Academic literature on the topic 'Réactions de contraction de cycle'

<p>Business cycle is the repeated expansions (from trough to peak) and contractions (from peak to trough) of real economic activity. Credit cycle is the cyclical process of the bank credit, ranging from short/long-term, loan to enterprise and loan to individual. Financial cycle reflects ups and downs in asset prices and financial institution's balance sheet. This paper examines the linkage among cycles as well as their lead-lag relationship. Theoretically, credit cycle is one of reasons driving business cycle, and financial cycle is a fundamental cause of credit cycle. Based on Taiwan’s quarterly data, this paper firstly identifies cyclical behavior of indicators of real economic activity, bank credit and assets prices in recent decade by defining expansion phases and contraction phases of cyclical variables. Second, this paper calculates concordance index to examine the degree of synchronization among cycles. Third, while the soundness for assets and liabilities of financial institution may drive financial cycle, this paper employs IMF’s Financial Soundness Indicator (FSI) as predictor of expansion and contraction phase of cyclical variables. Specifically, the paper assesses the health of bank’s balance sheet variables by Probit estimation on linkage between FSIs and expansion/contraction phase of cycle. Based on empirical evidence, the knowledge about the extent of assets/liability condition of financial institution corresponding to the expansion and contraction phase of financial, credit and business cycle is enhanced. Authority concerning about financial stability should oversight the performance of FSIs and then engage in prompt corrective actions when the level and volatility of those indicators sharply.</p>

Gated31P-nuclear magnetic resonance followed the metabolic fluctuation in rat gastrocnemius muscle during a contraction cycle. Within 16 ms after stimulation, the phosphocreatine (PCr) level drops 11.3% from its reference state. The PCr minimum corresponds closely to the time of maximum force contraction. Pi increases stoichiometrically, while ATP remains constant. During a twitch, PCr hydrolysis produces 3.1 μmol ATP/g tissue, which is substantially higher than the reported 0.3 μmol ATP ⋅ twitch−1 ⋅ g tissue−1 derived from steady-state experiments. The results reveal that a substantial energy fluctuation accompanies a muscle twitch.

The influence of cardiac phase on the response of the cardiac pacemaker to dynamic hand contraction in eight healthy young men was studied to determine whether heart rate response to muscle contraction varied as a function of timing within the cardiac cycle. Changes in R-R interval (RRI) in response to muscle contraction were measured at various cardiac phases during heartbeat-synchronized handgrip at a rate of one contraction per two heartbeats. To extract the direct effect of the muscle contraction on the RRI, spontaneous slow variations and respiratory sinus arrhythmia were removed from the total RRI fluctuations in the frequency domain. Cross-correlograms between the extracted RRI fluctuations and muscle contraction showed that the coupling was strong when the muscle contraction occurred at the middle phase of the cardiac cycle. Muscle contraction at the systolic phase of the cardiac cycle had a tendency to produce a phase advance (shortening of RRI), whereas muscle contraction at the middle phase or later had a tendency to produce a phase delay (prolongation of RRI). The results showed the presence of a neuronal circuit that modulates the cardiac pacemaker activity depending on the timing of muscle contraction in the cardiac cycle.

The effects of diaphragmatic contraction frequency (no. of intermittent tetanic contractions/min) at a given tension-time index and of duty cycle (contraction time/total cycle time) on diaphragmatic blood flow were measured in anesthetized mongrel dogs during bilateral supramaximal phrenic nerve stimulation. Diaphragmatic blood flow was measured by the radionuclide-labeled microsphere method. Contraction frequency was varied between 10 and 160/min at duty cycles of 0.25 and 0.75. Diaphragmatic blood flow increased with contraction frequency from 1.47 +/- 0.13 ml X min-1 X g-1 (mean +/- SE) at an average of 18/min to 2.65 +/- 0.16 ml X min-1 X g-1 at 74/min (P less than 0.01) with a duty cycle of 0.25 and from 1.32 +/- 0.19 ml X min-1 X g-1 at an average of 15/min to 1.96 +/- 0.15 ml X min-1 X g-1 at 80/min (P less than 0.02) with a duty cycle of 0.75. At higher contraction frequencies diaphragmatic blood flow did not increase further at both duty cycles. In addition, diaphragmatic blood flow was higher with a duty cycle of 0.25 than 0.75 at all contraction frequencies. We conclude that frequency of contraction is a major determinant of diaphragmatic blood flow and that high duty cycle impedes diaphragmatic blood flow.

