Evidence for Environmental Changes in the Submillimeter Dust Opacity

The submillimeter opacity of dust in the diffuse interstellar medium (ISM) in the Galactic plane has been quantified using a pixel-by-pixel correlation of images of continuum emission with a proxy for column density. We used multi-wavelength continuum data: three Balloon-borne Large Aperture Submillimeter Telescope bands at 250, 350, and 500 μm and one IRAS band at 100 μm. The proxy is the near-infrared color excess, E(J – K_s), obtained from the Two Micron All Sky Survey. Based on observations of stars, we show how well this color excess is correlated with the total hydrogen column density for regions of moderate extinction. The ratio of emission to column density, the emissivity, is then known from the correlations, as a function of frequency. The spectral distribution of this emissivity can be fit by a modified blackbody, whence the characteristic dust temperature T and the desired opacity σ_e(1200) at 1200 GHz or 250 μm can be obtained. We have analyzed 14 regions near the Galactic plane toward the Vela molecular cloud, mostly selected to avoid regions of high column density (N_H > 10^(22) cm^(–2)) and small enough to ensure a uniform dust temperature. We find σ_e(1200) is typically (2-4) × 10^(–25) cm^2 H^(–1) and thus about 2-4 times larger than the average value in the local high Galactic latitude diffuse atomic ISM. This is strong evidence for grain evolution. There is a range in total power per H nucleon absorbed (and re-radiated) by the dust, reflecting changes in the strength of the interstellar radiation field and/or the dust absorption opacity. These changes in emission opacity and power affect the equilibrium T, which is typically 15 K, colder than at high latitudes. Our analysis extends, to higher opacity and lower temperature, the trend of increasing σ_e(1200) with decreasing T that was found at high latitudes. The recognition of changes in the emission opacity raises a cautionary flag because all column densities deduced from dust emission maps, and the masses of compact structures within them, depend inversely on the value adopted

A Recursive Algorithm for Computing Inferences in Imprecise Markov Chains

We present an algorithm that can efficiently compute a broad class of inferences for discrete-time imprecise Markov chains, a generalised type of Markov chains that allows one to take into account partially specified probabilities and other types of model uncertainty. The class of inferences that we consider contains, as special cases, tight lower and upper bounds on expected hitting times, on hitting probabilities and on expectations of functions that are a sum or product of simpler ones. Our algorithm exploits the specific structure that is inherent in all these inferences: they admit a general recursive decomposition. This allows us to achieve a computational complexity that scales linearly in the number of time points on which the inference depends, instead of the exponential scaling that is typical for a naive approach

Harmonization of welfare standards for the protection of pigs with the EU-rules: the case of Croatia

Three quarters of Croatian pigs are produced in small production units (1-5 sows) and on family farms with mixed farming activities. Only few farms have specialized production units with up-to-date technologies and comply with EU standards. The future competitiveness of Croatian pig production is therefore questionable unless production systems are changing. Modernisation will most probably result in the expansion and intensification of larger farms and the termination of a great number of small farms. The aim of this study was to investigate how the welfare of pigs on Croatian farms would be affected by modernisation. Seventeen Croatian pig farmers were interviewed to describe the different pig production systems, while the welfare of pigs was assessed using resource-based and animal-based welfare indicators. Three production systems were distinguished: part-time family farms (PFF), full-time family farms (FFF) and farm enterprises (FE). Resources-based welfare indicators were investigated in 17 pens located on seven PFF, 25 pens distributed across six FFF and seven pens were visited at two FE. Animal-based welfare indicators were assessed on 21 pigs at PFF, 90 pigs at FFF and 18 pigs at FE. The study demonstrated that different production systems have different welfare problems. Based on resource-based indicators pig welfare was better ensured on FE, but based on animal-based indicators there was no clear difference in welfare between the three production systems. Based on these findings is it unlikely that the modernisation of current production systems in Croatia will significantly improve pig welfare. From a welfare point of view, neither the enlargement nor the termination of pig farms can be supported. However, the number of farms involved in this study was too small to allow for generalisation. The case-study does, however, point at the importance of further studies into the specific welfare problems of each of the production-systems and their different solutions. These studies should be of larger scale in order to get a representative picture of pig welfare in Croatia, and its assurance within the process of modernisation

The Phase Diagram and Spectrum of Gauge-Fixed Abelian Lattice Gauge Theory

We consider a lattice discretization of a covariantly gauge-fixed abelian gauge theory. The gauge fixing is part of the action defining the theory, and we study the phase diagram in detail. As there is no BRST symmetry on the lattice, counterterms are needed, and we construct those explicitly. We show that the proper adjustment of these counterterms drives the theory to a new type of phase transition, at which we recover a continuum theory of (free) photons. We present both numerical and (one-loop) perturbative results, and show that they are in good agreement near this phase transition. Since perturbation theory plays an important role, it is important to choose a discretization of the gauge-fixing action such that lattice perturbation theory is valid. Indeed, we find numerical evidence that lattice actions not satisfying this requirement do not lead to the desired continuum limit. While we do not consider fermions here, we argue that our results, in combination with previous work, provide very strong evidence that this new phase transition can be used to define abelian lattice chiral gauge theories.Comment: 42 pages, 30 figure

