Radiation in medicine: Origins, risks and aspirations.

The use of radiation in medicine is now pervasive and routine. From their crude beginnings 100 years ago, diagnostic radiology, nuclear medicine and radiation therapy have all evolved into advanced techniques, and are regarded as essential tools across all branches and specialties of medicine. The inherent properties of ionizing radiation provide many benefits, but can also cause potential harm. Its use within medical practice thus involves an informed judgment regarding the risk/benefit ratio. This judgment requires not only medical knowledge, but also an understanding of radiation itself. This work provides a global perspective on radiation risks, exposure and mitigation strategies

Braided Hopf algebras obtained from coquasitriangular Hopf algebras

Let $(H, \sigma)$ be a coquasitriangular Hopf algebra, not necessarily finite dimensional. Following methods of Doi and Takeuchi, which parallel the constructions of Radford in the case of finite dimensional quasitriangular Hopf algebras, we define $H_\sigma$, a sub-Hopf algebra of $H^0$, the finite dual of $H$. Using the generalized quantum double construction and the theory of Hopf algebras with a projection, we associate to $H$ a braided Hopf algebra structure in the category of Yetter-Drinfeld modules over $H_\sigma^{\rm cop}$. Specializing to $H={\rm SL}_q(N)$, we obtain explicit formulas which endow ${\rm SL}_q(N)$ with a braided Hopf algebra structure within the category of left Yetter-Drinfeld modules over $U_q^{\rm ext}({\rm sl}_N)^{\rm cop}$.Comment: 43 pages, 1 figur

Placental hypervascularity does not cause perinatal brain injury

Author Posting. © The Author(s), 2011. Poster presentation to the American Federation for Medical Research Eastern Regional Meeting, April 26-27, 2011, Washington, DC. Cite as: Journal of Investigative Medicine 59 (2011): 636Dizygotic twins at 38 weeks with separate placentas: twin A, a 2479 gram female, was healthy after vaginal delivery. Five minutes later when the amnion of twin B was ruptured artificially, the cord prolapsed and could not be repositioned. Some 25 minutes later a 2791 gram male was delivered by section. Brain injury was noted soon afterward and subsequent development was marked by severe cerebral palsy and mental retardation. Initial diagnosis of twin B's placenta was 'chorangiosis,' overlooking fresh thrombi blocking the umbilical vein and one umbilical artery. Subsequent assessment revealed the same change in twin A's placenta. Archival records had 18/500 (3.6%) stillborns and 17/418 (4.07%) newborns with central placental hypervascularity. Of 125 recent consult placentas there were 17/100 singleton and 11/25 (44%) twin placentas displaying this change. Of 229 section deliveries there were 0/42 stillborns and 5/187 newborns with this vascular pattern. Another set of 625 autopsies revealed none with both hypoxic encephalopathy and this placental finding. This structural change is the same often seen in placentas from high altitude such as in Denver. Cerebral palsy occurs less often in Colorado than in other American states, per epidemiological data

New Observations and a New Interpretation of CO(3--2) in IRAS F10214+4724

New observations with the IRAM interferometer of CO(3--2) from the highly luminous galaxy IRAS F10214+4724 show the source is 1.5'' x <= 0.9'' ; they display no evidence of any velocity gradient. This size, together with optical and IR data that show the galaxy is probably gravitationally lensed, lead to a new model for the CO distribution. In contrast to many lensed objects, we have a good estimate of the intrinsic CO and far IR surface brightnesses, so we can derive the CO and far IR/sub-mm magnifications. The CO is magnified 10 times and has a true radius of 400 pc. and the far IR is magnified 13 times and has a radius of 250 pc. The true far IR luminosity is 4 to 7e12 Lsun and the molecular gas mass is 2e10 Msun . This is nearly an order of magnitude less than previously estimated. Because the far IR magnification is lower than the mid and near IR magnification, the intrinsic spectral energy distribution now peaks in the far infrared. That is, nearly all of the energy of this object is absorbed and re-emitted in the far infrared. In CO luminosity, molecular gas content, CO linewidth, and corrected far IR luminosity, 10214+472 is a typical, warm, IR ultraluminous galaxy.Comment: 18 pages, including 3 figures, of gzipped, uuencoded postscript. To be published Ap.J. Letter