Benzoate displacement of the 2-triflyl derivative of methyl 3-azido or 3-O-benzoyl-4-deoxy-α-DL-thero-pentopyranoside (1 or 4) occurs with a pyranose to furanose contraction reaction at C-2. This contraction is not observed with an azido displacement.

Ces travaux de thèse s'inscrivent dans un projet à long terme concernant le développement de nouvelles réactions de contraction de cycle originales afin d'accéder à des édifices moléculaires organisés à activités biologiques potentielles. Généralement découvertes de manière fortuite, les réactions de contraction de cycle sont des réarrangements offrant l'avantage de modifier rapidement le squelette des molécules et permettant donc un accès facile à des analogues structurels, une propriété intéressante et utile aussi bien en chimie de synthèse qu'en chimie médicinale. Dans cette optique, trois réactions de contraction de cycle différentes ainsi que leurs applications seront rapportées dans ce manuscrit. La première décrit la réactivité particulière des bis-Boc 2,5-dicétopipérazines (DKPs) en milieu basique et leur conversion en hydantoïnes, deux squelettes hétérocycliques d'intérêt pharmacologique. Ce nouveau réarrangement a été appliqué à différentes DKPs avec des rendements satisfaisants et de bons excès énantio- ou diastéréoiso-mériques. L'intérêt des bis-Boc DKPs en tant que plateforme de départ dans la construction de structures complexes a ensuite été démontré lors de l'obtention de spirolactames grâce à l'utilisation de la réaction de réarrangement transannulaire de lactames activés (TRAL) et la mise au point d'une stratégie de cyclisation rapide et efficace. Après dimérisation de ces bicycles, les études par dichroïsme circulaire, RMN et modélisation moléculaire ont mis en évidence un comportement similaire à celui d'hélices de polyproline II (PPII), des structures peptidiques secondaires largement impliquées dans les interactions protéine-protéine et dans des processus pathogènes. Afin de valider le potentiel de mimes de nos dimères, une fonctionnalisation de ces substrats s'est avérée nécessaire, qui a été en partie réalisée grâce à la découverte d'une nouvelle réaction de contraction de cycle. Effectuée à chaud dans plusieurs solvants et en présence d'un catalyseur de type triflate, ce réarrangement permet la conversion de quelques bicycles accolés en spirocycles avec de bons rendements. L'intérêt de ces travaux réside ainsi sur l'utilisation de 2,5-dicétopipérazines activées comme substrat de départ et démontre la gamme d'applications multiples des réactions de contraction de cycle.

Cette thèse présente la découverte d'une nouvelle transformation, soit la contraction de cycle de lactames N -hétérosubstituées, ainsi que son application sur plusieurs substrats. Le premier chapitre présente la découverte de cette réaction lors de l'étude de la réactivité de radicaux amidyles générés à partir de l'irradiation de N -chlorolactames, envers des alcènes dans des réactions intramoléculaires. Le second chapitre est une revue de la littérature à propos de tous les types de réarrangements impliquant la formation d'un nouveau lien carbone - azote. Le troisième chapitre présente une étude permettant de connaître les possibilités et les limitations de ce réarrangement. Plusieurs substrats différents ont été synthétisés et leur réarrangement y est présenté. Le quatrième chapitre présente les détails de l'étude mécanistique qui a permis de proposer un mécanisme pour ce réarrangement, ainsi que les expériences effectuées dans le but d'augmenter le rendement de la réaction de contraction de cycle. Finalement le chapitre cinq présente la synthèse de dérivés N -mésyloxylactames ainsi que les résultats obtenus lors de leur photolyse. Ces dérivés ont permis d'obtenir des rendements en produit de contraction de cycle supérieurs à 70%, ce qui rend cette réaction utile du point de vue de la synthèse pour la préparation de composés naturels, par exemple.

