The dynamics of international capital flows: Results from a dynamic hierarchical factor model

The present paper examines the degree of comovement of gross capital inflows, which is a highly sensitive issue for policy makers. We estimate a dynamic hierarchical factor model that is able to decompose inflows in a sample of 47 economies into (i) a global factor common to all types of flows and all recipient countries, (ii) a factor specific to a given type of capital inflows, (iii) a regional factor and (iv) a country-specific component. We find that the latter explains by far the largest fraction of fluctuations in capital inflows followed by regional factors, which are particularly important for emerging markets' FDI and portfolio inflows as well as bank lending to emerging Europe. The global factor, however, explains only a small share of overall variation. The exposure to global drivers of capital flows, i.e. the global factor and the factor specific to each type of capital inflows, is particularly pronounced for countries with a more developed financial system. A fixed exchange rate regime does not shield countries from the ebb and flow of global capital flow cycles

Ankauf von Staatsanleihen durch die EZB: Wie ist die neue Offenmarktpolitik der Europäischen Zentralbank zu bewerten?

Seit Mai 2010 kauft die Europäische Zentralbank direkt Anleihen privater und öffentlicher Schuldner auf dem Sekundärmarkt. Markus C. Kerber, Technische Universität Berlin, vertritt die Ansicht, dass diese »neue Offenmarktpolitik« der EZB, der Erwerb von Staatsanleihen auf dem Sekundärmarkt, eigentlich nicht erlaubt sei und der Stabilität der Eurozone eher schade. Nach Ansicht von Martin Mandler und Peter Tillmann, Universität Gießen, ist mit dem Programm der EZB ein potentieller Ressourcentransfer an die Krisenstaaten und ihre Gläubiger verbunden, der grundsätzlich nicht in den Aufgabenbereich der Geldpolitik fällt. Dieses Programm in seiner gegenwärtigen Form sei aber nicht alternativlos. Vor dem Hintergrund der »unkonventionellen« Geldpolitik der Zentralbanken rund um den Globus könnte eine andere Ausgestaltung die Risiken solcher Transfers reduzieren

Detection and localization of multiple rate changes in Poisson spike trains : poster presentation from Twentieth Annual Computational Neuroscience Meeting CNS*2011 Stockholm, Sweden, 23 - 28 July 2011

Poster presentation from Twentieth Annual Computational Neuroscience Meeting: CNS*2011 Stockholm, Sweden. 23-28 July 2011. In statistical spike train analysis, stochastic point process models usually assume stationarity, in particular that the underlying spike train shows a constant firing rate (e.g. [1]). However, such models can lead to misinterpretation of the associated tests if the assumption of rate stationarity is not met (e.g. [2]). Therefore, the analysis of nonstationary data requires that rate changes can be located as precisely as possible. However, present statistical methods focus on rejecting the null hypothesis of stationarity without explicitly locating the change point(s) (e.g. [3]). We propose a test for stationarity of a given spike train that can also be used to estimate the change points in the firing rate. Assuming a Poisson process with piecewise constant firing rate, we propose a Step-Filter-Test (SFT) which can work simultaneously in different time scales, accounting for the high variety of firing patterns in experimental spike trains. Formally, we compare the numbers N1=N1(t,h) and N2=N2(t,h) of spikes in the time intervals (t-h,t] and (h,t+h]. By varying t within a fine time lattice and simultaneously varying the interval length h, we obtain a multivariate statistic D(h,t):=(N1-N2)/V(N1+N2), for which we prove asymptotic multivariate normality under homogeneity. From this a practical, graphical device to spot changes of the firing rate is constructed. Our graphical representation of D(h,t) (Figure 1A) visualizes the changes in the firing rate. For the statistical test, a threshold K is chosen such that under homogeneity, |D(h,t)|<K holds for all investigated h and t with probability 0.95. This threshold can indicate potential change points in order to estimate the inhomogeneous rate profile (Figure 1B). The SFT is applied to a sample data set of spontaneous single unit activity recorded from the substantia nigra of anesthetized mice. In this data set, multiple rate changes are identified which agree closely with visual inspection. In contrast to approaches choosing one fixed kernel width [4], our method has advantages in the flexibility of h

Ankauf von Staatsanleihen durch die EZB: Wie ist die neue Offenmarktpolitik der Europäischen Zentralbank zu bewerten?

