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dmwood
Joined 48 karma
retired physics professor
- dmwood parentA trip to Wanamakers at Christmas (including eating in the top-floor restaurant and listening to scheduled organ concerts) was a treasured fixture of my childhood in the late 50s and early 60s. If I remember correctly, there was a monorail-like tram that ran around the periphery of the toy department too. Christmas lights festooned the facade of the organ.
- Depending on the field, 3 Gy IS 'small' (with respect to doses to tissue during cancer treatment, which can be 60 Gy). Whole body doses of 1 milliGy in the environmental biz are considered worth examination. Even investigations of biomarkers for radiation exposure typically use doses in the range of 3 Gy.
- I welcome the new library! I have used a RadiaCode 103g for more than a month. I also have a more conventional NaI:Tl 5cmX5cm scintillator+PMT in my basement with 95 lbs of lead shielding (as lead shot). I'm painfully familiar with detector drift and recalibrations required with conventional (amateur) detectors. In my opinion the RCs are game changing: their calibration ranges from good to excellent, in that I can import a spectrum into the (exceptionally useful free Sandia National Labs) tool InterSpec, extremely quickly identify peaks and the relevant radionuclides. The RC is very compact with a well-defined detector volume (because it IS relatively small). If there is a weakness, it is that it's mostly targeted toward running on a smartphone and support for iOS vs. Android has lagged a bit, though very recently an excellent update has appeared for iOS. I have tested in on a variety of spectra (137Cs, 232Th, 60Co, 133Ba) and for long background counts and am quite happy with the resolution and stability. I have yet to use its interface to GPS data (I already have a bGeigie Nano built from a Safecast kit). Its impact is that almost everything one might like--count rates, dose rates and net dose, data logging, and GPS interface is all there in a sub pocket-size unit.
- As noted, ordinary maps may suffer (for example, in epidemiology)from the impact of a very non-uniform population density. A disease cluster then MAY be a cluster, or it may be ordinary disease rates in a highly populated area. In my limited experience a cartogram is a deliberate distortion of the SHAPE of a map region in order to make some property (say, population DENSITY) constant everywhere in the new region. Then anomalies jump out. Done with care, one can do careful statistics within the cartogram and then back-transform to get statistics for the original map area.
- "Updated fraction of cancer attributable to lifestyle and environmental factors in Denmark in 2018", Scientific Reports | (2022) 12:549 https://doi.org/10.1038/s41598-021-04564-2 attempts to tease out causes: 38% tobacco, alcohol 7%, obesity 9%, occupational 6%, air pollution 3%, infections (like HPV) 7%.
- Another data point, this time from a retired university faculty dude. I have recurring dreams of having to give a lecture (typically at a graduate physics level, which is what I taught most) but have not prepared. Worse--I'm not sure where the lecture room is. Sometimes I dream about winging it--and wake up mildly proud that I remembered as much as I did, though it was wrong in detail.
- The INWORKS study and reports are among the best there are. What's new about this report is that error bars for low doses are much smaller, presumably due to more stringent dose quality requirements and better dosimeters, which became available only well after may nuclear processing plants came online. For high cumulative dose, there are fewer workers exposed, so error bars are of necessity large. This paper reports excess relative cancer death RATES rather than excess relative death RISKS (of course very similar) Error bars crossing reference lines are not uncommon at low doses in this biz, and have been attributed to "radiation hormesis", a BENEFICIAL or protective effect of ionizing radiation exposure at "low doses", currently believed to be somewhat more than background radiation exposures. Such hormesis naturally implies serious corrections to the "linear, no threshold" picture almost universally used in radiation dose/response.
The figure at https://www.semanticscholar.org/paper/Radiobiology-and-Radia... shows hormetic response (ERR<0).
So the new results make it more difficult to defend radiation hormesis if the ERR vs. dose is STEEPER at low doses than at larger doses.
- No. The 'faceting' of a crystal is determined by a minimization of the 'Gibbs free energy' [a thermo quantity determined mostly by the relative energies of different faces of the crystal, at low temp] over all the faces. The relative energies of the facets are in turn determined by the crystal structure, and the favored crystal structure is determined by the 'electronic structure' of the material itself. Li is an alkali atom, so presumably in the metal donates its outermost 's' electron to make a relatively simple metal. Almost never does crystal shape in any way reflect directly the atomic structure
- Funny how often the word recollect has come up here, without mentioning the fantastic tool recoll, updated frequently and available for many operating systems. I use it on macOS for an immense library of scientific and other documents. I think there's a standalone installer, and it's also available via macports. It may be found at
https://www.lesbonscomptes.com/recoll/pages/index-recoll.htm...
It allows me to index and find words and phrases in files of many types AND view their contents independently of external readers, or using system readers, including text, PDF, or word processing files of common sorts.
- Yes. Thanks. The link below has the most up to date comprehensive diagram of typical doses. For the uninitiated: the 'relative biological effectiveness' of photons (X rays, gamma rays) is typically taken to be one; by contrast, for alpha particles it is generally taken to be 20 since they dump much more energy per unit path length than do photons.
https://www.energy.gov/sites/prod/files/2018/01/f46/doe-ioni...
- Pu in soil within the Rocky Flats National Wildlife Refuge contributes (NIST soil standard data) about 0.8% of total soil radioactivity. Remembering that 239Pu emits almost no gamma rays, it's no surprise that annual doses from soil inhalation plus ingestion give 50 year doses of less than 0.1 milliSievert. By contrast, ANNUAL doses from background radiation around RF are about 1850 times larger, and a chest X-ray is about 25 milliSieverts. Scope out rockyflatsneighbors.org for actual reliable Rocky Flats data. Former Rocky Flats workers contributed more than any other non-Soviet group to knowledge of biological effects of Pu on humans.