Extraterrestrial applications of solar optics for interior illumination

Solar optics is a terrestrial technology that has potential extraterrestrial applications. Active solar optics (ASO) and passive solar optics (PSO) are two approaches to the transmission of sunlight to remote interior spaces. Active solar optics is most appropriate for task illumination, while PSO is most appropriate for general illumination. Research into solar optics, motivated by energy conservation, has produced lightweight and low-cost materials, products that have applications to NASA's Controlled Ecological Life Support System (CELSS) program and its lunar base studies. Specifically, prism light guides have great potential in these contexts. Several applications of solar optics to lunar base concepts are illustrated

Climate-driven regime shifts in a mangrove-salt marsh ecotone over the past 250 years.

Climate change is driving the tropicalization of temperate ecosystems by shifting the range edges of numerous species poleward. Over the past few decades, mangroves have rapidly displaced salt marshes near multiple poleward mangrove range limits, including in northeast Florida. It is uncertain whether such mangrove expansions are due to anthropogenic climate change or natural climate variability. We combined historical accounts from books, personal journals, scientific articles, logbooks, photographs, and maps with climate data to show that the current ecotone between mangroves and salt marshes in northeast Florida has shifted between mangrove and salt marsh dominance at least 6 times between the late 1700s and 2017 due to decadal-scale fluctuations in the frequency and intensity of extreme cold events. Model projections of daily minimum temperature from 2000 through 2100 indicate an increase in annual minimum temperature by 0.5 °C/decade. Thus, although recent mangrove range expansion should indeed be placed into a broader historical context of an oscillating system, climate projections suggest that the recent trend may represent a more permanent regime shift due to the effects of climate change

Assessing indirect methods to determine black hole masses using NGC 4151

Accurately determining the black hole mass ($M_\mathrm{BH}$) in active galactic nuclei (AGN) is crucial to constraining their properties and to studying their evolution. While direct methods yield reliable measurements of $M_\mathrm{BH}$ in unobscured type 1 AGN, where the dynamics of stellar or gas components can be directly observed, only indirect methods can be applied to the vast majority of heavily absorbed type 2 AGN, which represent most of the AGN population. Since it is difficult to evaluate the accuracy and precision of these indirect methods, we utilize the nearby X-ray bright Seyfert galaxy NGC 4151, whose $M_\mathrm{BH}$ has been tightly constrained with several independent direct methods, as a laboratory to assess the reliability of three indirect methods that have been applied to obscured AGN. All three, the X-ray scaling method, the fundamental plane of black hole activity, and the M-$\sigma$ correlation, yield $M_\mathrm{BH}$ values consistent with those inferred from direct methods and can therefore be considered accurate. However, only the X-ray scaling method and the M-$\sigma$ correlation are precise because the substantial scatter in the fundamental plane of BH activity allows only for crude estimates. Of the four M-$\sigma$ correlations we used, only the one from Kormendy and Ho yields a value consistent with the dynamical estimates. This study suggests that the best approach to estimating the black hole mass in systems where direct dynamical methods cannot be applied is to utilize a combination of indirect methods, taking into account their different ranges of applicability.Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Societ

Integrating physiology into correlative models can alter projections of habitat suitability under climate change for a threatened amphibian

Rapid global change has increased interest in developing ways to identify suitable refu-gia for species of conservation concern. Correlative and mechanistic species distribu-tion models (SDMs) represent two approaches to generate spatially-explicit estimates of climate vulnerability. Correlative SDMs generate distributions using statistical associations between environmental variables and species presence data. In contrast, mechanistic SDMs use physiological traits and tolerances to identify areas that meet the conditions required for growth, survival and reproduction. Correlative approaches assume modeled environmental variables influence species distributions directly or indirectly; however, the mechanisms underlying these associations are rarely verified empirically. We compared habitat suitability predictions between a correlative-only SDM, a mechanistic SDM and a correlative framework that incorporated mechanis-tic layers (‘hybrid models’). Our comparison focused on green salamanders Aneides aeneus, a priority amphibian threatened by climate change throughout their disjunct range. We developed mechanistic SDMs using experiments to measure the thermal sensitivity of resistance to water loss (ri) and metabolism. Under current climate con-ditions, correlative-only, hybrid and mechanistic SDMs predicted similar overlap in habitat suitability; however, mechanistic SDMs predicted habitat suitability to extend into regions without green salamanders but known to harbor many lungless salaman-ders. Under future warming scenarios, habitat suitability depended on climate sce-nario and SDM type. Correlative and hybrid models predicted a 42% reduction or 260% increase in area considered to be suitable depending on the climate scenario. In mechanistic SDMs, energetically suitable habitat declined with both climate scenarios and was driven by the thermal sensitivity of ri. Our study indicates that correlative-only and hybrid approaches produce similar predictions of habitat suitability; however, discrepancies can arise for species that do not occupy their entire fundamental niche, which may hold consequences of conservation planning of threatened species

Agonist-Specific Calcium Signaling and Phosphoinositide Hydrolysis in Human SK-N-MCIXC Neuroepithelioma Cells