Le but de ce travail est d'essayer d'expliquer les modifications des propriétés élastiques d'un muscle soumis à l'étirement. Les études et les interprétations sont basées sur la modélisation du muscle réalisée à partir du modèle de Hill sur lequel sont venues se greffer les connaissances de l'ultrastucture des myofibrilles [. . . ]

Cette thèse est consacrée à la modélisation du fonctionnement mécanique de l'interaction myosine II / actine, qui est responsable de la génération de force active dans les muscles squelettiques à l'échelle nanomérique. Les unités contractiles du muscle contiennent les filaments d'actine et de myosine, les derniers sont formés par un assemblage des myosines II. La myosine II est un moteur moléculaire qui s'attache et se détache périodiquement au filament d'actine en présence d'ATP. Afin de comprendre le phénomène de la contraction musculaire d'un point de vue mécanique, nous suivons l'approche développée par la communauté de cliquets Browniens, qui remplace l'interprétation chimique traditionnelle de génération de force active par une étude de la dynamique de Langevin des systèmes mécaniques avec des paysages énergétiques bien définis. Nous mettons l'accent sur le rôle du changement conformationnel, ou " power stroke ", dans le fonctionnement de la myosine II. Nous identifions le "power stroke" comme le principal moteur de la contractilité, ce qui reflète la réalité biologique. Nous proposons un modèle mécanique innovant et, en mettant l'accent sur le rôle actif de " power stroke ", nous établissons un lien entre les moteurs processifs et nonprocessifs. Dans cette thèse, nous présentons les premiers exemples de modèles de moteur moléculaire nonprocessif actionnés exclusivement par "power stroke " et exploitant le phénomène de la résonance stochastique.

Le cation diphosphireniun, synthetise dans notre equipe en 1991, constitue la cle de voute de cette these. Ce derive cyclique a trois chainons, possedant deux electrons , est isoelectronique des cations cyclopropeniums. De ce fait, dans un premier temps, nous avons realise une etude bibliographique relative aux cycles a trois chainons et deux electrons en chimie des elements principaux. Dans un deuxieme temps, apres avoir determine le mecanisme de formation de ce cation diphosphirenium, sa reactivite a ete etudiee vis-a-vis de differents composes nucleophiles. Ainsi, l'action de lithiens conduit, par ouverture de cycle, aux c-phosphinophosphaalcenes correspondants. Ces derniers derives sont les precurseurs de nouveaux heterocycles a trois et quatre chainons: un 1h-diphosphirene et un 1,2,3-triphosphetene. L'addition d'un complexe zerovalent du palladium pd(pph#3)#4 sur le cation diphosphirenium nous a permis d'isoler deux nouveaux types de metallacycles: les 1-pallada(ii)-2#4,4#2-diphosphacyclobutenes et les 1,3-diphospha-2,4-dipallada(ii)tricyclo 1. 1. 1pentanes. La photolyse du cation diphosphirenium conduit, par un processus de retrocycloaddition 2+1, au diisopropylaminophosphaalcyne, alors que, par reduction chimique ou electrochimique, un compose cyclique radicalaire original a ete isole. Enfin, dans la derniere partie, la synthese d'un 1,3-diphosphetene cationique a ete decrite. Cet heterocycle est le precurseur de nouveaux cycles a quatre chainons: les 1,2-dihydro-1,2-diphosphetes et un 1,3-diphosphacyclobutene. Des cycles a quatre chainons et six electrons , les 1,3-diphosphacyclobutane-2,4-diyl, ont ete postules comme intermediaires reactionnels

