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In a variety of laboratory preparations, several animal species prefer signaled over unsignaled outcomes. Here we examine whether pigeons prefer options that signal the delay to impending reward over options that do not and how this preference changes with the ratio of the delays. We offered pigeons repeated choices between two alternatives leading to a short or a long delay to reward. For one alternative (informative), the short and long delays were reliably signaled by different stimuli (e.g. SS for short delays, SL for long delays). For the other (non-informative), the delays were not reliably signaled by the stimuli presented (S1 and S2). Across conditions, we varied the durations of the short and long delays while keeping the average delay to reward constant. Pigeons preferred the informative over the non-informative option and this preference became stronger as the ratio of the long to the short delay increased. A modified version of the Δ-Σ hypothesis (González et al., 2020a) incorporating a contrast-like process between the immediacies to reward signaled by each stimulus accounted well for our findings. Functionally, we argue that a preference for signaled delays hinges on the potential instrumental advantage typically conveyed by information.

Introduction COVID-19 vaccines have been highly effective in reducing morbidity and mortality during the pandemic. However, the emergence of the Omicron (B.1.1.529) variant and subvariants as the globally dominant strains have raised doubts about the effectiveness of currently-available vaccines and prompted debate about potential future vaccination strategies. Areas covered Using the publicly available IVAC VIEW-hub platform, we reviewed 52 studies on vaccine effectiveness (VE) after booster vaccinations. VE data were reported for SARS-CoV-2 symptomatic infection, severe disease and death and stratified by vaccine schedule and age. In addition, a non-systematic literature review of safety was performed to identify single or multi-country studies investigating adverse event rates for at least two of the currently-available COVID-19 vaccines. Expert opinion Booster shots of the current COVID-19 vaccines provide consistently high protection against Omicron-related severe disease and death. Additionally, this protection appears to be conserved for at least 3 months, with a small but significant waning after that time. The positive risk-benefit ratio of these vaccines is well established, thus increasing confidence in administering additional doses as required. Future vaccination strategies will likely include a combination of schedules based on a person’s risk profile, as overly frequent boosting may be neither beneficial nor sustainable for the general population.

Objective: To describe our experience with using intraoperative Transesophageal Echocardiography (TEE) to assess the size of the rapid deployment prosthetic valves by measuring the native aortic annulus. Methods: Retrospective review of single institution series of patients undergoing Aortic Valve Replacement with Rapid Deployment Bioprosthetic Valves. Included were patients who had their native aortic valve replaced either isolated or as part of any additional procedure. The aortic annulus was measured prior to initiation of the operation using TEE. An analysis was conducted between Echocardiographic annular measurements and actual implanted valve sizes. Results: Forty patients underwent rapid deployment valve implantation in the aortic position. Of these, 32.5% of patients had the same size valve as the measured aortic annulus, 40% of patients had a valve implanted that was 1 mm different, and 25% of patients had 2 mm difference. One patient (2.5%) was found to have an aortic annular measurement of 3mm less than the actual implanted valve. The mean annular size based on intraoperative TEE was 23.5 mm (range: 21-28 mm, sdv: 1.8). The mean valve size implanted was 23.7 mm (range: 21-27 mm, sdv: 1.9). There was no statistically significant difference between the mean annular measurement and the valve size selected (0.2 mm, p = 0.50). Conclusion: TEE can further enhance valve sizing and guidance through a proper and safe deployment. Although evident in our experience, larger scale studies are needed to further elucidate conclusions on the importance of avoiding under-sizing valves.

