Local Radiation Effects Research Articles

First observations of the CO J = 6-5 transition in starburst galaxies

view Abstract Citations (66) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS First Observations of the CO J = 6--5 Transition in Starburst Galaxies Harris, A. I. ; Hills, R. E. ; Stutzki, J. ; Graf, U. U. ; Russell, A. P. G. ; Genzel, R. Abstract We report the detection of carbon monoxide (CO) J = 6-5 emission from the starburst nuclei of the galaxies NGC 253, M82, and IC 342. We have used the 6-5 transition as a thermometer of warm molecular gas in starburst nuclei, unambiguously finding that the nuclear molecular gas in starburst galaxies is substantially warmer than in typical disk clouds. Nuclear-as heating could be either large scale, for example, turbulent motions or cloud-cloud collisions in noncircular bar orbits; more local effects of radiation from high-mass star formation and supernovae; or some combination. High CO excitation temperatures can affect galactic nuclear mass estimates and consequently star formation efficiencies deduced from lower J CO lines. Publication: The Astrophysical Journal Pub Date: December 1991 DOI: 10.1086/186216 Bibcode: 1991ApJ...382L..75H Keywords: Carbon Monoxide; Galactic Nuclei; Interstellar Gas; Molecular Spectra; Starburst Galaxies; Submillimeter Waves; Molecular Clouds; Rotational Spectra; Star Formation Rate; Astrophysics; GALAXIES: INDIVIDUAL ALPHANUMERIC: IC 342; GALAXIES: INDIVIDUAL MESSIER NUMBER: M82; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 253; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 6946; GALAXIES: INTERSTELLAR MATTER; STARS: FORMATION full text sources ADS | data products SIMBAD (4) NED (4)

Myeloablative combination chemotherapy without total body irradiation for neuroblastoma.

Myeloablative treatment intensification in 25 patients diagnosed when older than 12 months of age with stage IV neuroblastoma included sequential delivery of cisplatin 120 mg/m2 x 1, hyperfractionated radiation (2,100 cGy) to the primary site and adjacent lymph nodes, carmustine (BCNU) 200 mg/m2 x 1, melphalan 60 mg/m2/d x 3 (n = 13) or thiotepa 300 mg/m2/d x 3. (n = 12), and etoposide (VP 16) 300 mg/m2/d x 3. Seventy-two hours after the last dose of VP 16, histologically tumor-free and 4-hydroperoxycyclophosphamide (4-HC; 100 mumol/L)-purged autologous bone marrow (ABMT) was infused. Acute toxicities included grade 3 to 4 oral mucositis, grade 1 to 2 diarrhea, and fevers. No patient required infusion of unpurged reserve autografts. At ABMT, 16 patients (group I) were progression-free 6.5 months to 14 months (median, 9 months) from diagnosis: seven remain progression-free 20 months to 46 months (median, 39 months) off therapy, six relapsed 4 months to 17 months post-ABMT, and three died of toxicity (candidiasis, metabolic derangement, and venoocclusive disease [VOD]). The event-free survival of group I patients is 44% at 24 months post-ABMT. Nine patients (group II) were in second remission at ABMT, including three who had relapsed after other transplant procedures: two are progression-free 24 months and 41 months off therapy, four relapsed 3 months to 12 months post-ABMT, and three died of toxicity (aspergillosis, hemorrhagic cystitis, VOD). Only one of 10 relapses involved a primary site, suggesting a beneficial effect of local radiation. In terms of survival or toxicity, an advantage for melphalan or thiotepa was not evident. Regimens such as this may prolong the survival of selected patients with poor-risk neuroblastoma, but concerns over late relapses and toxicity mandate continuing efforts to devise alternative, less risky, and more clearly beneficial approaches for definitive ablation of neuroblastoma.

The Photochemistry of Ch3I in Various Matrices at Low Temperature

AbstractThe photodissociation of methyl iodide in various matrices at low temperature was studied. The observed Raman spectra excited by 514.5 nm laser radiation showed that there were two different photolytically produced iodine species isolated in the matrices after illumination by a medium pressure mercury lamp. One species which was dominant at lower iodine concentrations and exhibited a progression with an ωe of 201 cm−1, belonged to the matrix isolated iodine monomer (I2). The other species, which was dominant at higher iodine concentrations with an ωe of approximately 180 cm−1, belonged to the iodine aggregate ((I2)n). Five progressions of resonance Raman or resonance fluorescence of these two species were also observed in the other matrices. The iodine aggregate in the methyl iodide matrix at 77 K was formed in a crystalline structure, while the photolytically generated iodine aggregate from CH3I/Ar (2/3) matrix at 10 K, after illumination with a mercury lamp, was in amorphous form. The rearrangement of photolytically produced iodine aggregate in methyl iodide matrix was observed as a function of the duration of illumination. Local heating effects of the laser radiation might induce the iodine monomer to aggregate in matrices. The photodissociation mechanism of methyl iodide in matrices is also proposed.

