Simulations of Strong Gravitational Lensing with Substructure

Galactic sized gravitational lenses are simulated by combining a cosmological N-body simulation and models for the baryonic component of the galaxy. The lens caustics, critical curves, image locations and magnification ratios are calculated by ray-shooting on an adaptive grid. When the source is near a cusp in a smooth lens' caustic the sum of the magnifications of the three closest images should be close to zero. It is found that in the observed cases this sum is generally too large to be consistent with the simulations implying that there is not enough substructure in the simulations. This suggests that other factors play an important role. These may include limited numerical resolution, lensing by structure outside the halo, selection bias and the possibility that a randomly selected galaxy halo may be more irregular, for example due to recent mergers, than the isolated halo used in this study. It is also shown that, with the level of substructure computed from the N-body simulations, the image magnifications of the Einstein cross type lenses are very weak functions of source size up to \sim 1\kpc. This is also true for the magnification ratios of widely separated images in the fold and cusp caustic lenses. This means that selected magnification ratios for different the emission regions of a lensed quasar should agree with each other, barring microlensing by stars. The source size dependence of the magnification ratio between the closest pair of images is more sensitive to substructure.Comment: 28 pages, 2 tables and 14 figures. Accepted to MNRA

A Bayesian Analogue of Gleason's Theorem

We introduce a novel notion of probability within quantum history theories and give a Gleasonesque proof for these assignments. This involves introducing a tentative novel axiom of probability. We also discuss how we are to interpret these generalised probabilities as partially ordered notions of preference and we introduce a tentative generalised notion of Shannon entropy. A Bayesian approach to probability theory is adopted throughout, thus the axioms we use will be minimal criteria of rationality rather than ad hoc mathematical axioms.Comment: 14 pages, v2: minor stylistic changes, v3: changes made in-line with to-be-published versio

Shapes of Stellar Systems and Dark Halos from Simulations of Galaxy Major Mergers

Using a sample of 89 snapshots from 58 hydrodynamic binary galaxy major merger simulations, we find that stellar remnants are mostly oblate while dark matter halos are mostly prolate or triaxial. The stellar minor axis and the halo major axis are almost always nearly perpendicular. This can be understood by considering the influence of angular momentum and dissipation during the merger. If binary mergers of spiral galaxies are responsible for the formation of elliptical galaxies or some subpopulation thereof, these galaxies can be expected to be oblate and inhabit their halos with the predicted shapes and orientations. These predictions are potentially relevant to observational studies of weak gravitational lensing, where one must stack many optically aligned galaxies in order to determine the shape of the resulting stacked mass distribution. The simple relationship between the dark and luminous matter presented here can be used to guide the stacking of galaxies to minimize the information lost.Comment: 4 pages, 5 figures. Minor changes to match published versio

Simulating multiple merger pathways to the central kinematics of early-type galaxies

Two-dimensional integral field surveys such as ATLAS^3D are producing rich observational data sets yielding insights into galaxy formation. These new kinematic observations have highlighted the need to understand the evolutionary mechanisms leading to a spectrum of fast-rotators and slow-rotators in early-type galaxies. We address the formation of slow and fast rotators through a series of controlled, comprehensive hydrodynamical simulations sampling idealized galaxy merger scenarios constructed from model spiral galaxies. Idealized and controlled simulations of this sort complement the more 'realistic' cosmological simulations by isolating and analyzing the effects of specific parameters, as we do in this paper. We recreate minor and major binary mergers, binary merger trees with multiple progenitors, and multiple sequential mergers. Within each of these categories of formation history, we correlate progenitor gas fraction, mass ratio, orbital pericenter, orbital ellipticity, and spin with remnant kinematic properties. We create kinematic profiles of these 95 simulations comparable to ATLAS^3D data. By constructing remnant profiles of the projected specific angular momentum (lambda_R = / , triaxiality, and measuring the incidences of kinematic twists and kinematically decoupled cores, we distinguish between varying formation scenarios. We find that binary mergers nearly always form fast rotators. Slow rotators can be formed from zero initial angular momentum configurations and gas-poor mergers, but are not as round as the ATLAS^3D galaxies. Remnants of binary merger trees are triaxial slow rotators. Sequential mergers form round slow rotators that most resemble the ATLAS^3D rotators.Comment: MNRAS, in press, 12 pages, 15 figure

Characterizing the early vocabulary profiles of preverbal and minimally verbal children with autism spectrum disorder

Abstract Children with autism spectrum disorder (ASD) often have significant language delays. But do they learn language differently than neurotypical toddlers? We compared the lexical skills of 64 preverbal and minimally verbal children with ASD, to 461 vocabulary-size-matched typically developing (TD) toddlers. We also examined social features of verb knowledge using a novel collection of social ratings. Children with ASD produced proportionally more verbs than TD toddlers. Children with ASD produced proportionally more action and food words, while TD toddlers produced proportionally more animal, people words, and animal sounds and sound effects. Children with ASD also produced “mommy” and “daddy” at lower rates. We discuss how these differences may reflect an association between lexical development and weaknesses in social communication. Lay abstract Although preverbal and minimally verbal (PV-MV) children with autism spectrum disorder (ASD) represent a significant portion of the ASD population, we have a limited understanding of and characterization of them. Though it is a given that their lexical profiles contain fewer words, it is important to determine whether: a) the words PV-MV children with ASD produce are similar to the first words typically developing (TD) children produce, or b) there are unique features of the limited words that PV-MV children with ASD produce. The current study compared the early word profiles of PV-MV children with ASD to vocabulary-matched TD toddlers. Children with ASD produced proportionally more verbs than TD toddlers. Also, children with ASD produced proportionally more action and food words, while TD toddlers produced proportionally more animal words, animal sounds and sound effects, and people words. Children with ASD also produced “mommy” and “daddy” at lower rates. Our findings identified several areas of overlap in early word learning; however, our findings also point to differences that may be connected to core weaknesses in social communication (i.e., people words). The findings highlight words and categories that could serve as useful targets for communication intervention with PV-MV children with ASD