To establish the current situation of antimicrobial resistance and antibiotic consumption in Mexican hospitals.Antimicrobial susceptibility data from blood and urine isolates were collected. Defined daily dose (DDD) of antibiotic consumption/100 occupied beds (OBD) was calculated.Study period: 2016 and 2017. Of 4 382 blood isolates, E. coli and K. pneumoniae were most frequently reported, with antimicrobial resistance30% for most drugs tested, only for carbapenems and amikacin resistance were20%. A. baumannii had antimicrobial resistance20% to all drugs. Resistance to oxacillin in S. aureus was 20%. From 12 151 urine isolates, 90% corresponded to E. coli; resistance to ciprofloxacin, cephalosporins and trimethoprim/sulfamethoxazole was50%, with good susceptibility to nitrofurantoin, amikacin and carbapenems. Global median antimicrobial consumption was 57.2 DDD/100 OB.s. This report shows a high antimicrobial resistance level in Gram-negative bacilli and provides an insight into the seriousness of the problem of antibiotic consumption.Establecer la situación actual de la resistencia antimicrobiana y el consumo de antibióticos en hospitales mexicanos.Se colectaron datos de susceptibilidad antimicrobiana de aislamientos de sangre y orina. Se calculó la dosis diaria definida (DDD) del consumo de antibióticos/100 estancias.Periodo de estudio de 2016 a 2017. De 4 382 aislamientos en sangre, E. coli y K. pneumoniae fueron las más frecuentes, con resistencia30% a la mayoría de las drogas evaluadas; sólo para carbapenémicos y amikacina la resistencia fue20%. A. baumannii tuvo resistencia20% a todos los fármacos. La resistencia a oxacilina en S. aureus fue de 20%. De 12 151 aislamientos en urocultivos, 90% correspondió a E. coli; la resistencia a ciprofloxacina, cefalosporinas y trimetoprima/sulfametoxazol fue50%, con buena susceptibilidad a nitrofurantoína, amikacina y carbapenémicos. La mediana del consumo global de antibióticos en DDD/100 estancias fue de 57.2.Este reporte muestra el nivel elevado de resistencia en bacilos Gram-negativos y brinda una perspectiva de la gravedad del problema del consumo de antibióticos.

Objective: There is paucity of data on outcomes after isolated tricuspid valve surgery. This meta-analysis aims to compile available data on isolated tricuspid valve surgery and compare isolated tricuspid valve repair (iTVr) with isolated tricuspid valve replacement (iTVR) to elucidate outcomes after tricuspid valve surgery. Methods: A literature search of 6 databases was performed. The primary outcomes was 30-day mortality. Secondary outcomes were early stroke, post-op pacemaker placement, and tricuspid reoperation within 5 years. Publication bias was explored using the funnel plot. Results: Ten retrospective studies involving 1407 patients (iTVr group = 779 patients and iTVR group = 628 patients) were included. A cumulative analysis demonstrated a significant difference favoring iTVr for 30-day mortality [odds ratio – 10 studies (95% confidence interval) 0.34 (0.18-0.66)]; 4.7% versus 12.6%, for iTVr and iTVR, respectively. Post-op pacemaker placement favored iTVr [odds ratio – 6 studies (95% confidence interval) 0.37 (0.18-0.77)]. Although stroke rates and TV reoperation favored iTVr, they did not reach statistical significance. No publication bias was identified. Conclusions: This meta-analysis demonstrates that iTVr has better 30-day mortality and fewer permanent pacemaker placements. Etiology and severity of TR, as well as careful patient selection remain the most important factors for optimal outcomes.

Objective: To describe experience with using intraoperative Transesophageal Echocardiography to reliably predict the size of the rapid deployment prosthetic valve by measuring the native aortic annulus Methods: Retrospective review of single institution series of patients undergoing Aortic Valve Replacement with Rapid Deployement Bioprosthetic Valves. Included were patients that had their native aortic valve replaced either isolated or as part of any additional procedure. Aortic annulus was measured prior to initiation of the operation using transesophageal echocardiography (TEE). Correlation analysis was conducted between Echocardiographic annular measurements and actual implanted valve sizes. Results: Twenty five patients underwent rapid deployment valve implantation in the aortic position. Of these, 36% of patients had the same size valve as the measured aortic annulus, 48% of patients had a valve implanted that was 1 mm different, and 16% of patients had 2 mm difference. The mean annular size based was 22.4 mm (range: 21-28 mm). The mean valve size implanted was 23.3 mm (range: 21-27 mm). There was no statistically significant difference between the mean annular measurement and the valve size selected (0.9 mm , p = 0.8). Conclusion: TEE can further enhance valve sizing and guidance through a proper and safe deployment. Although evident in our experience, larger scale studies are needed to further elucidate conclusions on the importance of avoiding under-sizing valves.