A New Approach to Modelling Radiation from Open Flames

Abstract Radiation is important in all but the smallest flames. This paper describes a model designed to predict the local effects of radiation in flames which may be turbulent and burn at a finite rate. Such local effects are important because of the strongly nonlinear dependence of many properties on temperature. An accurate estimate of average properties may be made through the use of existing stochastic chemistry models in adiabalic processes. The model described in this paper is required to determine the divergence of radiant heat flux in random mixtures generated in stochastic processes where significant radiation is expected. Because there is an ensemble of such mixtures at each point in the flame, realizations are constructed by selecting one mixture at random from each point. Local radiative properties are determined and a governing equation is then solved over each realization. The divergence term is then calculated and the energy equation solved with the correct departure from adiabalic conditi...

Response and recovery kinetics of a solid tumour after irradiation

The effects of local tumour radiation over the dose range 7.5-30 Gy on the growth and cell kinetics of rat hepatoma H-4-II-E have been investigated. A plot of growth delays against log surviving fraction was linear below a fraction of 0.03, but failed to extrapolate to the origin. Following a single dose of 15 Gy to the tumour, DNA-precursor incorporation, labelling and mitotic indices were depressed for 7 days. Tumour cellularity, measured as DNA/g tumour, was reduced and the rate of increase of total clonogenic cells slower than after complete tumour recovery. From Day 7 to Day 9 all indices of proliferation recovered to about control levels, clonogenic cell numbers increased more rapidly and tumour cellularity was restored. Repopulation of the tumour therefore appeared to take place mainly after Day 7. Incorporation of [3H]-TdR into tumour DNA reached twice the control values on Day 9. The rate of tumour growth accelerated after the initial decrease, and maximum tumour growth rate was also twice the control values on Day 13. Accelerated growth rates in irradiated tumours, above those of control tumours, occurred 10-16 days after treatment. The effectiveness of sequential therapy may therefore be improved if given during this period of of accelerated tumour growth.

An experimental model to determine the effects of adjuvant therapy on the incidence of postoperative wound infection: I. Evaluating preoperative radiation therapy.

This study investigated the effects of local preoperative radiation on the tissue resistance to surgical infection. Preoperative radiation was given to the skin of the backs of 144 rats in two doses and wounded at intervals after the radiation. As determined by quantitative bacterial counts of the wounds 4 days after wounding, 80 to 100 percent of the rats in each group healed their wounds with counts that were 10(3) organisms per gram, or less, in spite of the dose of radiation or the interval to wounding. In an additional 560 rats, 10(4) S. aureus organisms were inoculated into the surgical wounds made at various intervals after three doses of radiation. In this part of the study, the rates of infection (as determined by bacterial counts of 10(5) per gram or more) increased significantly with the increasing dose of radiation, as well as with the increasing interval from radiation to wounding. These data demonstrate that radiated tissue cannot tolerate bacterial contamination as well as normal tissue. Since surgery in the head and neck area results in the contamination of the wounds with saliva rich in virulent organisms, we propose that preoperative radiation be discontinued in favor of postoperative radiation.

Chemical and biological consequences of?-decay

In Part 1 of this article physical and chemical effects of beta-decay in labelled molecules were reviewed and their potential importance for breaking predetermined and specific bonds were pointed out. After incorporation of labelled biomolecules in living systems, such as viruses, phages or cells, the radioactive decay of the label alters the biological behaviour of the system, in the extreme case causing loss of the ability to reproduce, the extent of these consequences depending strongly on the type of radioisotope. Now Part 2 includes a brief discussion of biological effects associated with beta-decay emphasizing the relative importance of local transmutation and internal radiation effects from the decay of 3H, 14C, 32P, 33P, 35S and 125I. Attempt is also made, whenever possible at the present stage of understanding, to correlate biological effects with chemical processes on a molecular level.