La modélisation des systèmes biologiques, particulièrement à l'échelle moléculaire, est une problématique nouvelle, issue de l'apport des techniques à haut débit. Le défi en modélisation mathématique est de pouvoir analyser le comportement de ces systèmes dynamiques de très grande dimension. L'enjeu est de taille, car la compréhension du fonctionnement normal et pathologique des cellules au niveau moléculaire, ouvre la voie aux thérapies ciblés pour des maladies systémiques telles que le cancer. Pour s'affranchir des problèmes liés à l'imprécision des valeurs des paramètres, cette thèse propose de travailler avec des ordres, plutôt qu'avec des valeurs précises de paramètres. Ceci conduit naturellement à l'utilisation de l'analyse tropicale pour obtenir des modèles réduits et hybrides. Ces développements ouvrent des nouvelles perspectives sur le plan mathématique, concernant l'étude de systèmes dynamiques. Cette étude propose quelques résultats concernant la tropicalisation des systèmes d'équations différentielles. Une autre partie de la thèse est consacrée à l'étude numérique des systèmes hybrides. La question ici est comment construire un modèle hybride qui reproduit un comportement expérimental donné, aussi comment identifier un modèle hybride à partir de séries temporelles. Cette thèse propose un algorithme original d'identification. Cet algorithme sépare le problème en deux sous-problèmes, notamment l'identification des paramètres des modes et l'identification des paramètres de commande des modes. Des applications à relativement grande échelle sont abordées par cette approche, notamment un modèle de cycle cellulaire chez les mammifères.

Lors de ce travail nous avons synthétisé plusieurs benzothiénoindolizidinones, indolizidinédiones et quinolizidinones par réaction de type Friedel et Crafts à partir des acides carboxyliques correspondants. La réaction de Schmidt appliquée à ces cétones conduit sélectivement aux benzothiéno |1,3| diazépines fusionnées à divers cycles azotes : pyrrolidine, pyrrolidone et pipéridine. Une transposition de Beckmann aboutit également en série pyrrolidinique à la même |1,3| diazépine. La thermolyse de carbonylazides convenablement substitues en série benzothiophenique, dans l'acide acétique glacial, nous a permis d'accéder aux benzothienopyrrolo |1,4| diazepines et diazépinones. Un mécanisme rendant compte de ce réarrangement est discuté. La cyclodésydratation intramoléculaire de Diols ainsi que l'application de la réaction de Pictet-Spengler en série thiophénique, aboutissent aux thiénopyrroloxazocines et thienopyrrolodiazocines. Par ailleurs, une voie originale permettant d'obtenir la thiénophyrrolo |1,3| diazépine est proposée. Enfin, la première synthèse d'indolizines |2(3), 3(2)-f| fusionnées au thiophène et au |1| benzothiophène est présentée. L'étude de certaines propriétés chimiques de ces structures, notamment vis-à-vis de dienophiles actifs, nous a permis d'accéder dans de bonnes conditions aux |3,2,2| cyclazines correspondantes par cycloadditions (1,3) dipolaires

La distillation réactive constitue une voie de production prometteuse pour améliorer les procédés conventionnels. Cependant les méthodes, outils et applications proposés dans la littérature se limitent aux systèmes réactifs en phase liquide. L'objectif majeur des travaux est ainsi de généraliser l'approche de conception séquentielle et hiérarchisée proposée par R. Théry (2002). Au niveau des outils, un modèle mathématique général de condensation et d'évaporation ouvertes de systèmes réactifs à l'équilibre, applicable quelque soit la phase dans laquelle a lieu la réaction est développé. Au niveau de l'approche, les méthodes pour l'analyse de faisabilité, la synthèse et la conception sont étendues et adaptées au cas d'une réaction chimique en phase vapeur. Les outils développés et la méthodologie proposée sont appliqués à la conception d'un procédé de distillation réactive en phase vapeur pour la production d'hydrogène à partir de solutions de H2O-HI-I2 du cycle thermochimique I-S.
Reactive distillation is a promising way to improve classical processes. This interest has been comforted by numerous successful applications involving reactive systems in liquid phase but never in vapour phase. In this context, general design tools have been developed for the analysis of reactive distillation processes whatever the reactive phase. A general model for open condensation and evaporation of vapour or liquid reactive systems in chemical equilibrium has been written and applied to extend the feasibility analysis, synthesis and design methods of the sequential design methodology of R. Thery (2002). The extended design methodology is applied to the industrial production of hydrogen through the iodine-Sulphur thermochemical cycle by vapour phase reactive distillation. A column configuration is proposed with better performance formerly published configuration