Seit Mai 2010 kauft die Europäische Zentralbank direkt Anleihen privater und öffentlicher Schuldner auf dem Sekundärmarkt. Markus C. Kerber, Technische Universität Berlin, vertritt die Ansicht, dass diese »neue Offenmarktpolitik« der EZB, der Erwerb von Staatsanleihen auf dem Sekundärmarkt, eigentlich nicht erlaubt sei und der Stabilität der Eurozone eher schade. Nach Ansicht von Martin Mandler und Peter Tillmann, Universität Gießen, ist mit dem Programm der EZB ein potentieller Ressourcentransfer an die Krisenstaaten und ihre Gläubiger verbunden, der grundsätzlich nicht in den Aufgabenbereich der Geldpolitik fällt. Dieses Programm in seiner gegenwärtigen Form sei aber nicht alternativlos. Vor dem Hintergrund der »unkonventionellen« Geldpolitik der Zentralbanken rund um den Globus könnte eine andere Ausgestaltung die Risiken solcher Transfers reduzieren.Öffentliche Anleihe, Zentralbank, Öffentliche Schulden, Offenmarktpolitik, EU-Staaten

Schätzung einer zeitabhängigen Reproduktionszahl R für Daten mit einer wöchentlichen Periodizität am Beispiel von SARS-CoV-2-Infektionen und COVID-19

Der Beitrag analysiert die Auswirkungen von wöchentlichen Periodizitäten und zeitlichen Korrekturen auf die Schätzung einer zeitabhängigen Reproduktionszahl R bei Infektionskrankheiten. Zur Reduktion dieser Schwankungen wird eine einfache Methode vorgeschlagen, die auf einem akausalen Filter der Filterlänge 7 und optionalen Schätzungen zukünftiger Fallzahlen beruht. Dabei werden die gleichen Tage der Vorwoche als Basis für die Schätzungen verwendet, weil sich das in einer anderen Domäne mit wöchentlichen Periodizitäten-der Lastprognose in Energiezeitreihen-bewährt hat. Akausale Filter vermeiden unerwünschte Zeitverzögerungen, die bei kausalen Filtern auftreten. Die Ergebnisse werden anhand der Fallzahlen von SARS-CoV-2-Infektionen und COVID-19 (Coronavirus Disease 19) in Deutschland mit existierenden Ansätzen des Robert-Koch-Instituts in Deutschland verglichen. Die vorgeschlagene Methode kompensiert wöchentliche Periodizitäten besser und reduziert Phasen mit einer scheinbarenÜberschreitung von R > 1, die oftmals eine besondere öffentliche Aufmerksamkeit hervorrufen. Darüberhinaus werden die Potenziale und Grenzen von verschiedenen Nowcasting-Modellen aufgezeigt, die Fallzahlen auf ein Erkrankungsdatum projizieren

Ferritin encapsulation of artificial metalloenzymes: engineering a tertiary coordination sphere for an artificial transfer hydrogenase

Ferritin, a naturally occuring iron-storage protein, plays an important role in nanoengineering and biomedical applications. Upon iron removal, apoferritin was shown to allow the encapsulation of an artificial transfer hydrogenase (ATHase) based on the streptavidin-biotin technology. The third coordination sphere, provided by ferritin, significantly influences the catalytic activity of an ATHase for the reduction of cyclic imines

