Essays on Monotone Comparative Statics for Constrained Optimization Problems with Applications

My dissertation consists of three chapters. Chapters 1 and 2 both address extensions to existing monotone comparative statics results for constrained optimization problems using lattice programming techniques. Chapter 3 applies monotone comparative statics results to the question how environmental regulation affects investment in innovation in imperfectly competitive markets. Generally we can distinguish between two types of comparative statics problems. The first type of problem considers the change of the optimal solution to a maximization problem as the objective function changes, the other type considers the change due to a change in the constraint set. Lattice-based comparative statics theorems have been developed for both types of problems in the literature. The strengths of these lattice-theoretic comparative statics results are that they don't depend on the usual smoothness, interiority and concavity assumptions as required by the classical approach based on the Implicit Function Theorem, as well as convexity of the constraint set. Moreover, these comparative statics results also apply in the case of non-unique solutions.Quah (2007) expanded existing results by Milgrom and Shannon (1994) by making them applicable to some non-lattice constraint sets. In the first chapter, I extend existing comparative statics theorems to parametrized objective functions and non-lattice constraint sets. This generalization makes it possible to analyze a variety of economic optimization problems that fall into this class of problems which cannot be addressed using existing lattice-based techniques. I provide examples from consumer theory, producer theory and environmental economics that show the result's broad scope of applications. The second chapter studies monotone comparative statics with respect to price changes in the consumer's utility maximization problem. Most attempts to derive this property rely on aspects of the demand curve, and it has been hard to derive this property using assumptions on the primitive utility function. Using new results on the comparative statics of demand in Quah (2007), I provide simple and easy conditions on utility functions that yield the gross substitutes property. Quah (2007) provides conditions on utility functions that yield normal demand. I add an assumption on elasticity of marginal rate of substitution, which combined with Quah's assumptions yields gross substitutes. I apply this assumption to the family of constant elasticity of substitution preferences. My approach is grounded in the standard comparative statics decomposition of a change in demand due to a change in price into a substitution effect and an income effect. Quah's assumptions are helpful to sign the income effect. Combined with the elasticity assumption, we can sign the overall effect. As a by-product, I also present conditions which yield the gross complements property. Chapter 3 is an application of monotone comparative statics results to the question how environmental regulation affects incentives for R&D investment. For decades, there has been debate among economists whether environmental regulation hurts firms by restricting their choices or provides them with a comparative advantage through investment in innovation in more efficient technology. This chapter studies the effect of environmental regulation on firms' investment in R&D in imperfectly competitive output markets using a monotone comparative statics approach. I provide necessary and sufficient conditions on the profit function that guarantee nondecreasing R&D investment as regulation is tightened and find that a form of weak complementarity between environmental R&D investment and the policy variable plays a crucial role. Moreover, I provide properties of such profit functions through assumptions on demand, Cournot output and cost functions

Repenser la musicologie au sein des sciences humaines

À ceux qui traditionnellement mettent en doute la musicologie, proposons une réponse précise : nous musicologues cherchons par tous les moyens à comprendre comment et pourquoi l’homme a toujours et partout estimé si important de créer des formes symboliques à l’aide de formes sonores. (François-Bernard Mâche, « Éclectisme et synthèse. Les conditions d’une nouvelles musicologie générale », 1994) Au seuil de son activité d’enseignement et de direction de recherche à l’EHESS, la conférence « Les..

Moving in the Dark-Evidence for an Influence of Artificial Light at Night on the Movement Behaviour of European Hedgehogs (Erinaceus europaeus).

Berger A, Lozano B, Barthel LMF, Schubert N. Moving in the Dark-Evidence for an Influence of Artificial Light at Night on the Movement Behaviour of European Hedgehogs (Erinaceus europaeus). Animals. 2020;10(8): 1306.With urban areas growing worldwide comes an increase in artificial light at night (ALAN), causing a significant impact on wildlife behaviour and its ecological relationships. The effects of ALAN on nocturnal and protected European hedgehogs (Erinaceus europaeus) are unknown but their identification is important for sustainable species conservation and management. In a pilot study, we investigated the influence of ALAN on the natural movement behaviour of 22 hedgehogs (nine females, 13 males) in urban environments. Over the course of four years, we equipped hedgehogs at three different study locations in Berlin with biologgers to record their behaviour for several weeks. We used Global Positioning System (GPS) tags to monitor their spatial behaviour, very high-frequency (VHF) loggers to locate their nests during daytime, and accelerometers to distinguish between active and passive behaviours. We compared the mean light intensity of the locations recorded when the hedgehogs were active with the mean light intensity of simulated locations randomly distributed in the individual's home range. We were able to show that the ALAN intensity of the hedgehogs' habitations was significantly lower compared to the simulated values, regardless of the animal's sex. This ALAN-related avoidance in the movement behaviour can be used for applied hedgehog conservation

