Persistent currents in normal metal rings

The authors have measured the magnetic response of 33 individual cold mesoscopic gold rings, one ring at a time. The response of some sufficiently small rings has a component that is periodic in the flux through the ring and is attributed to a persistent current. Its period is close to h/e, and its sign and amplitude vary between rings. The amplitude distribution agrees well with predictions for the typical h/e current in diffusive rings. The temperature dependence of the amplitude, measured for four rings, is also consistent with theory. These results disagree with previous measurements of three individual metal rings that showed a much larger periodic response than expected. The use of a scanning SQUID microscope enabled in situ measurements of the sensor background. A paramagnetic linear susceptibility and a poorly understood anomaly around zero field are attributed to defect spins.Comment: Journal version. 4+ pages, 3 figures. See http://stanford.edu/group/moler/publications.html for the auxiliary document containing additional data and discussion (Ref. 29). Changes w.r.t. v1: Clarified some details in introduction and regarding experimental procedures, shortened abstract, added references and fixed some typo

Fueling conflict? (De)escalation and bilateral aid

This paper studies the effects of bilateral foreign aid on conflict escalation and deescalation. First, we develop a new ordinal measure capturing the two-sided and multifaceted nature of conflict. Second, we propose a dynamic ordered probit estimator that allows for unobserved heterogeneity and corrects for endogeneity. Third, we identify the causal effect of foreign aid on conflict by predicting bilateral aid flows based on electoral outcomes of donor countries which are exogenous to recipients. Receiving bilateral aid raises the chances of escalating from small conflict to armed conflict, but we find little evidence that aid ignites conflict in truly peaceful countries. © 2020 The Authors. Journal of Applied Econometrics published by John Wiley & Sons Lt

Die Bedeutung von Factory Outlets aus der Sicht von Herstellern und Kunden

Der Fabrikverkauf hat in Deutschland eine lange Tradition. Schon seit vielen Jahrzehnten bieten Hersteller am Fertigungsstandort überschüssige Produktion oder leicht fehlerhafte Ware zu niedrigen Preisen feil. Neu ist indes die heftige Diskussion über dieses Absatzkonzept. Im Mittelpunkt der öffentlichen Auseinandersetzung stehen die Bedenken des Handels hinsichtlich der Planung großflächiger Factory Outlet Center. Dieser befürchtet, daß hierdurch Kaufkraft aus dem innerstädtischen Einzelhandel abgezogen wird und damit dort Arbeitsplätze verloren gehen. Auch in den herkömmlichen Fabrikverkaufsläden tut sich etwas. Durch die Verbreitung sogenannter Schnäppchenführer haben viele Factory Outlets in Deutschland überregionale Beachtung erfahren. Da diesen aber bislang wenig Aufmerksamkeit in der wissenschaftlichen Literatur geschenkt wurde, besteht Unklarheit über die Beurteilung vorhandener Fabrikverkaufsstellen seitens der Betreiber sowie die zukünftige Entwicklung dieses Absatzkonzeptes. Auch hinsichtlich der Kunden dieser Vertriebsform, der Motive für den Kauf ab Werk sowie der Bewertung von Factory Outlets durch die Konsumenten gibt es noch Wissenslücken. Zur Versachlichung der Diskussion erscheint es daher geboten, diese Aspekte näher zu beleuchten. Im Anschluß an eine Erläuterung der Begriffe Factory Outlet und Factory Outlet Center (FOC) werden Entwicklungstrends auf seiten des Handels sowie der Konsumenten aufgezeigt, die die Bedeutung des Fabrikverkaufs als Absatzkonzept beeinflussen. In Kapitel 4 folgt die Darstellung der Ergebnisse einer empirischen Untersuchung bei Geschäftsführern von Fabrikverkaufsstellen sowie deren Kunden, aus der Empfehlungen für die Betreiber von Factory Outlets sowie den Fachhandel abgeleitet werden