Detection and localization of multiple rate changes in Poisson spike trains

Poster presentation from Twentieth Annual Computational Neuroscience Meeting: CNS*2011 Stockholm, Sweden. 23-28 July 2011. In statistical spike train analysis, stochastic point process models usually assume stationarity, in particular that the underlying spike train shows a constant firing rate (e.g. [1]). However, such models can lead to misinterpretation of the associated tests if the assumption of rate stationarity is not met (e.g. [2]). Therefore, the analysis of nonstationary data requires that rate changes can be located as precisely as possible. However, present statistical methods focus on rejecting the null hypothesis of stationarity without explicitly locating the change point(s) (e.g. [3]). We propose a test for stationarity of a given spike train that can also be used to estimate the change points in the firing rate. Assuming a Poisson process with piecewise constant firing rate, we propose a Step-Filter-Test (SFT) which can work simultaneously in different time scales, accounting for the high variety of firing patterns in experimental spike trains. Formally, we compare the numbers N1=N1(t,h) and N2=N2(t,h) of spikes in the time intervals (t-h,t] and (h,t+h]. By varying t within a fine time lattice and simultaneously varying the interval length h, we obtain a multivariate statistic D(h,t):=(N1-N2)/V(N1+N2), for which we prove asymptotic multivariate normality under homogeneity. From this a practical, graphical device to spot changes of the firing rate is constructed. Our graphical representation of D(h,t) (Figure 1A) visualizes the changes in the firing rate. For the statistical test, a threshold K is chosen such that under homogeneity, |D(h,t)|<K holds for all investigated h and t with probability 0.95. This threshold can indicate potential change points in order to estimate the inhomogeneous rate profile (Figure 1B). The SFT is applied to a sample data set of spontaneous single unit activity recorded from the substantia nigra of anesthetized mice. In this data set, multiple rate changes are identified which agree closely with visual inspection. In contrast to approaches choosing one fixed kernel width [4], our method has advantages in the flexibility of h

Directed evolution of artificial metalloenzymes for in vivo metathesis

The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions. For example, artificial metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist: repurposing natural metalloenzymes for abiotic transformations; in silico metalloenzyme (re-)design; and incorporation of abiotic cofactors into proteins. The third strategy offers the opportunity to design a wide variety of artificial metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein. This limits the throughput of genetic optimization schemes applied to artificial metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction without equivalent in nature. Building on previous work on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the 'metathase' because it offers an auspicious environment for artificial metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the workflow. Our results represent the systematic implementation and evolution of an artificial metalloenzyme that catalyses an abiotic reaction in vivo, with potential applications in, for example, non-natural metabolism

Pluralism about Knowledge

In this paper I consider the prospects for pluralism about knowledge, that is, the view that there is a plurality of knowledge relations. After a brief overview of some views that entail a sort of pluralism about knowledge, I focus on a particular kind of knowledge pluralism I call standards pluralism. Put roughly, standards pluralism is the view that one never knows anything simpliciter. Rather, one knows by this-or-that epistemic standard. Because there is a plurality of epistemic standards, there is a plurality of knowledge relations. In §1 I argue that one can construct an impressive case for standards pluralism. In §2 I clarify the relationship between standards pluralism, epistemic contextualism and epistemic relativism. In §3 I argue that standards pluralism faces a serious objection. The gist of the objection is that standards pluralism is incompatible with plausible claims about the normative role of knowledge. In §4 I finish by sketching the form that a standards pluralist response to this objection might take

Hepatitis B surface antigen quantification: Why and how to use it in 2011 – A core group report

Quantitative HBsAg had been suggested to be helpful in management of HBV, but assays were cumbersome. The recent availability of commercial quantitative assays has restarted the interest in quantitative serum hepatitis B surface antigen (HBsAg) as a biomarker for prognosis and treatment response in chronic hepatitis B. HBsAg level reflects the transcriptional activity of cccDNA rather than the absolute amount of cccDNA copies. Serum HBsAg level tends to be higher in hepatitis B e antigen (HBeAg)-positive than HBeAg-negative patients. Among patients with a low HBV DNA (<2000IU/ml), HBsAg <1000IU/ml in genotype D HBV infection and HBsAg <100IU/ml in genotype B/C HBV infection is associated with inactive carrier state in HBeAg-negative patients. The HBsAg reduction by nucleos(t)ide analogues (NA) is not as pronounced as by interferon treatment. On peginterferon treatment, sustained responders tend to show greater HBsAg decline than the non-responders. The optimal on-treatment HBsAg cutoff to predict response needs further evaluation in HBeAg-positive patients, but an absence of HBsAg decline together with a <2 log reduction in HBV DNA at week 12 can serve as stopping rule in HBeAg-negative patients with genotype D HBV infection. A rapid serum HBsAg decline during NA therapy may identify patients who will clear HBsAg in the long-term. There are early reports among Asian patients that an HBsAg level of <100IU/ml might predict lower risk of relapse after stopping NA treatment. In clinical practice, serum HBsAg level should be used together with, but not as a substitute for, HBV DNA