Favorability as influenced by frequency of exposure to black and white college seniors

Zajonc\u27s (1968) mere exposure effect was replicated by measuring change in favorability toward black and white college seniors. Following a preexperimental selection of the five most neutral slides for each race by sex category, 40 experimental and 40 control group subjects rated ten black and ten white slides on a pre- and a posttest. The experimental treatment consisted of ten exposure sequences of the 20 slides, whereas the control group performed an inverted alphabet printing task. A repeated measures analysis of variance, conducted on the subjects, favorability ratings for both the pre- and the posttests, supported the hypothesis that a significant attitudinal enhancement will be obtained by white subjects exposed to a slide sequence of blacks and whites. In addition, an analysis of variance on the pretest ratings revealed several significant interactions. An absence of differential demand characteristics for both treatments was indicated by a postexperimental inquiry

Pseudomonas as Causative Agents of Fluorescence in Anguispira kochi (Pfeiffer) Mucus

The mucus from land snail specimens of Anguispira kochi collected from Coles and Edgar counties, Illinois, emits a blue fluorescence when exposed to ultra-violet light. Pseudomonas, a genus of bacteria which produces fluorescent pigments, has been isolated from the mucus of these snails. The object of the study was to compare the fluorescence of the mucus from individuals of A. kochi with the fluorescence of the pigments produced on a synthetic medium by pseudomonads isolated from the mucus of these snails. An effort was made to establish that Pseudomonas is the causative agent of fluorescence in the mucus of A. kochi by comparing the physical character and the spectrophotometric records of the two substances. The pigment produced by these bacteria and the fluorescent substance in the mucus were identical in regard to dialysis, withstanding high temperatures, and solubility in the 18 solvents used. Differences in fluorescent color were explained experimentally. The absorption curve of the bacterial pigment (maxima at about 265 and 400 nm) was similar to that of the A. kochi mucus (maxima at about 265 and 385 nm). The results from the study indicate that Pseudomonas is the causative agent of the fluorescence in the mucus of A. kochi. It is plausible that the mucus of these snails contains the appropriate nutritional requirements which allow the bacterial to produce diffusible pigments that fluoresce under ultra-violet light

Neutron-Scattering Studies on Chiral Multiferroics

Magnetoelectric multiferroics exhibit a strong correlation of magnetism and ferroelectricity. Among the multiferroics with a strong magnetoelectric effect many have a chiral antiferromagnetic structure. In these materials it is possible to control the electric polarisation by an applied magnetic field and, inversely, to manipulate the antiferromagnetic domains by an applied electric field. The observation of antiferromagnetic domains requires a microscopic method, which neutron scattering with polarised neutrons is particularly suitable for. This thesis reports on neutron and X-ray measurements on several (chiral) antiferromagnetic multiferroics. Special attention is devoted to the switching of (chiral) antiferromagnetic domains. Neutron-diffraction data on the magnetic structures of the pyroxenes NaFeSi2O6 and LiFeSi2O6 are presented. LiFeSi2O6 undergoes a single magnetic phase transition below 18 K into a canted antiferromagnetic structure with the magnetic space group P21/c. NaFeSi2O6 undergoes two magnetic phase transitions. Both phases are incommensurate with propagation vector k = (0, 0.77, 0). Below 8 K a transverse spin-density wave with moments in the ac plane sets in and below 6 K a helix with moments remaining in the ac plane evolves. By the use of spherical neutron polarisation analysis it is demonstrated that antiferromagnetic domains in LiFeSi2O6 can be reversed by a combination of electric and magnetic fields. The magnetic structure of LiFeSi2O6 gives rise to a toroidal moment. Therefore, the results are discussed in the context of manipulating toroidal domains. Furthermore, the magnon dispersion and the spin density of LiFeSi2O6 are presented. In many chiral multiferroics it is possible to reverse the chirality of the magnetic structure by an applied electric field providing the opportunity of driving hysteresis loops (chiral ratio vs. electric field). Results of the time dependence of this switching process in MnWO4 studied by stroboscopic techniques for polarised neutron scattering reveal a surprisingly slow relaxation process in the time scale of 2 ms to 30 ms and a strong temperature dependence. Furthermore, static hysteresis loops recorded on TbMnO3 and DyMnO3 are reported. In TbMnO3, the coercive field increases linearly with decreasing temperature. In DyMnO3, driving of hysteresis loops is possible only close to the ferroelectric phase transition. Further investigations on TbMnO3 show that the quasi-lock-in of the magnetic propagation vector takes place at temperatures slightly above the development of the chiral magnetic structure. In addition, the propagation vector increases linearly with isotropic pressure. X-ray diffraction on single crystals of TbMnO3 and YMn2O5 reveals that the deviation of the ions from their centrosymmetric positions in the ferroelectric phase is beyond the resolution limit of the performed diffraction experiments

