Analysis of 3D-printed metal for rapid-prototyped reflective terahertz optics

We explore the potential of 3D metal printing to realize complex conductive terahertz devices. Factors impacting performance such as printing resolution, surface roughness, oxidation, and material loss are investigated via analytical, numerical, and experimental approaches. The high degree of control offered by a 3D-printed topology is exploited to realize a zone plate operating at 530 GHz. Reflection efficiency at this frequency is found to be over 90%. The high-performance of this preliminary device suggest that 3D metal printing can play a strong role in guided-wave and general beam control devices in the terahertz range.Comment: 13 pages, 6 figures, submitted to Optics Expres

Alpha1 -adrenergic stimulation selectively enhances endothelium-mediated vasodilation in rat cremaster arteries.

We have systematically investigated how vascular smooth muscle α1 -adrenoceptor activation impacts endothelium-mediated vasodilation in isolated, myogenically active, rat cremaster muscle 1A arteries. Cannulated cremaster arteries were pressurized intraluminally to 70 mmHg to induce myogenic tone, and exposed to vasoactive agents via bath superfusion at 34°C. Smooth muscle membrane potential was measured via sharp microelectrode recordings in pressurized, myogenic arteries. The α1 -adrenergic agonist phenylephrine (25-100 nmol/L) produced further constriction of myogenic arteries, but did not alter the vasorelaxant responses to acetylcholine (0.3 μmol/L), SKA-31 (an activator of endothelial Ca2+ -dependent K+ channels) (3 μmol/L) or sodium nitroprusside (10 μmol/L). Exposure to 0.25-1 μmol/L phenylephrine or 1 μmol/L norepinephrine generated more robust constrictions, and also enhanced the vasodilations evoked by acetylcholine and SKA-31, but not by sodium nitroprusside. In contrast, the thromboxane receptor agonist U46619 (250 nmol/L) dampened responses to all three vasodilators. Phenylephrine exposure depolarized myogenic arteries, and mimicking this effect with 4-aminopyridine (1 mmol/L) was sufficient to augment the SKA-31-evoked vasodilation. Inhibition of L-type Ca2+ channels by 1 μmol/L nifedipine decreased myogenic tone, phenylephrine-induced constriction and prevented α1 -adrenergic enhancement of endothelium-evoked vasodilation; these latter deficits were overcome by exposure to 3 and 10 μmol/L phenylephrine. Mechanistically, augmentation of ACh-evoked dilation by phenylephrine was dampened by eNOS inhibition and abolished by blockade of endothelial KCa channels. Collectively, these data suggest that increasing α1 -adrenoceptor activation beyond a threshold level augments endothelium-evoked vasodilation, likely by triggering transcellular signaling between smooth muscle and the endothelium. Physiologically, this negative feedback process may serve as a "brake" to limit the extent of vasoconstriction in the skeletal microcirculation evoked by the elevated sympathetic tone

Subsidiarity between economic freedom and harmonized regulation: is there an optimal degree of European integration?

According to the European Union's (EU's) principle of subsidiarity, responsibilities of any kind should always be allocated to the lowest level possible. When applying this to the EU's economic union, one might assume that the decentralization of trading structures as well as the ensuring of national economic freedoms are basic necessities for a reliable implementation of the concept of subsidiarity. Nevertheless, with view to the sustained enlargement of the European Single Market, it seems that the centralization of trading structures has not lost its attractiveness yet. The permanent progress in European trade integration raises the important question whether there may be some optimal degree of economic integration in the sense of subsidiarity and, if so, how this optimal level of integration might be determined. Answers to this burning issue will be of fundamental importance for future European policy making. As long as it is not clear-cut whether the principle of subsidiarity is of an integrationist or a more anti-integrationist nature regarding deeper trade integration, an adequate implementation of the subsidiarity principle appears impossible for policymakers at both the national and the European level

Class of their own

Leading universities still cluster in established centres, but within a shifting global framework. Australia including Melbourne is one of the knowledge nodes emerging outside of North America and Europe, write Michael Hoyler and Heike Jöns