Gearing Time Toward Musical Creativity: Conceptual Integration and Material Anchoring in Xenakis’ Psappha

Understanding compositional practices is a major goal of musicology and music theory. Compositional practices have been traditionally viewed as disembodied and idiosyncratic. This view makes it hard to integrate musical creativity into our understanding of the general cognitive processes underlying meaning construction. To overcome this unnecessary isolation of musical composition from cognitive science, in this conceptual analysis, we approach compositional processes with the analytic tools of blending theory, material anchoring, and enaction. Our case study is Iannis Xenakis’ use of sieves for distributing rhythmic patterns in Psappha. Though disregarded in previous accounts, the timeline and the gearwheel provide crucial conceptual templates for anchoring Xenakis’ idea of time for this score. This case study of conceptual integration templates for temporal representation seeks to gain insight into musical creativity, embodiment, and blending, especially into how virtual interactions with material structures facilitate the construction of complex meanings

Assessing the plastic response of amorphous silica, a multiscale approach

En dépit de sa fragilité, la silice amorphe se déforme plastiquement aux échelles microscopiques. C'est ce qu'on observe par exemple en indentation. De façon remarquable, cette déformation irréversible de la silice amorphe mobilise deux processus : 1) l'écoulement en cissaillement ; 2) la densification ou compaction. Pour déterminer phénoménologiquement une loi de comportement plastique de la silice amorphe, nous avons développé des expériences de mesure mécanique à l'échelle locale (Fig., gauche). En particulier, récemment, nous avons effectué des mesures de compression uniaxiale sur des piliers de silice de petite taille [1]. Dans nos expériences les plus récentes, nous dépassons même le stade plastique et génèrons, de façon inattendue, de la fracture à ces échelles très réduites. Tous nos résultats expérimentaux sont en très bon accord avec une loi de comportement qui couple pression hydrostatique et cisaillement selon un comportement compactant (Fig., centre), en introduisant un écrouissage paramétré par la densité. Afin de mieux comprendre les origines physiques de ce comportement, nous avons conduit des simulations par dynamique moléculaire [2] (Fig., droite). En utilisant des potentiels relativement classiques, nous retrouvons qualitativement une forme de surface de charge proche de celle que nous avions identifiée à partir des expériences. En outre l'approche locale permet de donner corps à l'hypothèse que c'est le comportement de flambement de la structure locale, initialement très ouverte, qui est à l'origine de ce comportement très caractéristique. Nous montrerons alors en quoi cette vision de la plasticité de la silice amorphes est cohérente avec les autres propriétés mécaniques et physiques remarquables de la silice amorphe comme la nonlinéarité élastique anormale, le faible coefficient de Poisson et le faible coefficient de dilalation

Additive value of [18F]PI-2620 perfusion imaging in progressive supranuclear palsy and corticobasal syndrome

Purpose: Early after [18F]PI-2620 PET tracer administration, perfusion imaging has potential for regional assessment of neuronal injury in neurodegenerative diseases. This is while standard late-phase [18F]PI-2620 tau-PET is able to discriminate the 4-repeat tauopathies progressive supranuclear palsy and corticobasal syndrome (4RTs) from disease controls and healthy controls. Here, we investigated whether early-phase [18F]PI-2620 PET has an additive value for biomarker based evaluation of 4RTs. Methods: Seventy-eight patients with 4RTs (71 ± 7 years, 39 female), 79 patients with other neurodegenerative diseases (67 ± 12 years, 35 female) and twelve age-matched controls (69 ± 8 years, 8 female) underwent dynamic (0-60 min) [18F]PI-2620 PET imaging. Regional perfusion (0.5-2.5 min p.i.) and tau load (20-40 min p.i.) were measured in 246 predefined brain regions [standardized-uptake-value ratios (SUVr), cerebellar reference]. Regional SUVr were compared between 4RTs and controls by an ANOVA including false-discovery-rate (FDR, p < 0.01) correction. Hypoperfusion in resulting 4RT target regions was evaluated at the patient level in all patients (mean value - 2SD threshold). Additionally, perfusion and tau pattern expression levels were explored regarding their potential discriminatory value of 4RTs against other neurodegenerative disorders, including validation in an independent external dataset (n = 37), and correlated with clinical severity in 4RTs (PSP rating scale, MoCA, activities of daily living). Results: Patients with 4RTs had significant hypoperfusion in 21/246 brain regions, most dominant in thalamus, caudate nucleus, and anterior cingulate cortex, fitting to the topology of the 4RT disease spectrum. However, single region hypoperfusion was not specific regarding the discrimination of patients with 4RTs against patients with other neurodegenerative diseases. In contrast, perfusion pattern expression showed promise for discrimination of patients with 4RTs from other neurodegenerative diseases (AUC: 0.850). Discrimination by the combined perfusion-tau pattern expression (AUC: 0.903) exceeded that of the sole tau pattern expression (AUC: 0.864) and the discriminatory power of the combined perfusion-tau pattern expression was replicated in the external dataset (AUC: 0.917). Perfusion but not tau pattern expression was associated with PSP rating scale (R = 0.402; p = 0.0012) and activities of daily living (R = - 0.431; p = 0.0005). Conclusion: [18F]PI-2620 perfusion imaging mirrors known topology of regional hypoperfusion in 4RTs. Single region hypoperfusion is not specific for 4RTs, but perfusion pattern expression may provide an additive value for the discrimination of 4RTs from other neurodegenerative diseases and correlates closer with clinical severity than tau pattern expression

