Bertrand Competition with an Asymmetric No-Discrimination Constraint

Abstract: We study the competitive and welfare consequences when only one firm must commit to uniform pricing while the competitor’s pricing policy is left unconstrained. The asymmetric no-discrimination constraint prohibits both behaviour-based price discrimination within the competitive segment and third-degree price discrimination across the monopolistic and competitive segments. We find that an asymmetric no-discrimination constraint only leads to higher profits for the unconstrained firm if the monopolistic segment is large enough. Therefore, a regulatory policy objective of encouraging entry is not served by an asymmetric no-discrimination constraint if the monopolistic segment is small. Only when the monopolistic segment is small and rivalry exists in the competitive segment does the asymmetric no-discrimination constraint enhance welfare.Dominant firms;price discrimination;competition policy;regulation

Price Discrimination Bans on Dominant Firms

Competition authorities and regulatory agencies sometimes impose pricing restrictions on firms with substantial market power — the “dominant” firms. We analyze the welfare effects of a ban on behaviour-based price discrimination in a two-period setting where the market displays a competitive and a sheltered segment. A ban on “higher-prices-to-shelteredconsumers” decreases prices in the sheltered segment, relaxes competition in the competitive segment, increases the rival’s profits, and may harm the dominant firm’s profits. We show that a ban on “higher-prices-to-sheltered-consumers” increases the dominant firm’s share of the first-period market. A ban on “lower-prices-to-rival’s-customers” decreases prices in the competitive segment, lowers the rival’s profits, and augments the consumer surplus. In particular, while second-period competition is relaxed by a ban on “lower-prices-to-rival’scustomers”, first-period competition is intensified substantially, which leads to lower prices “on-average” over the two periods. Our findings indicate that a dynamic two-period analysis may lead to conclusions opposite to those drawn from a static one-period analysis.dominant firms;price discrimination;competition policy;regulation

The influence of water vapour on the photocatalytic oxidation of cyclohexane in an internally illuminated monolith reactor

This paper discusses effects of humidity on photocatalytic cyclohexane oxidation performed in an internally illuminated monolith reactor equipped with an immobilised layer of approximately 3 μm titania (Hombikat uv100). Using dry nitrogen containing 10–20% of oxygen, cyclohexanone is produced with high selectivity (>90%) over cyclohexanol. The photocatalytic monolith deactivates within 80 min of operation. Regeneration of activity of such deactivated monolith is possible by air treatment at 450 °C. When the applied nitrogen/oxygen gas is humidified, stable ketone production rates are obtained around 5 × 10−6 mol h−1 at an optimised relative humidity of 65%. Ketone over alcohol selectivity is lower in humidified conditions, the ratio of the cyclohexanol/cyclohexanone production rates increases from 0.4 to 1.0 as a function of increasing humidity from 30% to 90%. Rapid transients in water vapour content lead to relatively slow changes in concentration of in situ produced cyclohexanone and cyclohexanol. The observation of these changes is used to explain the effect of humidity on reactor performance

Teeltvervroeging bij consumptieaardappel en snijmaïs op zand ten behoeve van vanggewassen

Een na-oogstmaatregel om het verlies van stikstof (N) naar het grond- en oppervlaktewater te beperken, is het telen van een onbemeste groenbemester als stikstofvanggewas na de hoofdteelt. Belangrijke factoren die de effectiviteit van een vanggewas bepalen, zijn een voldoende gewasontwikkeling en opname van de reststikstof in de nazomer/herfst en een goede benutting van de door het vanggewas opgenomen stikstof door het volggewas. De mate van ontwikkeling en stikstofopname van het vanggewas hangt onder meer af van het zaaitijdstip. Op circa 18% van het aardappelareaal op zuidelijk zand (zo‟n 2.200 ha, incl. pootgoedteelt) worden op dit moment de aardappelen vroeg genoeg gerooid (vóór 1 september) om een geslaagd vanggewas te kunnen tele

