Parameter-Conditioned Reachable Sets for Updating Safety Assurances Online

Hamilton-Jacobi (HJ) reachability analysis is a powerful tool for analyzing the safety of autonomous systems. However, the provided safety assurances are often predicated on the assumption that once deployed, the system or its environment does not evolve. Online, however, an autonomous system might experience changes in system dynamics, control authority, external disturbances, and/or the surrounding environment, requiring updated safety assurances. Rather than restarting the safety analysis from scratch, which can be time-consuming and often intractable to perform online, we propose to compute \textit{parameter-conditioned} reachable sets. Assuming expected system and environment changes can be parameterized, we treat these parameters as virtual states in the system and leverage recent advances in high-dimensional reachability analysis to solve the corresponding reachability problem offline. This results in a family of reachable sets that is parameterized by the environment and system factors. Online, as these factors change, the system can simply query the corresponding safety function from this family to ensure system safety, enabling a real-time update of the safety assurances. Through various simulation studies, we demonstrate the capability of our approach in maintaining system safety despite the system and environment evolution

Hamilton-Jacobi Reachability Analysis for Hybrid Systems with Controlled and Forced Transitions

Hybrid dynamical systems with non-linear dynamics are one of the most general modeling tools for representing robotic systems, especially contact-rich systems. However, providing guarantees regarding the safety or performance of such hybrid systems can still prove to be a challenging problem because it requires simultaneous reasoning about continuous state evolution and discrete mode switching. In this work, we address this problem by extending classical Hamilton-Jacobi (HJ) reachability analysis, a formal verification method for continuous non-linear dynamics in the presence of bounded inputs and disturbances, to hybrid dynamical systems. Our framework can compute reachable sets for hybrid systems consisting of multiple discrete modes, each with its own set of non-linear continuous dynamics, discrete transitions that can be directly commanded or forced by a discrete control input, while still accounting for control bounds and adversarial disturbances in the state evolution. Along with the reachable set, the proposed framework also provides an optimal continuous and discrete controller to ensure system safety. We demonstrate our framework in simulation on an aircraft collision avoidance problem, as well as on a real-world testbed to solve the optimal mode planning problem for a quadruped with multiple gaits

Estimacion de costos de produccion de smolt de salmon del Atlantico (Salmo salar) : caso de estudio: Salmones Colbun S.A.

92 p.Durante los últimos años la acuicultura chilena ha presentado un importante crecimiento sustentada principalmente por la salmonicultura. El carácter de emergente de este sector, ha generado una industria acuícola altamente competitiva, cuyas ventajas vienen dadas por los costos de producción. Además, las empresas de la industria salmonera se han integrado verticalmente en los últimos años. El objetivo principal del estudio es estimar los costos de producción de smolt del Salmón del Atlántico (Salmo salar) de la empresa Salmones Colbún S.A. Se propuso una estructura de costos con el objetivo de lograr una mayor eficiencia en la administración y control de costos de producción. En la estructura se distinguen dos tipos de costos, los costos explícitos (costos de operación fijos y variables) y los costos de oportunidad (costo de capital asociado a las inversiones). Para la determinación de la tasa de descuento relevante, utilizada para el cálculo del costo de capital, se tomó como referencia la empresa Salmones Maistream S.A., ya que es la única del sector que transa sus acciones en la Bolsa de Comercio de Santiago. Para su estimación, se utilizó el modelo de mercado tradicional, sin embargo hubo que realizar algunas modificaciones, ya que esta empresa presenta transacciones discontinuas, por lo tanto, es necesario ajustar el parámetro de riesgo sistemático f3j, lo cual se realizó a través del estimador de riesgo sistemático propuesto por Scholes y Williams. El Costo de Capital Total mensual (CCT), se calculó utilizando la ecuación simple de amortización de pago vencido, considerando el valor de mercado de las inversiones existentes en infraestructuras, y máquinas y equipos. Posteriormente se determinó el Costo Medio de Capital (CMeC), dividiendo el CCT por la producción mensual de smolt. También se calcularon los costos medios de operación. Los resultados obtenidos muestran que el CMeC asociado a máquinas y equipos aporta el mayor porcentaje al CCT. Por otro lado el componente más relevante dentro del Costo Medio Fijo (CMeF), es la mano de obra. Con relación al Costo Medio Variable (CMeV), podemos mencionar la mayor importancia que tiene el costo de las ovas, el alimento y el oxígeno con respecto al resto de los componentes. Al considerar la nueva estructura de costos observamos que la empresa Salmones Colbún S.A. presentó utilidades económicas positivas durante el año 1998

