The recurrence time of Dansgaard-Oeschger events and limits on the possible periodic component

By comparing the high-resolution isotopic records from the GRIP and NGRIP icecores, we approximately separate the climate signal from local noise to obtain an objective criterion for defining Dansgaard-Oeschger events. Our analysis identifies several additional short lasting events, increasing the total number of DO events to 27 in the period 12-90 kyr BP. The quasi-regular occurrence of the DO events could indicate a stochastic or coherent resonance mechanism governing their origin. From the distribution of waiting times we obtain a statistical upper bound on the strength of a possible periodic forcing. This finding indicates that the climate shifts are purely noise driven with no underlying periodicity.Comment: 9 figure

Crossing the Logarithmic Barrier for Dynamic Boolean Data Structure Lower Bounds

This paper proves the first super-logarithmic lower bounds on the cell probe complexity of dynamic boolean (a.k.a. decision) data structure problems, a long-standing milestone in data structure lower bounds. We introduce a new method for proving dynamic cell probe lower bounds and use it to prove a $\tilde{\Omega}(\log^{1.5} n)$ lower bound on the operational time of a wide range of boolean data structure problems, most notably, on the query time of dynamic range counting over $\mathbb{F}_2$ ([Pat07]). Proving an $\omega(\lg n)$ lower bound for this problem was explicitly posed as one of five important open problems in the late Mihai P\v{a}tra\c{s}cu's obituary [Tho13]. This result also implies the first $\omega(\lg n)$ lower bound for the classical 2D range counting problem, one of the most fundamental data structure problems in computational geometry and spatial databases. We derive similar lower bounds for boolean versions of dynamic polynomial evaluation and 2D rectangle stabbing, and for the (non-boolean) problems of range selection and range median. Our technical centerpiece is a new way of "weakly" simulating dynamic data structures using efficient one-way communication protocols with small advantage over random guessing. This simulation involves a surprising excursion to low-degree (Chebychev) polynomials which may be of independent interest, and offers an entirely new algorithmic angle on the "cell sampling" method of Panigrahy et al. [PTW10]

Assessing Self-shading Benefits of Twisting Towers

Over the last number of decades, tall building geometries have been shifting from rectangular boxes towards shapes that are defined through geometrical transformations such as twisting. While, from an aesthetical point of view, these twisting geometries make tall buildings appear contemporary and iconic, from an environmental point of view, however, the benefits are not as straightforward. They may vary significantly based on climatic loads and urban conditions, among others. This study aims to assess the self-shading benefits of twisting geometries by finding a correlation between floor-to-floor rotation and façade solar irradiation across climates, primarily focusing on hot ones, where self-shading is used as a passive solar design strategy. The study analysed three types of irradiation studies: Cumulative Annual Irradiation, Cumulative Harmful Irradiation during Cooling Design Day, and lastly, Solar Irradiation Self-Shading Balance. The latter compares beneficial and harmful solar irradiation during Hot and Cold Degree Days to quantify the impact of floor-to-floor rotation on optical and thermal performance. The study explored hundreds of possible scenarios across different climates and various floor-to-floor rotation angles, revealing a variety of positive, negative, and neutral situations. The study recommends careful examination of environmental conditions via a combination of multiple irradiation studies, particularly in the case of a smooth façade scenario

Instrumental Variable Identification of Dynamic Variance Decompositions

Macroeconomists increasingly use external sources of exogenous variation for causal inference. However, unless such external instruments (proxies) capture the underlying shock without measurement error, existing methods are silent on the importance of that shock for macroeconomic fluctuations. We show that, in a general moving average model with external instruments, variance decompositions for the instrumented shock are interval-identified, with informative bounds. Various additional restrictions guarantee point identification of both variance and historical decompositions. Unlike SVAR analysis, our methods do not require invertibility. Applied to U.S. data, they give a tight upper bound on the importance of monetary shocks for inflation dynamics

Graphene-based Josephson junction single photon detector

We propose to use graphene-based Josephson junctions (gJjs) to detect single photons in a wide electromagnetic spectrum from visible to radio frequencies. Our approach takes advantage of the exceptionally low electronic heat capacity of monolayer graphene and its constricted thermal conductance to its phonon degrees of freedom. Such a system could provide high sensitivity photon detection required for research areas including quantum information processing and radio-astronomy. As an example, we present our device concepts for gJj single photon detectors in both the microwave and infrared regimes. The dark count rate and intrinsic quantum efficiency are computed based on parameters from a measured gJj, demonstrating feasibility within existing technologies.Comment: 11 pages, 6 figures, and 1 table in the main tex

Succes eller fiasko? – Et komparativt blik på den danske konkurrencestat

Artiklen belyser den danske konkurrencestat sammenlignet med andre vestlige lande. I analysen fokuseres på fire dimensioner: 2. Ulighed, fattigdom og skat, 2. Social mobilitet, 3. Økonomisk vækst, konkurrenceevne og økonomisk holdbarhed, og 4. Beskæftigelse, arbejdsløshed og arbejdsmarkedspolitik. Sideløbende analyseres sammenhænge mellem dimensionerne, eksempelvis ligheds betydning for social mobilitet, vækst mv. På baggrund af den komparative analyse argumenterer vi for, at Danmark overordnet set kan karakteriseres som en universalistisk konkurrencestat med en lav grad af ulighed (om end den er steget) og fattigdom kombineret med en konkurrencedygtig og holdbar økonomi, der fastholder den traditionelle velfærdsstats fokus på social sikring og lige adgang til velfærdsservice, om end reformer af dagpenge og kontanthjælp har mindsket graden af sikring i forbindelse med arbejdsløshed. Som den største udfordring for den danske konkurrencestat peger vi på, at Danmark på trods af et stærkt fokus på området stadig er udfordret af, at erhvervsdeltagelsen blandt 25-54 årige mænd er væsentligt lavere, end den var før 1973 og end i de lande, der klarer sig bedst på dette parameter (Schweiz, Japan, Island). På denne baggrund diskuteres, hvad der skal til for at øge beskæftigelsesfrekvensen. ENGELSK ABSTRACT Mikkel Dehlholm and Ove K. Pedersen: Success or failure: a comparative look at the Danish competition state This article analyzes the Danish competition state in comparison with other western states on four dimensions: 1) inequality, poverty and tax, 2) social mobility, 3) economic growth, competitiveness and economic stability and 4) employment, unemployment and labor market policy. It also analyzes relations between these dimensions. Based on the analysis, we argue that Denmark can be characterized as a universalistic competition state. We point out that the greatest challenge for the Danish competition state is the low employment rate for men between the ages of 25-54, which is lower than it was in 1973 and also lower than other countries (such as Switzerland, Japan, Iceland). We discuss ways of increasing this employment . Keywords: Competition state, Welfare state, employment, unemployment, inequality, social mobility

Effects of glucagon-like peptide-1 receptor agonists on weight loss: systematic review and meta-analyses of randomised controlled trials

Objective To determine whether treatment with agonists of glucagon-like peptide-1 receptor (GLP-1R) result in weight loss in overweight or obese patients with or without type 2 diabetes mellitus