RNF168 Ubiquitinates K13-15 on H2A/H2AX to Drive DNA Damage Signaling

SummaryUbiquitin-dependent signaling during the DNA damage response (DDR) to double-strand breaks (DSBs) is initiated by two E3 ligases, RNF8 and RNF168, targeting histone H2A and H2AX. RNF8 is the first ligase recruited to the damage site, and RNF168 follows RNF8-dependent ubiquitination. This suggests that RNF8 initiates H2A/H2AX ubiquitination with K63-linked ubiquitin chains and RNF168 extends them. Here, we show that RNF8 is inactive toward nucleosomal H2A, whereas RNF168 catalyzes the monoubiquitination of the histones specifically on K13-15. Structure-based mutagenesis of RNF8 and RNF168 RING domains shows that a charged residue determines whether nucleosomal proteins are recognized. We find that K63 ubiquitin chains are conjugated to RNF168-dependent H2A/H2AX monoubiquitination at K13-15 and not on K118-119. Using a mutant of RNF168 unable to target histones but still catalyzing ubiquitin chains at DSBs, we show that ubiquitin chains per se are insufficient for signaling, but RNF168 target ubiquitination is required for DDR

Duurzame maïsteelt op zandgrond : verslag van een deskundigendag, gehouden op 22 april 2010

Voor de melkveehouderij op zandgrond is de maïsteelt belangrijk. Zetmeelrijke, eiwitarme maïs combineert uitstekend met zetmeelarm maar eiwitrijk gras, wat goed is voor de koe maar ook voor het milieu omdat een maïsgewas zeer efficiënt met water omgaat en omdat een rantsoen met maïs de emissies van lachgas en ammoniak beperkt. Bovendien kan door de voeding van maïs op krachtvoer worden bespaard. Daar staat tegenover dat op veel bedrijven bij de maïsteelt te veel meststoffen en herbiciden naar het grond- en oppervlaktewater verloren gaan. Dat maakt het voor waterbeheerders moeilijk te voldoen aan de kwaliteitsnormen die de Kaderrichtlijn Water (KRW) stelt. Ook de maïstelers zijn daar niet blij mee, omdat dit duidt op een slechte benutting van grondstoffen. De teeltkosten zijn dan te hoog, de gewasopbrengsten te laag, of de bodemkwaliteit lijdt eronder

Stroke Etiology and Thrombus Computed Tomography Characteristics in Patients With Acute Ischemic Stroke:A MR CLEAN Registry Substudy

Background and Purpose - If a relationship between stroke etiology and thrombus computed tomography characteristics exists, assessing these characteristics in clinical practice could serve as a useful additional diagnostic tool for the identification of stroke subtype. Our purpose was to study the association of stroke etiology and thrombus computed tomography characteristics in patients with acute ischemic stroke due to a large vessel occlusion. Methods - For 1429 consecutive patients enrolled in the MR CLEAN Registry, we determined stroke cause as defined by the TOAST (Trial of ORG 10172 in Acute Stroke Treatment) criteria. The association of stroke etiology with the hyperdense artery sign, clot burden score, and thrombus location was estimated with univariable and multivariable binary and ordinal logistic regression. Additionally, for 367 patients with available thin-section imaging, we assessed the association of stroke etiology with absolute and relative thrombus attenuation, distance from internal carotid artery-terminus to thrombus, thrombus length, and thrombus attenuation increase with univariable and multivariable linear regression. Results - Compared with cardioembolic strokes, noncardioembolic strokes were associated with presence of hyperdense artery sign (odds ratio, 2.2 [95% CI, 1.6-3.0]), lower clot burden score (common odds ratio, 0.4 [95% CI, 0.3-0.6]), shift towards a more proximal thrombus location (common odds ratio, 0.2 [95% CI, 0.2-0.3]), higher absolute thrombus attenuation (β, 3.6 [95% CI, 0.9-6.4]), decrease in distance from the ICA-terminus (β, -5.7 [95% CI, -8.3 to -3.0]), and longer thrombi (β, 8.6 [95% CI, 6.5-10.7]), based on univariable analysis. Thrombus characteristics of strokes with undetermined cause were similar to those of cardioembolic strokes. Conclusions - Thrombus computed tomography characteristics of cardioembolic stroke are distinct from those of noncardioembolic stroke. Additionally, our study supports the general hypothesis that many cryptogenic strokes have a cardioembolic cause. Further research should focus on the use of thrombus computed tomography characteristics as a diagnostic tool for stroke cause in clinical practice

