1,979 research outputs found
[[alternative]]The Dedekind-mertens number and the Polarized Dedekind-mertens number
No full text[[abstract]]We study content ideals of polynomials and their behavior under multiplication. In [HH2] and [CHH], they give a sharpening of the Dedekind-Mertens Lemma relating the contents of two polynomials to the content of their product. Therefore, we study the Dedekind-Mertens number, the Polarized Dedekind-Mertens number and give some examples about them.
Riprap stability for deep water, shallow water and steep foreshores
No full textIn the Rock Manual [2007] two sets of equations for the determination of rock stability in breakwaters armour layers are presented. One set is the original formula presented by Van der Meer [1988], valid for deep water conditions. This set uses the parameters Hs and Tm. The other set is an adaptation of these formulae, using the parameters H2% and Tm-1,0, and is recommended for shallow water conditions. Tests by Van Gent et al. [2003] have lead to a calibration coefficient slightly different than the original Van der Meer values. Recently the second author [Mertens, 2007] has reanalysed the datasets of Van der Meer and Van Gent, corrected some of the numbers, and explained a part of the differences. This paper tried to unify both sets of formulae and come to one single equation.Hydraulic EngineeringCivil Engineering and Geoscience
Interview with Peter Mertens and Wolfgang König: “From Reasonable Automation to (Sustainable) Autonomous Systems”
No full textPeter Mertens is Professor Emeritus of Wirtschaftsinformatik at the Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg. After studying industrial engineering, he completed his doctoral studies and his habilitation at the TH Darmstadt (1961) and the TU München (1966), respectively. From 1966 to 1968, he worked for a large software and consulting firm in Switzerland, first as a system designer and later as a managing director. In 1968, Peter Mertens took over the first chaired professorship specialized in business data processing at the University of Linz. He is considered one of the founding fathers of Wirtschaftsinformatik in the German-speaking world. Until September 2005, Peter Mertens held the Chair of Business Administration, especially Wirtschaftsinformatik I at the Faculty of Business and Social Sciences of FAU. In parallel, he was head of the computer science research group “Business Applications” at FAU’s Faculty of Engineering. Since fall 2005, he works as an emeritus professor at his former chair. Peter Mertens is the author of numerous books, including 23 monographs. He has also been involved in the editing of 26 collective works. The first volume of his book “Integrated Information Processing” has been published in 18 editions. Some of his books have been translated into English, Chinese, Italian, and Russian. Among other awards, he is a Fellow of the German Informatics Society, an honorary doctor of five universities in Germany, Austria, and Switzerland, and has been awarded the Order of Merit of the Federal Republic of Germany. From 1990 until 2000, Peter Mertens served as Editor-in-Chief for WIRTSCHAFTSINFORMATIK (now: BISE).
Until 2016, Wolfgang König was Professor of Business Administration, especially Information Systems and Information Management at the Faculty of Economics and Business Administration of Goethe University Frankfurt a. M., and until January 2022, he was Chairman of the E-Finance Lab (since 2020: efl – the Data Science Institute) at Goethe University. Since 2008, he holds the position of Executive Director of the House of Finance of Goethe University, and since 2016, he serves as Senior Professor at Goethe University. From 1998 until 2008, König served as Editor-in-Chief for WIRTSCHAFTSINFORMATIK (now: BISE).
Both Peter Mertens and Wolfgang König are clearly among the research pioneers when it comes to automated systems, which can be seen as a precursor of the central topic of this special issue: autonomous systems (AS). The key difference between automated systems and AS is that, in AS, machines or other technology actors have at least some agency (i.e., they can act autonomously), whereas in automated systems, the agency still lies with humans – who, for example, define the relevant rule system – and machines/technologies merely automate the execution of these predefined rules
Data on land holdings and land transactions in Uganda
No full text/* Credits
Dataset and do file of : "Investing in land to change your risk exposure? Land transactions in a landslide prone region"
Authors: Kewan Mertens & Liesbet Vranken
Corresponding author: [email protected] (or if previous email is not applicable anymore: [email protected]).
Date: April 2018
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/* Explanation
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These are the data of an original household survey, implemented by Kewan Mertens with enumerators in Uganda.
