Distribution of satellite galaxies in high redshift groups

We use galaxy groups at redshifts between 0.4 and 1.0 selected from the Great Observatories Origins Deep Survey (GOODS) to study the color-morphological properties of satellite galaxies, and investigate possible alignment between the distribution of the satellites and the orientation of their central galaxy. We confirm the bimodal color and morphological type distribution for satellite galaxies at this redshift range: the red and blue classes corresponds to the early and late morphological types respectively, and the early-type satellites are on average brighter than the late-type ones. Furthermore, there is a {\it morphological conformity} between the central and satellite galaxies: the fraction of early-type satellites in groups with an early-type central is higher than those with a late-type central galaxy. This effect is stronger at smaller separations from the central galaxy. We find a marginally significant signal of alignment between the major axis of the early-type central galaxy and its satellite system, while for the late-type centrals no significant alignment signal is found. We discuss the alignment signal in the context of shape evolution of groups.Comment: 7 pages, 7 figures, accepted by Ap

Minimizing the Cost of Team Exploration

A group of mobile agents is given a task to explore an edge-weighted graph $G$, i.e., every vertex of $G$ has to be visited by at least one agent. There is no centralized unit to coordinate their actions, but they can freely communicate with each other. The goal is to construct a deterministic strategy which allows agents to complete their task optimally. In this paper we are interested in a cost-optimal strategy, where the cost is understood as the total distance traversed by agents coupled with the cost of invoking them. Two graph classes are analyzed, rings and trees, in the off-line and on-line setting, i.e., when a structure of a graph is known and not known to agents in advance. We present algorithms that compute the optimal solutions for a given ring and tree of order $n$, in $O(n)$ time units. For rings in the on-line setting, we give the $2$-competitive algorithm and prove the lower bound of $3/2$ for the competitive ratio for any on-line strategy. For every strategy for trees in the on-line setting, we prove the competitive ratio to be no less than $2$, which can be achieved by the $DFS$ algorithm.Comment: 25 pages, 4 figures, 5 pseudo-code

Aiming Low Is Harder -- Induction for Lower Bounds in Probabilistic Program Verification

We present a new inductive rule for verifying lower bounds on expected values of random variables after execution of probabilistic loops as well as on their expected runtimes. Our rule is simple in the sense that loop body semantics need to be applied only finitely often in order to verify that the candidates are indeed lower bounds. In particular, it is not necessary to find the limit of a sequence as in many previous rules

Bounded Model Checking for Probabilistic Programs

In this paper we investigate the applicability of standard model checking approaches to verifying properties in probabilistic programming. As the operational model for a standard probabilistic program is a potentially infinite parametric Markov decision process, no direct adaption of existing techniques is possible. Therefore, we propose an on-the-fly approach where the operational model is successively created and verified via a step-wise execution of the program. This approach enables to take key features of many probabilistic programs into account: nondeterminism and conditioning. We discuss the restrictions and demonstrate the scalability on several benchmarks

Antimicrobial diterpenoids and triterpenoids from the stem bark of Croton macrostachys

Antimicrobial-guided fractionation of the EtOAc extract of the stem bark of Croton macrostachys afforded five known compounds including two lupane triterpenoids, lupeol (1) and betulin (2), and three clerodane diterpenoids, floridolide A (3), hardwickic acid (4) and 12-oxo-hardwickic acid (5). Their structures were elucidated on the basis of spectral studies and comparison with published data. The EtOAc extract and compounds 1, 2, 4 and 5 were evaluated for their antibacterial and antifungal activities by macro-dilutionmethod. The extract displayed significant antibacterial and antifungal activities (MIC = 31.25-1000 μg/ml). Betulin (2) and 12-oxo-hardwickic acid (5) were the most active compounds (MIC = 7.81-500 μg/ml). Themost sensitive microorganisms were Staphylococcus aureus ATCC 25922 for bacteria and two Candida species, Candida albicans ATCC 24433 and Candida krusei ATCC 6258, for fungi. The isolation of these active antibacterial and antifungal principles supports the use of C. macrostachys in traditional medicine for the treatment of microbial infections.Keywords: Croton macrostachys; Euphorbiaceae; triterpenes; diterpenes; antibacterial; antifungal

Pore network analysis of Brae Formation sandstone, North Sea

In this work, we apply digital rock physics (DRP) to characterize the pore networks of the Brae Formation sandstones from two different wells in the Miller field area (North Sea, UK). Using X-ray micro-CT scans, we calculate the porosity and permeability and generate pore network models to assess pore shape characteristics. The porous samples are marked by macroporosities ranging from 4.9% to 15.2% with the effective porosities varying from 0 to 14.8%. The samples also contained some microporosity hosted in secondary and accessory mineral phases, varying between 2.6% and 10.7%. Pore network model results for total porosity indicate that the samples have median pore and throat radii ranging from 5.5 μm to 16.8 μm and 6.4 μm–12.9 μm, respectively. The throat length of all samples has a median value ranging between 36.3 μm and 82.4 μm. The ratio between effective porosity and total porosity (φ∗) varies with total porosity (φ) following the exponential relation φ∗ = 0.98 − e− (φ− 0.032)/0.028. Pore network connectivity is established at a porosity of 3% and full communication is achieved at porosities exceeding 10%. Permeability was found to vary with total porosity with an exponent of 3.67. Based on these observations and the results from our models, the connectivity of the pore network has important implications for predicting reservoir performance during large scale subsurface projects such as hydrocarbon production and CO2 storage

CARMA1 is a novel regulator of T-ALL disease and leukemic cell migration to the CNS

No abstract available