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Kirkby C, Field C, MacKenzie M, Syme A, Fallone BG. A Monte Carlo study of the variation of electron fluence in water from a 6 MV photon beam outside of the field. Phys Med Biol 2007; 52:3563-78. [PMID: 17664560 DOI: 10.1088/0031-9155/52/12/015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Existing studies have suggested some debate on whether the quality of radiation that delivers dose outside of the primary field of a radiotherapy photon beam can be considered the same as that inside the primary field. We used a Monte Carlo approach to simulate the electron fluence differential in energy inside a water phantom in response to irradiation by a 6 MV photon beam. The goal was to quantify how significantly the electron fluence changes when moving from a volume exposed to the primary field to one outside of the primary field, and understand any potential biological implications. We scored the electron fluence outwards in annular volumes in response to a 5 cm radius 6 MV beam and at the central axis in response to a rectangular 6 MV beam partially blocked by an MLC. The resulting fluence spectra were compared to different low-LET sources for which biological response in the form of chromosomal aberrations has been published. Our results show a significant increase in the low energy component of the fluence spectra outside of the primary field, which increases the mean LET to values similar to that seen in response to a 137Cs photon source. In turn, it is shown that this has the potential to increase the RBE.
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52
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Cantoni E, Field C, Mills Flemming J, Ronchetti E. Longitudinal variable selection by cross-validation in the case of many covariates. Stat Med 2007; 26:919-30. [PMID: 16625521 DOI: 10.1002/sim.2572] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Longitudinal models are commonly used for studying data collected on individuals repeatedly through time. While there are now a variety of such models available (marginal models, mixed effects models, etc.), far fewer options exist for the closely related issue of variable selection. In addition, longitudinal data typically derive from medical or other large-scale studies where often large numbers of potential explanatory variables and hence even larger numbers of candidate models must be considered. Cross-validation is a popular method for variable selection based on the predictive ability of the model. Here, we propose a cross-validation Markov chain Monte Carlo procedure as a general variable selection tool which avoids the need to visit all candidate models. Inclusion of a 'one-standard error' rule provides users with a collection of good models as is often desired. We demonstrate the effectiveness of our procedure both in a simulation setting and in a real application.
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53
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Murtha A, Chowdhury R, Duc L, Quon H, John T, Field C, Bistritz A, Smerdley M, Levesque J, Greiner R. 2071. Int J Radiat Oncol Biol Phys 2006. [DOI: 10.1016/j.ijrobp.2006.07.474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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54
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Goldman BS, Nierman WC, Kaiser D, Slater SC, Durkin AS, Eisen JA, Ronning CM, Barbazuk WB, Blanchard M, Field C, Halling C, Hinkle G, Iartchuk O, Kim HS, Mackenzie C, Madupu R, Miller N, Shvartsbeyn A, Sullivan SA, Vaudin M, Wiegand R, Kaplan HB. Evolution of sensory complexity recorded in a myxobacterial genome. Proc Natl Acad Sci U S A 2006; 103:15200-5. [PMID: 17015832 PMCID: PMC1622800 DOI: 10.1073/pnas.0607335103] [Citation(s) in RCA: 334] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myxobacteria are single-celled, but social, eubacterial predators. Upon starvation they build multicellular fruiting bodies using a developmental program that progressively changes the pattern of cell movement and the repertoire of genes expressed. Development terminates with spore differentiation and is coordinated by both diffusible and cell-bound signals. The growth and development of Myxococcus xanthus is regulated by the integration of multiple signals from outside the cells with physiological signals from within. A collection of M. xanthus cells behaves, in many respects, like a multicellular organism. For these reasons M. xanthus offers unparalleled access to a regulatory network that controls development and that organizes cell movement on surfaces. The genome of M. xanthus is large (9.14 Mb), considerably larger than the other sequenced delta-proteobacteria. We suggest that gene duplication and divergence were major contributors to genomic expansion from its progenitor. More than 1,500 duplications specific to the myxobacterial lineage were identified, representing >15% of the total genes. Genes were not duplicated at random; rather, genes for cell-cell signaling, small molecule sensing, and integrative transcription control were amplified selectively. Families of genes encoding the production of secondary metabolites are overrepresented in the genome but may have been received by horizontal gene transfer and are likely to be important for predation.