Humanitarian Aid and the Struggle for Peace and Justice: Organizational Innovation after a Blind Date

Humanitarian organizations working in developing countries have gone through a transformation since the thaw of the Cold War. Their increased programming to promote justice and peace has resulted in disparate partnership configurations. Illustrative examples of these configurations show how organizational deficiencies and challenges have spawned innovation. These innovations provide insight about how similar organizations might usefully be engaged in the struggle to promote greater justice and peace in areas of the world suffering from violent conflict

Rapa Nui: The Easter Island Legend on Film (Review)

RAPA NUl: THE EASTER ISLAND LEGEND ON FILM by Kevin Reynolds and Tim Rose Price, Photographs by Ben Glass. A Newmarket Pictorial Moviebook, Newmarket Press, New York 1994. 160 pp., ill, (Colorplates)</p

A low noise, high thermal stability, 0.1 K test facility for the Planck HFI bolometers

We are developing a facility which will be used to characterize the bolometric detectors for Planck, an ESA mission to investigate the Cosmic Microwave Background. The bolometers operate at 0.1 K, employing neutron-transmutation doped (NTD) Ge thermistors with resistances of several megohms to achieve NEPs~1×10^(–17) W Hz^(–1/2). Characterization of the intrinsic noise of the bolometers at frequencies as low as 0.010 Hz dictates a test apparatus thermal stability of 40 nK Hz^(–1/2) to that frequency. This temperature stability is achieved via a multi-stage isolation and control geometry with high resolution thermometry implemented with NTD Ge thermistors, JFET source followers, and dedicated lock-in amplifiers. The test facility accommodates 24 channels of differential signal readout, for measurement of bolometer V(I) characteristics and intrinsic noise. The test facility also provides for modulated radiation in the submillimeter band incident on the bolometers, for measurement of the optical speed-of-response; this illumination can be reduced below detectable limits without interrupting cryogenic operation. A commercial Oxford Instruments dilution refrigerator provides the cryogenic environment for the test facility

Archaeological investigations at Anakena, Easter island (Review)

Archaeological investigations at Anakena, Easter island Edited by Arne Skjolsvold. 1994. The Kon-Tiki Museum, Occasional Papers. Vol. 3, Oslo. Softcover, 216 pages, maps, black and white line drawings and sketches. photographs. No index. In English. Price: US $29 plus freight. Kon Tiki Museum, Bygdaynesveien 36, N-0286, Oslo, Norway</p

Pre-service Elementary Teachers\u27 Use of Spatial Diagrams: Investigations of Unbounded Shearing on Solid Figures

Mithala and Balacheff (2019) describe three difficulties with two-dimensional representations of three-dimensional geometrical objects: “it is no longer possible to confuse the representation with the object itself,” visually observed relationships can be misleading, and analysis of the representation requires the use of lower-dimensional theoretical properties. Despite these difficulties, students are routinely expected to learn about three-dimensional figures through interacting with two-dimensional inscriptions. Three-dimensional alternatives include diagrams realized through various spatial inscriptions (e.g., Dimmel & Bock, 2019; Gecu-Parmaksiz & Delialioglu, 2019; Lai, McMahan, Kitagawa & Connolly, 2016; Ng and Sinclair, 2018). Such diagrams are three-dimensional in the sense that they occupy real (e.g., 3D pen drawings) or rendered (e.g., Virtual Reality/Augmented Reality environments) spaces as opposed to being inscribed or displayed on surfaces. Digital spatial diagrams can be grasped and transformed by gestures (e.g., stretching, pinching, spinning), even though they can’t be physically touched (Dimmel & Bock, 2019). Spatial diagrams make it possible to use natural movements of one’s head or body to explore figures from new perspectives (e.g., one can step inside a diagram), as they natively share the three-dimensional space. In this study I ask: How do learners use perspective to make arguments while exploring spatial diagrams? In particular, how do participants use perspectives outside and within geometric figures to make arguments while exploring spatial diagrams? To investigate this question, I designed a large-scale spatial diagram of a pyramid whose apex and base were confined to parallel planes. The diagram was rendered in an apparently unbounded spatial canvas that was accessible via a head-mounted display. The pyramid was roughly 1 meter in height and the parallel planes appeared to extend indefinitely when viewed from within the immersive environment. I created this diagram as a mathematical context for exploring shearing, a “continuous and temporal” measure-preserving transformation of plane and solid figures (Ng & Sinclair, 2015, p.85). I report on pairs of pre-service elementary teachers’ arguments about shearing of pyramids, using Pedemonte and Balacheff’s (2016) ck¢-enriched Toulmin model of argument. Shearing is a mathematical context that is likely novel to pre-service elementary teachers and provides an opportunity to connect transformations of plane and solid figures. Participants used perspectives outside and within the diagram to make arguments about the shearing of pyramids that would not be practicable with rigid three-dimensional models or dynamic two-dimensional representations. The results of this study suggest that the dimensionality of the spatial diagrams supported participants’ arguments about three-dimensional figures without mediation through projection or lower-dimensional components. The findings of this study offer a case that challenges the constraints of two-dimensional representations of three-dimensional figures, while maintaining theoretical constraints in a spatiographically accurate representation