRs (IC(50) = 2.4 nM) correlated well with the inhibition constant of MII[H9A;L15A] for [(125)I]alpha-conotoxin MII binding to putative alpha6beta2(*) nAChRs in mouse brain homogenates (K(i) = 3.3 nM). Thus, structure-function analysis of alpha-conotoxin MII enabled the creation of novel selective antagonists for discriminating among nAChRs containing alpha3 and alpha6 subunits. PMID:15044624

McIntosh, J Michael; Azam, Layla; Staheli, Sarah; Dowell, Cheryl; Lindstrom, Jon M; Kuryatov, Alexander; Garrett, James E; Marks, Michael J; Whiteaker, Paul

2004-04-01

333

Time-dependent theory of alpha decay  

Microsoft Academic Search

Using Green's function techniques a time-dependent theory of ..cap alpha.. decay in the standard one-body model is developed. Formulas are obtained for the decay rate and ..cap alpha.. energy. These formulas are combined with experimental information to show that to a good approximation the initial ..cap alpha..-particle wave function vanishes on or near the nuclear surface.

Michael G. Fuda

1984-01-01

334

Time-dependent theory of alpha decay  

SciTech Connect

Using Green's function techniques a time-dependent theory of ..cap alpha.. decay in the standard one-body model is developed. Formulas are obtained for the decay rate and ..cap alpha.. energy. These formulas are combined with experimental information to show that to a good approximation the initial ..cap alpha..-particle wave function vanishes on or near the nuclear surface.

Fuda, M.G.

1984-09-01

335

Alpha particle condensation and nuclear rainbow scattering  

E-print Network

It is shown that a dilute property of an $\\alpha$ particle condensate can be seen in the Airy structure of nuclear rainbow and prerainbow scattering. The dilute property of the Hoyle state of $^{12}$C with a developed $\\alpha$ cluster structure is discussed by studying refractive $^3$He+$^{12}$C and $\\alpha$+$^{12}$C scattering.

S Ohkubo; Y Hirabayashi

2011-02-09

336

Recent Results on the CKM Angle Alpha  

SciTech Connect

The method to measure the CKM angle {alpha} and the modes sensitive to it are discussed. It is shown that the B {yields} {rho}{rho} decays provide the most stringent constraint on {alpha}, which is found to be {alpha} = 96{sup o} {+-} 10{sup o}(stat) {+-} 4{sup o}(syst){+-} 13{sup o}(penguin).

Mihalyi, A.; /Wisconsin U., Madison

2005-10-18

337

Atypical Alpha Asymmetry in Adults with ADHD  

ERIC Educational Resources Information Center

Introduction: A growing body of literature suggests atypical cerebral asymmetry and interhemispheric interaction in ADHD. A common means of assessing lateralized brain function in clinical populations has been to examine the relative proportion of EEG alpha activity (8-12 Hz) in each hemisphere (i.e., alpha asymmetry). Increased rightward alpha

Hale, T. Sigi; Smalley, Susan L.; Hanada, Grant; Macion, James; McCracken, James T.; McGough, James J.; Loo, Sandra K.

2009-01-01

338

Refinement of the $n-\\alpha$ and $p-\\alpha$ fish-bone potential  

E-print Network

The fishbone potential of composite particles simulates the Pauli effect by nonlocal terms. We determine the $n-\\alpha$ and $p-\\alpha$ fish-bone potential by simultaneously fitting to the experimental phase shifts. We found that with a double Gaussian parametrization of the local potential can describe the $n-\\alpha$ and $p-\\alpha$ phase shifts for all partial waves.

Smith, E; Papp, Z

2012-01-01

339

Efficient synthesis of serically constrained smmetrically alpha,alpha-disubstituted alpha-amino acids under operationally convenient conditions.  

PubMed

Homologation of the nucleophilic glycine equivalent Ni-Gly-PABP [Ni(II) complex of glycine Schiff base with 2-[N-(alpha-picolyl)amino]benzophenone (PABP)] 2 via alkyl halide alkylations and Michael addition reactions was systematically studied as a general method for preparing symmetrically alpha,alpha-disubstituted alpha-amino acids (sym-alpha,alpha-AA). The dialkylation reactions are conducted under operationally convenient conditions without recourse to inert atmosphere, dried solvents, and low temperatures, thus enjoying key advantages of the experimental simplicity and attractive cost structure. The method has been shown to be particularly successful for the dialkylation of complex 2 with activated and nonactivated alkyl halides, including propargyl derivatives, affording a generalized and practical access to the corresponding sym-alpha,alpha-AA. This study has also shown some limitation of the method, as it cannot be extended to alpha- or beta-branched alkyl halides or Michael acceptors to be used for the dialkylation of glycine equivalent 2. High chemical yields of the dialkylated products, combined with the simplicity of the experimental procedure, render this method worth immediate use for multigram scale preparation of the sym-alpha,alpha-AA. PMID:12895052

Ellis, Trevor K; Martin, Collin H; Tsai, Gary M; Ueki, Hisanori; Soloshonok, Vadim A

2003-08-01

340

The Alpha 21264 microprocessor architecture  

Microsoft Academic Search

The 21264 is the third generation Alpha microprocessor from Compaq Computer (formerly Digital Equipment) Corporation. This microprocessor achieves the industry-leading performance levels of 30+ Specint95 and 50+ Specfp95. In addition to the aggressive 600 MHz cycle time in a 0.35 ?m CMOS process, there are also many architectural features that enable the outstanding performance level of the 21264. This paper

R. E. Kessler; E. J. McLellan; D. A. Webb

1998-01-01

341

Possible bioactive conformations of alpha-melanotropin.  

PubMed

By comparing the results of energy calculation for alpha-MSH and its semirigid analogues Ac-[ Cys4 , Cys10 ]-alpha- MSH4 -10-NH2, Ac-[ Cys4 , Cys10 ]-alpha- MSH4 -13-NH2, and [ Cys4 - Cys10 ]-alpha-MSH, a detailed description of two possible bioactive conformations for the 'specific' central site of alpha- MSH6 -9 is proposed representing variants of chain-reversal structure. A possible explanation of the rise in melanotropic activity of the latter two semirigid analogues is presented. PMID:6723968

Nikiforovich, G V; Rozenblit, S A; Shenderovich, M D; Chipens, G I

1984-05-21

342

Alpha voltaic batteries and methods thereof  

NASA Technical Reports Server (NTRS)

An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

Raffaelle, Ryne P. (Inventor); Jenkins, Phillip (Inventor); Wilt, David (Inventor); Scheiman, David (Inventor); Chubb, Donald (Inventor); Castro, Stephanie (Inventor)

2011-01-01

343

THE LYMAN ALPHA REFERENCE SAMPLE: EXTENDED LYMAN ALPHA HALOS PRODUCED AT LOW DUST CONTENT  

SciTech Connect

We report on new imaging observations of the Lyman alpha emission line (Ly{alpha}), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028 < z < 0.18 in continuum-subtracted Ly{alpha}, H{alpha}, and the far ultraviolet continuum. We show that Ly{alpha} is emitted on scales that systematically exceed those of the massive stellar population and recombination nebulae: as measured by the Petrosian 20% radius, R{sub P20}, Ly{alpha} radii are larger than those of H{alpha} by factors ranging from 1 to 3.6, with an average of 2.4. The average ratio of Ly{alpha}-to-FUV radii is 2.9. This suggests that much of the Ly{alpha} light is pushed to large radii by resonance scattering. Defining the Relative Petrosian Extension of Ly{alpha} compared to H{alpha}, {xi}{sub Ly{alpha}} = R {sup Ly{alpha}}{sub P20}/R {sup H{alpha}}{sub P20}, we find {xi}{sub Ly{alpha}} to be uncorrelated with total Ly{alpha} luminosity. However, {xi}{sub Ly{alpha}} is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Ly{alpha} photons throughout the interstellar medium and drive a large extended Ly{alpha} halo.

Hayes, Matthew [Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France); Oestlin, Goeran; Duval, Florent; Guaita, Lucia; Melinder, Jens; Sandberg, Andreas [Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Schaerer, Daniel [CNRS, IRAP, 14, avenue Edouard Belin, F-31400 Toulouse (France); Verhamme, Anne; Orlitova, Ivana [Geneva Observatory, University of Geneva, 51 Chemin des Maillettes, CH-1290 Versoix (Switzerland); Mas-Hesse, J. Miguel; Oti-Floranes, Hector [Centro de Astrobiologia (CSIC-INTA), Departamento de Astrofisica, POB 78, 28691 Villanueva de la Canada (Spain); Adamo, Angela [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Atek, Hakim [Laboratoire d'Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Observatoire, CH-1290 Sauverny (Switzerland); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Herenz, E. Christian [Leibniz-Institut fuer Astrophysik (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Kunth, Daniel [Institut d'Astrophysique de Paris, UMR 7095 CNRS and UPMC, 98 bis Bd Arago, F-75014 Paris (France); Laursen, Peter, E-mail: matthew@astro.su.se [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

2013-03-10

344

In Vitro Cytotoxicity of Low-Dose-Rate Radioimmunotherapy by the Alpha-Emitting Radioimmunoconjugate Thorium-227-DOTA-Rituximab  

SciTech Connect

Purpose: To determine whether the low-dose-rate alpha-particle-emitting radioimmunoconjugate {sup 227}Th-1,4,7,10-p-isothiocyanato-benzyl-tetraazacyclododecane-1,4,7, 10-tetraacetic acid (DOTA)-rituximab can be used to inactivate lymphoma cells growing as single cells and small colonies. Methods and Materials: CD20-positive lymphoma cell lines were treated with {sup 227}Th-DOTA-rituximab for 1-5 weeks. To simulate the in vivo situation with continuous but decreasing supply of radioimmunoconjugates from the blood pool, the cells were not washed after incubation with {sup 227}Th-DOTA-rituximab, but half of the medium was replaced with fresh medium, and cell concentration and cell-bound activity were determined every other day after start of incubation. A microdosimetric model was established to estimate the average number of hits in the nucleus for different localizations of activity. Results: There was a specific targeted effect on cell growth of the {sup 227}Th-DOTA-rituximab treatment. Although the cells were not washed after incubation with {sup 227}Th-DOTA-rituximab, the average contribution of activity in the medium to the mean dose was only 6%, whereas the average contribution from activity on the cells' own surface was 78%. The mean dose rates after incubation with 800 Bq/mL {sup 227}Th-DOTA-rituximab varied from 0.01 to 0.03 cGy/min. The average delay in growing from 10{sup 5} to 10{sup 7} cells/mL was 15 days when the cells were treated with a mean absorbed radiation dose of 2 Gy alpha-particle radiation from {sup 227}Th-DOTA-rituximab, whereas it was 11 days when the cells were irradiated with 6 Gy of X-radiation. The relative biologic effect of the treatment was estimated to be 2.9-3.4. Conclusions: The low-dose-rate radioimmunoconjugate {sup 227}Th-DOTA-rituximab is suitable for inactivation of single lymphoma cells and small colonies of lymphoma cells.

