Discovery of a planetary-sized object in the scattered Kuiper belt

We present the discovery and initial physical and dynamical characterization of the object 2003 UB313. The object is sufficiently bright that for all reasonable values of the albedo it is certain to be larger than Pluto. Pre-discovery observations back to 1989 are used to obtain an orbit with extremely small errors. The object is currently at aphelion in what appears to be a typical orbit for a scattered Kuiper belt object except that it is inclined by about 44 degrees from the ecliptic. The presence of such a large object at this extreme inclination suggests that high inclination Kuiper belt objects formed preferentially closer to the sun. Observations from Gemini Observatory show that the infrared spectrum is, like that of Pluto, dominated by the presence of frozen methane, though visible photometry shows that the object is almost neutral in color compared to Pluto's extremely red color. 2003 UB313 is likely to undergo substantial seasonal change over the large range of heliocentric distances that it travels; Pluto at its current distance is likely to prove a useful analog for better understanding the range of seasonal changes on this body.Comment: 9 pages, 1 figur

Putting hydrodynamic interactions to work: tagged particle separation

Separation of magnetically tagged cells is performed by attaching markers to a subset of cells in suspension and applying fields to pull from them in a variety of ways. The magnetic force is proportional to the field gradient, and the hydrodynamic interactions play only a passive, adverse role. Here we propose using a homogeneous rotating magnetic field only to make tagged particles rotate, and then performing the actual separation by means of hydrodynamic interactions, which thus play an active role. The method, which we explore here theoretically and by means of numerical simulations, lends itself naturally to sorting on large scales.Comment: Version accepted for publication - Europhysics Letter

Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope

We have used the Hubble Space Telescope to directly measure the angular size of the large Kuiper belt object 2003 UB313. By carefully calibrating the point spread function of a nearby field star, we measure the size of 2003 UB313 to be 34.3$\pm$1.4 milliarcseconds, corresponding to a diameter of 2400$\pm$100 km or a size $\sim5$% larger than Pluto. The V band geometric albedo of 2003 UB313 is $86\pm7$%. The extremely high albedo is consistent with the frosty methane spectrum, the lack of red coloring, and the lack of observed photometric variation on the surface of 2003 UB313. Methane photolysis should quickly darken the surface of 2003 UB313, but continuous evaporation and redeposition of surface ices appears capable of maintaining the extreme alebdo of this body

Determination of the Age and Optimal Cutting Time Based on the Concentration of Soluble Carbohydrates in a Rye grass Tetraploide

This study was conducted in Toacaso Town in the northwest of Latacunga City, Cotopaxi Province, Ecuador. The researchers aimed to establish in situ the optimal age and cutting time of REMINGTON Ryegrass (Lolium perenne) based on the concentration of soluble carbohydrates using a digital refractometer. The research used 48 experimental units, each with an area of 16 m2 (4×4 m) and a total area of 768 m2. The experiment was carried out for 60 days in which the highest concentration of carbohydrates was evaluated taking into account (i) the age of the pasture – 45 and 60 days (factor A) and (ii) the cutting time – 08H00, 10H00, 12H00, 14H00, 16H00, and 18H00 hours (factor B0) for which a randomized complete block design (RCBD) was used under a bifactorial arrangement with four repetitions per treatment. The results reported that the highest concentration of soluble carbohydrates was obtained at 60 days of age with 13.15º Brix (ºBx), while the optimal cut-off time was 2:00 p.m. with a concentration of 16.33 ºBx. The authors conclude that the older the pasture, and considering the time of the day, the higher the concentration of soluble carbohydrates will be. The highest cost-benefit was obtained at 4:00 p.m. presenting a cost-benefit of $1.44 which means that for every dollar invested a profit of 44 cents was obtained. Therefore, it is recommended to harvest the REMINGTON Ryegrass at 60 days of age at 2:00 p.m. Keywords: soluble carbohydrates, Ryegrass (Lolium perenne), remintong, digital refractometer, Brix degrees. RESUMEN Se estableció in situ la edad y hora de corte óptima sobre la concentración de carbohidratos solubles en un Rye grass tetraploide (Lolium perenne) variedad REMINTONG, mediante la utilización de un refractómetro digital en la parroquia Toacaso ubicada al noroccidente del cantón Latacunga, provincia de Cotopaxi. En la investigación se utilizó 48 unidades experimentales con un área de 16 m2 (4 m x 4 m), en una superficie total de 768 m2. El trabajo experimental tuvo una duración de 60 días en los cuales se e valuó la mayor concentración de carbohidratos con relación a la edad del pasto 45 y 60 días (factor A), y la hora de corte 08H00, 10H0 0, 12H00, 14H00, 16H00 y 18H00 horas (factor B), para lo cual se aplicó un Diseño de Bloques Completamente al Azar (DBCA) bajo arreglo bifactorial con cuatro repeticiones por tratamiento. Los resultados reportaron que la mayor concentración de carbohidratos solubles se obtuvo a los 60 días de edad con 13,15 grados Brix (∘Bx), relacionados con la hora de corte optima que fue a las 14h00 con una concentración de 16,33 ∘Bx, concluyendo que a mayor edad y conforme la hora del día, mayor será la concentración de carbohidr atos solubles. El mayor beneficio costo se obtuvo a las 16h00 presentando un beneficio/costo de$ 1,44 USD, lo que quiere decir que por cada dólar invertido se obtuvo una ganancia de 44 centavos, por lo tanto, se recomienda cosechar el pasto Rye grass variedad REMINGTON a los 60 días de edad a las 14h00. Palabras Clave: Carbohidratos Solubles, Rye grass (Lolium perenne), Remintong, Refractómetro digital, grados brix

