The Price-Setting Newsvendor with Poisson Demand

The price-setting newsvendor (PSN) model has received considerable attention since it was first introduced by Whitin (1955). However, the existing publications that study this model consistently assume the existence of a continuous density function of demand. In this paper, we study the PSN model with Poisson demand — that is, a discrete demand distribution without density function. The Poisson PSN has an important property, it combines price-dependency of variance and coefficient of variation of the (standard) additive and multiplicative models: demand variance decreases and the coefficient of variation increases in the selling price. We develop an analytical solution approach that covers a broad class of demand models, including linear and logit demand, explain how to apply our approach to more general demand functions via piece-wise linear approximation, and develop analytical and numerical insights. We characterize the behavior of the optimal price and we analyze the performance gap of different price-setting heuristics. Among other insights, we observe some instances in which a significant share of profits would be lost if the discrete nature of demand were not modeled explicitly. To help companies overcome this risk, we present an easily applicable decision rule with which to determine when to use simple heuristics and when to solve the associated discrete optimization problem

The imaginative geographies of climate wars

This contribution is based on a set of reflections presented at the REGov Workshop. These reflections were offered as part of a panel discussion around the topic “Regional security and the environment.” Additional presentations provided in the context of this panel discussion include those of Richard Matthew, University of California Irvine (this volume) and Saleem H. Ali, University of Vermont (this volume). Webcasts of all presentations are available at http://www.reg-observatory.org/outputs.html

Molecule–metal bond of alternant versus nonalternant aromatic systems on coinage metal surfaces : naphthalene versus azulene on Ag(111) and Cu(111)

Interfaces between polycyclic π-electron systems and metals play prominent roles in organic or graphene-based (opto)electronic devices, in which performance-related parameters depend critically on the properties of metal/semiconductor contacts. Here, we explore how the topology of the π-electron system influences the bonding and the electronic properties of the interface. We use azulene as a model for nonalternant pentagon–heptagon (5–7) ring pairs and compare it to its isomer naphthalene, which represents the alternant 6–6 ring pair. Their coverage-dependent interaction with Ag(111) and Cu(111) surfaces was studied with the normal-incidence X-ray standing wave (NIXSW) technique, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, UV and X-ray photoelectron spectroscopies (UPS and XPS), and density functional theory (DFT). Coverage-dependent adsorption heights and spectroscopic data reveal that azulene forms shorter interfacial bonds than naphthalene and engages in stronger electronic interactions with both surfaces. These differences are more pronounced on Cu. Increasing coverages lead to larger adsorption heights, indicating bond weakening by intermolecular repulsion. The extensive DFT calculations include dispersive interactions using (1) the DFT-D3 scheme, (2) the vdWsurf correction based on DFT-TS, (3) a many-body dispersion (MBD) correction scheme, and (4) the D3surf scheme. All methods predict the adsorption heights reasonably well with an average error below 0.1 Å. The stronger bond of azulene is attributed to its nonalternant topology, which results in a reduced highest occupied molecular orbital (HOMO)–lowest occupied molecular orbital (LUMO) gap and brings the LUMO energetically close to the Fermi energy of the metal, causing stronger hybridization with electronic states of the metal surfaces

Binary Lead Fluoride Pb3F8

The binary lead fluoride Pb3F8 was synthesized by the reaction of anhydrous HF with Pb3O4 or by the reaction of BrF3 with PbF2. The compound was characterized by single-crystal and powder X-ray diffraction, IR, Raman, and solid-state MAS 19F NMR spectroscopy, as well as thermogravimetric analysis, XP and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Solid-state quantum-chemical calculations are provided for the vibrational analyses and band assignments. The electronic band structure offers an inside view of the mixed valence compound.Peer reviewe

Impaired immune response drives age-dependent severity of COVID-19.

Severity of COVID-19 shows an extraordinary correlation with increasing age. We generated a mouse model for severe COVID-19 and show that the age-dependent disease severity is caused by the disruption of a timely and well-coordinated innate and adaptive immune response due to impaired interferon (IFN) immunity. Aggravated disease in aged mice was characterized by a diminished IFN-γ response and excessive virus replication. Accordingly, adult IFN-γ receptor-deficient mice phenocopied the age-related disease severity, and supplementation of IFN-γ reversed the increased disease susceptibility of aged mice. Further, we show that therapeutic treatment with IFN-λ in adults and a combinatorial treatment with IFN-γ and IFN-λ in aged Ifnar1-/- mice was highly efficient in protecting against severe disease. Our findings provide an explanation for the age-dependent disease severity and clarify the nonredundant antiviral functions of type I, II, and III IFNs during SARS-CoV-2 infection in an age-dependent manner. Our data suggest that highly vulnerable individuals could benefit from immunotherapy combining IFN-γ and IFN-λ