Dahle, Jostein, E-mail: jostein.dahle@rr-research.n [Department of Radiation Biology, Norwegian Radium Hospital, Montebello, Oslo (Norway); Krogh, Cecilie; Melhus, Katrine B. [Department of Radiation Biology, Norwegian Radium Hospital, Montebello, Oslo (Norway); Borrebaek, Jorgen [Algeta ASA, Oslo (Norway); Larsen, Roy H. [Department of Radiation Biology, Norwegian Radium Hospital, Montebello, Oslo (Norway); Kvinnsland, Yngve [Nordic Neurolabs, Bergen (Norway)

2009-11-01

345

Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48 + Am-243  

E-print Network

Products of the fusion-evaporation reaction Ca-48 + Am-243 were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum f\\"ur Schwerionenforschung. Amongst the detected thirty correlated alpha-decay chains associated with the production of element Z=115, two recoil-alpha-fission and five recoil-alpha-alpha-fission events were observed. The latter are similar to four such events reported from experiments performed at the Dubna gas-filled separator. Contrary to their interpretation, we propose an alternative view, namely to assign eight of these eleven decay chains of recoil-alpha(-alpha)-fission type to start from the 3n-evaporation channel 115-288. The other three decay chains remain viable candidates for the 2n-evaporation channel 115-289.

Forsberg, U; Andersson, L -L; Di Nitto, A; Düllmann, Ch E; Gates, J M; Golubev, P; Gregorich, K E; Gross, C J; Herzberg, R -D; Hessberger, F P; Khuyagbaatar, J; Kratz, J V; Rykaczewski, K; Sarmiento, L G; Schädel, M; Yakushev, A; Åberg, S; Ackermann, D; Block, M; Brand, H; Carlsson, B G; Cox, D; Derkx, X; Dobaczewski, J; Eberhardt, K; Even, J; Fahlander, C; Gerl, J; Jäger, E; Kindler, B; Krier, J; Kojouharov, I; Kurz, N; Lommel, B; Mistry, A; Mokry, C; Nazarewicz, W; Nitsche, H; Omtvedt, J P; Papadakis, P; Ragnarsson, I; Runke, J; Schaffner, H; Schausten, B; Shi, Y; Thörle-Pospiech, P; Torres, T; Traut, T; Trautmann, N; Türler, A; Ward, A; Ward, D E; Wiehl, N

2015-01-01

346

Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48 + Am-243  

E-print Network

Products of the fusion-evaporation reaction Ca-48 + Am-243 were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum f\\"ur Schwerionenforschung. Amongst the detected thirty correlated alpha-decay chains associated with the production of element Z=115, two recoil-alpha-fission and five recoil-alpha-alpha-fission events were observed. The latter are similar to four such events reported from experiments performed at the Dubna gas-filled separator. Contrary to their interpretation, we propose an alternative view, namely to assign eight of these eleven decay chains of recoil-alpha(-alpha)-fission type to start from the 3n-evaporation channel 115-288. The other three decay chains remain viable candidates for the 2n-evaporation channel 115-289.

U. Forsberg; D. Rudolph; L. -L. Andersson; A. Di Nitto; Ch. E. Düllmann; J. M. Gates; P. Golubev; K. E. Gregorich; C. J. Gross; R. -D. Herzberg; F. P. Hessberger; J. Khuyagbaatar; J. V. Kratz; K. Rykaczewski; L. G. Sarmiento; M. Schädel; A. Yakushev; S. Åberg; D. Ackermann; M. Block; H. Brand; B. G. Carlsson; D. Cox; X. Derkx; J. Dobaczewski; K. Eberhardt; J. Even; C. Fahlander; J. Gerl; E. Jäger; B. Kindler; J. Krier; I. Kojouharov; N. Kurz; B. Lommel; A. Mistry; C. Mokry; W. Nazarewicz; H. Nitsche; J. P. Omtvedt; P. Papadakis; I. Ragnarsson; J. Runke; H. Schaffner; B. Schausten; Y. Shi; P. Thörle-Pospiech; T. Torres; T. Traut; N. Trautmann; A. Türler; A. Ward; D. E. Ward; N. Wiehl

2015-02-10

347

High gas flow alpha detector  

DOEpatents

An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors. 4 figs.

Bolton, R.D.; Bounds, J.A.; Rawool-Sullivan, M.W.

1996-05-07

348

High gas flow alpha detector  

DOEpatents

An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors.

Bolton, Richard D. (Los Alamos, NM); Bounds, John A. (Los Alamos, NM); Rawool-Sullivan, Mohini W. (Los Alamos, NM)

1996-01-01

349

Targeted alpha therapy for cancer  

NASA Astrophysics Data System (ADS)

Targeted alpha therapy (TAT) offers the potential to inhibit the growth of micrometastases by selectively killing isolated and preangiogenic clusters of cancer cells. The practicality and efficacy of TAT is tested by in vitro and in vivo studies in melanoma, leukaemia, colorectal, breast and prostate cancers, and by a phase 1 trial of intralesional TAT for melanoma. The alpha-emitting radioisotope used is Bi-213, which is eluted from the Ac-225 generator and chelated to a cancer specific monoclonal antibody (mab) or protein (e.g. plasminogen activator inhibitor-2 PAI2) to form the alpha-conjugate (AC). Stable alpha-ACs have been produced which have been tested for specificity and cytotoxicity in vitro against melanoma (9.2.27 mab), leukaemia (WM60), colorectal (C30.6), breast (PAI2, herceptin), ovarian (PAI2, herceptin, C595), prostate (PAI2, J591) and pancreatic (PAI2, C595) cancers. Subcutaneous inoculation of 1-1.5 million human cancer cells into the flanks of nude mice causes tumours to grow in all mice. Tumour growth is compared for untreated controls, nonspecific AC and specific AC, for local (subcutaneous) and systemic (tail vein or intraperitoneal) injection models. The 213Bi-9.2.27 AC is injected into secondary skin melanomas in stage 4 patients in a dose escalation study to determine the effective tolerance dose, and to measure kinematics to obtain the equivalent dose to organs. In vitro studies show that TAT is one to two orders of magnitude more cytotoxic to targeted cells than non-specific ACs, specific beta emitting conjugates or free isotopes. In vivo local TAT at 2 days post-inoculation completely prevents tumour formation for all cancers tested so far. Intra-lesional TAT can completely regress advanced sc melanoma but is less successful for breast and prostate cancers. Systemic TAT inhibits the growth of sc melanoma xenografts and gives almost complete control of breast and prostate cancer tumour growth. Intralesional doses up to 450 µCi in human patients are effective in regressing melanomas, with no concomitant complications. These results point to the application of local and systemic TAT in the management of secondary cancer. Results of the phase 1 clinical trial of TAT of subcutaneous, secondary melanoma indicate proof of the principle that TAT can make tumours in patients regress.

Allen, Barry J.; Raja, Chand; Rizvi, Syed; Li, Yong; Tsui, Wendy; Zhang, David; Song, Emma; Qu, Chang Fa; Kearsley, John; Graham, Peter; Thompson, John

2004-08-01

350

Concomitant dehydration mechanisms in single crystals of alpha,alpha-trehalose.  

PubMed

The dehydration behaviour of alpha,alpha-trehalose (alpha-D-glucopyranosyl alpha-D-glucopyranoside) dihydrate single crystals is investigated by thermomicroscopy, Raman microscopy, and differential scanning calorimetry. The results show at a given stage the simultaneous presence of two polymorphic forms, amorphous material, and movement of a fluid phase. The study also underlines that the characterization of the average phase by conventional XRPD and DSC techniques is not sufficient to describe the dehydration mechanisms of alpha,alpha-trehalose particles. Moreover, it confirms that the dehydration behaviour is mainly driven by heterogeneities and the rate of water loss. PMID:19875105

Dupray, Valérie; Berton, Benjamin; Ossart, Stephen; Atmani, Hassan; Petit, Marie-Noëlle; Coquerel, Gérard

2009-12-14

351

{alpha} decay of {sup 105}Te  

SciTech Connect

The {alpha} decay of the neutron-deficient nuclide {sup 105}Te was observed. The {sup 50}Cr({sup 58}Ni,3n) reaction was used to produce {sup 105}Te nuclei. The {sup 105}Te residues were selected with the Argonne Fragment Mass Analyzer and implanted into a double-sided Si strip detector where their subsequent {alpha} decay was detected. An {alpha}-decay Q value of Q{sub {alpha}}=4900(50) keV and a half life of T{sub 1/2}=0.70(-0.17+0.25){mu}s were measured for {sup 105}Te and a reduced {alpha}-decay width of W{sub {alpha}}=3.3(-1.7+2.1) was deduced. The decay properties of {sup 105}Te are compared with those of heavier Te isotopes and theoretical predictions.