Spatial and Geomorphological Analysis of Mammoth Localites in Western Oklahoma

Up until recently research on Paleoindian archaeology has focused on Clovis hunters and the demise of 35 genera of megafauna at the end of the Pleistocene. However, with increasing evidence of Pre-Clovis settlement many megafaunal sites older than Clovis are now under scrutiny. In this endeavor, geoarchaeology plays a key role, particularly with assessing the stratigraphic and geomorphological aspects of sites suspected of being Pre-Clovis. This Thesis looks at, and analyzes three mammoth sites in western Oklahoma; Helena, Grandfield, and Foss. These sites were analyzed on a geologic, geomorphologic, hydrologic, anthropologic, and soil pedogenic basis. Understanding of soils and their developmental processes can help give us a better understanding of the landscape and the environment in which they were formed. These sites were then compared to known sites Domebo, Hajny, and Burnham, all of which have had both an absolute date and an in depth soil analysis. The purpose of the comparison is to try and apply relative dating to a site when absolute dating is not obtainable, either due to funding, or technical issues that prevent obtaining a reliable date. It has been hypothesized that older mammoth finds should be found in higher terraces, while those of younger age, possibly with archaeological significance, should be found in lower terraces near flood plains. The three mammoth sites studied through this research are associated with lower terraces regardless of age. This example shows how complex the relationship is between site age and site distribution in the landscape. This research shows also how important is to evaluate soil development for estimating relative ages. This approach in turn is important for assessing late Pleistocene paleontological sites with potential association with Pre-Clovis human populations.Geograph

A Natural Plasmid Uniquely Encodes Two Biosynthetic Pathways Creating a Potent Anti-MRSA Antibiotic

Background Understanding how complex antibiotics are synthesised by their producer bacteria is essential for creation of new families of bioactive compounds. Thiomarinols, produced by marine bacteria belonging to the genus Pseudoalteromonas, are hybrids of two independently active species: the pseudomonic acid mixture, mupirocin, which is used clinically against MRSA, and the pyrrothine core of holomycin. Methodology/Principal Findings High throughput DNA sequencing of the complete genome of the producer bacterium revealed a novel 97 kb plasmid, pTML1, consisting almost entirely of two distinct gene clusters. Targeted gene knockouts confirmed the role of these clusters in biosynthesis of the two separate components, pseudomonic acid and the pyrrothine, and identified a putative amide synthetase that joins them together. Feeding mupirocin to a mutant unable to make the endogenous pseudomonic acid created a novel hybrid with the pyrrothine via “mutasynthesis” that allows inhibition of mupirocin-resistant isoleucyl-tRNA synthetase, the mupirocin target. A mutant defective in pyrrothine biosynthesis was also able to incorporate alternative amine substrates. Conclusions/Significance Plasmid pTML1 provides a paradigm for combining independent antibiotic biosynthetic pathways or using mutasynthesis to develop a new family of hybrid derivatives that may extend the effective use of mupirocin against MRSA

A diagnostic procedure for applying the social-ecological systems framework in diverse cases

The framework for analyzing sustainability of social-ecological systems (SES) framework of Elinor Ostrom is a multitier collection of concepts and variables that have proven to be relevant for understanding outcomes in diverse SES. The first tier of this framework includes the concepts resource system (RS) and resource units (RU), which are then further characterized through lower tier variables such as clarity of system boundaries and mobility. The long-term goal of framework development is to derive conclusions about which combinations of variables explain outcomes across diverse types of SES. This will only be possible if the concepts and variables of the framework can be made operational unambiguously for the different types of SES, which, however, remains a challenge. Reasons for this are that case studies examine other types of RS than those for which the framework has been developed or consider RS for which different actors obtain different kinds of RU. We explore these difficulties and relate them to antecedent work on common-pool resources and public goods. We propose a diagnostic procedure which resolves some of these difficulties by establishing a sequence of questions that facilitate the step-wise and unambiguous application of the SES framework to a given case. The questions relate to the actors benefiting from the SES, the collective goods involved in the generation of those benefits, and the action situations in which the collective goods are provided and appropriated. We illustrate the diagnostic procedure for four case studies in the context of irrigated agriculture in New Mexico, common property meadows in the Swiss Alps, recreational fishery in Germany, and energy regions in Austria. We conclude that the current SES framework has limitations when applied to complex, multiuse SES, because it does not sufficiently capture the actor interdependencies introduced through RS and RU characteristics and dynamics

Optical fiber sensors and signal processing for intelligent structure monitoring

Few mode optical fibers have been shown to produce predictable interference patterns when placed under strain. The use is described of a modal domain sensor in a vibration control experiment. An optical fiber is bonded along the length of a flexible beam. Output from the modal domain sensor is used to suppress vibrations induced in the beam. A distributed effect model for the modal domain sensor is developed. This model is combined with the beam and actuator dynamics to produce a system suitable for control design. Computer simulations predict open and closed loop dynamic responses. An experimental apparatus is described and experimental results are presented