Dysfunctional telomeres in primary cells from Fanconi anemia FANCD2 patients

© 2012 Joksic et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Background: Fanconi anemia (FA) is characterized by sensitivity to DNA cross-linking agents, mild cellular, and marked clinical radio sensitivity. In this study we investigated telomeric abnormalities of non-immortalized primary cells (lymphocytes and fibroblasts) derived from FA patients of the FA-D2 complementation group, which provides a more accurate physiological assessment than is possible with transformed cells or animal models. Results: We analyzed telomere length, telomere dysfunction-induced foci (TIFs), sister chromatid exchanges (SCE), telomere sister chromatid exchanges (T-SCE), apoptosis and expression of shelterin components TRF1 and TRF2. FANCD2 lymphocytes exhibited multiple types of telomeric abnormalities, including premature telomere shortening, increase in telomeric recombination and aberrant telomeric structures ranging from fragile to long-string extended telomeres. The baseline incidence of SCE in FANCD2 lymphocytes was reduced when compared to control, but in response to diepoxybutane (DEB) the 2-fold higher rate of SCE was observed. In contrast, control lymphocytes showed decreased SCE incidence in response to DEB treatment. FANCD2 fibroblasts revealed a high percentage of TIFs, decreased expression of TRF1 and invariable expression of TRF2. The percentage of TIFs inversely correlated with telomere length, emphasizing that telomere shortening is the major reason for the loss of telomere capping function. Upon irradiation, a significant decrease of TIFs was observed at all recovery times. Surprisingly, a considerable percentage of TIF positive cells disappeared at the same time when incidence of γ-H2AX foci was maximal. Both FANCD2 leucocytes and fibroblasts appeared to die spontaneously at higher rate than control. This trend was more evident upon irradiation; the percentage of leucocytes underwent apoptosis was 2.59- fold higher than that in control, while fibroblasts exhibited a 2- h delay before entering apoptosis. Conclusion: The results of our study showed that primary cells originating from FA-D2 patients display shorten telomeres, elevated incidence of T-SCEs and high frequency of TIFs. Disappearance of TIFs in early response to irradiation represent distinctive feature of FANCD2 cells that should be examined further.This article is made available through the Brunel Open Access Publishing Fund. This work was supported by the Ministry of Education and Science of the Republic of Serbia (Project No.173046)

Measuring star formation in high-z massive galaxies: A mid-infrared to submillimeter study of the GOODS NICMOS Survey sample

We present measurements of the mean mid-infrared-to-submillimeter flux densities of massive (M\ast \approx 2 \times 10^11 Msun) galaxies at redshifts 1.7 < z < 2.9, obtained by stacking positions of known objects taken from the GOODS NICMOS Survey (GNS) catalog on maps: at 24 {\mu}m (Spitzer/MIPS); 70, 100, and 160{\mu}m (Herschel/PACS); 250, 350, 500{\mu}m (BLAST); and 870{\mu}m (LABOCA). A modified blackbody spectrum fit to the stacked flux densities indicates a median [interquartile] star-formation rate of SFR = 63 [48, 81] Msun yr^-1 . We note that not properly accounting for correlations between bands when fitting stacked data can significantly bias the result. The galaxies are divided into two groups, disk-like and spheroid-like, according to their Sersic indices, n. We find evidence that most of the star formation is occurring in n \leq 2 (disk-like) galaxies, with median [interquartile] SFR = 122 [100,150] Msun yr^-1, while there are indications that the n > 2 (spheroid-like) population may be forming stars at a median [interquartile] SFR = 14 [9,20] Msun yr^-1, if at all. Finally, we show that star formation is a plausible mechanism for size evolution in this population as a whole, but find only marginal evidence that it is what drives the expansion of the spheroid-like galaxies.Comment: Accepted by MNRAS. 10 pages, 3 figures, 3 table

Keck Observatory Laser Guide Star Adaptive Optics Discovery and Characterization of a Satellite to the Large Kuiper Belt Object 2003 EL_(61)

The newly commissioned laser guide star adaptive optics system at Keck Observatory has been used to discover and characterize the orbit of a satellite to the bright Kuiper Belt object 2003 EL_(61). Observations over a 6 month period show that the satellite has a semimajor axis of 49,500 ± 400 km, an orbital period of 49.12 ± 0.03 days, and an eccentricity of 0.050 ± 0.003. The inferred mass of the system is (4.2 ± 0.1) × 10^(21) kg, or ~32% of the mass of Pluto and 28.6% ± 0.7% of the mass of the Pluto-Charon system. Mutual occultations occurred in 1999 and will not occur again until 2138. The orbit is fully consistent neither with one tidally evolved from an earlier closer configuration nor with one evolved inward by dynamical friction from an earlier more distant configuration

Parallel refined Isogeometric Analysis in 3D

We study three-dimensional isogeometric analysis (IGA) and the solution of the resulting system of linear equations via a direct solver. IGA uses highly continuous $C^{p-1}$ basis functions, which provide multiple benefits in terms of stability and convergence properties. However, smooth basis significantly deteriorate the direct solver performance and its parallel scalability. As a partial remedy for this, refined Isogeometric Analysis (rIGA) method improves the sequential execution of direct solvers. The refinement strategy enriches traditional highly-continuous $C^{p-1}$ IGA spaces by introducing low-continuity $C^{0}$ 0-hyperplanes along the boundaries of certain pre-defined macro-elements. In this work, propose a solution strategy for rIGA for parallel distributed memory machines and compare the computational costs of solving rIGA vs IGA discretizations. We verify our estimates with parallel numerical experiments. Results show that the weak parallel scalability of the direct solver improves approximately by a factor of $p^{2}$ when considering rIGA discretizations rather than highly-continuous IGA spaces