Seweryniak, D.; Davids, C.N.; Gros, S.; Khoo, T.L.; Peterson, D.; Robinson, A.; Zhu, S. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Starosta, K.; Vaman, C. [National Superconducting Cyclotron Laboratory, East Lansing, Michigan 48824 (United States); Hecht, A.A.; Hoteling, N.; Walters, W.B. [University of Maryland, College Park, Maryland 20742 (United States); Lagergren, K.; Woods, P.J. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States); Lotay, G. [University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)

2006-06-15

352

Alpha Subunit Position and GABA Receptor Function  

NSDL National Science Digital Library

GABAA (γ-aminobutyric acid type A) receptors are ligand-gated ion channels composed of five subunits, generally two &alpha;s, two βs, and a γ2. Recent research in which sets of subunits containing &alpha;1 or &alpha;6 subunits were artificially linked has revealed the importance of subunit position in determining GABAA receptor function. Sensitivity to benzodiazepines depended on juxtaposition of an &alpha;1 subunit with the γ2 subunit, whereas sensitivity to furosemide depended only on the presence of an &alpha;6 subunit and not on its specific location. The major utility of the linked subunit approach is to provide a mechanism for discovering the functional signatures of defined subunit arrangements, and thus a route to identifying such arrangements in vivo.

David R. Burt (University of Maryland School of Medicine;Department of Pharmacology REV)

2005-02-08

353

Local Varying-Alpha Theories  

E-print Network

In a recent paper we demonstrated how the simplest model for varying alpha may be interpreted as the effect of a dielectric material, generalized to be consistent with Lorentz invariance. Unlike normal dielectrics, such a medium cannot change the speed of light, and its dynamics obey a Klein-Gordon equation. This work immediately suggests an extension of the standard theory, even if we require compliance with Lorentz invariance. Instead of a wave equation, the dynamics may satisfy a local algebraic relation involving the permittivity and the properties of the electromagnetic field, in analogy with more conventional dielectric (but still preserving Lorentz invariance). We develop the formalism for such theories and investigate some phenomenological implications. The problem of the divergence of the classical self-energy can be solved, or at least softened, in this framework. Some interesting new cosmological solutions for the very early universe are found, including the possibility of a bounce, inflation and expansion with a loitering phase, all of which are induced by early variations in alpha.

John D. Barrow; Joao Magueijo

2015-01-30

354

Beta/alpha continuous air monitor  

DOEpatents

A single deep layer silicon detector in combination with a microcomputer, recording both alpha and beta activity and the energy of each pulse, distinguishing energy peaks using a novel curve fitting technique to reduce the natural alpha counts in the energy region where plutonium and other transuranic alpha emitters are present, and using a novel algorithm to strip out radon daughter contribution to actual beta counts.

Becker, Gregory K. (Idaho Falls, ID); Martz, Dowell E. (Grand Junction, CO)

1989-01-01

355

Beta/alpha continuous air monitor  

DOEpatents

A single deep layer silicon detector in combination with a microcomputer, recording both alpha and beta activity and the energy of each pulse, distinquishing energy peaks using a novel curve fitting technique to reduce the natural alpha counts in the energy region where plutonium and other transuranic alpha emitters are present, and using a novel algorithm to strip out radon daughter contribution to actual beta counts. 7 figs.

Becker, G.K.; Martz, D.E.

1988-06-27

356

On strongly [alpha]-preinvex functions  

NASA Astrophysics Data System (ADS)

In this paper, by means of a series of counterexamples, we study in a systematic way the relationships among (pseudo, quasi) [alpha]-preinvexity, (strict, strong, pseudo, quasi) [alpha]-invexity and (strict, strong, pseudo, quasi) [alpha][eta]-monotonicity. Results obtained in this paper can be viewed as a refinement and improvement of the results of Noor and Noor [M.A. Noor, K.I. Noor, Some characterizations of strongly preinvex functions, J. Math. Anal. Appl. 316 (2006) 697-706].

Fan, Liya; Guo, Yunlian

2007-06-01

357

/sup 20/Ne(. cap alpha. ,2. cap alpha. )/sup 16/O reaction  

SciTech Connect

The /sup 20/Ne(..cap alpha..,2..cap alpha..)/sup 16/O reaction at 140 MeV incident energy is analyzed in the framework of the distorted-wave impulse approximation. The bound state ..cap alpha.. wave functions in /sup 20/Ne are generated using the orthogonal condition model. The predicted results agree with the experimental data. They are also in rough accord with the results obtained with the Woods-Saxon ..cap alpha.. wave function.

Sharma, N.R.; Jain, B.K.; Shyam, R.

1988-02-01

358

The first transformation of aliphatic alpha,beta-epoxyamides into alpha-hydroxyamides.  

PubMed

A general synthesis of aliphatic alpha-hydroxyamides with total regioselectivity by a reductive cleaveage of the C(beta)-O bond of aliphatic alpha,beta-epoxyamides, promoted by samarium diiodide and MeOH, is described. The treatment of enantiopure aliphatic alpha,beta-epoxyamides afforded enantiomerically enriched aliphatic alpha-hydroxyamides. A radical mechanism has been proposed to explain this reaction. [reaction: see text] PMID:14653673

Concellón, José M; Bardales, Eva

2003-12-11

359

Stereoselective desymmetrisation of prochiral alpha,alpha-dicyanoalkenes via domino Michael-Michael addition reactions.  

PubMed

The desymmetrisation of prochiral alpha,alpha-dicyanoalkenes via tandem Michael-Michael addition reactions with alpha,beta-unsaturated ketones catalysed by 9-amino-9-deoxyepicinchona alkaloids was investigated, from which bicyclic products bearing four stereogenic centers were afforded in a single operation with high stereoselectivities (>99% de, up to >99.5% ee). PMID:18633522

Kang, Tai-Ran; Xie, Jian-Wu; Du, Wei; Feng, Xin; Chen, Ying-Chun

2008-08-01

360

Alpha-conotoxin PIA is selective for alpha6 subunit-containing nicotinic acetylcholine receptors.  

PubMed

Until now, there have been no antagonists to discriminate between heteromeric nicotinic acetylcholine receptors (nAChRs) containing the very closely related alpha6 and alpha3 subunits. nAChRs containing alpha3, alpha4, or alpha6 subunits in combination with beta2, occasionally beta4, and sometimes beta3 or alpha5 subunits, are thought to play important roles in cognitive function, pain perception, and the reinforcing properties of nicotine. We cloned a novel gene from the predatory marine snail Conus purpurascens. The predicted peptide, alpha-conotoxin PIA, potently blocks the chimeric alpha6/alpha3beta2beta3 subunit combination as expressed in oocytes but neither the muscle nor the major neuronal nAChR alpha4beta2. Additionally, this toxin is the first described ligand to discriminate between nAChRs containing alpha6 and alpha3 subunits. Exploiting the unusual intron conservation of conotoxin genes may represent a more general approach for defining conotoxin ligand scaffolds to discriminate among closely related receptor populations. PMID:13679412

Dowell, Cheryl; Olivera, Baldomero M; Garrett, James E; Staheli, Sarah T; Watkins, Maren; Kuryatov, Alexander; Yoshikami, Doju; Lindstrom, Jon M; McIntosh, J Michael

2003-09-17

361

Evidence for an alpha cluster condensed state in 16O(alpha,alpha') at 400 MeV  

E-print Network

Inelastic $\\alpha$ scattering on 16O is studied at 400 MeV by using an ice target. Near the 4-alpha breakup threshold of 14.4 MeV, a broad peak is observed at an excitation energy of 13.6+/-0.2 MeV with a width of 0.6+/-0.2 MeV. The spin-parity is estimated to be 0+ from the momentum-transfer dependence. The observed width is significantly larger than those of the neighboring 0+ states indicating a state with a well-developed alpha cluster structure. The magnitude of the cross section is sensitive to the density distribution of the constituent alpha clusters. The observed cross section is consistent with the theoretical prediction for the alpha cluster condensed state characterized by its dilute density distribution with a large root-mean-square radius of about 4.3 fm.

T. Wakasa; E. Ihara; K. Fujita; Y. Funaki; K. Hatanaka; H. Horiuchi; M. Itoh; J. Kamiya; G. Ropke; H. Sakaguchi; N. Sakamoto; Y. Sakemi; P. Schuck; Y. Shimizu; M. Takashina; S. Terashima; A. Tohsaki; M. Uchida; H. P. Yoshida; M. Yosoi

2006-11-13

362

Local Varying-Alpha Theories  

E-print Network

In a recent paper we demonstrated how the simplest model for varying alpha may be interpreted as the effect of a dielectric material, generalized to be consistent with Lorentz invariance. Unlike normal dielectrics, such a medium cannot change the speed of light, and its dynamics obey a Klein-Gordon equation. This work immediately suggests an extension of the standard theory, even if we require compliance with Lorentz invariance. Instead of a wave equation, the dynamics may satisfy a local algebraic relation involving the permittivity and the properties of the electromagnetic field, in analogy with more conventional dielectric (but still preserving Lorentz invariance). We develop the formalism for such theories and investigate some phenomenological implications. The problem of the divergence of the classical self-energy can be solved, or at least softened, in this framework. Some interesting new cosmological solutions for the very early universe are found, including the possibility of a bounce, inflation and e...

