Contact Whiskers for Millimeter Wave Diodes

Several techniques are investigated for making short conical tips on wires (whiskers) used for contacting millimeter-wave Schottky diodes. One procedure, using a phosphoric and chromic acid etching solution (PCE), is found to give good results on 12 microns phosphor-bronze wires. Full cone angles of 60 degrees-80 degrees are consistently obtained, compared with the 15 degrees-20 degrees angles obtained with the widely used sodium hydroxide etch. Methods are also described for cleaning, increasing the tip diameter (i.e. blunting), gold plating, and testing the contact resistance of the whiskers. The effects of the whisker tip shape on the electrical resistance, inductance, and capacitance of the whiskers are studied, and examples given for typical sets of parameters

Optical characterization of semiconductor saturable absorbers

Semiconductor saturable absorber mirror (SESAM) devices have become a key component of ultrafast passive mode-locked laser sources. Here we describe in more detail how the key SESAM parameters such as saturation fluence, modulation depth, and nonsaturable losses are measured with a high accuracy. These parameters need to be known and controlled to obtain stable pulse generation for a given laser. A high-precision, wide dynamic range setup is required to measure this nonlinear reflectivity of saturable absorbers. The challenge to measure a low modulation depth and key measures necessary to obtain an accurate calibration are described in detail. The model function for the nonlinear reflectivity is based on a simple two-level travelling wave system. We include spatial beam profiles, nonsaturable losses and higher-order absorption, such as two-photon absorption and other induced absorption. Guidelines to extract the key parameters from the measured data are give

The Anglo-Norman Bible's Book of Judges: A Critical Edition (BL Royal 1 C III)

A silver-tongued assassin, a motherly prophetess, a consecrated strongman unable to resist the charms of foreign women: the Anglo-Norman Bible’s Book of Judges features a roll-call of unlikely heroes. At the book’s core is a cycle of saviour stories. Twelve times the Israelites embrace foreign gods, succumb to neighbouring enemies, repent and are delivered by a ‘judge’. As Israel itself descends into ever-greater religious, moral and political decay, the narrative pattern also unravels. The book ends bleakly, with stories of rape, murder and civil war. The stage is set for a king. Gideon-a doubting Thomas who repeatedly ‘tests’ God-and Samson-lion-killer and lover of Delilah-were firm medieval favourites. Their tales and those of other flawed judges inspired heroic deeds on the battlefield and provided lessons on how to behave (and indeed how not to behave). With its remarkable heroines, moreover-from cut-throat Jael, who wields a tent-peg to devastating effect, to Jephthah’s dignified daughter, sacrificed because of her father’s rash vow-this is a book that prompted much reflection in the Middle Ages on the place of women in society. The Anglo-Norman Bible’s Book of Judges survives in two fourteenth-century manuscripts: British Library Royal MS 1 C III (L), noted for its multilingual glosses, and the richly illustrated Paris, Bibliothèque nationale de France, fonds français 1 (P). The critical text, based on L, has been prepared by Pitts. An introduction and notes by Grange aim to elucidate and interpret the Anglo-Norman Bible’s Book of Judges for the modern reader

Climate change science: The literacy of Geography teachers in the Western Cape Province, South Africa

One of the universal responses to tackling global climate change is teaching climate change concepts at all levels of formal education. This response requires, among other things, teachers who are fully literate about climate change science, so that they can explain the concepts underlying the causes, impacts and solutions of climate change as accurately as possible to learners. The main intention of this study was to understand high school Geography teachers’ levels of knowledge about climate change science. A 15-item, criterion-referenced, multiple-choice Climate Change Literacy Questionnaire with a reliability coefficient of 0.74 using the Guttman’s spit-half test was administered to 194 high school Geography teachers in the Western Cape Province of South Africa. Data collected were analysed with the Pearson’s Chi-square test and One-Way Analysis of Variance (ANOVA). The results showed that the majority of the participants demonstrated significantly high literacy levels in climate science, with their literacy levels higher in climate processes and causes of climate change than climate change impacts and solutions. Misconceptions were found in all three categories of climate change science as represented in the survey instrument. These findings suggest that teacher educators and policymakers should improve professional development programmes and support interventions in teacher knowledge and understanding of climate change concepts, so as to enhance climate change education in schools.Keywords: climate change education; climate change misconceptions; climate change science literacy; Geography teachers; survey researc

A critical analysis of alcohol hangover research methodology for surveys or studies of effects on cognition

Rationale: Alcohol hangover may be defined as an adverse effect of heavy alcohol consumption present after sufficient time has elapsed for the alcohol to have been eliminated from the blood. Understanding how hangover may impair performance is important for public safety; yet, there is relatively little hangover research. This paper outlines good practice for future studies. Objectives: This paper presents a critical analysis of hangover methodology for surveys or studies of effects on cognition with human subjects and provides suggestions for optimum research practice for laboratory-based and naturalistic alcohol hangover studies. Results: Four hangover symptom scales have been developed and subjected to psychometric testing. For retrospective assessment, we recommend the Hangover Symptoms Scale (HSS) or the Alcohol Hangover Severity Scale (AHSS). For concurrent assessment of hangover symptoms, we recommend either the Acute Hangover Scale (AHS), the five-item version of the HSS, or the AHSS. In research aiming to assess the cognitive effects of alcohol hangover, we suggest focusing on the cognitive domains of attention, memory and executive function, and we specify a number of tests within these cognitive domains that are likely to be sensitive to any decrements due to hangover. Finally, we argue that naturalistic studies should assess biological markers to improve the accuracy of estimates of alcohol consumption. Specifically, we recommend the assessment of ethyl glucuronide (EtG) for this purpose. Conclusions: Recommendations are made with respect to assessing hangover symptoms, cognitive effects of hangover and biological markers of alcohol consumption