The effect of delaying radiation on wound healing

The effect of postwounding local radiation was measured in an animal model. Tensile strength and histologic appearance of wounds irradiated on Day 0, 3, and 5 were studied. The irradiated wounds were all significantly weaker than the nonirradiated wounds, but delaying the radiation did not benefit wound healing.

University of Cambridge Natural Radiocarbon Measurements XIV

The dates presented in this paper comprise results of determinations made at the University Radiocarbon Dating Research Laboratory, mostly during the latter half of 1974. Radioactivity was measured with proportional counters using pure carbon dioxide at 2 atmospheres pressure as filling gas. Effects of cosmic and local environmental radiation on the counters were reduced by surrounding them completely with 1) a plastic scintillator anticoincidence shield, 7.5cm thick, viewed by 2 photomultiplier tubes operating in coincidence mode, the output pulses of which were in anticoincidence with the proportional counters signals, and 2) by a 17.5 ton lead castle.

Cancer and Immune Mechanisms

To the Editor.— A recent issue ofThe Journalcontained an editorial entitled "Cancer and Immune Mechanisms" (224:1286, 1973). The articles cited as reference do not, we believe, entirely support the theory of cancer and immune mechanisms. General immunosuppression, whether by chemotherapy, radiation, or other means, is known to increase the General incidence of malignant disease in the body. However, when the author cites the effect of local radiation as a primary disturbance of the immune mechanism, such as in the relationship of cancer of the thyroid to adjacent radiation for tonsilar disease, it does not imply the general suppression of immunity or even possibly the destruction of the immune T-cell lymphocyte mechanisms by damaging the thymus. It does imply that alteration in the cell line of the thyroid gland in the adolescent or developing prepubertal stage has produced a mutated line of cells to which the immune system may

Local and generalized effects of local radiation. I. Effects of local radiation to the liver and upper intestines in partially hepatectomized, sham-operated, and normal rats.

Regenerating liver has been used in the study of the effects of radiation on the basic biological mechanisms of DNA, RNA, and protein synthesis. Advantage has been taken of the fact that increases in DNA, RNA, and protein synthesis, as well as synthesis of many of the enzymes involved, occur sequentially following partial hepatectomy (1, 2). Regenerating liver has also been used extensively to study the roles and interrelationships of these basic biological processes in mammalian cells. In addition, it has been used to obtain information about these biological processes in rapidly proliferating tissue compared to normal liver, in attempting to reach a better understanding of normal and neoplastic growth. Most of the radiation studies utilizing regenerating liver have been carried out following total-body irradiation (2). This study was designed to obtain additional information about the reactions of organs locally irradiated, as well as about the more generalized reactions of the animal to local irradiati...

The Nurse's Contribution in a Radiation Therapy Outpatient Department

A course of radiation therapy can, in many instances, be administered to the patient on an outpatient basis. This allows him to remain in an environment which is more comfortable and familiar to him and gives him an opportunity to carry on his normal daily activities as much as possible. The registered nurse in the radiation therapy department can be effective in giving support to the patient during this period by special attention to his attitudes and anxieties toward radiation therapy, the management and control of the local and systemic effects of radiation, and seeking the cooperation of the family in continuing support to the patient who is at home. The nurse must be aware of services available to the patient through community agencies, for she will encounter situations where this assistance is needed to provide more comprehensive nursing care.

Radiation dose fractionation and DNA replication.

IT has been shown that the magnitude of depression of DNA synthesis following radiation can be altered by altering the dose-rate1. These preliminary results suggest that the total dose alone may be inadequate in the assessment of the effects of radiation on DNA synthesis. Dose-rate and the duration of radiation are additional factors which might be needed for an adequate assessment of the effects of radiation on this key biological process. This investigation was carried out on a synchronous population of hepatocytes, near the mid-point of the 8-h replication period following partial hepatectomy. A subsequent investigation was made into the dependence of DNA depression on dose-rate both in synchronous liver cells and in asynchronous cells of the first part of the small intestine2. These two series of experiments have permitted comparison of the effects of localized radiation on DNA synthesis both in synchronous liver cells and in asynchronous intestinal cells in the same animal. The curves describing the depression in the two organs were similar in character; however, the magnitude of the depression in the intestines, initially, was greater than in the liver.