Barrow, John D

2014-01-01

363

Characterization and Control of Airborne Particles Emitted During Production of Epoxy\\/Carbon Nanotube Nanocomposites  

Microsoft Academic Search

This work characterized airborne particles generated from the weighing of bulk, multiwall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable

Lorenzo G. Cena; Thomas M. Peters

2011-01-01

364

Characterization and control of airborne particles emitted during production of epoxy/carbon nanotube nanocomposites.  

PubMed

This work characterized airborne particles generated from the weighing of bulk, multiwall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured using an optical particle counter (OPC) and a condensation particle counter (CPC), and particle morphology was assessed by transmission electron microscopy. The ratios of the geometric mean (GM) concentrations measured during the process to that measured in the background (P/B ratios) were used as indices of the impact of the process and the LEVs on observed concentrations. Processing CNT-epoxy nanocomposites materials released respirable size airborne particles (P/B ratio: weighing = 1.79; sanding = 5.90) but generally no nanoparticles (P/B ratio ?1). The particles generated during sanding were predominantly micron sized with protruding CNTs and very different from bulk CNTs that tended to remain in large (>1 ?m) tangled clusters. Respirable mass concentrations in the operator's breathing zone were lower when sanding was performed in the biological safety cabinet (GM = 0.20 ?g/m(3) compared with those with no LEV (GM = 2.68 ?g/m(3) or those when sanding was performed inside the fume hood (GM = 21.4 ?g/m(3); p-value < 0.0001). The poor performance of the custom fume hood used in this study may have been exacerbated by its lack of a front sash and rear baffles and its low face velocity (0.39 m/sec). PMID:21253981

Cena, Lorenzo G; Peters, Thomas M

2011-02-01

365

A model to predict the breathing zone concentrations of particles emitted from surfaces.  

PubMed

Activity based sampling (ABS) is typically performed to assess inhalation exposure to particulate contaminants known to have low, heterogeneous concentrations on a surface. Activity based sampling determines the contaminant concentration in a person's breathing zone as they perform a scripted activity, such as raking a specified area of soil, while wearing appropriate sample collection instrumentation. As an alternative approach, a probabilistic model based on aerosol physics and fluid dynamics was developed to predict the breathing zone concentration of a particulate contaminant emitted from a surface during activities of variable intensity. The model predicted the particle emission rate, tracked particle transport to the breathing zone, and calculated the breathing zone concentration for two scenarios. One scenario used an Eulerian model based on a Gaussian concentration distribution to quantify aerosol exposure in the trailing wake of a moving object. The second scenario modeled exposure in a quiescent environment. A Lagrangian model tracked the cumulative number of individual particles entering the breathing zone volume at a particular time. A Monte Carlo simulation calculated the breathing zone concentration probability distribution for each scenario. Both models predicted probability distributions of asbestos breathing zone concentrations that bracketed experimentally measured personal exposure concentrations. Modeled breathing zone concentrations were statistically correlated (p-value < 0.001) with independently collected ABS concentrations. The linear regression slope of 0.70 and intercept of 0.03 were influenced by the quantity of ABS data collected and model parameter input distributions at a site broader than those at other sites. PMID:20383380

Thornburg, Jonathan; Kominsky, John; Brown, G Gordon; Frechtel, Peter; Barrett, William; Shaul, Glenn

2010-04-01

366

METHODS FOR ANALYZING INORGANIC COMPOUNDS IN PARTICLES EMITTED FROM STATIONARY SOURCES  

EPA Science Inventory

The research described was initiated with the objective of developing methods to identify and measure inorganic compounds in particulate emissions which emanate from sources using or processing fossil fuels. An extensive literature review was carried out to ascertain prior knowle...

367

Ionization of the Atmosphere Due to Beta Particles Emitted by Fission Products  

Microsoft Academic Search

Persistent ionization of air at moderate heights, just below the E ; layer, after high-altitude nuclear detonations is predominantly due to radiations ; accompanying radioactive decay of fission products. The most important are BETA ; particles, which are restricted in their movements by the earth's magnetic field ; and thus create ionized clouds of high density in localized regions. A

S. Kownacki

1963-01-01

368

CHARACTERIZATION OF INDIVIDUAL FLY ASH PARTICLES EMITTED FROM COAL- AND OIL-FIRED POWER PLANTS  

EPA Science Inventory

Individual particles from coal- and oil-fired power plants were analyzed by a scanning electron microscope equipped with an energy dispersive X-ray spectrometer to investigate the morphology and composition as a function of size. Samples were collected on filters by a dichotomous...

369

Large-scale negative polarity magnetic fields on the sun and particle-emitting flares  

NASA Technical Reports Server (NTRS)

Some observational facts about the large-scale patterns formed by solar negative polarity magnetic fields during the 19th and 20th cycles of solar activity are presented. The close relation of the position of occurrence of very large flares accompanied by cosmic ray and PCA events as well as other phenomena of solar activity during the declining part of the 19th cycle of the regularities in the internal structure of large scale negative polarity features are demonstrated.

Bumba, V.

1972-01-01

370

TOXICITY OF PARTICLES EMITTED FROM COMBUSTION OF WASTE CRANKCASE OIL: IN VITRO AND IN VIVO STUDIES  

EPA Science Inventory

The ever-rising cost of energy provides incentives for the utilization of waste crankcase oil (WCO) for space heating. The potential health hazards of emissions and waste products resulting from the combustion of WCO are unknown. The toxicity of the emission particles and waste p...

371

Toxicity of particles emitted from combustion of waste crankcase oil: in vitro and in vivo studies.  

PubMed

The ever-rising cost of energy provides incentives for the utilization of low-cost waste crankcase oil (WCO) for space heating. Although WCO is known to contain toxic heavy metals, the potential health hazards of emissions and waste products resulting from the combustion of WCO are unknown. Thus, the toxicity of the emission particles and waste products from two different types of burners, a Dravo atomizing oil burner (AOB) and a Kroll vaporizing oil burner (VOB), is evaluated using automotive WCO. Samples are characterized by performing elemental analysis and scanning electron microscopy. Both burners emitted fine (less than or equal to 3 microns), respirable particles. The AOB emission particles contained high concentrations of toxic heavy metals, especially Pb, which showed concentrations as high as 7.5%. The VOB retained a significant amount of heavy metals in the burner residue and emitted a much smaller quantity into the air. The toxicity of AOB emission particles, VOB emission particles, and VOB waste residue is evaluated in three bioassay systems, including a rabbit alveolar macrophage (RAM) cytotoxicity in vitro assay, an intratracheal injection infectivity assay, and a peritoneal irritancy test in mice. The emission particles from both burners and leachate from VOB residue produce a dose-related reduction in viability and cellular adenosine triphosphate (ATP) in alveolar macrophages following 20-hr exposure. Acidity of the RAM medium due to the presence of VOB emission particles and waste leachate contributes to its toxicity.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3732672

Mumford, J L; Hatch, G E; Hall, R E; Jackson, M A; Merrill, R G; Lewtas, J

1986-07-01

372

A Model to Predict the Breathing Zone Concentrations of Particles Emitted from Surfaces  

EPA Science Inventory

Activity based sampling (ABS) is typically performed to assess inhalation exposure to particulate contaminants known to have low, heterogeneous concentrations on a surface. Activity based sampling determines the contaminant concentration in a person's breathing zone as they perfo...

373

The characteristics of particles emitted in energetic nucleus-nucleus interactions  

NASA Technical Reports Server (NTRS)

The analysis of the interactions of heavy cosmic ray nuclei in nuclear emulsion exposed over Texas is continued, with 500 interactions of nuclei of E greater than 1.5 GeV/nucleon added. In this paper the experimental data correlating meson production with fragmentation of the projectile and target nuclei are given. These data, combined with earlier results, are also used to reexamine the problem of the mean free path of secondary fragments. Using the same techniques of analysis used for the accelerator ions, evidence is found for anomalously short mean free paths of secondary fragments in the first centimeter after production.

Barber, H. B.; Freier, P. S.; Waddington, C. J.

1982-01-01

374

Identification of platinum and palladium particles emitted from vehicles and dispersed into the surface environment.  

PubMed

Platinum, palladium, and rhodium are emitted from vehicle catalytic converters. Until now, the form of precious metal particles in road dust and urban waste has not been identified. This study has located, imaged, and analyzed these particles in road dust and gully waste. Two fragments of catalytic converter have been observed in road dust. They are 40-80 ?m in size and covered in many minute particles (<0.3 ?m) of either platinum with minor rhodium or palladium. One fragment identified in gully sediment is smaller, 25 ?m in diameter, hosting only one attached particle of palladium with minor rhodium. As fragments are washed off roads they begin to disintegrate and the precious metals become detached. Also precious metal-bearing particles have been located in incinerated sewage ash including a 20 ?m diameter cluster of <3 ?m sized platinum particles that may be the remains of a catalytic converter fragment that has survived incineration. The form of these precious metal-bearing particles described here reveals that as they are dispersed from roads they are likely to be present predominantly as two particle sizes. Either they are attached to larger fragments of catalytic converter or they are released as individual detached tiny <0.3 ?m to nanoparticle sizes. PMID:22313190

Prichard, Hazel M; Fisher, Peter C

2012-03-20

375

Combustion particles emitted during church services: implications for human respiratory health.  

