The Relationship Between Moisture Content and X-Ray Sensitivity of Oat Seeds, Avena sativa

About a decade ago, Gustafsson (3) reported that the sensitivity of barley seeds to x-ray treatment was positively related to their moisture content. Sensitivity was measured by germination percentage and vigor of seedlings produced from treated seeds. However, Caldecott (1) recently has shown that barley seeds with a moisture percentage between 8 and 16 were more resistant to x-ray damage than those with either a lower or higher water content. These conflicting results probably are related to differences in methods used to temper the seeds by the two investigators. Gustafsson (3) soaked the seeds in water while Caldecott (1) placed them in desicators with different relative humidities. Metabolic activity and x-ray sensitivity of seed would be expected to be enhanced more by the first method. For a discussion of the physical significance of moisture content of seeds on x-ray sensitivity the reader is referred to a paper by Caldecott (2). This paper reports experiments conducted to determine the relationships between moisture content of seeds and x-ray sensitivity in hexaploid oats

Effect of Recurrent X-Radiation on Germination and Seedling Vigor in Oats

The immediate effects of exposing oat seeds to high dosages of X-ray are generally twofold: (a) many of the seeds fail to germinate, and (b) the seedlings produced are stunted. It is generally accepted that these physiologic effects react the same as other environmental variation in biological materials. However, it is possible that even though the physiologic effects disappear in one generation that certain weaknesses may persist but remain hidden. Weakened linkages of some type within chromosomes could conceivably be a case in point. If this is the case, one might expect the effects to be cumulative with repeated x-ray treatment in successive generations, since the basic units affected are probably chromosomes and genes. The study reported herein was conducted to determine to what extent the X-ray damage to oat seeds, measured as germination percentage and seedling vigor, was cumulative with recurrent radiation in one, two, and three seed generations. The measures of seedling vigor were plant height and weight per 100 seedlings

Radiometric calibration and processing procedure for reflective bands on LANDSAT-4 protoflight Thematic Mapper

The radiometric subsystem of NASA's LANDSAT-4 Thematic Mapper (TM) sensor is described. Special emphasis is placed on the internal calibrator (IC) pulse shapes and timing cycle. The procedures for the absolute radiometric calibration of the TM channels with a 122-centimeter integrating sphere and the transfer of radiometric calibration from the channels to the IC are reviewed. The use of the IC to calibrate TM data in the ground processing system consists of pulse integration, pulse averaging, IC state identification, linear regression analysis, and histogram equalization. An overview of the SCROUNGE-era (before August 1983) method is presented. Procedural differences between SCROUNGE and the TIPS-era (after July 1983) and the implications of these differences are discussed

Characterization of radiometric calibration of LANDSAT-4 TM reflective bands

Prelaunch and postlaunch internal calibrator, image, and background data is to characterize the radiometric performance of the LANDSAT-4 TM and to recommend improved procedures for radiometric calibration. All but two channels (band 2, channel 4; band 5, channel 3) behave normally. Gain changes relative to a postlaunch reference for channels within a band vary within 0.5 percent as a group. Instrument gain for channels in the cold focal plane oscillates. Noise in background and image data ranges from 0.5 to 1.7 counts. Average differences in forward and reverse image data indicate a need for separate calibration processing of forward and reverse scans. Precision is improved by increasing the pulse integration width from 31 to 41 minor frames, depending on the band

The growing rural–urban divide in US life expectancy : contribution of cardiovascular disease and other major causes of death

Background The US rural disadvantage in life expectancy (LE) relative to urban areas has grown over time. We measured the contribution of cardiovascular disease (CVD), drug-overdose deaths (DODs) and other major causes of death to LE trends in rural and urban counties and the rural–urban LE gap. Methods Counterfactual life tables and cause-of-death decompositions were constructed using data on all US deaths in 1999–2019 (N = 51 998 560) from the Centers for Disease Control and Prevention. Results During 1999–2009, rural and urban counties experienced robust LE gains, but urban LE increased by 1.19 years more in women and 0.86 years more in men compared with rural LE. During 2010–2019, rural counties experienced absolute declines in LE (women −0.20, men −0.30 years), whereas urban counties experienced modest increases (women 0.55, men 0.29 years). Counterfactual analysis showed that slowed CVD-mortality declines, particularly in ages 65+ years, were the main reason why rural LE stopped increasing after 2010. However, slow progress in CVD-mortality influenced LE trends more in urban areas. If CVD-mortality had continued to decline at its pre-2010 pace, the rural–urban LE gap would have grown even more post 2010. DODs and other causes of death also contributed to the LE trends and differences in each period, but their impact in comparison to that of CVD was relatively small. Conclusions Rural disadvantage in LE continues to grow, but at a slower pace than pre 2010. This slowdown is more attributable to adverse trends in CVD and DOD mortality in urban areas than improvements in rural areas.Peer reviewe

Nonlinear quantum mechanics implies polynomial-time solution for NP-complete and #P problems

If quantum states exhibit small nonlinearities during time evolution, then quantum computers can be used to solve NP-complete problems in polynomial time. We provide algorithms that solve NP-complete and #P oracle problems by exploiting nonlinear quantum logic gates. It is argued that virtually any deterministic nonlinear quantum theory will include such gates, and the method is explicitly demonstrated using the Weinberg model of nonlinear quantum mechanics.Comment: 10 pages, no figures, submitted to Phys. Rev. Let

Discrete Morse functions for graph configuration spaces

We present an alternative application of discrete Morse theory for two-particle graph configuration spaces. In contrast to previous constructions, which are based on discrete Morse vector fields, our approach is through Morse functions, which have a nice physical interpretation as two-body potentials constructed from one-body potentials. We also give a brief introduction to discrete Morse theory. Our motivation comes from the problem of quantum statistics for particles on networks, for which generalized versions of anyon statistics can appear.Comment: 26 page

High-Sensitivity Measurement of 3He-4He Isotopic Ratios for Ultracold Neutron Experiments

Research efforts ranging from studies of solid helium to searches for a neutron electric dipole moment require isotopically purified helium with a ratio of 3He to 4He at levels below that which can be measured using traditional mass spectroscopy techniques. We demonstrate an approach to such a measurement using accelerator mass spectroscopy, reaching the 10e-14 level of sensitivity, several orders of magnitude more sensitive than other techniques. Measurements of 3He/4He in samples relevant to the measurement of the neutron lifetime indicate the need for substantial corrections. We also argue that there is a clear path forward to sensitivity increases of at least another order of magnitude.Comment: 11 pages, 10 figure