Medical Image Registration Using Deep Neural Networks

Registration is a fundamental problem in medical image analysis wherein images are transformed spatially to align corresponding anatomical structures in each image. Recently, the development of learning-based methods, which exploit deep neural networks and can outperform classical iterative methods, has received considerable interest from the research community. This interest is due in part to the substantially reduced computational requirements that learning-based methods have during inference, which makes them particularly well-suited to real-time registration applications. Despite these successes, learning-based methods can perform poorly when applied to images from different modalities where intensity characteristics can vary greatly, such as in magnetic resonance and ultrasound imaging. Moreover, registration performance is often demonstrated on well-curated datasets, closely matching the distribution of the training data. This makes it difficult to determine whether demonstrated performance accurately represents the generalization and robustness required for clinical use. This thesis presents learning-based methods which address the aforementioned difficulties by utilizing intuitive point-set-based representations, user interaction and meta-learning-based training strategies. Primarily, this is demonstrated with a focus on the non-rigid registration of 3D magnetic resonance imaging to sparse 2D transrectal ultrasound images to assist in the delivery of targeted prostate biopsies. While conventional systematic prostate biopsy methods can require many samples to be taken to confidently produce a diagnosis, tumor-targeted approaches have shown improved patient, diagnostic, and disease management outcomes with fewer samples. However, the available intraoperative transrectal ultrasound imaging alone is insufficient for accurate targeted guidance. As such, this exemplar application is used to illustrate the effectiveness of sparse, interactively-acquired ultrasound imaging for real-time, interventional registration. The presented methods are found to improve registration accuracy, relative to state-of-the-art, with substantially lower computation time and require a fraction of the data at inference. As a result, these methods are particularly attractive given their potential for real-time registration in interventional applications

A tip-based source of femtosecond electron pulses at 30keV

We present a nano-scale photoelectron source, optimized towards ultrashort pulse durations and well-suited for time-resolved diffraction experiments. A tungsten tip, mounted in a suppressor-extractor electrode configuration, allows the generation of 30 keV electron pulses with an estimated pulse duration of 37 fs at the gun exit. We infer the pulse duration from particle tracking simulations, which are in excellent agreement with experimental measurements of the electron-optical properties of the source. We furthermore demonstrate femtosecond laser-triggered operation. Besides the short electron pulse duration, a tip-based source is expected to feature a large transverse coherence as well as a nanometric emittance.Comment: 4 pages, 3 figure

Reconsidering Prenatal Hormonal Influences on Human Sexual Orientation: Lessons from Animal Research.

peer reviewe

Portugal's Quota-Parity Law: An Analysis of its Adoption

In August 2006, Portugal approved a new quota law, called the parity law. According to this, all candidate lists presented for local, parliamentary, and European elections must guarantee a minimum representation of 33 per cent for each sex. This article analyses the proximate causes that led to the adoption of gender quotas by the Portuguese Parliament. The simple answer is that the law’s passage was a direct consequence of a draft piece of legislation presented by the Socialist Party (PS), which enjoyed a majority. However, the reasons that led the PS to push through a quota law remain unclear. Using open-ended interviews with key women deputies from all the main Portuguese political parties, and national public opinion data, among other sources, the role of four actors/factors that were involved in the law’s adoption are critically examined: notably, civil society actors, state actors, international and transnational actors, and the Portuguese political context