This chapter explains what the business cycle is and what causes business-cycle fluctuations. We call fluctuations in economic activity around the long-term growth trend ‘the business cycle’. The business cycle consists of two phases. The first is a period of strong economic activity. The second, following the first, is a period of weak economic activity. We call the first phase of the business cycle an ‘expansion’ and the second phase a ‘contraction’ or ‘recession’. The chapter explains what causes business cycles, and examines the empirical evidence on the lengths and strengths of the typical business cycle. It finds that expansions typically last longer than recessions. The chapter also shows that the length of expansions has increased during recent decades.

Generally all firms can operate only in the environment of the economy. The changes in corporate performance are closely related to expansion and contraction of the business cycle. The economic climate might have a greater impact on profits than the firm's performance within its industry. The corporate performance in the hotel industry may also rely on economic conditions. Thus, the significance of a firm is closely tied to the state of the economy (or economic climate).

In this paper, a novel technology based on the zero CO2 emission MATIANT (contraction of the names of the 2 designers: MATHIEU and IANTOVSKI) cycle is presented. This latter is basically a gas cycle and consists of a supercritical CO2 Rankine-like cycle on top of regenerative CO2 Brayton cycle. CO2 is the working fluid and O2 is the fuel oxidizer in the combustion chambers. The cycle uses the highest temperatures and pressures compatible with the most advanced materials in the steam and gas turbines. In addition, a reheat and a staged compression with intercooling are used. Therefore the optimized cycle efficiency rises up to around 45% when operating on natural gas. A big asset of the system is its ability to remove the CO2 produced in the combustion process in liquid state and at high pressure, making it ready for transportation, for reuse or for final storage. The assets of the cycle are mentioned. The technical issues for the predesign of a prototype plant are reviewed.

Power generating gas turbines employ an inlet duct or contraction to accelerate air to the operating inlet velocity of the compressor. Multiple passages of this kind are necessary in gas turbines with cycle modifications such as intercooling. An experimental investigation was carried out to obtain flow characteristics of a curved wall annular contraction. The results are described in terms of the velocity vectors, surface pressure coefficients, static and stagnation pressure distributions, and profiles of mean velocities, turbulence intensity, and Reynolds shear stress. The upstream flow conditions were changed to evaluate how they affected the flow development in the passage. Results show that the static pressure and axial velocity profiles at the contraction exit were uniform. Higher inlet turbulence increased the Reynolds shear stress although the effect on the static and total pressure fields was negligible. The overall stagnation pressure loss was approximately 2 to 3 percent of the dynamic head at the contraction exit.

This contribution presents the development and design of a two-stage contraction zone and modular test section for a closed loop Organic Rankine Cycle (ORC) wind tunnel. The first contraction consists of four truncated cones, whose length and angle of inclination are derived from a two-stage optimization procedure, with the objective to minimize flow deviation and to avoid boundary-layer separation. The geometrical optimization yields a profile with minor deviation to the ideal polynomial shape, whereas the flow optimized shape minimizes flow separation at the break-points between the single conical pieces. The second contraction has to perform two major tasks, namely the acceleration of the flow up to a Mach number of Ma = 0.8 for organic fluids and the transformation of the circular inlet to a rectangular outlet cross-sectional shape, required by the working section. The circular-to-rectangular transition is accomplished by variation of the generalized ellipse, also known as Lamé curve. Smooth polynomials are then used to define the reduction of cross-sectional area. A comprehensive number of contraction geometries with fixed contraction ratio, variable length, and different points of inflection are analyzed with regards to minimum flow deviation, the avoidance of flow separation, as well as a uniform velocity field at the contraction outlet. A semi-analytical approach based on a potential flow solution in combination with the Stratford criterion is the basis for evaluating boundary-layer separation. The design of a two-part modular diffuser, based on the concept of a dumped diffuser, as commonly encountered in gas turbine design, is presented. The numerical results are compared with analytical findings and special characteristics of the different designs are explained. Finally, the overall design concept of the test section is presented.