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Yee D, Pearcey R, Dundas G, Hanson J, Mackenzie M, Robinson D, Underwood L, Field C, Urtasun R, Pervez N, Fallone G. 170 Comparison of tomotherapy versus four-field pelvic box altered fractionation radiotherapy treatment plans for locally advanced squamous cell carcinoma of the cervix. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80911-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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56
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Quon H, Sasaki D, Lian J, Field C, Scrimger R, Fallone G, Roa W, Pervez N. 105 MVCT Versus kVCT images for radiotherapy planning in prostate cancer patients with hip prostheses. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80846-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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57
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Murtha A, Chowdhury R, Le D, Quon H, Thorns J, Field C, Bistritz A, Smerdely M, Levesque J, Schmidt M, Morrrs M, Lee C, Levner I, Sanderz J, Greiner R. 41 A novel approach to constructing more “Intelligent” planning target volumes for glioma patients. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80782-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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58
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Murray B, Dundas G, Campbell K, Chwyl B, Connors S, Eberle S, Fawcett S, Field C, Richardson S, Sandahl D, Schouten M, Yakimovich C. 206 Innovative teaching strategies in the modern era: Our experiences providing web-based education. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80947-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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59
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Murray B, Chwyl B, Campbell K, Connors S, Dundas G, Eberle S, Fawcett S, Field C, Richardson S, Sandahl D, Schouten M, Yakimovich C. Po-Thur Eve General-38: The Virtual Radiotherapy Department. Med Phys 2006. [DOI: 10.1118/1.2244665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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60
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Rathee S, Murray B, Newcomb C, Breitman K, Connors S, Dunscombe P, Field C, MacKenzie M, Robinson D, Warkentin H, Fallone B. SU-FF-T-137: Commissioning the Eclipse AAA Algorithm with Golden Beam Data. Med Phys 2006. [DOI: 10.1118/1.2241062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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61
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Field C, Parulekar W, Elliott E, Hunt S, Pho L, Schellenberoer S, Frouhar V, Palta J. 227 Electronic submission and review of radiotherapy planning data for NCIC CTG protocols. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80704-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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62
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Field C, MacKenzie M, Rathee S, Murray B, Robinson D, Abdulkarim B, Dundas G, Murtha A, Parliament M, Pearcey R, Pervez N, Roa W, Scrimger R, Severin D, Sinha R, Urtasun R, van Vulpen M, Yee D, Fallone G. 197 Introduction of image-guided adaptive radiotherapy techniques. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80674-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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63
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Damaraju S, Murray D, Dufour J, Carandang D, Myrehaug S, Fallone G, Field C, Greiner R, Hanson J, Cass C, Parliament M. 128 A comprehensive genomic approach to the identification of predictive markers using dna and tissue repair gene polymorphisms in radiation induced late toxicity in prostate cancer patients treated with conformal radiotherapy. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80607-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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64
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Field C, Parulekar W, Elliot E, Hunt S, Pho L, Schellenberger S, Frouhar V, Palta J. 106 Introduction of Electronic Rapid Review for the NCIC CTG MA.20 Protocol. Radiother Oncol 2005. [DOI: 10.1016/s0167-8140(05)80267-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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65
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Anthony PL, Arnold RG, Arroyo C, Bega K, Biesiada J, Bosted PE, Bower G, Cahoon J, Carr R, Cates GD, Chen JP, Chudakov E, Cooke M, Decowski P, Deur A, Emam W, Erickson R, Fieguth T, Field C, Gao J, Gary M, Gustafsson K, Hicks RS, Holmes R, Hughes EW, Humensky TB, Jones GM, Kaufman LJ, Keller L, Kolomensky YG, Kumar KS, LaViolette P, Lhuillier D, Lombard-Nelsen RM, Marshall Z, Mastromarino P, McKeown RD, Michaels R, Niedziela J, Olson M, Paschke KD, Peterson GA, Pitthan R, Relyea D, Rock SE, Saxton O, Singh J, Souder PA, Szalata ZM, Turner J, Tweedie B, Vacheret A, Walz D, Weber T, Weisend J, Woods M, Younus I. Precision measurement of the weak mixing angle in Møller scattering. PHYSICAL REVIEW LETTERS 2005; 95:081601. [PMID: 16196849 DOI: 10.1103/physrevlett.95.081601] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Indexed: 05/04/2023]
Abstract
We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.