Diagnostic Accuracy of 4 Commercially Available Semiautomatic Packages for Carotid Artery Stenosis Measurement on CTA

BACKGROUND AND PURPOSE: Semiautomatic measurement of ICA stenosis potentially increases observer reproducibility. In this study, we assessed the diagnostic accuracy and interobserver reproducibility of a commercially available semiautomatic ICA stenosis measurement on CTA and estimated the agreement among different software packages. MATERIALS AND METHODS: We analyzed 141 arteries from 90 patients with TIA or ischemic stroke. Manual stenosis measurements were performed by 2 neuroradiologists. Semiautomatic measurements by using 4 methods (3mensio and comparable software from Philips, TeraRecon, and Siemens) were performed by 2 observers. Diagnostic accuracy was estimated by comparing semiautomatic with manual measurements. Interobserver reproducibility and agreement between different packages was assessed by calculation of the intraclass correlation coefficient and Bland-Altman 95% limits of agreement. False-negative classifications were retrospectively inspected by a neuroradiologist. RESULTS: There was no significant difference in the diagnostic performance of the 4 semiautomatic methods. The sensitivity for detecting >= 50% and >= 70% degree of stenosis was between 76% and 82% and 46% and 62%, respectively. Specificity and overall diagnostic accuracy were between 92% and 97% and 85% and 90%, respectively. The interobserver intraclass correlation coefficient was between 0.83 and 0.96 for semiautomatic measurements and 0.81 for manual measurement. The limits of agreement between each pair of semiautomatic packages ranged from -18%-24% to -33%-31%. False-negative classifications were caused by ulcerative plaques and observer variation in stenosis and reference measurements. CONCLUSIONS: Semiautomatic methods have a low-to-good sensitivity and a good specificity and overall diagnostic accuracy. The high interobserver reproducibility makes semiautomatic stenosis measurement valuable for clinical practice, but semiautomatic measurements should be checked by an experienced radiologist

Long-Term outcome of two-stage revision surgery after hip and knee prosthetic joint infections: An observational study

Introduction: Two-stage revision surgery is the most frequently performed procedure in patients with a chronic periprosthetic joint infection (PJI). The infection eradication rates in the current literature differ between 54 % and 100 %, which could be attributed to different treatment strategies. The aim of this study was to retrospectively evaluate the infection eradication rate in patients with chronic PJI treated with two-stage revision surgery of the hip or knee in primary and re-revision cases. Methods: All patients treated with a two-stage revision for chronic PJI between 2005 and 2011 were analysed. Patient and infection characteristics were retrieved. Primary outcome was successful infection eradication at last follow-up. Successful eradication is specified as no need for subsequent revision surgery or suppressive antibiotic treatment. Results: Forty-seven patients were treated with a two-stage revision. Infection eradication was achieved in 36 out of 47 cases. Thirty-eight patients had positive cultures: 35 monomicrobial infections and 3 polymicrobial infections. Nine cases of culture-negative infections were identified. Accompanying eradication rates were 26 out of 35 cases, 2 out of 3 cases, and 8 out of 9 cases respectively. Mean follow-up was 128 (27-186) months. For hip and knee revisions the eradication rates were 22 out of 31 cases and 14 out of 16 cases respectively. After primary arthroplasty the infection was eradicated in 29 out of 38 cases and after re-revision in 7 out of 9 cases. Conclusion: In this study, the infection eradication rate for two-stage revision surgery after PJI of the hip and knee in primary and re-revision cases was 77 %. No statistically significant patient, infection and micro-organism characteristics were found which influence the infection eradication rates at long-term follow-up of 128 (27-186) months