Constraining the IMF using TeV gamma ray absorption

Gamma rays of ~TeV energies from distant sources suffer attenuation due to pair production off of ~1 micron EBL photons. We may exploit this process in order to indirectly measure the EBL and constrain models of galaxy formation. Here, using semi-analytic models of galaxy formation, we examine how gamma ray absorption may be used as an indirect probe of the stellar initial mass function (IMF), although there is a degeneracy with dust modeling. We point out that with the new generation of gamma ray telescopes including STACEE, MAGIC, HESS, VERITAS, and Milagro, we should soon possess a wealth of new data and a new method for probing the nature of the IMF.Comment: contribution to "TeV Astrophysics of Extragalactic Sources" VERITAS workshop, editors M. Catanese, J. Quinn, T. Weekes; 3 pages 1 figur

Alien Registration- Somerville, Lillian D. (Mars Hill, Aroostook County)

https://digitalmaine.com/alien_docs/34036/thumbnail.jp

TTC5 is required to prevent apoptosis of acute myeloid leukemia stem cells

Using a screening strategy, we identified the tetratricopeptide repeat (TPR) motif protein, Tetratricopeptide repeat domain 5 (TTC5, also known as stress responsive activator of p300 or Strap) as required for the survival of human acute myeloid leukemia (AML) cells. TTC5 is a stress-inducible transcription cofactor known to interact directly with the histone acetyltransferase EP300 to augment the TP53 response. Knockdown (KD) of TTC5 induced apoptosis of both murine and human AML cells, with concomitant loss of clonogenic and leukemia-initiating potential; KD of EP300 elicited a similar phenotype. Consistent with the physical interaction of TTC5 and EP300, the onset of apoptosis following KD of either gene was preceded by reduced expression of BCL2 and increased expression of pro-apoptotic genes. Forced expression of BCL2 blocked apoptosis and partially rescued the clonogenic potential of AML cells following TTC5 KD. KD of both genes also led to the accumulation of MYC, an acetylation target of EP300, and the form of MYC that accumulated exhibited relative hypoacetylation at K148 and K157, residues targeted by EP300. In view of the ability of excess cellular MYC to sensitize cells to apoptosis, our data suggest a model whereby TTC5 and EP300 cooperate to prevent excessive accumulation of MYC in AML cells and their sensitization to cell death. They further reveal a hitherto unappreciated role for TTC5 in leukemic hematopoiesis