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Parliament M, Alidrisi M, Munroe M, Wolfaardt J, Scrimger R, Thompson H, Field C, Kurien E, Hanson J. Implications of radiation dosimetry of the mandible in patients with carcinomas of the oral cavity and nasopharynx treated with intensity modulated radiation therapy. Int J Oral Maxillofac Surg 2005; 34:114-21. [PMID: 15695037 DOI: 10.1016/j.ijom.2004.06.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2004] [Indexed: 10/26/2022]
Abstract
Intensity modulated radiation therapy (IMRT) is a newer method of delivering highly conformal, salivary gland sparing radiation treatment that is finding increasing applications in head and neck malignancies. However, the radiation dose distribution to the mandible is rarely considered with IMRT, and the potential risks of osteoradionecrosis or osseointegrated implant failure are not well characterized for this modality. In a series of 10 patients with oral cavity and nasopharyngeal cancers who previously underwent IMRT, examination of the three-dimensional mandibular dose distribution was undertaken. The findings indicate a modest potential risk of osteoradionecrosis and osseointegrated implant failure in cases where IMRT optimization constraints are not specifically aimed at sparing the mandibular bone. Significantly higher mandibular doses (P < 0.04) were received in cases of oral cavity as opposed to nasopharyngeal cancers with IMRT. Efforts to optimize IMRT to further reduce doses to the mandible should be considered, and development of software tools to integrate three-dimensional dose distributions into planning of post-radiotherapy osseointegration would be beneficial.
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67
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Butler K, Field C, Herbinger CM, Smith BR. Accuracy, efficiency and robustness of four algorithms allowing full sibship reconstruction from DNA marker data. Mol Ecol 2004; 13:1589-600. [PMID: 15140101 DOI: 10.1111/j.1365-294x.2004.02152.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the problem of reconstructing full sib pedigrees from DNA marker data, three existing algorithms and one new algorithm are compared in terms of accuracy, efficiency and robustness using real and simulated data sets. An algorithm based on the exclusion principle and another based on a maximization of the Simpson index were very accurate at reconstructing data sets comprising a few large families but had problems with data sets with limited family structure, while a Markov Chain Monte Carlo (MCMC) algorithm based on the maximization of a partition score had the opposite behaviour. An MCMC algorithm based on maximizing the full joint likelihood performed best in small data sets comprising several medium-sized families but did not work well under most other conditions. It appears that the likelihood surface may be rough and presents challenges for the MCMC algorithm to find the global maximum. This likelihood algorithm also exhibited problems in reconstructing large family groups, due possibly to limits in computational precision. The accuracy of each algorithm improved with an increasing amount of information in the data set, and was very high with eight loci with eight alleles each. All four algorithms were quite robust to deviation from an idealized uniform allelic distribution, to departures from idealized Mendelian inheritance in simulated data sets and to the presence of null alleles. In contrast, none of the algorithms were very robust to the probable presence of error/mutation in the data. Depending upon the type of mutation or errors and the algorithm used, between 70 and 98% of the affected individuals were classified improperly on average.
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68
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Anthony PL, Arnold RG, Arroyo C, Baird K, Bega K, Biesiada J, Bosted PE, Breuer M, Carr R, Cates GD, Chen JP, Chudakov E, Cooke M, Decker FJ, Decowski P, Deur A, Emam W, Erickson R, Fieguth T, Field C, Gao J, Gustafsson K, Hicks RS, Holmes R, Hughes EW, Humensky TB, Jones GM, Kaufman LJ, Kolomensky YG, Kumar KS, Lhuillier D, Lombard-Nelsen R, Mastromarino P, Mayer B, McKeown RD, Michaels R, Olson M, Paschke KD, Peterson GA, Pitthan R, Pope K, Relyea D, Rock SE, Saxton O, Shapiro G, Singh J, Souder PA, Szalata ZM, Tobias WA, Tonguc BT, Turner J, Tweedie B, Vacheret A, Walz D, Weber T, Weisend J, Whittum D, Woods M, Younus I. Observation of parity nonconservation in møller scattering. PHYSICAL REVIEW LETTERS 2004; 92:181602. [PMID: 15169482 DOI: 10.1103/physrevlett.92.181602] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Indexed: 05/24/2023]
Abstract
We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV)=[-175+/-30(stat)+/-20(syst)] x 10(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron's weak charge at low energy Q(e)(W)=-0.053+/-0.011. This is consistent with the standard model expectation at the current level of precision: sin((2)theta(W)(M(Z))((-)MS)=0.2293+/-0.0024(stat)+/-0.0016(syst)+/-0.0006(theory).