Fura-2 digital imaging microfluorimetry was used to evaluate the Ca 2+ signals generated in single clonal human neuroepithelioma cells (SK-N-MCIXC) in response to agonists that stimulate phosphoinositide hydrolysis. Addition of optimal concentrations of either endothelin-1 (ET-1), ATP, oxotremorine-M (Oxo-M), or norepinephrine (NE) all resulted in an increase in the concentration of cytosolic calcium (Ca 2+ i ) but of different magnitudes (ET-1 = ATP> NE). The Ca 2+ signals elicited by the individual agonists also differed from each other in terms of their latency of onset, rate of rise and decay, and prevalence of a sustained phase of Ca 2+ influx. The Ca 2+ signals that occurred in response to ATP had a shorter latency and more rapid rates of rise and decay than those observed for the other three agonists. Furthermore, a sustained plateau phase of the Ca 2+ signal, which was characteristic of the response to Oxo-M, was observed in 94% of cells responded to ET-1 or ATP, whereas corresponding values for Oxo-M and NE were ∼74 and ∼48%. Sequential addition of agonists to cells maintained in a Ca 2+ -free buffer indicated that each ligand mobilized Ca 2+ from a common intracellular pool. When monitored as a release of a total inositol phosphate fraction, all four agonists elicited similar (four- to sixfold) increases in phosphoinositide hydrolysis. However, the addition of ET-1 or ATP resulted in larger increases in the net formation of inositol 1,4,5-trisphosphate than did either Oxo-M or NE. These results indicate that, in SK-N-MCIXC cells, the characteristics of both Ca 2+ signaling and inositol phosphate production are agonist specific.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66414/1/j.1471-4159.1994.63062099.x.pd

Realizability of the Lorentzian (n,1)-Simplex

In a previous article [JHEP 1111 (2011) 072; arXiv:1108.4965] we have developed a Lorentzian version of the Quantum Regge Calculus in which the significant differences between simplices in Lorentzian signature and Euclidean signature are crucial. In this article we extend a central result used in the previous article, regarding the realizability of Lorentzian triangles, to arbitrary dimension. This technical step will be crucial for developing the Lorentzian model in the case of most physical interest: 3+1 dimensions. We first state (and derive in an appendix) the realizability conditions on the edge-lengths of a Lorentzian n-simplex in total dimension n=d+1, where d is the number of space-like dimensions. We then show that in any dimension there is a certain type of simplex which has all of its time-like edge lengths completely unconstrained by any sort of triangle inequality. This result is the d+1 dimensional analogue of the 1+1 dimensional case of the Lorentzian triangle.Comment: V1: 15 pages, 2 figures. V2: Minor clarifications added to Introduction and Discussion sections. 1 reference updated. This version accepted for publication in JHEP. V3: minor updates and clarifications, this version closely corresponds to the version published in JHE

Learning to Read Bushman

The notebooks in the Bleek and Lloyd collection contain handwritten stories that metaphorically encode the Bushman culture and are useful to researchers and scholars trying to understand Bushman language and culture. These notebooks, however, only exist as scanned images and therefore the stories they contain cannot be searched, indexed or compared. This research seeks to investigate how accurately the Bushman stories can be automatically converted from images to text, in a process known as transcription, and also to explore the various techniques for doing this. The expected contribution is a measurement of how accurately transcription can be automatically performed as well as a comparison of different techniques for doing this

A search of CO emission lines in blazars: the low molecular gas content of BL Lac objects compared to quasars

BL Lacertae (Lac) objects that are detected at very high energies (VHE) are of fundamental importance to study multiple astrophysical processes, including the physics of jets, the properties of the extragalactic background light and the strength of the intergalactic magnetic field. Unfortunately, since most blazars have featureless optical spectra that preclude a redshift determination, a substantial fraction of these VHE extragalactic sources cannot be used for cosmological studies. To assess whether molecular lines are a viable way to establish distances, we have undertaken a pilot programme at the Institut of Millimétrique (IRAM) 30 m telescope to search for CO lines in three BL Lac objects with known redshifts. We report a positive detection of  M⊙ towards 1ES 1959+650, but due to the poor quality of the baseline, this value is affected by a large systematic uncertainty. For the remaining two sources, W Comae and RGB J0710+591, we derive 3σ upper limits at, respectively, and 1.6 × 109  M⊙, assuming a line width of 150 km s−1 and a standard conversion factor α = 4  M⊙ (K km s−1 pc2)−1. If these low molecular gas masses are typical for blazars, blind redshift searches in molecular lines are currently unfeasible. However, deep observations are still a promising way to obtain precise redshifts for sources whose approximate distances are known via indirect methods. Our observations further reveal a deficiency of molecular gas in BL Lac objects compared to quasars, suggesting that the host galaxies of these two types of active galactic nuclei (AGN) are not drawn from the same parent population. Future observations are needed to assess whether this discrepancy is statistically significant, but our pilot programme shows how studies of the interstellar medium in AGN can provide key information to explore the connection between the active nuclei and the host galaxie