This is the do-file that is used to come to the analysis and the tables presented in the paper:
Mertens, K., Vranken, L., 2018. Investing in land to change your risk exposure? Land transactions and inequality in a landslide prone region. World Development
We have tried to provide all primary variables, as obtained after data cleaning, as well as all secondary variable that were constructed from
these primary variables to do the analysis. All steps and regressions based on these primary and secondary variables are presented here. In case
you would want additional information, please contact the corresponding author.
Each household is uniquely identified through the combination of EnumID (VilID) HHID, and each plot is identified through EnumID (VilID) HHID PlotID.
EnumID refers to the enumerator that collected the data, VilID to the village, HHID to the nth household interviewed by the enumerator. The order of PlotID
is determined by the order in the interview and does not necessarily correspond with the order of plot acquisition
Replication Data for: 'The Macroeconomic Effects of Government Asset Purchases: Evidence from Postwar US Housing Credit Policy'
No full textThe data and programs replicate tables and figures from "The Macroeconomic Effects of Government Asset Purchases: Evidence from Postwar US Housing Credit Policy", by Fieldhouse, Mertens, and Ravn. Please see the Readme file for additional details
Replication Data for: 'The Macroeconomic Effects of Government Asset Purchases: Evidence from Postwar US Housing Credit Policy'
No full textThe data and programs replicate tables and figures from "The Macroeconomic Effects of Government Asset Purchases: Evidence from Postwar US Housing Credit Policy", by Fieldhouse, Mertens, and Ravn. Please see the Readme file for additional details
Turby - sustainable urban wind power from the roof top
No full textIf current trends are anything to go by, in future we will no longer produce all our electricity in large, central power stations. Small-scale local electricity generation will gain in importance. Sander Mertens, a post-doctoral student at TU Delft, developed the aerodynamic design of a wind turbine which is specifically suitable for built-up areas. Compact, mobile, low-noise, and vibration-free, it is the ideal alternative for use on top of high-rise office blocks, where wind speeds can easily reach twenty percent more than with the same height away from buildings. The electricity can be fed straight into the buildings power system, saving on energy transport costs and losses, and producing high feed-in yields. Prototypes have already been installed on the town hall in The Hague (designed by Richard Meier), on an apartment block in Tilburg, on an office block in Breda, and on top of the Delft ChemTech faculty building. Interest has been generated in London and Leicester in the UK, New Mexico and New York in the USA, and in France and Canada
On Some Properties of the Hofstadter–Mertens Function
No full textMany mathematicians have been interested in the study of recursive sequences. Among them, a class of “chaotic” sequences are named “meta-Fibonacci sequences.” The main example of meta-Fibonacci sequence was introduced by Hofstadter, and it is called the Q-sequence. Recently, Alkan–Fox–Aybar and the author studied the pattern induced by the connection between the Q-sequence and other known sequences. Here, we continue this program by studying a “Mertens’ version” of the Hofstadter sequence, defined (for x>0) by x↦∑n≤xμnQn, where µ(n) is the Möbius function. In particular, as we shall see, this function encodes many interesting properties which relate prime numbers to “meta-sequences”
A genomic study of the invasive red alga Bangia atropurpurea (Mertens ex Roth) C. Agardh
No full textThe phylum Rhodophyta comprises the red algae, which are morphologically diverse organisms present in marine and freshwater environments. The red algae order, Bangiales, is an ancient lineage and molecular studies have focused on elucidating the phylogenetic relationships and differentiating species within this group, which is complicated by their known phenotypic plasticity.