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69
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Li X, Field C, Doyle R. Estimation of Additive Genetic Variance Components in Aquaculture Populations Selectively Pedigreed by DNA Fingerprinting. Biom J 2003. [DOI: 10.1002/bimj.200290016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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70
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Parliament M, Scrimger R, Kurien E, Anderson S, Field C, Thompson H, Hanson J. Preservation of oral health-related quality of life and salivary flow rates after inverse-planned intensity modulated radiotherapy (IMRT) for head and neck cancer (HNC). Int J Radiat Oncol Biol Phys 2002. [DOI: 10.1016/s0360-3016(02)03344-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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71
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72
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Ng JS, Chen P, Baldis H, Bolton P, Cline D, Craddock W, Crawford C, Decker FJ, Field C, Fukui Y, Kumar V, Iverson R, King F, Kirby RE, Nakajima K, Noble R, Ogata A, Raimondi P, Walz D, Weidemann AW. Observation of plasma focusing of a 28.5 GeV positron beam. PHYSICAL REVIEW LETTERS 2001; 87:244801. [PMID: 11736507 DOI: 10.1103/physrevlett.87.244801] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2001] [Indexed: 05/23/2023]
Abstract
The observation of plasma focusing of a 28.5 GeV positron beam is reported. The plasma was formed by ionizing a nitrogen jet only 3 mm thick. Simultaneous focusing in both transverse dimensions was observed with effective focusing strengths of order tesla per micron. The minimum area of the beam spot was reduced by a factor of 2.0+/-0.3 by the plasma. The longitudinal beam envelope was measured and compared with numerical calculations.
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73
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Winter S, Birek L, Walker T, Phalin-Roque J, Chandler MJ, Field C, Zorn E. Therapy of metabolic disorders with intravenous (IV) access ports and long term intravenous L-carnitine therapy. THE SOUTHEAST ASIAN JOURNAL OF TROPICAL MEDICINE AND PUBLIC HEALTH 2001; 30 Suppl 2:152-3. [PMID: 11400757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
With the expansion of newborn screening to include many organic acidurias and fatty acid oxidation defects, effective therapies of these disorders will be needed. Currently severe disorders such as methylmalonic and propionic aciduria. conventional therapy with diet and oral L-camitine often prove ineffective in preventing failure to thrive and recurrent metabolic decompensations. L-carnitine provides a natural pathway for removal of the toxic metabolites in these disorders and is life saving therapy but, with poor oral absorption (25%), it is difficult to supply adequate carnitine to meet the metabolic needs of these patients. Long term intravenous L-carnitine therapy, administered through a subcutaneous venous access port in 5 patients with organic acidurias [propionic aciduria (2), methylmalonic aciduria (2), 3 methylglutaconic aciduria(1)] resulted in improved growth, lower frequency of metabolic decompensations and increased tolerance of natural protein in the diet. An added benefit was the ability to initiate fluid. electrolytes, and antibiotics during metabolic decompensations at home thus averting hospitalizations.
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74
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Rastetter EB, Vitousek PM, Field C, Shaver GR, Herbert D, gren GI. Resource Optimization and Symbiotic Nitrogen Fixation. Ecosystems 2001. [DOI: 10.1007/s10021-001-0018-z] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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75
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Saltzberg D, Gorham P, Walz D, Field C, Iverson R, Odian A, Resch G, Schoessow P, Williams D. Observation of the Askaryan effect: coherent microwave Cherenkov emission from charge asymmetry in high-energy particle cascades. PHYSICAL REVIEW LETTERS 2001; 86:2802-2805. [PMID: 11290043 DOI: 10.1103/physrevlett.86.2802] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2000] [Indexed: 05/23/2023]
Abstract
We present the first direct experimental evidence for the charge excess in high-energy particle showers and corresponding radio emission predicted nearly 40 years ago by Askaryan. We directed picosecond pulses of GeV bremsstrahlung photons at the SLAC Final Focus Test Beam into a 3.5 ton silica sand target, producing electromagnetic showers several meters long. A series of antennas spanning 0.3 to 6 GHz detected strong, subnanosecond radio-frequency pulses produced by the showers. Measurements of the polarization, coherence, timing, field strength vs shower depth, and field strength vs frequency are completely consistent with predictions. These measurements thus provide strong support for experiments designed to detect high-energy cosmic rays such as neutrinos via coherent radio emission from their cascades.
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