Localized Gamma Irradiation from Cobalt-60 on Synthesis of Collagen by Subcutaneous Granulomas

Structural changes in the collagen fibril have been shown to occur after irradiation under an electron beam. For these effects to be visible by electron microscopy, doses greater than 10 Mrads had to be applied to the fibers in either the wet or the dry state (1). Other physical changes, such as loss of crystallinity, as reflected by the X-ray diffraction pattern, and increase in solubility indicative of breakdown to smaller units, were induced by y-radiation originating from fission products. Again, radiation levels of relatively high magnitude were required (2). An increase in collagen breakdown after whole-body X-irradiation of rats with 750 R was postulated on the basis of increased specific activity of proline metabolites appearing in urine (3). Experiments in our laboratory indicated a decreased synthesis of collagen at the site of subcutaneously implanted polyvinyl sponges after 450 R, with a return to normality as the animals recovered from the acute effects of the exposure.4 In all these instances the dose is so high as to make these results unphysiological or to induce secondary changes which could allow us to attribute these to a systemic rather than to a localized effect. For this reason we decided to investigate the effects of localized radiation at the site of active collagen synthesis, such as that of a granuloma caused by the subcutaneous implantation of a polyvinyl sponge.

An Autoradiogaphic and Biochemical Study of the Effects of Radiation on Deoxyribonucleic Acid Synthesis in the Intact Animal

This is part of a continuing study of the effects of localized radiation on mammalian cells in the intact animal. Exploration of the immediate effects of radiation, as well as recovery and long-term survival of somatic cells, is in progress (1, 2). Previous studies have shown that one specific dose (3000 r) decreased the rate of deoxyribonucleic acid (DNA) synthesis to 40 % of the control values. Combined autoradiographic and cytochemical studies on individual cells demonstrated that these cells continued to synthesize DNA at a slower rate than the paired controls. The mean time for DNA replication in the irradiated cells was 13 hours, and the mean time for replication in the controls was 8 hours (1). Regenerating rat liver was used in this study of the effects of irradiation on DNA synthesis. Since regenerating rat liver is a semisynchronous system it is possible to confine the studies to the DNA synthetic period and separate them from other cell functions such as mitosis. The studies were made at the beginning, near the midpoint, and at the end of the 8-hour period of DNA replication of the first cycle of hepatocytes. Quantitative autoradiographic methods have been utilized to assess radiation effects on individual cells. Biochemical methods have been utilized to assess radiation effects on the total population of cells. Chromatographic separation of labeled precursors has been made in order to study changes in the biosynthetic pathways of DNA synthesis after irradiation. Local irradiation to the liver has permitted the study of the dose range from 750 r to 40,000 r.

THE IMMEDIATE EFFECTS OF LOCAL RADIATION ON THE CELLS IN THE PERITONEAL CAVITY OF MICE.

Studies on the peritoneal fluid of mice subjected to 375 and 465 rads of ionising radiation delivered locally in one dose to the mouse abdomen indicate that: (1) Cells vary in their response to radiation. (2) Mast cells and histiocytes showed a definite increase at 15 minutes, and at no time was there any evidence that either cell types was damaged by radiation. (3) Lymphocytes on the other hand, showed a definite decrease in numbers, and abnormal morphology.

UHF-TV Taboos: The FCC Electromagnetic Compatibility Plan for UHF Television

The constraints of assignment of channels to UHF TV stations are discussed, taking into account the radiated signal characteristics, the various undesired responses of receivers to signals on other than the channel to which they are tuned and effects of receiver local oscillator radiation. These "taboos" affect the assignment of many other channels for each assigned channel, due to the geographical separation requirements associated with the respective taboos. The basis for each taboo, the mileage separation required and the effects on assignment planning are discussed.

Influence d'irradiations UV localisées sur l'incorporation de l'adénine-8- 14C, de l'uridine- 3H et de la dl-méthionine- 35S dans l'algue Acetabularia mediterranea

The effects of localized UV radiation (tip or rhizoid) on cap formation and incorporation of labeled precursors (adenine-8- 14C, uridine- 3H and dl-methionine- 35S) into RNA and proteins have been followed in Acetabularia. It has been found that the three precursors studied are incorporated first in the nucleus and that they are then distributed according to a decreasing apico-basal gradient in normal algae. After UV irradiation of the tip, cap production and incorporation of the precursors in the apical region are markedly decreased. Irradiation of the rhizoid has less effect on cap formation and markedly reduces the incorporation, but without modifying the apico-basal gradient. It is concluded that the nucleus controls the synthesis of RNA and sulfur-containing proteins, which accumulate in the apical part of the alga where they play an important role in morphogenesis.

The mechanism of local radiation effects

The mechanism of local radiation effects

The Mechanism of Local Radiation Effects

The Mechanism of Local Radiation Effects