Pigeons and other animals prefer signaled over unsignaled outcomes in different choice situations, even if by doing so they fail to maximize their rate of return. The suboptimal-choice procedure is a prototypical example. In this task, pigeons choose between two options associated with different probabilities of delayed food reward. Choosing the informative (but leaner) option leads to differential stimuli that immediately signal whether the outcome of the trial will be food or no-food; choosing the non-informative (but richer) option leads to different stimuli too, but they do not reliably signal the outcome. Pigeons prefer the informative option despite its lower rate of reinforcement. The present dissertation furthers our knowledge of this phenomenon. In the first study, we compared two coexisting versions of the suboptimal-choice task that are usually regarded as equivalent. In the second study, we explored the effect of delaying the disambiguation of the food or no-food outcome in the informative option; also, we studied if and how preference varies with the time under certainty and uncertainty about the outcome. In the third study, we analyzed the effect of signaling different delays to food reward on choice; also, we studied if preference varied with how different the signaled delays were. From the three studies, we concluded that: (1) the two coexisting versions are equivalent; (2) delaying the moment of disambiguation of the outcome reduces the value of the informative option; this value varies with the delay to information, and; (3) when the options lead to multiple delays to food, pigeons prefer to know in advance the delay in effect, but this preference varies with the ratio of the possible delays. Theoretically, we tackled these findings from both a functional and a mechanistic standpoint. Functionally, we assumed that evolution shaped preference for information because information can be used by animals to adjust their behavior (e.g., chasing valuable outcomes and avoiding less-valuable ones). Mechanistically, we expanded the Δ-Σ hypothesis (González et al., 2020) to account for our findings. The model proposes that preference for information arises from two higher-order variables: a contrast between the signaled outcomes within each option and the overall rate of reinforcement offered by each option. These two theorethical approaches to the same findings bring us closer to Tinbergen’s (1963) desideratum to illustrate how functional and mechanistic explanations complement each other. Pombos e outros animais preferem consequências sinalizadas a não sinalizadas em diferentes situações de escolha, mesmo que isso signifique não maximizar a taxa de retorno. O procedimento experimental de escolha subótima é um exemplo prototípico. Nesta tarefa, os pombos escolhem entre duas alternativas associadas a diferentes probabilidades de recompensa com atraso. Escolher a opção informativa (mas mais pobre) conduz a estímulos diferenciados que sinalizam de imediato se o ensaio resultará em comida ou não; escolher a opção não informativa (mas mais rica) também conduz a diferentes estímulos, no entanto, estes não sinalizam qual será a consequência. Os pombos preferem a opção informativa apesar da sua taxa de recompensa ser menor. A presente dissertação aprofunda o nosso conhecimento acerca deste fenómeno. No primeiro estudo, comparamos duas versões coexistentes da tarefa de escolha subótima que geralmente são consideradas equivalentes. No segundo, exploramos o efeito de atrasar a desambiguação da consequência, comida ou não, na opção informativa. Também estudamos se e como é que a preferência varia em função da duração da certeza ou incerteza acerca da consequência. No terceiro estudo, analisamos a escolha ao sinalizar diferentes atrasos na recompensa; também estudamos se a preferência varia em função de quão diferentes os atrasos sinalizados são. Dos três estudos, concluímos que: (1) as duas versões da tarefa são equivalentes; (2) atrasar o momento de desambiguação da consequência reduz o valor da opção informativa; e que esse valor varia com o atraso da informação; e (3) quando as opções conduzem a múltiplos atrasos até à recompensa, os pombos preferem conhecer antecipadamente o atraso em vigor, mas essa preferência varia de acordo o rácio entre os atrasos possíveis. Em termos teóricos, analisamos os nossos resultados do ponto de vista funcional e mecanicista. Do ponto de vista funcional, assumimos que a evolução modelou a preferência pela informação porque esta pode ser usada pelos animais para ajustar o seu comportamento (e.g. a perseguir recompensas mais valiosas e a evitar as menos valiosas). Do ponto de vista mecanicista, expandimos a hipótese Δ-Σ (González et al., 2020) de forma a dar conta dos nossos resultados. O modelo propõe que a preferência pela informação surge de duas variáveis de ordem superior: o contraste entre as consequências sinalizadas dentro de cada opção e a taxa geral da recompensa associada a cada opção. As duas abordagens teóricas aproximam-nos da aspiração de Tinbergen (1963) de ilustrar como é que explicações funcionais e mecanicistas se complementam. Programa Doutoral em Psicologia

Three Cr(III)–salen catalysts supported onto macrocyclic oligomeric cyclooctene through linkers of different lengths were synthesized. The influences of the linker length and the oligomeric support on the activity and the enantioselectivity of catalysts were investigated in the asymmetric ring opening of a meso -epoxide and the kinetic resolution of terminal epoxides. For both reactions all three catalysts exhibited significantly higher catalytic efficiency than the unsupported monomeric Cr(III)–salen catalyst. The catalyst with the shortest linker 1 showed the highest reaction rate while the catalyst with the longest linker 3 afforded the highest enantioselectivity in both reactions. The recoverability of catalyst 1 was also studied.