The Organic Rankine Cycle (ORC) offers a great potential for recovering waste heat and using low-temperature sources for power generation. However, the ORC thermal efficiency is limited by the relatively low temperature level, and, therefore, designing ORC components with high efficiencies and minimized losses is of major importance. Such an approach requires the use of a specially designed closed cascade wind tunnel. This contribution presents the design of the contraction zone shape. The ideal shape can be defined by a sixth order polynomial yielding a smooth curve for the nozzle profile. Due to pressure vessel costs, it is not possible to realize the whole contraction zone as one piece for this wind tunnel. Instead, a piece-wise conical design approach is chosen. Classical nozzle design guidelines do not offer an analytical solution to this flow problem. Therefore, computational fluid dynamics (CFD) in combination with Stratford’s separation criterion is used for an optimization study of a piece-wise conical contraction zone. Different combination of numbers of components, length, and inflection points are investigated. The optimization minimizes the flow deviation of the chosen profile to the optimal shape in two steps: a geometrical approach to the optimal shape and an optimization of the flow field within the contraction zone. The geometrical optimization yields a profile with minor deviation to the ideal shape. For the flow field optimization, a CFD analysis is used to minimize flow separations at the break points between the single conical pieces, especially those at the far end of the contraction zone. All shapes are investigated by Stratford’s separation criterion, which is adopted to conical pieces. The presented analysis indicates that the flow field optimization yields a much better approach for the fluid dynamics of the wind tunnel than the geometrical approach.

Diastolic heart dysfunction (DHD) is a common finding in a variety of cardiac diseases including hypertension, coronary disease and cardiomyopathy. Its prevalence increases with age and it manifests as incomplete or/and delayed ventricular relaxation and a compensatory stronger atrial contraction. DHD is often associated with heart failure and contributes greatly to morbidity and hospitalizations especially in the elderly[3]. DHD is a very rich problem in fluid mechanics and it involves complex hemodynamic interactions among all of major cardiac phases during the whole cardiac cycle including ventricular filling, diastatsis, atrial filling, and systole[1]. Most studies to-date have, however, employed simple time varying volume-change profiles to model and examine the dynamics of ventricular filling[2]. Intercardiac flow effects i.e. interaction between filling and ejection have, however, not been investigated in detail. Also not studied in detail is the role of multiphasic filling which consists of early (E) filling, diastasis, and atrial (A) filling. In the current study, we will utilize three dimensional simulations to study the hemodynamics of DHD during the whole cardiac cycle. The vortex structure, filling velocity, intraventricular pressure gradient and energy budget will be analyzed to uncover the biomechanical effects and genesis of DHD.

Simulation of a dissimilar metal weld (DMW) in a pressurised water reactor (PWR) nozzle was performed to predict both axial distortion and hoop residual stresses in the weld. For this work a computationally efficient axi-symmetric finite element (FE) simulation was carried out rather than a full 3D analysis. Due to the 2-dimensional nature of the analysis it was necessary to examine the effect of structural restraint during welding of the main dissimilar metal weld (DMW). Traditionally this type of analysis is set up to allow one end of the structure, in this case the safe-end forging, to be unrestrained in the axial direction during welding. In reality axial expansion and subsequent contraction of deposited weld metal at the current torch position is restrained by solidified material both ahead and behind the torch. Thus the conventional axi-symmetric analysis is under-restrained in the axial direction at least during the early weld passes. The significance of this was examined by repeating the current simulation with the safe-end forging fixed to limit expansion during the heat up cycle. Contraction was however, allowed during cooling cycle. This modified boundary control method provided a significantly improved prediction of the axial distortion across the weld as well as improved prediction of through wall axial and hoop residual stresses.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.