Los Axophyllinae del Suroeste de España: una revisión

A revision of the state of knowledge of the solitary axophyllids that have been grouped in the subfamily Axophyllinae (family Axophyllidae) and the description of the specimens collected in Sierra Morena (south-western Spain) is accomplished. This group of rugose corals has been reported frequently in the Carboniferous from Australia to North America and from China to Western Europe. However, some of the supposed records belong to other coral families that show some features in common, such as Geyerophyllidae and Aulophyllidae. After a detailed revision of the bibliographic references and some of the types, the genera included in this subfamily are: Axophyllum, Gangamophyllum, Pareynia, Semenophyllum, Protocarcinophyllum and the new genus Morenaphyllum. The genus Axoclisia remains as a doubtful member of the family. Axophyllinae are common in south-western Spain. They have been recorded and cited from the Guadiato Area and Los Santos de Maimona Basin comprising upper Viséan (Asbian, Brigantian) and Serpukhovian rocks, but most of those records remain undescribed. The record of Axophyllinae in Sierra Morena comprises ten species belonging to Axophyllum (four of them are new; A. cozari, A. julianaense, A. spinosum, A. spiralum), two species belonging to Gangamophyllum, one belonging to Pareynia (a new one, P. viacrucense) and two belonging to the new genus Morenaphyllum (M. antolinense, M. boyerense). The stratigraphic record of the Axophyllinae in Sierra Morena fi ts well with the distribution of the same species in other regions (mainly Western Europe and North Africa), with a few exceptions. A.mendipense occurs later than in Britain and Belgium and A. tazoultense and A.pseudokirsopianum occur earlier than in North Africa. A tentative phylogeny is proposed. The genus Axophyllum is the ancestor of all other genera of the subfamily and at least five evolutionary lineages can be traced in that genus, from the ancestor (Axophyllum simplex) to the youngest record, A. moroccoense. The Axophyllinae should be considered as biogeographic markers of the Palaeotethys, because all citations of taxa beyond that ocean are erroneous. Their stratigraphic range is from lower Viséan to Bashkirian, having an acme in the upper Viséan, both in abundance and diversity. Their occurrences in the Bashkirian are local records in some refuges before their extinction.Se ha abordado una revision de los corales solitarios de la subfamilia Axophyllinae y la descripción de los axophyllinos recolectados en el Carbonífero de Sierra Morena (Suroeste de España). Este grupo de corales ha sido mencionado frecuentemente en el Cabonífero desde Australia hasta América del Norte y desde China hasta Europa Occidental. Sin embargo, muchos de los supuestos registros correponden a otras familias de corales rugosos tales como Geyerophyllidae o Aulophyllidae. Tras una detallada revisión que ha incluido el estudio de algunos de los tipos, los géneros que se incluyen en esta familia son: Axophyllum, Gangamophyllum, Pareynia, Semenophyllum, Protocarcinophyllum y el nuevo género Morenaphyllum. El género Axoclisia se considera como dudoso miembro de esta familia. Los Axophyllinae son frecuentes en el suroeste de España. Se han citado y descrito en el Área del Guadiato y en la Cuenca de Los Santos de Maimona en rocas del Asbiense, Brigantiense y Serpukhoviense, pero la mayoría de los hallazgos no han sido descritos aún. El registro de Axophyllinae en Sierra Morena comprende diez especies de Axophyllum (cuatro nuevas), dos especies de Gangamophyllum, una de Pareynia (nueva) y dos del nuevo género Morenaphyllum. La distribución estratigráfica de los Axophyllinae en Sierra Morena es consistente con la distribución de las mismas especies en otras áreas (básicamente Europa Occidental y Norte de África), con tres excepciones. A.mendipense aparece más tarde que en las islas Británicas y Bélgica y A. tazoultense y A.pseudokirsopianum aparecen antes que en el Norte de África. Se ha establecido un árbol filogenético tentativo para los Axophyllinae. Parece claro que el género Axophyllum es el ancestor de los demás géneros de la subfamilia y se proponen al menos cinco líneas evolutivas desde la especie más antigua y posible ancestro de todo el grupo (Axophyllum simplex) hasta el registro más moderno, A. moroccoense. Los Axophyllinae deben ser considerados como marcadores del Palaeotethys , porque todas las citas externas a este océano son erróneas. La distribución estratigráfica de los Axophyllinos va desde el Viseense inferior hasta el Bashkiriense, estando su apogeo, tanto en abundancia como en diversidad, en el Viseense superior. Las menciones en el Bashkiriense son registros locales en algunos refugios antes de su definitiva extinción.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)Universidad Complutense de Madridpu

Non-linear Stochastic Galaxy Biasing in Cosmological Simulations

We study the biasing relation between dark-matter halos or galaxies and the underlying mass distribution, using cosmological $N$-body simulations in which galaxies are modelled via semi-analytic recipes. The nonlinear, stochastic biasing is quantified in terms of the mean biasing function and the scatter about it as a function of time, scale and object properties. The biasing of galaxies and halos shows a general similarity and a characteristic shape, with no galaxies in deep voids and a steep slope in moderately underdense regions. At \sim 8\hmpc, the nonlinearity is typically \lsim 10 percent and the stochasticity is a few tens of percent, corresponding to $\sim 30$ percent variations in the cosmological parameter $\beta=\Omega^{0.6}/b$. Biasing depends weakly on halo mass, galaxy luminosity, and scale. The time evolution is rapid, with the mean biasing larger by a factor of a few at $z\sim 3$ compared to $z=0$, and with a minimum for the nonlinearity and stochasticity at an intermediate redshift. Biasing today is a weak function of the cosmological model, reflecting the weak dependence on the power-spectrum shape, but the time evolution is more cosmology-dependent, relecting the effect of the growth rate. We provide predictions for the relative biasing of galaxies of different type and color, to be compared with upcoming large redshift surveys. Analytic models in which the number of objects is conserved underestimate the evolution of biasing, while models that explicitly account for merging provide a good description of the biasing of halos and its evolution, suggesting that merging is a crucial element in the evolution of biasing.Comment: 27 pages, 21 figures, submitted to MNRA