PubMed

Burning candles and incense generate particulate matter (PM) that produces poor indoor air quality and may cause human pulmonary problems. This study physically characterised combustion particles collected in a church during services. In addition, the emissions from five types of candles and two types of incense were investigated using a combustion chamber. The plasmid scission assay was used to determine the oxidative capacities of these church particles. The corresponding risk factor (CRf) was derived from the emission factor (Ef) and the oxidative DNA damage, and used to evaluate the relative respiratory exposure risks. Real-time PM measurements in the church during candle-incense burning services showed that the levels (91.6 ?g/m(3) for PM(10); 38.9 ?g/m(3) for PM(2.5)) exceeded the European Union (EU) air quality guidelines. The combustion chamber testing, using the same environmental conditions, showed that the incense Ef for both PM(10) (490.6-587.9 mg/g) and PM(2.5) (290.1-417.2 mg/g) exceeded that of candles; particularly the PM(2.5) emissions. These CRf results suggested that the exposure to significant amounts of incense PM could result in a higher risk of oxidative DNA adducts (27.4-32.8 times) than tobacco PM. The generation and subsequent inhalation of PM during church activities may therefore pose significant risks in terms of respiratory health effects. PMID:21831441

Chuang, Hsiao-Chi; Jones, Tim; BéruBé, Kelly

2012-04-01

376

Alpha-1 Antitrypsin Deficiency: It's All in the Family  

MedlinePLUS

... It’s All in the Family Whether you have Alpha-1 Antitrypsin Deficiency (Alpha-1) — or are an Alpha-1 “carrier” — we strongly suggest that your relatives ... share with them what you have learned about Alpha-1. How is Alpha-1 inherited? Your genes ...

377

Solution conformation of a neuronal nicotinic acetylcholine receptor antagonist {alpha}-conotoxin OmIA that discriminates {alpha}3 vs. {alpha}6 nAChR subtypes  

SciTech Connect

{alpha}-Conotoxin OmIA from Conus omaria is the only {alpha}-conotoxin that shows a {approx}20-fold higher affinity to the {alpha}3{beta}2 over the {alpha}6{beta}2 subtype of nicotinic acetylcholine receptor. We have determined a three-dimensional structure of {alpha}-conotoxin OmIA by nuclear magnetic resonance spectroscopy. {alpha}-Conotoxin OmIA has an '{omega}-shaped' overall topology with His{sup 5}-Asn{sup 12} forming an {alpha}-helix. Structural features of {alpha}-conotoxin OmIA responsible for its selectivity are suggested by comparing its surface characteristics with other functionally related {alpha}4/7 subfamily conotoxins. Reduced size of the hydrophilic area in {alpha}-conotoxin OmIA seems to be associated with the reduced affinity towards the {alpha}6{beta}2 nAChR subtype.

Chi, Seung-Wook [Molecular Anti-Cancer Research Center, Division of Molecular Therapeutics, Korea Research Institute of Bioscience and Biotechnology, Yusong P.O. Box 115, Daejon (Korea, Republic of); Kim, Do-Hyoung [Molecular Anti-Cancer Research Center, Division of Molecular Therapeutics, Korea Research Institute of Bioscience and Biotechnology, Yusong P.O. Box 115, Daejon (Korea, Republic of); Olivera, Baldomero M. [Department of Biology, University of Utah, Salt Lake City, UT 84112 (United States); McIntosh, J. Michael [Department of Biology, University of Utah, Salt Lake City, UT 84112 (United States); Department of Psychiatry, University of Utah, Salt Lake City, UT 84112 (United States); Han, Kyou-Hoon [Molecular Anti-Cancer Research Center, Division of Molecular Therapeutics, Korea Research Institute of Bioscience and Biotechnology, Yusong P.O. Box 115, Daejon (Korea, Republic of)]. E-mail: khhan600@kribb.re.kr

2006-06-23

378

Psychiatric Symptoms in Alpha-Mannosidosis  

ERIC Educational Resources Information Center

Alpha-mannosidosis is characterized by mild to moderate intellectual disability (ID), moderate to severe neurosensory hearing loss, frequent infections, psychomotor disturbances and skeletal dysmorphism. For the first time, a panel of nine alpha-mannosidosis patients with psychiatric symptoms is presented. The clinical picture has several…

Malm, D.; Pantel, J.; Linaker, O. M.

2005-01-01

379

Alpha-thalassemia in two Mediterranean populations.  

PubMed

We used restriction endonuclease analysis to determine the incidence of alpha-thalassemia in two Mediterranean islands. In a random population sample, the gene frequency of deletion-type alpha-thalassemia-2 (-alpha) was 0.18 in Sardinians and 0.07 in Greek Cypriots. All cases were the rightward crossover type. From these frequencies and the known incidence of hemoglobin-H disease in these populations, we calculated the frequency of the alpha-thalassemia-1 genotype (--) and determined that it was low. We also found that beta-thalassemia homozygotes in sardinia have a higher incidence of alpha-thalassemia than normals and beta thalassemia heterozygotes because a significantly greater number of these homozygotes are also homozygous for the alpha-thalassemia-2 lesion. These findings support the theory that coinheritance of alpha-thalassemia mitigates the severity of beta-thalassemia and suggest that the protection is most pronounced when two alpha-globin genes are deleted. PMID:7093530

Pirastu, M; Lee, K Y; Dozy, A M; Kan, Y W; Stamatoyannopoulos, G; Hadjiminas, M G; Zachariades, Z; Angius, A; Furbetta, M; Rosatelli, C; Cao, A

1982-08-01

380

27 CFR 21.95 - Alpha terpineol.  

Code of Federal Regulations, 2011 CFR

...and Firearms 1 2011-04-01 2011-04-01 false Alpha terpineol. 21.95 Section 21.95 Alcohol, Tobacco...ALCOHOL AND RUM Specifications for Denaturants § 21.95 Alpha terpineol. (a) Boiling point at 752mm...

2011-04-01

381

Coefficient Alpha Bootstrap Confidence Interval under Nonnormality  

ERIC Educational Resources Information Center

Three different bootstrap methods for estimating confidence intervals (CIs) for coefficient alpha were investigated. In addition, the bootstrap methods were compared with the most promising coefficient alpha CI estimation methods reported in the literature. The CI methods were assessed through a Monte Carlo simulation utilizing conditions…

Padilla, Miguel A.; Divers, Jasmin; Newton, Matthew

2012-01-01

382

Commentary on Coefficient Alpha: A Cautionary Tale  

ERIC Educational Resources Information Center

The general use of coefficient alpha to assess reliability should be discouraged on a number of grounds. The assumptions underlying coefficient alpha are unlikely to hold in practice, and violation of these assumptions can result in nontrivial negative or positive bias. Structural equation modeling was discussed as an informative process both to…

Green, Samuel B.; Yang, Yanyun

2009-01-01

383

Teaching Calculus with Wolfram|Alpha  

ERIC Educational Resources Information Center

This article describes the benefits and drawbacks of using Wolfram|Alpha as the platform for teaching calculus concepts in the lab setting. It is a result of our experiences designing and creating an entirely new set of labs using Wolfram|Alpha. We present the reasoning behind our transition from using a standard computer algebra system (CAS) to…

Dimiceli, Vincent E.; Lang, Andrew S. I. D.; Locke, LeighAnne

2010-01-01

384

27 CFR 21.95 - Alpha terpineol.  

Code of Federal Regulations, 2010 CFR

...and Firearms 1 2010-04-01 2010-04-01 false Alpha terpineol. 21.95 Section 21.95 Alcohol, Tobacco...ALCOHOL AND RUM Specifications for Denaturants § 21.95 Alpha terpineol. (a) Boiling point at 752mm...

2010-04-01

385

Meta-Analysis of Coefficient Alpha  

ERIC Educational Resources Information Center

The meta-analysis of coefficient alpha across many studies is becoming more common in psychology by a methodology labeled reliability generalization. Existing reliability generalization studies have not used the sampling distribution of coefficient alpha for precision weighting and other common meta-analytic procedures. A framework is provided for…

Rodriguez, Michael C.; Maeda, Yukiko

2006-01-01

386

Elementary Processes Underlying Alpha Channeling in Tokamaks  

SciTech Connect

Alpha channeling in tokamaks is speculative, but also extraordinarily attractive. Waves that can accomplish this effect have been identified. Key aspects of the theory now enjoy experimental confirmation. This paper will review the elementary processes of wave-particle interactions in plasma that underlie the alpha channeling effect

NM.J. Fisch

2012-06-15

387

Fatty acylation of alpha z. Effects of palmitoylation and myristoylation on alpha z signaling.  

PubMed

As the first step in an investigation of roles played by fatty acylation of G protein alpha chains in membrane targeting and signal transmission, we inserted monoclonal antibody epitopes, hemagglutinin (HA) or Glu-Glu (EE), at two internal sites in three alpha subunits. At site I, only HA-tagged alpha q and alpha z functioned normally. alpha s, alpha q, and alpha z subunits tagged at site II with the EE epitope showed normal expression, membrane localization, and signaling activity. Using epitope-tagged alpha z, we investigated effects of mutations in sites for fatty acylation. Mutational substitution of Ala for Gly2 (G2A) prevented incorporation of myristate and decreased but did not abolish incorporation of palmitate. Substitution of Ala for Cys3 (C3A) prevented incorporation of palmitate but had no effect on incorporation of myristate. Substitution of Ala for both Gly2 and Cys3 (G2AC3A) prevented incorporation of both myristate and palmitate. All three mutations substantially disrupted association of alpha z with the particulate fraction. Gz-mediated inhibition of adenylyl cyclase, triggered by activation of the D2-dopamine receptor, was, respectively, abolished (G2AC3A), impaired (G2A), and enhanced (C3A). Constitutive inhibition of adenylyl cyclase by alpha z was unchanged (G2AC3A), strongly diminished (G2A), or strongly enhanced (C3A). A nonacylated, mutationally activated alpha z mutant inhibited adenylyl cyclase, although less potently than normally acylated, mutationally activated alpha z. From these findings we conclude: (a) fatty acylations of alpha z increase its association with membranes; (b) myristoylation is not required for palmitoylation of alpha z or for its productive interactions with adenylyl cyclase; (c) palmitoylation is not required for, but may instead inhibit, signaling by alpha z. PMID:7536745

Wilson, P T; Bourne, H R

1995-04-21

388

Improved peak shape fitting in alpha spectra.  