El presente trabajo pretende analizar aspectos del modelo económico y político de los países que han transitado por reformas constitucionales en las que se han incorporado principios indígenas basados, principalmente, en cosmovisiones antagónicas a las que caracterizan al Estado, la economía y la integración que se han desarrollado en América Latina. Se estudiará a Bolivia y a Ecuador por sus procesos constitucionales de 2009 y 2008, por sus economías basadas en la extracción de recursos naturales y por su participación en el espacio de integración denominado UNASUR.

El aguacate es el cultivo que mayor dinamismo registra en el sur del estado de Jalisco en la primera década del siglo XXI. Ello corresponde a los cambios que se vienen dando en la relación comercial entre México y los Estados Unidos, así como a la cercanía de la región con Michoacán, principal zona productora. Esta actividad económica, que se presenta como potencial detonadora de la economía regional, forma parte de un modelo agroindustrial que en aras de la rentabilidad económica, puede resultar depredador de los recursos locales e incrementar los niveles de vulnerabilidad de los territorio de producción, tanto desde el punto de vista económico, como medioambiental.

Desde mediados de la década de 1980, el cultivo de jitomate, brócoli y otras hortalizas ha cobrado importancia en Sayula, Jalisco. Este tipo de actividad se enmarca en mallas de valor en las que existen dinámicas extraterritoriales evidentes, como la provisión de insumos, factores de producción (incluida la mano de obra), comercialización y consumo, cuya labor central se ubica en otros territorios. Ahora bien, dentro de estas mallas de valor existen formas de organización diversas de la relación entre agricultores y compradores, de acuerdo con las características del producto, de los mercados y actores involucrados. Esto genera una diversidad de estructuras de gobierno, estudiadas en este trabajo, para así entender tanto los beneficios que le generan al agricultor, como las limitaciones que éste enfrenta ante tales relaciones.

La producción y exportación de frutas y hortalizas se ha convertido en el área más dinámica de la agricultura mexicana durante las últimas décadas. México es actualmente uno de los países que más exportan estos productos, lo cual suele explicarse en gran medida por el proceso de apertura comercial iniciado desde la década de 1990. Sin embargo, pese a sus evidentes fortalezas, una característica de este tipo de agricultura ha sido la concentración: en pocos cultivos, pocas regiones productoras y pocos mercados de destino. Además, un análisis de competitividad de las principales frutas y hortalizas que México exporta a Estados Unidos de América, muestra que si bien demuestra que aquél país sostiene su liderazgo, hoy compite con otras naciones, las cuales cada vez ganan más cuotas de mercado. Este es un elemento a considerar, pues puede en el futuro próximo disminuir las ventajas con que hoy cuenta el sector agroexportador mexicano. The production and exports of fruits and vegetables had become the most dynamic area of its Mexican agriculture during the last decades. Today, Mexico is great exporter of these products, as a result of the free trade initiated in the last decade of the XX Century. Nevertheless, in spite of his strengths, a characteristic feature of this kind of agriculture has been its concentration: in few products, few regions and few markets. In addition, a competitiveness analysis of main Mexican fruits and vegetables exported to the United States reveals that such country is still a leader, and that it competes today with other nations which are winning market shares. This is a key element to be considering in the near future, due to the advantages of Mexican agroexporter sector could diminish. La production et l’exportation de fruits et légumes est devenu le secteur le plus dynamique de l’agriculture mexicaine au cours des dernières décennies. Le Mexique est actuellement l’un des pays qui exportent plus ces produits, événement expliqué en grand partie par le processus de libéralisation des échanges commencé depuis les années 1990. Cependant, malgré ses forces évidentes, une caractéristique de ce type d’agriculture a été la concentration: dans peu de cultures, peu de régions productrices et peu de marchés de destination. De plus, une analyse de la compétitivité des principaux fruits et légumes que le Mexique exporte vers les États-Unis d’Amérique, montre que bien que ce pays soutient bien son leadership, aujourd’hui il est en concurrence avec d’autres pays, lesquelles gagnent chaque fois plus de parts de marché. C’est un élément à prendre en considération, puisqu’il est probable dans le future proche voir une diminution des avantages sur lesquels aujourd’hui compte le secteur agro-exportateur mexicain. 31-48 alejandrom@cusur.udg.mx semestral