Salmonella Type III Effector AvrA Stabilizes Cell Tight Junctions to Inhibit Inflammation in Intestinal Epithelial Cells

Salmonella Typhimurium is a major cause of human gastroenteritis. The Salmonella type III secretory system secretes virulence proteins, called effectors. Effectors are responsible for the alteration of tight junction (TJ) structure and function in intestinal epithelial cells. AvrA is a newly described bacterial effector found in Salmonella. We report here that AvrA expression stabilizes cell permeability and tight junctions in intestinal epithelial cells. Cells colonized with an AvrA-deficient bacterial strain (AvrA−) displayed decreased cell permeability, disruption of TJs, and an increased inflammatory response. Western blot data showed that TJ proteins, such as ZO-1, claudin-1, decreased after AvrA- colonization for only 1 hour. In contrast, cells colonized with AvrA-sufficient bacteria maintained cell permeability with stabilized TJ structure. This difference was confirmed in vivo. Fluorescent tracer studies showed increased fluorescence in the blood of mice infected with AvrA- compared to those infected with the AvrA-sufficient strains. AvrA- disrupted TJ structure and function and increased inflammation in vivo, compared to the AvrA- sufficient strain. Additionally, AvrA overexpression increased TJ protein expression when transfected into colonic epithelial cells. An intriguing aspect of this study is that AvrA stabilized TJs, even though the other TTSS proteins, SopB, SopE, and SopE2, are known to disrupt TJs. AvrA may play a role in stabilizing TJs and balancing the opposing action of other bacterial effectors. Our findings indicate an important role for the bacterial effector AvrA in regulation of intestinal epithelial cell TJs during inflammation. The role of AvrA represents a highly refined bacterial strategy that helps the bacteria survive in the host and dampen the inflammatory response

Safety and efficacy of endoscopic spray cryotherapy for Barrett's esophagus with high-grade dysplasia

Endoscopic ablation to treat Barrett’s esophagus (BE) with high-grade dysplasia (HGD) is associated with a decreased incidence of esophageal adenocarcinoma. Endoscopic spray cryotherapy (CRYO) demonstrates promising preliminary data

Serum Neurotrophin Profile in Systemic Sclerosis

International audienceBACKGROUND: Neurotrophins (NTs) are able to activate lymphocytes and fibroblasts; they can modulate angiogenesis and sympathic vascular function. Thus, they can be implicated in the three pathogenic processes of systemic sclerosis (SSc). The aims of this study are to determine blood levels of Nerve Growth Factor (NGF), Brain-Derived Neurotrophic Factor (BDNF) and Neurotrophin-3 (NT-3) in SSc and to correlate them with clinical and biological data.METHODS: Serum samples were obtained from 55 SSc patients and 32 control subjects to measure NTs levels by ELISA and to determine their relationships with SSc profiles. FINDINGS: Serum NGF levels were higher in SSc patients (288.26 ± 170.34 pg/mL) than in control subjects (170.34 ± 50.8 pg/mL, p<0.001) and correlated with gammaglobulins levels and the presence of both anti-cardiolipin and anti-Scl-70 antibodies (p<0.05). In contrast, BDNF levels were lower in SSc patients than in controls (1121.9 ± 158.1 vs 1372.9 ± 190.9 pg/mL, p<0.0001), especially in pulmonary arterial hypertension and diffuse SSc as compared to limited forms (all p<0.05). NT-3 levels were similar in SSc and in the control group (2657.2 ± 2296 vs 2959.3 ± 2555 pg/mL, NS). BDNF levels correlated negatively with increased NGF levels in the SSc group (and not in controls). CONCLUSION: Low BDNF serum levels were not previously documented in SSc, particularly in the diffuse SSc subset and in patients with pulmonary hypertension or anti-Scl-70 antibodies. The negative correlation between NGF and BDNF levels observed in SSc and not in healthy controls could be implicated in sympathic vascular dysfunction in SSc