The genus Bangia (Bangiales) has been observed in both marine coastal environments and in freshwater, and for many years it was thought that the organisms in these habitats were conspecific. Studies showed that the species could acclimate well when transitioning from one habitat to another, with preservation of morphology. Molecular research, however, has shown that the species are not conspecific, and that the freshwater species, Bangia atropurpurea (Mertens ex Roth) C. Agardh, is more closely related to species from the genus Porphyra than to the marine Bangia. This discovery points out other curiosities about B. atropurpurea: it is the only known freshwater Bangiales, it is considered an invasive species of the Great Lakes, is strictly asexual, and has a filamentous thallus while its closest relative has a foliose thallus. To understand the similarities and differences of B. atropurpurea when compared to other Rhodophyta genomes, this thesis investigates the species at a genomic level using high-throughput sequencing and bioinformatics approaches
Essays on U.S. Federal Housing Credit Policy
No full textCongress has heavily intervened in U.S. mortgage markets ever since the Great Depression, when federal housing credit policies were first deployed to resuscitate housing and mortgage markets. Congress chartered federal agencies and government-sponsored enterprises (GSEs) to promote access to mortgage credit by purchasing or guaranteeing mortgages. Since the onset of the Great Recession the Federal Reserve has conducted its own form of housing credit policy aimed at reducing the cost and increasing the availability of mortgage credit: large-scale purchases of government agency mortgage-backed securities (MBS). Whereas monetary policy targets a term structure of risk-free interest rates, credit policies aim to alter the allocation of credit by absorbing or subsidizing lending risks. Government purchases of mortgage debt might simply displace private mortgage lending, or housing credit policies could channel resources toward housing by subsidizing a reduction in mortgage risk premia. Despite the federal government's expansive use of housing credit policies, evidence on the macroeconomic effects of government mortgage purchases has been constrained by an identification problem. Regressing housing or mortgage market activity on government agency mortgage purchases would capture reverse causality bias arising from policy endogeneity and profit motives; these sources of reverse causality bias would similarly undermine common macroeconometric identification strategies. Studying the Fed's MBS purchases during the Great Recession faces related intrinsic challenges. My dissertation develops a novel identification strategy to circumvent these challenges to inference regarding the macroeconomic effects of government agencies purchasing or selling mortgage debt. I construct instrumental variables from observable policy interventions over 1967--2006 and use them to tease apart the intended versus unintended causal effects of government purchases of mortgage debt. The novel identification strategy underpinning my dissertation is a narrative analysis of regulatory policy changes affecting government agency purchases of mortgage debt. The narrative approach to time series identification exploits the historical record for exogenous policy shocks, as opposed to backing out shocks from latent variables with modeling assumptions or statistical techniques. I contribute the first narrative analysis of U.S. housing credit policies, using primary sources to identify and quantify regulatory shocks affecting the mortgage holdings of Fannie Mae, Freddie Mac, Ginnie Mae, the Federal Reserve, and the U.S. Treasury Department. Regulatory policy changes that I classify as not cyclically motivated are intended as instrumental variables for government agency mortgage purchases, circumventing concerns about reverse causality bias. The first chapter of my dissertation exploits identifying variation from my narrative analysis to document whether government mortgage purchases advance stated housing policy objectives and to study interactions with monetary policy. We find that agency purchases boost total mortgage lending and lower mortgage rates, indicating that policymakers are capable of directing credit toward housing, as intended, as opposed to simply crowding out private mortgage lending. Agency purchases also advance periodic policy objectives of increasing housing starts and homeownership rates. We identify similarities in the transmission of monetary policy shocks and agency mortgage purchases, and document significant interactions between monetary and housing credit policies; Congress frequently used cyclically motivated credit policies to cushion housing and mortgage markets from contractionary monetary shocks. If housing credit policies expand targeted lending volumes by subsidizing or absorbing private credit risks, they may inadvertently reduce other lending. My second dissertation chapter empirically tests whether the mortgage purchases of Fannie Mae and Freddie Mac unintentionally displace commercial lending and related real activity by subsidizing an expansion in mortgage lending. I use my narrative analysis for exogenous variation in the mortgage purchases of Fannie and Freddie. Regulatory shocks to GSE mortgage purchases boost private home mortgage lending yet unintentionally reduce commercial real estate and business lending. U.S. housing credit policies similarly reallocate construction activity toward housing and away from commercial real estate, negating any intended stimulus to aggregate construction spending or employment. The third chapter of my dissertation is the narrative analysis underpinning the identification strategies behind the first two chapters. My findings are relevant to efforts in Congress to resolve the fate of Fannie and Freddie, as well as to the ongoing reduction in the Fed's MBS holdings. Government agency mortgage purchases are capable of increasing mortgage borrowing, reducing mortgage rates, boosting housing investment, and raising homeownership rates, as intended, through a subsidy channel. Subsidizing mortgage borrowing, however, involves an unintended tradeoff with respect to commercial lending and commercial real estate investment. Government agency mortgage purchases appear ineffectual as a tool of stabilization policy---as they have been employed on and off since the Great Depression
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