Identification risk for microdata stemming from official statistics

In diesem methodologischen Forschungsbericht wird über das Risiko der Identifizierung von Individuen aufgrund von Mikrodaten aus der amtlichen Statistik referiert. Bei ihrer Untersuchung, das Identifizierungsrisiko einzelner Individualdatensätze zu klären, gingen die Forscher von dem Umstand aus, daß für die Daten aus amtlichen Quellen keineswegs eine absolute Anonymität, sondern lediglich eine faktische Anonymität gesetzlich vorgeschrieben ist. Das bedeutet, daß zur Identifizierung ein so hoher Einsatz an Zeit, Mitteln und Kosten erforderlich sein muß, daß der Aufwand für einen Interessenten, der Mikrodaten bestimmten Individuen oder Haushalten zuordnen möchte, jede vernünftige Zweck-Mittel-Relation übersteigt und somit jedes alternative Vorgehen, um an die gewünschten Informationen zu gelangen eher beschritten würde. Es handelt sich mithin um ein sozialwissenschaftliches Szenario für das Testen der Anonymität. Für den Test wurden Daten aus dem Mikrozensus 1987 verwendet und mit Informationen aus 'Kürschners Deutscher Gelehrtenkalender' zusammengebracht. Mit den zehn Attributen (Variablen), die dem Gelehrtenkalender entnommen werden können, wurde ein Vergleichsdatensatz konstruiert, der mit den Daten aus dem Mikrozensus in einem 'simple-matching' zusammengeführt wurde, um 'statistische Zwillinge' aufzufinden. Es zeigte sich jedoch, daß weder dieses Suchen beim 'simple-matching' zu dem 'gewünschten' Erfolg führt, noch verschiedene Verbesserungen der Versuchsanordnung. Auch dann, wenn - rein mathematisch - 'statistische Zwillinge' identifiziert werden, so ist damit über die Realität noch nicht viel ausgesagt. Denn zum einen gibt es zahlreiche fehlerhafte Identifizierungen von 'statistischen Zwillingen', andererseits ist unbekannt, ob die gesuchte Person (wenn nach einer Einzelperson gesucht wird) in der Stichprobe des Mikrozensus enthalten ist. In jedem Fall wurde offensichtlich, daß andere Wege viel effektiver und preiswerter sind, um an Informationen über Privatpersonen oder Privathaushalte zu gelangen. (ICF

Research travel and disciplinary identities in the University of Cambridge, 1885-1955

This article considers the role of overseas academic travel in the development of the modern research university, with particular reference to the University of Cambridge from the 1880s to the 1950s. The Cambridge academic community, relatively sedentary at the beginning of this period, became progressively more mobile and globalized through the early twentieth century, facilitated by regular research sabbaticals. The culture of research travel diffused at varying rates, and with differing consequences, across the arts and humanities and the field, laboratory and theoretical sciences, reshaping disciplinary identities and practices in the process. The nature of research travel also changed as the genteel scholarly excursion was replaced by the purposeful, output-orientated expedition

Global geographies of higher education: the perspective of world university rankings

This paper contributes to emerging debates about uneven global geographies of higher education through a critical analysis of world university rankings. Drawing on recent work in geography, international higher education and bibliometrics, the paper examines two of the major international ranking schemes that have had significant public impact in the context of the on-going neoliberalization of higher education. We argue that the emergence of these global rankings reflects a scalar shift in the geopolitics and geoeconomics of higher education from the national to the global that prioritizes academic practices and discourses conducted in particular places and fields of research. Our analysis illustrates how the substantial variation in ranking criteria produces not only necessarily partial but also very specific global geographies of higher education. In comparison, these reveal a wider tension in the knowledge-based economy between established knowledge centres in Europe and the United States and emerging knowledge hubs in Asia Pacific. An analysis of individual ranking criteria, however, suggests that other measures and subject-specific perspectives would produce very different landscapes of higher education

Degrees of influence: the politics of honorary degrees in the Universities of Oxford and Cambridge, 1900-2000

The universities of Oxford and Cambridge had developed different attitudes towards the award of honorary degrees through the early and middle decades of the twentieth century. Recently, both have adopted a similar cautious and apolitical stance. This essay describes the role of honorary degrees in the production and reproduction of their cultural and intellectual authority of these two ancient universities

The carrot or the stick: Self-regulation for gender-diverse boards via codes of good governance

Scholars have emphasized the potential of self-regulation, realized through "codes of good governance", to improve gender diversity on boards. Yet, unconvinced of the effectiveness of this self-regulation, many regulators have implemented mandatory quota laws. Our study sheds light on this dilemma. Seeking to broaden our conceptual knowledge of how such "codes" work in the specific case of gender diversity on boards, we ask: Under which conditions is self-regulation via voluntary principles of good governance effective? Expanding recent institutional-theory perspectives from the literature of women on boards, we show that, in the case of Austria, self-regulation via code recommendations is ineffective unless supported by additional forces. The primary reason for this, we argue, is that nominators do not expect benefits from gender-diverse boards. Furthermore, non-compliant companies face little pressure to change due to the small number of companies that have already adopted respective code recommendations. We identify two potential alternatives to boost the effectiveness of voluntary self-regulation for gender diverse boards: First, the introduction of concrete targets for female representation and the public monitoring of fulfillment; and, second, the establishment of a credible threat that mandatory quotas will be imposed if diversity goals are not achieved. Drawing on longitudinal data from 2006-2016 on listed and state-owned companies in Austria, we give an empirical account of the conditions that assure effective self-regulation. Arguing that codes suffer from what we call "opportunity bias", we conclude that political goals (such as gender equality) based on ethical rather than instrumental considerations are unlikely to be effectively implemented solely by codes of good governance