Ambiguity in the Determination of the Free Energy for a Model of the Circle Map

We consider a simple model to describe the widths of the mode locked intervals for the critical circle map. Using two different partitions of the rational numbers, based on Farey series and Farey tree levels respectively, we calculate the free energy analytically at selected points for each partition. It is found that the result of the calculation depends on the method of partition. An implication of this is that the generalized dimensions $D_q$ are different for each partition except when $q=0$, i.e. only the Hausdorff dimension is the same in each case.Comment: 14 page

Teaching the Basics of Reactive Oxygen Species and their Relevance to Cancer Biology: Mitochondrial Reactive Oxygen Species Detection, Redox Signaling, and Targeted Therapies

Reactive oxygen species (ROS) have been implicated in tumorigenesis (tumor initiation, tumor progression, and metastasis). Of the many cellular sources of ROS generation, the mitochondria and the NADPH oxidase family of enzymes are possibly the most prevalent intracellular sources. In this article, we discuss the methodologies to detect mitochondria-derived superoxide and hydrogen peroxide using conventional probes as well as newly developed assays and probes, and the necessity of characterizing the diagnostic marker products with HPLC and LC-MS in order to rigorously identify the oxidizing species. The redox signaling roles of mitochondrial ROS, mitochondrial thiolperoxidases, and transcription factors in response to mitochondria-targeted drugs are highlighted. ROS generation and ROS detoxification in drug-resistant cancer cells and the relationship to metabolic reprogramming are discussed. Understanding the subtle role of ROS in redox signaling and in tumor proliferation, progression, and metastasis as well as the molecular and cellular mechanisms (e.g., autophagy) could help in the development of combination therapies. The paradoxical aspects of antioxidants in cancer treatment are highlighted in relation to the ROS mechanisms in normal and cancer cells. Finally, the potential uses of newly synthesized exomarker probes for in vivo superoxide and hydrogen peroxide detection and the low-temperature electron paramagnetic resonance technique for monitoring oxidant production in tumor tissues are discussed

Studying the Earth at Night from CubeSats

This paper presents examples of the latest imaging data of the Earth at night from multiple CubeSat platforms. Beginning in 2012, with AeroCube-4, The Aerospace Corporation has launched multiple CubeSat platforms in different orbits equipped with a common suite of CMOS sensors. Originally designed as utility cameras to assist with attitude control system studies and star sensor development, we have been using these simple camera sensors to image the Earth at night since 2014. Our initial work focused on observing nighttime urban lights and global gas flare signals at higher resolution than is possible with the VIIRS sensor. To achieve optimum sensitivity and resolution, orbital motion is compensated for via the use of on-board reaction wheels to perform point-and-stare experiments, often with multiple frame exposures as the sensor moves in orbit. Ground sample distances for these systems range from approximately 100 to 130 meters for the narrow-field-of-view cameras, to 500 meters for the medium-field-of-view cameras. In our initial work, we demonstrated that CMOS sensors flown on AeroCube satellites can achieve a nighttime light detection sensitivity on the order of 20 nW-cm-2 -sr-1 . This resolution and sensitivity allows for detection of urban lighting, road networks, major infrastructure illumination, natural gas flares, and other phenomena of interest. For wide-area surveys, we can also program our cameras to observe regions of interest and co-add pixels to reduce the data bandwidth. This allows for a greater number of frames to be collected and downloaded. These results may then be used to task later satellite passes. Here, we present new examples of our nighttime Earth observation studies using CubeSats. These include: 1) detecting urban growth and change via repeat imaging, 2) investigating the utility of color observations, 3) spotting major sources of light pollution, 4) studying urban-wildland interface regions where lighting may be important to understanding wildlife corridors, 5) imaging lightning and cloud cover at night using wide-area imaging, 6) observations of the very bright lights of fishing boats, and 7) observing other interesting natural phenomenon, including airglow emissions, and the streaking caused by proton strikes in the South Atlantic Anomaly. Our ongoing work includes utilizing a diversity in overpass times from multiple satellites to observe nighttime scenes, imaging high-latitude cities not optimally accessed by the international space station’s cameras, and building a catalogue of observations of rapidly developing megacities and global infrastructure nodes. Data from CMOS sensors flown in common on 5 different AeroCubes in 4 different orbits have been collected. Our results show that enhanced CubeSat sensors can improve mapping of the human footprint in targeted regions via nighttime lights and contribute to better monitoring of: urban growth, light pollution, energy usage, the urban-wildland interface, the improvement of electrical power grids in developing countries, light-induced fisheries, and oil industry flare activity. Future CubeSat sensors should be able to contribute to nightlights monitoring efforts by organizations such as NOAA, NASA, ESA, the World Bank and others, and offer low-cost options for nighttime studies

On Understanding and Desire: A Reflection

This paper reflects on aspects of seeking to live fully within our present culture whilst living according to the Christian faith. In the face of a society where reference points are no longer fixed and the where church is viewed with diminished regard – if not suspicion – Brian Hardy suggests that at the heart of what is being lost is an adequate evaluation of the human person. With particular regard to the writings of Rowan Williams, he explores the territory of human understanding and desire, taking in issues such as belonging and loneliness and sexual orientation

Long-term effects of satellite megaconstellations on the debris environment in low earth orbit

This thesis examines the potential long-term impacts of satellite megaconstellations in Low Earth Orbit, with a focus on how post-mission disposal rates for megaconstellations will affect their contributions to orbital debris over the next 150 years. A new, medium-fidelity simulation for modeling orbital debris is developed and described, and several test cases are run with SpaceX’s Starlink megaconstellation and varying success rates for post-mission disposal. In cases where Starlink’s post-mission disposal rate is insufficient to prevent debris growth, varying amounts of active debris removal are explored as a potential mitigation measure. It is shown that LEO debris levels will grow at almost double their baseline rate if Starlink meets only the minimum regulatory requirements for post-mission disposal, and even relatively high rates of active debris removal cannot always return the LEO environment to its non-megaconstellation baseline. Still, the potential exists to minimize the debris-generating effects of large megaconstellations like Starlink if post-mission disposal rates of 95% or better can be achieved

The Settlement History of the Lucre Basin (Cusco, Peru)

This article reports the results of archaeological survey from Oropesa to Andahuayllilas, Peru