Surplus Identification with Non-Linear Returns. ESRI WP522. December 2015

We present evidence from two experiments designed to quantify the impact of cognitive constraints on consumers' ability to identify surpluses. Participants made repeated forced-choice decisions about whether products conferred surpluses, comparing one or two plainly perceptible attributes against displayed prices. Returns to attributes varied in linearity, scale and relative weight. Despite the apparent simplicity of this task, in which participants were incentivised and able to attend fully to all relevant information, surplus identification was surprisingly imprecise and subject to systematic bias. Performance was unaffected by monotonic non-linearities in returns, but non-monotonic non-linearities reduced the likelihood of detecting a surplus. Regardless of the shape of returns, learning was minimal and largely confined to initial exposures. Although product value was objectively determined, participants exhibited biases previously observed in subjective discrete choice, suggesting common cognitive mechanisms. These findings have implications for consumer choice models and for ongoing attempts to account for cognitive constraints in applied microeconomic contexts

Hubble Space Telescope Imaging of the Ultracompact Blue Dwarf Galaxy HS 0822+3542: An Assembling Galaxy in a Local Void?

We present deep U, narrow-V, and I-band images of the ultracompact blue dwarf galaxy HS 0822+3542, obtained with the Advanced Camera for Surveys / High Resolution Channel of the Hubble Space Telescope. This object is extremely metal-poor (12 + log(O/H) = 7.45) and resides in a nearby void. The images resolve it into two physically separate components that were previously described as star clusters in a single galaxy. The primary component is only \~100 pc in maximum extent, and consists of starburst region surrounded by a ring-like structure of relatively redder stars. The secondary component is ~50 pc in size and lies at a projected distance of ~80 pc away from the primary, and is also actively star-forming. We estimate masses ~10^7 M(sol) and ~10^6 M(sol) for the two components, based on their luminosities, with an associated dynamical timescale for the system of a few Myr. This timescale and the structure of the components suggests that a collision between them triggered their starbursts. The spectral energy distributions of both components can be fitted by the combination of recent (few Myr old) starburst and an evolved (several Gyr old) underlying stellar population, similar to larger blue compact dwarf galaxies. This indicates that despite its metal deficiency the object is not forming its first generation of stars. However, the small sizes and masses of the two components suggests that HS 0822+3542 represents a dwarf galaxy in the process of assembling from clumps of stars intermediate in size between globular clusters and objects previously classified as galaxies. Its relatively high ratio of neutral gas mass to stellar mass (~1) and high specific star formation rate, log(SFR/M(sol) = -9.2, suggests that it is still converting much of its gas to stars.Comment: 11 pages, 2 figures, accepted for publication in Astrophysical Journal Letter

Genetic evidence that cellulose synthase activity influences microtubule cortical array organization

To identify factors that influence cytoskeletal organization we screened for Arabidopsis ( Arabidopsis thaliana) mutants that show hypersensitivity to the microtubule destabilizing drug oryzalin. We cloned the genes corresponding to two of the 131 mutant lines obtained. The genes encoded mutant alleles of PROCUSTE1 and KORRIGAN, which both encode proteins that have previously been implicated in cellulose synthesis. Analysis of microtubules in the mutants revealed that both mutants have altered orientation of root cortical microtubules. Similarly, isoxaben, an inhibitor of cellulose synthesis, also altered the orientation of cortical microtubules while exogenous cellulose degradation did not. Thus, our results substantiate that proteins involved in cell wall biosynthesis influence cytoskeletal organization and indicate that this influence on cortical microtubule stability and orientation is correlated with cellulose synthesis rather than the integrity of the cell wall