The Molecular Interstellar Medium in Ultraluminous Infrared Galaxies

We present CO observations of a large sample of ultraluminous IR galaxies out to z = 0.3. Most of the galaxies are interacting, but not completed mergers. All but one have high CO(1-0) luminosities, log(Lco [K-km/s-pc^2]) = 9.92 +/- 0.12. The dispersion in Lco is only 30%, less than that in the FIR luminosity. The integrated CO intensity correlates Strongly with the 100 micron flux density, as expected for a black body model in which the mid and far IR radiation are optically thick. We use this model to derive sizes of the FIR and CO emitting regions and the enclosed dynamical masses. Both the IR and CO emission originate in regions a few hundred parsecs in radius. The median value of Lfir/Lco = 160 Lsun/(K-km/s-pc^2), within a factor of two of the black body limit for the observed FIR temperatures. The entire ISM is a scaled up version of a normal galactic disk with densities a factor of 100 higher, making even the intercloud medium a molecular region. Using three different techniques of H2 mass estimation, we conclude that the ratio of gas mass to Lco is about a factor of four lower than for Galactic molecular clouds, but that the gas mass is a large fraction of the dynamical mass. Our analysis of CO emission reduces the H2 mass from previous estimates of 2-5e10 Msun to 0.4-1.5e10 Msun, which is in the range found for molecular gas rich spiral galaxies. A collision involving a molecular gas rich spiral could lead to an ultraluminous galaxy powered by central starbursts triggered by the compression of infalling preexisting GMC's.Comment: 34 pages LaTeX with aasms.sty, 14 Postscript figures, submitted to ApJ Higher quality versions of Figs 2a-f and 7a-c available by anonymous FTP from ftp://sbast1.ess.sunysb.edu/solomon/

Increasing the susceptibility of the rat 208F fibroblast cell line to radiation-induced apoptosis does not alter its clonogenic survival dose-response.

Recent studies have suggested a correlation between the rate and incidence of apoptosis and the radiation response of particular cell lines. However, we found that increasing the rate of induction of apoptosis in the fibroblast line 208F, by transfecting it with human c-myc, did not lead to a change in its clonogenic survival dose-response for either gamma-irradiation or 125I-induced DNA damage. It was also found that expression of mutant (T24) Ha-ras in the 208F line appeared to decrease the level of apoptosis per mitosis after irradiation and inhibited the formation of nucleosomal ladders, but did not affect either the onset of the morphological features of apoptosis or the clonogenic survival dose-response of the cells to either gamma-irradiation or 125I-induced DNA damage. Our findings suggest that it may be incorrect to make predictions about the radiosensitivity of cells based only on knowledge of their mode of death

Factorizable ribbon quantum groups in logarithmic conformal field theories

We review the properties of quantum groups occurring as Kazhdan--Lusztig dual to logarithmic conformal field theory models. These quantum groups at even roots of unity are not quasitriangular but are factorizable and have a ribbon structure; the modular group representation on their center coincides with the representation on generalized characters of the chiral algebra in logarithmic conformal field models.Comment: 27pp., amsart++, xy. v2: references added, some other minor addition

Male fertility after VAPEC-B chemotherapy for Hodgkin's disease and non-Hodgkin's lymphoma.

Semen analysis was performed in 14 men a median of 13.5 months after completion of VAPEC-B chemotherapy for Hodgkin's disease or non-Hodgkin's lymphoma. Semen from 12 patients contained motile spermatozoa, and in nine cases the count was > 20 million ml-1. One patient was azoospermic (VAPEC-B followed by pelvic radiotherapy) and another had a count of 21 million ml-1 but sperm were non-motile. These findings suggest that, in the majority of cases, VAPEC-B chemotherapy does not cause permanent damage to the male germinal epithelium. A more detailed study of gonadal function in males and females before and after treatment with VAPEC-B for Hodgkin's disease is currently in progress