Ionizing radiation fluctuations and large-scale structure in the Lyman-alpha forest

We investigate the large-scale inhomogeneities of the hydrogen ionizing radiation field in the Universe at redshift z=3. Using a raytracing algorithm, we simulate a model in which quasars are the dominant sources of radiation. We make use of large scale N-body simulations of a LambdaCDM universe, and include such effects as finite quasar lifetimes and output on the lightcone, which affects the shape of quasar light echoes. We create Lya forest spectra that would be generated in the presence of such a fluctuating radiation field, finding that the power spectrum of the Lya forest can be suppressed by as much as 15 % for modes with k=0.05-1 Mpc/h. This relatively small effect may have consequences for high precision measurements of the Lya power spectrum on larger scales than have yet been published. We also investigate another radiation field probe, the cross-correlation of quasar positions and the Lya forest. For both quasar lifetimes which we simulate (10^7 yr and 10^8 yr), we expect to see a strong decrease in the Lya absorption close to other quasars (the ``foreground'' proximity effect). We then use data from the Sloan Digital Sky Survey First Data Release to make an observational determination of this statistic. We find no sign of our predicted lack of absorption, but instead increased absorption close to quasars. If the bursts of radiation from quasars last on average < 10^6 yr, then we would not expect to be able to see the foreground effect. However, the strength of the absorption itself seems to be indicative of rare objects, and hence much longer total times of emission per quasar. Variability of quasars in bursts with timescales > 10^4yr and < 10^6 yr could reconcile these two facts.Comment: Submitted to ApJ, 21 pages, 17 postscript figures, emulateapj.st

Human Perception-Inspired Grain Segmentation Refinement Using Conditional Random Fields

Accurate segmentation of interconnected line networks, such as grain boundaries in polycrystalline material microstructures, poses a significant challenge due to the fragmented masks produced by conventional computer vision algorithms, including convolutional neural networks. These algorithms struggle with thin masks, often necessitating intricate post-processing for effective contour closure and continuity. Addressing this issue, this paper introduces a fast, high-fidelity post-processing technique, leveraging domain knowledge about grain boundary connectivity and employing conditional random fields and perceptual grouping rules. This approach significantly enhances segmentation mask accuracy, achieving a 79% segment identification accuracy in validation with a U-Net model on electron microscopy images of a polycrystalline oxide. Additionally, a novel grain alignment metric is introduced, showing a 51% improvement in grain alignment, providing a more detailed assessment of segmentation performance for complex microstructures. This method not only enables rapid and accurate segmentation but also facilitates an unprecedented level of data analysis, significantly improving the statistical representation of grain boundary networks, making it suitable for a range of disciplines where precise segmentation of interconnected line networks is essential

Validity and repeatability of a simple index derived from the short physical activity questionnaire used in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Original article can be found at: http://journals.cambridge.org/action/displayJournal?jid=PHN Copyright The Authors. DOI: 10.1079/PHN2002439Peer reviewe

Quantum teleportation and entanglement swapping with linear optics logic gates

We report on the usage of a linear optics phase gate for distinguishing all four Bell states simultaneously in a quantum teleportation and entanglement swapping protocol. This is demonstrated by full state tomography of the one and two qubit output states of the two protocols, yielding average state fidelities of about 0.83 and 0.77, respectively. In addition, the performance of the teleportation channel is characterised by quantum process tomography. The non classical properties of the entanglement swapping output states are further confirmed by the violation of a CHSH-type Bell inequality of 2.14 on average.Comment: 11 pages, 3 figure

Rethinking globalised resistance : feminist activism and critical theorising in international relations

This article argues that a feminist approach to the 'politics of resistance' offers a number of important empirical insights which, in turn, open up lines of theoretical inquiry which critical theorists in IR would do well to explore. Concretely, we draw on our ongoing research into feminist 'anti-globalisation' activism to rethink the nature of the subject of the politics of resistance, the conditions under which resistance emerges and how resistance is enacted and expressed. We begin by discussing the relationship of feminism to critical IR theory as a way of situating and explaining the focus and approach of our research project. We then summarise our key empirical arguments regarding the emergence, structure, beliefs, identities and practices of feminist 'anti-globalisation' activism before exploring the implications of these for a renewed critical theoretical agenda in IR

Effects of on-farm hatching on short term stress indicators, weight gain, and cognitive ability in layer chicks

Layer chicks are usually transported early in life, experiencing immediate post-hatch food and water deprivation and various transport-related stressors with potentially negative long-term consequences for learning, cognition and welfare. In contrast, as chicks are only temporarily exposed to these stressors, the experienced stress could be sub-chronic which may improve cognitive flexibility. The aim of this exploratory study was therefore to investigate the acute and long-term effects of on-farm hatching (OFH) compared to conventional hatching. Dekalb White layer chicks were subjected to either OFH (n = 47) with ad libitum access to feed and water or temporary post-hatch resource deprivation and eight hour transport (RDT; n = 42). Physical and behavioural measures were collected to examine short-term effects of the treatment procedures. To determine longer term effects, treatment differences in learning and cognitive flexibility were assessed in a Y-maze using several paradigms (reversal, attentional-shift, extinction) between 4 and 12 weeks of age (WOA). Compared to OFH chicks, RDT had: greater corticosterone levels after transport (F1,19 =8.15, p = 0.01, RDT (16.24 ± 1.20 ng/mL) vs. OFH (8.13 ± 1.20 ng/mL) and post-recovery (F1,19 =4.93, p = 0.04; RDT (11.69 ± 1.35 ng/mL) vs. OFH (5.31 ± 1.37)), and lower body mass after resource deprivation and transport (F2258 =9.7, p < 0.001, RDT (33.14 ± 0.33 g) vs. OFH (37.62 ± 0.28 g)). Performance of activity behaviours (foraging, drinking, resting, wing-assisted running) after transport exhibited treatment by time interactions. Additionally, a tendency for OFH being heavier than RDT chicks was observed up to 11 WOA. The majority of birds learned the initial association in the Y-maze between a reward and location (77% of n = 19 RDT and n = 29 OFH chicks) or light stimulus (91% of n = 12 RDT and n = 11 OFH chicks). Subsequently, a number of chicks reached the learning criterion in the location reversal (24% of n = 13 RDT and n = 24 OFH chicks) and the light-to-location attentional-shift (47% of n = 11 RDT and n = 10 OFH chicks), and most of these chicks succeeded in the following extinction paradigm (80% of n = 3 RDT and n = 7 OFH chicks). No treatment effects were detected in any phase of cognitive testing. In conclusion, treatment affected behaviour and health parameters suggesting RDT animals were recovering from resource deprivation and transport. Continued treatment differences in body mass throughout rearing demonstrated long term effects as well although no effects on initial learning and cognitive flexibility were identified. Future work is needed to determine what mechanisms are responsible for the observed health and behavioural differences

Zonation of Central U. S. Earthquake Sources

A variety of analyses are utilized in developing potential earthquake ground shaking at a specific location. Geological procedures for estimating causes of earthquakes are fundamental to the prediction of ground motions. Evaluations of geologic factors compliment mathematical assessments of seismological data. Earthquake potential in the Central United States is predicted using the concept of seismic source zones due to the difficulty of determining active faults. Resolution of these geographic source zones is dependent upon knowledge of historic seismicity, pertinent geologic features, and causative tectonics. Regardless of the method used to delineate source zones, these zones must be geologically and seismologically unique. Statistical testing of historic earthquake catalogues is required for reduction of the data base. The resolution of zones is an iterative process of bounding the zones and determining recurrence rates. Earthquake potential and risk assessment should be understood by the owner and the designer of a facility