The effect of alcohol hangover on choice response time

The effect of alcohol hangover on cognitive processing has received little attention. We explored the effect of alcohol hangover on choice response time (RT), a dominant dependent variable (DV) in cognitive research. Prior research of the effect of hangover on RT has produced mixed findings; all studies reviewed relied exclusively on estimates of central tendency (e.g. mean RT), which has limited information value. Here we present novel analytical methods by going beyond mean RT analysis. Specifically, we examined performance in hangover conditions (n=31) across the whole RT distribution by fitting ex-Gaussian models to participant data, providing a formal description of the RT distribution. This analysis showed detriments to performance under hangover conditions at the slower end of the RT distribution and increased RT variance under hangover conditions. We also fitted an explicit mathematical process model of choice RT – the diffusion model – which estimates parameters reflecting psychologically-meaningful processes underlying choice RT. This analysis showed that hangover reduced information processing efficiency during response selection, and increased response caution; changes in these parameters reflect hangover affecting core decisional-components of RT performance. The implications of the data as well as the methods used for hangover research are discussed

Estimating turbulent velocities in the elliptical galaxies NGC 5044 and NGC 5813

The interstellar and intra-cluster medium in giant elliptical galaxies and clusters of galaxies is often assumed to be in hydrostatic equilibrium. Numerical simulations, however, show that about 5-30% of the pressure in a cluster is provided by turbulence induced by, for example, the central AGN and merger activity. We aim to put constraints on the turbulent velocities and turbulent pressure in the ICM of the giant elliptical galaxies NGC 5044 and NGC 5813 using XMM-Newton RGS observations. The magnitude of the turbulence is estimated using the Fe XVII lines at 15.01 A, 17.05 A, and 17.10 A in the RGS spectra. At low turbulent velocities, the gas becomes optically thick in the 15.01 A line due to resonant scattering, while the 17 A lines remain optically thin. By comparing the (I(17.05)+I(17.10))/I(15.01) line ratio from RGS with simulated line ratios for different Mach numbers, the level of turbulence is constrained. The measurement is limited by systematic uncertainties in the atomic data, which are at the 20-30% level. We find that the line ratio in NGC 5813 is significantly higher than in NGC 5044. This difference can be explained by a higher level of turbulence in NGC 5044. The high turbulent velocities and the fraction of the turbulent pressure support of >40% in NGC 5044, assuming isotropic turbulence, confirm that it is a highly disturbed system, probably due to an off-axis merger. The turbulent pressure support in NGC 5813 is more modest at 15-45%. The (I(17.05)+I(17.10))/I(15.01) line ratio in an optically thin plasma, calculated using AtomDB v2.0.1, is 2 sigma above the ratio measured in NGC 5044, which cannot be explained by resonant scattering. This shows that the discrepancies between theoretical, laboratory, and astrophysical data on Fe XVII lines need to be reduced to improve the accuracy of the determination of turbulent velocities using resonant scattering.Comment: 11 pages, 5 figures, accepted for publication in A&

Interpolation, dés-interpolation, ré-interpolation. Le Tristan en prose et l'Agravain

Vers la fin de la séquence d’épisodes repris à l’Agravain qui se trouvent interpolés dans certains manuscrits du Tristan en prose, les chevaliers partis en quête de Lancelot retournent à la cour du roi Arthur à Camaalot. Ils rentrent non seulement avec leur héros, mais encore avec leurs histoires : une fois tous confortablement installés – toute armure dûment enlevée – le roi invite ses chevaliers à raconter l’un après l’autre leurs aventures. En affirmant par la suite que ces témoignages oraux furent mis par écrit à la demande du roi, le narrateur nous laisse croire que les épisodes que nous venons de lire (ou d’entendre lire) dérivent directement des chevaliers eux-mêmes2. Cette explication de la genèse de l’interpolation de l’Agravain dans le Tristan nie et reconnaît simultanément les lourdes dettes du remanieur envers l’auteur (ou bien les auteurs) du Lancelot en prose : cela les nie dans la mesure où les chevaliers deviennent autobiographes (le roi Arthur, de son côté, dirigera le travail de rédaction) et les reconnaît dans la mesure où ce motif du chevalierautobiographe s’emploie souvent dans le Lancelot lui-même3. L’histoire que nous proposons de découvrir ici est une version alternative de la genèse de l’interpolation de l’Agravain dans le Tristan en prose. La question des rapports entre le Tristan et la dernière branche du Lancelot propre, traditionnellement appelée l’Agravain, a reçu moins d’attention de la part des spécialistes que les relations sans doute plus complexes entre le Tristan et la Quête, voire entre le Tristan et Guiron le Courtois. Elle mérite pourtant d’être abordée puisqu’elle remet nécessairement en cause le classement admis des « versions » des manuscrits du Tristan