PubMed

Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. PMID:25497323

Pommé, S; Caro Marroyo, B

2015-02-01

389

Determination of alpha_s from the QCD static energy: an update  

E-print Network

We present an update of our determination of the strong coupling alpha_s from the quantum chromodynamics static energy. This updated analysis includes new lattice data, at smaller lattice spacings and reaching shorter distances, the use of better suited perturbative expressions to compare with data in a wider distance range, and a comprehensive and detailed estimate of the error sources that contribute to the uncertainty of the final result. Our updated value for alpha_s at the Z-mass scale, M_Z, is alpha_s(M_Z)=0.1166^{+0.0012}_{-0.0008}, which supersedes our previous result.

Alexei Bazavov; Nora Brambilla; Xavier Garcia i Tormo; Peter Petreczky; Joan Soto; Antonio Vairo

2014-11-04

390

Alpha1 and Alpha2 Integrins Mediate Invasive Activity of Mouse Mammary Carcinoma Cells through Regulation of Stromelysin-1 Expression  

SciTech Connect

Tumor cell invasion relies on cell migration and extracellular matrix proteolysis. We investigated the contribution of different integrins to the invasive activity of mouse mammary carcinoma cells. Antibodies against integrin subunits {alpha}6 and {beta}1, but not against {alpha}1 and {alpha}2, inhibited cell locomotion on a reconstituted basement membrane in two-dimensional cell migration assays, whereas antibodies against {beta}1, but not against a6 or {alpha}2, interfered with cell adhesion to basement membrane constituents. Blocking antibodies against {alpha}1 integrins impaired only cell adhesion to type IV collagen. Antibodies against {alpha}1, {alpha}2, {alpha}6, and {beta}1, but not {alpha}5, integrin subunits reduced invasion of a reconstituted basement membrane. Integrins {alpha}1 and {alpha}2, which contributed only marginally to motility and adhesion, regulated proteinase production. Antibodies against {alpha}1 and {alpha}2, but not {alpha}6 and {beta}1, integrin subunits inhibited both transcription and protein expression of the matrix metalloproteinase stromelysin-1. Inhibition of tumor cell invasion by antibodies against {alpha}1 and {alpha}2 was reversed by addition of recombinant stromelysin-1. In contrast, stromelysin-1 could not rescue invasion inhibited by anti-{alpha}6 antibodies. Our data indicate that {alpha}1 and {alpha}2 integrins confer invasive behavior by regulating stromelysin-1 expression, whereas {alpha}6 integrins regulate cell motility. These results provide new insights into the specific functions of integrins during tumor cell invasion.

Lochter, Andre; Navre, Marc; Werb, Zena; Bissell, Mina J

1998-06-29

391

Nonlinear interface dynamos with alpha -quenching  

NASA Astrophysics Data System (ADS)

There exist various mechanisms capable of limiting the magnitude of the (presumably) dynamo-generated, large-scale solar magnetic field. One such mechanism is the so-called ``alpha -quenching''. The underlying idea is that the Lorentz force associated with the dynamo-generated magnetic fields impedes the small scale, turbulent fluid motions giving rise to the so-called ``alpha -effect'' (the production of poloidal from toroidal fields in the framework of mean-field dynamo theory). In mean-field models, a popular ---yet essentially ad hoc--- prescription for alpha -quenching consists in replacing the coefficient (alpha ) of the alpha -effect source term in the dynamo equations by an expression of the form alpha -> alpha (B) =alpha_0 /(1+(|B|/B_eq)(2)) , where alpha_0 is a measure of the strength of the alpha -effect in the linear regime, and B_eq is the equipartition field strength, based on the kinetic energy of the turbulent, convective fluid motions (B_eq ~ 10(4) G at the base of the solar convection zone). In principle, such ``Weak Quenching'' allows the production of magnetic fields of roughly equipartition strength, as demonstrated by the numerous conventional mean-field dynamo models making use of eq. (1), or some close variant, published to date. Vainshtein & Cattaneo (1992, ApJ 393, 165) and Gruzinov & Diamond (1995, Phys. Plasmas 2, 1941) have argued, however, that alpha -quenching should be described by alpha -> alpha (B) =alpha_0 /(R_m(|B|/B_eq)(2)) where R_m is a magnetic Reynolds number based on the microscopic properties of the flow (R_m>> 1 for solar interior conditions). This now describes a much stronger form of alpha -quenching, and, with R_m>> 1, could be fatal to large-scale dynamo action, in the sense that the dynamo could only produce magnetic fields of strength << B_eq. This is in marked contradiction with the demands set by recent models of bipolar magnetic region emergence, which require field strengths of order 10x B_eq ~ 10(5) G for the observed latitudes and tilt of emergence to be adequately reproduced. In this contribution, we investigate the circumstances under which interface dynamos can avoid alpha -quenching, either in the ``Weak'' or ``Strong'' forms defined above. In interface dynamos the alpha -effect is assumed to operate within the solar convective envelope, while the strongest magnetic fields are generated by shearing below the core-envelope interface (Parker 1993, ApJ 408, 707; Charbonneau & MacGregor, submitted to ApJ). This spatial segregation of the alpha -effect source region is the key to avoiding alpha -quenching. This is illustrated using a few nonlinear, kinematic interface dynamo solutions applicable to the Sun.

Charbonneau, P.; MacGregor, K. B.

1996-05-01

392

Genetics Home Reference: Mucolipidosis III alpha/beta  

MedlinePLUS

... literature OMIM Genetic disorder catalog Conditions > Mucolipidosis III alpha/beta On this page: Description Genetic changes Inheritance ... definitions Reviewed October 2014 What is mucolipidosis III alpha/beta? Mucolipidosis III alpha/beta is a slowly ...

393

77 FR 44511 - Airworthiness Directives; Alpha Aviation Concept Limited Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Alpha Aviation Concept Limited Airplanes AGENCY...new airworthiness directive (AD) for Alpha Aviation Concept Limited Model R2160 Airplanes...identified in this proposed AD, contact Alpha Aviation, 59 Hautapu Road, RD...

2012-07-30

394

Genetics Home Reference: Mucolipidosis II alpha/beta  

MedlinePLUS

... literature OMIM Genetic disorder catalog Conditions > Mucolipidosis II alpha/beta On this page: Description Genetic changes Inheritance ... definitions Reviewed June 2014 What is mucolipidosis II alpha/beta? Mucolipidosis II alpha/beta (also known as ...

395

77 FR 60887 - Airworthiness Directives; Alpha Aviation Concept Limited Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Alpha Aviation Concept Limited Airplanes AGENCY...new airworthiness directive (AD) for Alpha Aviation Concept Limited Model R2160 Airplanes...information identified in this AD, contact Alpha Aviation, 59 Hautapu Road, RD 1,...

2012-10-05

396

Who Is at Risk for Alpha-1 Antitrypsin Deficiency?  

MedlinePLUS

... NHLBI on Twitter. Who Is at Risk for Alpha-1 Antitrypsin Deficiency? Alpha-1 antitrypsin (AAT) deficiency occurs in all ethnic ... substances. Rate This Content: Next >> October 11, 2011 Alpha-1 Antitrypsin Deficiency Clinical Trials Clinical trials are ...

397

What Does It Mean to Be an Alpha-1 Carrier?  

MedlinePLUS

... CSL Behring Talecris Biotherapeutics The mission of the Alpha-1 Foundation is to provide the leadership and ... more information, visit: www.alpha-1foundation.org. The Alpha-1 Association is the leading national patient membership ...

398

alpha-Crystallin can Function as a Molecular Chaperone  

Microsoft Academic Search

The alpha-crystallins (alphaA and alphaB) are major lens structural proteins of the vertebrate eye that are related to the small heat shock protein family. In addition, crystallins (especially alphaB) are found in many cells and organs outside the lens, and alphaB is overexpressed in several neurological disorders and in cell lines under stress conditions. Here I show that alpha-crystallin can

Joseph Horwitz

1992-01-01

399

Lucid dreaming and alpha activity: a preliminary report.  

PubMed

10 good dream recallers spent 2 nights in the sleep lab during which they were awakened 4 times per night from REM sleep, twice during their highest alpha activity in REM, and twice during low REM alpha. 5 were given alpha feedback training prior to sleep onset. Arousals from high alpha REM sleep yielded significantly higher lucidity ratings. Alpha feedback had no effect upon lucidity or REM alpha levels. Similarities between lucid dreams and meditative phenomena are discussed. PMID:7162915

Ogilvie, R D; Hunt, H T; Tyson, P D; Lucescu, M L; Jeakins, D B

1982-12-01

400

Autoregulation of I kappa B alpha activity.  