What we do in the dark: Prevalence of omnivorous feeding activity in Arctic zooplankton during polar night

During the productive polar day, zooplankton and sea-ice amphipods fulfill a critical role in energy transfer from primary producers to higher trophic-level species in Arctic marine ecosystems. Recent polar night studies on zooplankton and sea-ice amphipods suggest higher levels of biological activity than previously assumed. However, it is unknown if these invertebrates maintain polar night activity on stored lipids, opportunistic feeding, or a combination of both. To assess how zooplankton (copepods, amphipods, and krill) and sea-ice amphipods support themselves on seasonally varying resources, we studied their lipid classes, fatty acid compositions, and compound-specific stable isotopes of trophic biomarker fatty acids during polar day (June/July) and polar night (January). Lipid storage and fatty acid results confirm previously described dietary sources in all species during polar day. We found evidence of polar night feeding in all species, including shifts from herbivory to omnivory. Sympagic-, pelagic-, and Calanus spp.-derived carbon sources supported zooplankton and sea-ice amphipods in both seasons. We provide a first indication of polar night feeding of sea-ice amphipods in the pelagic realm

Numerically stable computation of CreditRisk+

The CreditRisk+ model launched by CSFB in 1997 is widely used by practitioners in the banking sector as a simple means for the quantification of credit risk, primarily of the loan book. We present an alternative numerical recursion scheme for CreditRisk+, equivalent to an algorithm recently proposed by Giese, based on well-known expansions of the logarithm and the exponential of a power series. We show that it is advantageous to the Panjer recursion advocated in the original CreditRisk+ document, in that it is numerically stable. The crucial stability arguments are explained in detail. Furthermore, the computational complexity of the resulting algorithm is stated

Fueling Conflict? (De)Escalation and Bilateral Aid

This paper studies the effects of bilateral foreign aid on conflict escalation and de-escalation. We make three major contributions. First, we combine data on civil wars with data on low level conflicts in a new ordinal measure capturing the two-sided and multifaceted nature of conflict. Second, we develop a novel empirical framework. We propose a dynamic ordered probit estimator that allows for unobserved heterogeneity and corrects for endogeneity. Third, we identify the causal effect of foreign aid on conflict by predicting bilateral aid flows based on electoral outcomes of donor countries that are exogenous to recipients. We establish that the effect of foreign aid on the various transition probabilities is heterogeneous and can be substantial. Receiving bilateral aid raises the chances of escalating from small conflict to armed conflict, but we find no evidence that aid ignites conflict in truly peaceful countries

Ice-algal carbon supports harp and ringed seal diets in the European Arctic: evidence from fatty acid and stable isotope markers

Sea-ice declines in the European Arctic have led to substantial changes in marine food webs. To better understand the biological implications of these changes, we quantified the contributions of ice-associated and pelagic carbon sources to the diets of Arctic harp and ringed seals using compound-specific stable isotope ratios of fatty acids in specific primary producer biomarkers derived from sea-ice algae and phytoplankton. Comparison of fatty acid patterns between these 2 seal species indicated clear dietary separation, while the compound-specific stable isotope ratios of the same fatty acids showed partial overlap. These findings suggest that harp and ringed seals target different prey sources, yet their prey rely on ice and pelagic primary production in similar ways. From Bayesian stable isotope mixing models, we estimated that relative contributions of sympagic and pelagic carbon in seal blubber was an average of 69% and 31% for harp seals, and 72% and 28% for ringed seals, respectively. The similarity in the Bayesian estimations also indicates overlapping carbon sourcing by these 2 species. Our findings demonstrate that the seasonal ice-associated carbon pathway contributes substantially to the diets of both harp and ringed seals

Detecting changes in the Arctic Ecosystem – Long-Term Benthos Monitoring network for detecting changes in the Arctic benthic ecosystem (LTM-Benthos) 2017-2020

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