PubMed Central

Transcription factor NF-kappa B regulates the expression of a plethora of genes. The activity of NF-kappa B proteins is regulated by I kappa B proteins. We report that induction of I kappa B alpha, a member of the I kappa B family of proteins, is preceded by activation of NF-kappa B complex. The promoter of the I kappa B alpha gene contains a kappa B site that is directly involved in its induction by the NF-kappa B complex. Degradation of I kappa B alpha protein precedes activation of NF-kappa B DNA binding activity, whereas newly synthesized I kappa B alpha protein inhibits NF-kappa B activity. If the degradation of I kappa B alpha is prevented, the induction of DNA binding activity of NF-kappa B complex is severely curtailed. These data suggest the existence of an autoregulatory loop whereby I kappa B alpha regulates the activity of transcription factor NF-kappa B, which in turn regulates the I kappa B alpha activity. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:8278379

Chiao, P J; Miyamoto, S; Verma, I M

1994-01-01

401

Alpha-Particle Condensation in Nuclear Systems  

E-print Network

The onset of quartetting, i.e. alpha-particle condensation, in symmetric nuclear matter is studied with the help of an in-medium modified four nucleon equation. It is found that at very low density quartetting wins over pairing, because of the strong binding of the alpha-particles. The critical temperature can reach values up to around 6 MeV. Also the disappearance of alpha-particles with increasing density, i.e. the Mott transition, is investigated. In finite nuclei the Hoyle state, that is the 0_2^+ of 12C, is identified as an "alpha-particle condensate" state. It is conjectured that such states also exist in heavier n alpha-nuclei, like 16O, 20Ne, etc. For instance the 6-th 0^+ state of 16O at 15.1 MeV is identified from a theoretical analysis as being a strong candidate for an alpha condensate state. Exploratory calculations are performed for the density dependence of the alpha condensate fraction at zero temperature to address the suppression of the four-particle condensate below nuclear-matter density. Possible quartet condensation in other systems is discussed briefly

Y. Funaki; T. Yamada; H. Horiuchi; G. Röpke; P. Schuck; A. Tohsaki

2008-09-03

402

Lyman Alpha Spicule Observatory (LASO)  

NASA Technical Reports Server (NTRS)

The Lyman Alpha Spicule Observatory (LASO) sounding rocket will observe smallscale eruptive events called "Rapid Blue-shifted Events" (RBEs) [Rouppe van der Voort et al., 2009], the on-disk equivalent of Type-II spicules, and extend observations that explore their role in the solar coronal heating problem [De Pontieu et al., 2011]. LASO utilizes a new and novel optical design to simultaneously observe two spatial dimensions at 4.2" spatial resolution (2.1" pixels) over a 2'x2' field of view with high spectral resolution of 66mAngstroms (33mAngstroms pixels) across a broad 20Angstrom spectral window. This spectral window contains three strong chromospheric and transition region emissions and is centered on the strong Hydrogen Lyman-a emission at 1216Angstroms. This instrument makes it possible to obtain new data crucial to the physical understanding of these phenomena and their role in the overall energy and momentum balance from the upper chromosphere to lower corona. LASO was submitted March 2011 in response to the ROSES SHP-LCAS call.

Chamberlin, Phillip C.

2011-01-01

403

Glucosylation of alpha-butyl- and alpha-octyl-D-glucopyranosides by dextransucrase and alternansucrase from Leuconostoc mesenteroides.  

PubMed

For the first time, glucosylation of alpha-butyl- and alpha-octylglucopyranoside was achieved using dextransucrase (DS) of various specificities, and alternansucrase (AS) from Leuconostoc mesenteroides. All the glucansucrases (GS) tested used alpha-butylglucopyranoside as acceptor; in particular, DS produced alpha-D-glucopyranosyl-(1-->6)-O-butyl-alpha-D-glucopyranoside and alpha-D-glucopyranosyl-(1-->6)-alpha-D-glucopyranosyl-(1-->6)-O-butyl-alpha-D-glucopyranoside. In contrast, alpha-octylglucopyranoside was glucosylated only by AS which was shown to be the most efficient catalyst. The conversion rates, obtained with this enzyme at sucrose to acceptor molar ratio of 2:1 reached 81 and 61% for alpha-butylglucopyranoside and alpha-octylglucopyranoside, respectively. Analyses obtained from liquid chromatography coupled with mass spectrometry revealed that different series of alpha-alkylpolyglucopyranosides regioisomers of increasing polymerization degree can be formed depending on the specificity of the catalyst. PMID:12681910

Richard, Gaëtan; Morel, Sandrine; Willemot, René-Marc; Monsan, Pierre; Remaud-Simeon, Magali

2003-04-22

404

Collagen alpha5 and alpha2(IV) chain coexpression: analysis of skin biopsies of Alport patients.  

PubMed

Alport syndrome is a collagen type IV disease caused by mutations in the COL4A5 gene with the X-linked form being most prevalent. The resultant alpha5(IV) collagen chain is a component of the glomerular and skin basement membranes (SBMs). Immunofluorescent determination of the alpha5(IV) chain in skin biopsies is the procedure of choice to identify patients. In 30% of patients, however, the mutant protein is still found in the SBM resulting in a normal staining pattern. In order to minimize or eliminate false results, we compared the distribution of the alpha2(IV) chain (another SBM component) and the alpha5(IV) chain by standard double label immunofluorescence (IF) and by confocal laser scanning microscopy. The study was performed on 55 skin biopsies of patients suspected of Alports and five normal control specimens. In normal skin, IF showed the classical linear pattern for both collagens along the basement membrane. Additionally, decreased alpha5(IV) was found in the bottom of the dermal papillary basement membrane. Confocal analysis confirmed the results and show alpha5(IV) focal interruptions. In suspected patients, both techniques showed the same rate of abnormal alpha5(IV) expression: segmental in women and absent in men. Our results show a physiological variation of alpha5(IV) location with focal interruptions and decreased expression in the bottom of the dermal basement membrane. Comparison of alpha5(IV) with alpha2(IV) expression is simple and eliminates technical artifacts. PMID:17554254

Patey-Mariaud de Serre, N; Garfa, M; Bessiéres, B; Noël, L H; Knebelmann, B

2007-08-01

405

Fibrinogen {alpha} genes: Conservation of bipartite transcripts and carboxy-terminal-extended {alpha} subunits in vertebrates  

SciTech Connect

All three well-studied subunits of the clotting protein fibrinogen ({alpha}, {beta}, {gamma}) share N-terminal structural homologies, but until recently only the {beta} and {gamma} chains were recognized as having similar globular C-termini. With the discovery of an extra exon in the human fibrinogen {alpha} gene (exon VI), a minor form of the {alpha} subunit ({alpha}{sub E}) with an extended {beta}- and {gamma}-like C-terminus has been identified. In the present study, the polymerase chain reaction has been used to identify sequences that encode counterparts to {alpha}{sub E} in chicken, rabbit, rat, and baboon. The basic six-exon structure of the fibrinogen {alpha} genes is shown to be conserved among mammals and birds, as are the intron positions. Bipartite transcripts - still bearing an intron prior to the last exon - are found among the products of the various vertebrate fibrinogen {alpha} genes. The last exon represents the largest conserved segment of the gene and, in each species examined, encodes exactly 236 amino acids. The C-termini of these {alpha}{sub E} chains align without a single gap and are between 76 and 99% identical. Since the exon VI-encoded domain of {alpha}{sub E} is as well conserved as the corresponding regions of the {beta} and {gamma} chains, it follows that it is equally important and that {alpha}{sub E}-fibrinogen plays a vital, if as-yet unrecognized physiological role. 21 refs., 7 figs., 1 tab.

Fu, Y.; Cao, Y.; Hertzberg, K.M.; Grieninger, G. [Lindsley F. Kimball Research Inst. of the New York Blood Center, NY (United States)] [Lindsley F. Kimball Research Inst. of the New York Blood Center, NY (United States)

1995-11-01

406

Strong absorption model analysis of alpha scattering  

NASA Astrophysics Data System (ADS)

Angular distribution of alpha particles at several energies, E(sub alpha) = 21 approx. 85.6 MeV from a number of nuclei between Ni-20 and Sn-119, extending to wide angular range up to approx. 160 C in some cases, have been analyzed in terms of three-parameter strong absorption model of Frahn and Venter. Interaction radius and surface diffuseness are obtained from the parameter values rendering the best fit to the elastic scattering data. The inelastic scattering of alpha particles from a number of nuclei, leading to quadrupole and octupole excitations has also been studied giving the deformation parameters (beta sub L).

Rahman, M. A.; Chandrapaul, S.; Sengupta, H. M.; Rahman, M.

1991-07-01

407

Alpha cluster structure in 56Ni  

NASA Astrophysics Data System (ADS)

The inelastic ?-scattering experiment on 56Ni in inverse kinematics was performed at an incident energy of 50 MeV/u at GANIL. A very high multiplicity for ?-particle emission was observed with our phase-space limited experimental set-up. The maximum observed multiplicity, which cannot be explained by means of the statistical decay model, amounted to seven. The ideal classical gas model at kT = 3 MeV fairly well reproduced the experimental momentum distribution and multiplicity of alpha particles. This result strongly suggests that an alpha-gas state in 56Ni may be excited via inelastic alpha scattering.

Akimune, H.; Fujiwara, M.; Gibelin, J.; Harakeh, M. N.; Achouri, L.; Bagchi, S.; Bastin, B.; Boretzky, K.; Bouzomita, H.; Caceres, L.; Damoy, S.; Delaunay, F.; Fernández-Domínguez, B.; Caamano, M.; Garg, U.; Grinyer, G. F.; Kalantar-Nayestanaki, N.; Kamalou, O.; Khan, E.; Krasznahorkay, A.; Lhoutellier, G.; Lukyanov, S.; Mazurek, K.; Najafi, M.; Pancin, J.; Penionzkhevich, Y.; Perrot, L.; Raabe, R.; Rigollet, C. E.; Roger, T.; Sambi, S.; Savajols, H.; Senoville, M.; Stodel, C.; Suen, L.; Thomas, J. C.; van de Walle, J.; Vandebrouck, M.

2013-04-01

408

Tumor necrosis factor alpha inhibits collagen alpha 1(I) gene expression in rat hepatic stellate cells through a G protein  

Microsoft Academic Search

BACKGROUND & AIMS: Tumor necrosis factor alpha (TNF-alpha) inhibits collagen gene expression in cultured fibroblasts. By binding to cell surface receptors, TNF-alpha promotes signals within the cells. The purpose of this study was to investigate the role played by G proteins in TNF-alpha-induced inhibition of collagen gene expression.METHODS: Effect of TNF-alpha on collagen alpha 1(I) messenger RNA (mRNA) level was

I Hernandez-Munoz; P de la Torre; JA Sanchez-Alcazar; I Garcia; E Santiago; MT Munoz-Yague; JA Solis-Herruzo

1997-01-01

409

New annual and short-lived perennial pasture legumes for Australian agriculture—15 years of revolution  

Microsoft Academic Search

Fifteen years ago subterranean clover (Trifolium subterraneum) and annual medics (Medicago spp.) dominated annual pasture legume sowings in southern Australia, while limited pasture legume options existed for cropping areas of subtropical Australia. Since then a number of sustainability and economic challenges to existing farming systems have emerged, exposing shortcomings in these species and the lack of legume biodiversity. Public breeding

P. G. H. Nichols; A. Loi; B. J. Nutt; P. M. Evans; A. D. Craig; B. C. Pengelly; B. S. Dear; D. L. Lloyd; C. K. Revell; R. M. Nair; M. A. Ewing; J. G. Howieson; G. A. Auricht; J. H. Howie; G. A. Sandral; S. J. Carr; C. T. de Koning; B. F. Hackney; G. J. Crocker; R. Snowball; S. J. Hughes; E. J. Hall; K. J. Foster; P. W. Skinner; M. J. Barbetti; M. P. You

2007-01-01

410

Long- and short-lived electrons with anomalously high collision rates in laser-ionized gases  

SciTech Connect

Ultrashort broadband terahertz pulses are applied to probe the electron dynamics of gaseous Ar and O{sub 2} following ionization by an intense femtosecond laser pulse. The conductivity in the plasma center is extracted by a modified Wentzel-Kramers-Brillouin approach. It exhibits a nearly perfect Drude-like spectral shape and yields the temporal evolution of the free-electron density and collision rate. While the electron density in the Ar plasma remains nearly constant during the first 200 ps after generation, it decays much faster in O{sub 2} due to dissociative recombination which is only possible in molecular plasmas. Adding a small amount of the electron scavenger SF{sub 6} to Ar reduces the electron lifetime in the plasma dramatically and allows us to determine the electron temperature to about 20 000 K. Furthermore, anomalously high, metal-like electron collision rates of up to 25 THz are found. Kinetic plasma theory substantially underestimates these rates pointing towards additional and more complex processes randomizing the total electronic momentum. Our results are relevant to both lightning control and generation of terahertz radiation by intense laser pulses in gases.

Kampfrath, Tobias; Perfetti, Luca; Tegeder, Petra; Wolf, Martin; Frischkorn, Christian [Fachbereich Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Gericke, Dirk O. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2007-12-15

411

New Developments for Isochronous Mass Measurements of Short-Lived Nuclei  

SciTech Connect

The combination of the in-flight separator FRS and the storage-ring ESR at GSI offers unique possibilities for high accuracy mass and lifetime measurements of bare and few-electron fragments. Operating the ESR in the isochronous mode allows for measurements of revolution frequencies of stored ions without cooling. Isochronous Mass Spectrometry (IMS) can be applied to fragments with half-lives as short as several tens of microseconds. Newly developed magnetic rigidity tagging increases the resolving power of IMS to about 500000. IMS can be used to measure masses of nuclei with rates even lower than one ion per day, a property also needed for the purpose of the ILIMA project at the future facility FAIR.

Knoebel, R.; Litvinov, S. A.; Boutin, D.; Chen, L.; Geissel, H.; Litvinov, Yu. A.; Scheidenberger, C.; Winckler, N. [Gesellschaft fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Justus-Liebig-Universitaet Giessen, 35392 Giessen (Germany); Sun, B. [Gesellschaft fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); School of Physics, Peking University, Beijing 100871 (China); Beckert, K.; Beller, P.; Bosch, F.; Brandau, C.; Dimopoulou, C.; Dolinskii, A.; Kozhuharov, C.; Mazzocco, M.; Montes, F.; Muenzenberg, G.; Nociforo, C. [Gesellschaft fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany)] (and others)

2007-02-26

412

Methods to Collect, Compile, and Analyze Observed Short-lived Fission Product Gamma Data  

SciTech Connect

A unique set of fission product gamma spectra was collected at short times (4 minutes to 1 week) on various fissionable materials. Gamma spectra were collected from the neutron-induced fission of uranium, neptunium, and plutonium isotopes at thermal, epithermal, fission spectrum, and 14-MeV neutron energies. This report describes the experimental methods used to produce and collect the gamma data, defines the experimental parameters for each method, and demonstrates the consistency of the measurements.

Finn, Erin C.; Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.; Ellis, Tere A.

2011-09-29

413

Copper-free click chemistry with the short-lived positron emitter fluorine-18.  

PubMed

The copper-free strain-promoted click chemistry between (18)F-labeled aza-dibenzocyclooctyne [(18)F]FB-DBCO and various azides is described. [(18)F]FB-DBCO was prepared in 85% isolated radiochemical yield (decay-corrected) through acylation of amino aza-dibenzocyclooctyne 1 with N-succinimidyl 4-[(18)F]fluorobenzoate ([(18)F]SFB). [(18)F]FB-DBCO showed promising radiopharmacological profil with fast blood clearance as assessed with dynamic small animal PET studies. Metabolic stability of [(18)F]FB-DBCO was 60% of intact compound after 60 min post injection in normal Balb/C mice and blood clearance half-life was determined to be 53 s based on the time-activity-curve (TAC). Copper-free click chemistry was performed with various azides at low concentrations (1-2 ?M) which differed in their structural complexity in different solvents (methanol, water, phosphate buffer and in bovine serum albumin (BSA) solution). Reaction proceeded best in methanol (>95% yield after 15 min at room temperature), whereas reaction in BSA required longer reaction times of 60 min and 40 °C upon completion. PMID:21938294

Bouvet, Vincent; Wuest, Melinda; Wuest, Frank

2011-11-01

414

Identification of functional, short-lived isoform of linker for activation of T cells (LAT).  

PubMed

Linker for activation of T cells (LAT) is a transmembrane adaptor protein playing a key role in the development, activation and maintenance of peripheral homeostasis of T cells. In this study we identified a functional isoform of LAT. It originates from an intron 6 retention event generating an in-frame splice variant of LAT mRNA denoted as LATi6. Comparison of LATi6 expression in peripheral blood leukocytes of human and several other mammalian species revealed that it varied from being virtually absent in the mouse to being predominant in the cow. Analysis of LAT isoform frequency expressed from minigene splicing reporters carrying loss- or gain-of-function point mutations within intronic polyguanine sequences showed that these elements are critical for controlling the intron 6 removal. The protein product of LATi6 isoform (LATi6) ectopically expressed in LAT-deficient JCam 2.5 cell line localized correctly to subcellular compartments and supported T-cell receptor signaling but differed from the canonical LAT protein by displaying a shorter half-life and mediating an increased interleukin-2 secretion upon prolonged CD3/CD28 crosslinking. Altogether, our data suggest that the appearance of LATi6 isoform is an evolutionary innovation that may contribute to a more efficient proofreading control of effector T-cell response. PMID:25008862

K?ossowicz, M; Marek-Bukowiec, K; Arbulo-Echevarria, M M; ?cirka, B; Majkowski, M; Sikorski, A F; Aguado, E; Miazek, A

2014-10-01

415

Measuring (n,f) cross-sections of short-lived states  

E-print Network

In order to test theories of fission cross-sections, it is desirable to measure the (n,f) cross-sections of both an isomeric state and the ground state of the same isotope of the same element. This would test the ability to calculate effects that depend only on spin and parity without the confusion of effects that depend on (Z,A). At present there is no isotope for which the (n,f) cross-section has been measured successfully at MeV energies, where theoretical predictions can be made. There have been a few measurements of the cross-section U235m at thermal and cold energies. At these energies the cross-section is expected to be dominated by incalculable resonances, so that it may not be a useful test of theoretical predictions. I suggest methods for measuring the (n,f) cross-sections to neutrons with a fission spectrum of 1/2+ (26 m) isomeric U235m and of 1- (16 h) (shorter lived than the isomer) Am242gs.

J. I. Katz

2010-03-24

416

Evaluation of Uncertainties in Decay Constants of ``Short-Lived'' Radionuclides: A Meta-Analysis Approach  

NASA Astrophysics Data System (ADS)

We have performed a meta-analysis of half-lives for cosmochemically relevant radionuclides. We show that there is a range of behavior from well (e.g., 10Be) to poorly constrained (e.g., 53Mn or 129I).

Boehnke, P.; Steele, R. C. J.

2014-09-01

417

Global Distributions and Natural Sources of Brominated very Short-Lived Substances  

E-print Network

in the Pacific and Atlantic Oceans. Results from field observations showed that BrVSLS tend to be elevated in biologically active waters, such as coastal waters, the productive surface open ocean, and at chlorophyll maximum depths. The production of natural Br...

Liu, Yina

2013-07-09

418