Estimating the contribution of stimulant injection to HIV and HCV epidemics among people who inject drugs and implications for harm reduction:A modeling analysis

BACKGROUND: Stimulants, such as amphetamines and cocaine, are widely injected among people who inject drugs (PWID). Systematic reviews indicate stimulant injection is associated with HIV and HCV among PWID. Using these associations, we estimated the contribution of stimulant injection to HIV and HCV transmission among PWID. METHODS: We modeled HIV and HCV transmission among PWID, incorporating excess injecting and sexual risk among PWID who inject stimulants. We simulated three illustrative settings with different stimulants injected, prevalence of stimulant injecting, and HIV/HCV epidemiology. We estimated one-year population attributable fractions of stimulant injection on new HIV and HCV infections, and impact of scaling up needle-syringe programs (NSP). RESULTS: In low prevalence settings of stimulant injection (St. Petersburg-like, where 13% inject amphetamine), 9% (2.5-97.5% interval [95%I]: 6-15%) and 7% (95%I 4-11%) of incident HIV and HCV cases, respectively, could be associated with stimulant injection in the next year. With moderate stimulant injection (Montreal-like, where 34% inject cocaine), 29% (95%I: 19–37%) and 19% (95%I: 16-21%) of incident HIV and HCV cases, respectively, could be associated with stimulant injection. In high-burden settings like Bangkok where 65% inject methamphetamine, 23% (95%I:10–34%) and 20% (95%I: 9-27%) of incident HIV and HCV cases could be due to stimulant injection. High-coverage NSP (60%) among PWID who inject stimulants could reduce HIV (by 22-65%) and HCV incidence (by 7-11%) in a decade. DISCUSSION: Stimulant injection contributes substantially to HIV and HCV among PWID. NSP scale-up and development of novel interventions among PWID who inject stimulants are warranted

Eco-efficiency assessment of shrimp aquaculture production in Mexico

Globally, human society faces the challenge of providing food to a growing population, at the same time that the effects of climate change and resource depletion must be addressed. Aquaculture allows to ensure a safe supply of different marine species and is a major technological and biological undertaking. Taking into account that in Sonora (Mexico), there are more than 200 aquaculture plants, the analysis of this sector implies a joint and harmonized assessment, considering not only life cycle assessment (LCA), but also data envelopment analysis (DEA). This study focuses on the application of LCA + DEA methodology to assess the ecoefficiency of 38 semi-intensive shrimp farms located in the state of Sonora. LCA results showed that feed management and electricity consumption are the main critical points in almost all the impact categories. Further improvement actions were evaluated, the replacement of wheat meal for Dried Distiller Grains with Solubles (DDGS) resulted in environmental impact reductions ranged from 2% to 57%, depending on the impact category. On the other hand, the installation of photovoltaic panels in the area was evaluated, looking for a shift towards a less carbon-intensive energy production. Overall, the implementation of these improvement measures will contribute to increased environmental protection and resource efficiencyThis research was supported by the Comité de Sanidad Acuícola del Estado de Sonora (COSAES). A. Cortés, C. Cambeses Franco, G. Feijoo and M.T. Moreira belong to CRETUS and the Galician Competitive Research Group GRC (ED431C 2017/29), co-founded by Xunta de Galicia and FEDER (EU)S

Caracterización del semen y efecto de la hormona GnRh-a en la calidad espermática del lenguado chileno Paralichthys adspersus (Steindachner, 1867) bajo condiciones de cultivo

Tesis (Ingeniero en Acuicultura)En el presente trabajo se caracterizó el semen bajo distintos parámetros de calidad de machos de Paralichthys adspersus mantenidos en cautiverio. Además se observó el efecto de la hormona factor liberador de gonadotropina análoga (GnRH-a, [des-Gly10 , D-Ala6 ]LHRH etilamida) en la calidad del semen de un grupo de estos machos. Con este objetivo los peces se dividieron en dos grupos: control (sin tratamiento) e inducidos, estos últimos, fueron inyectados intraperitonialmente con una dosis de 20 f.lg/Kg pez de GnRH-a, en tres fechas distintas. Después de tres días de la inyección hormonal se evaluó en ambos grupos los siguientes parámetros: volumen total de semen extraído, densidad espermática, espermatocríto, motilidad espermática a O, 30, 60, 90 y 120 min de almacenaje a 4 oc, capacidad fecundante con dos volúmenes de semen distintos {20 y 50 f.lL) para 200 f.lL de ovas, en ambos grupos, y morfología básica en el grupo control. Los resultados dan cuenta de un aumento significativo en el volumen total promedio de semen extraído para el grupo inducido con GnRH-a (619,18 ± 46,79 f.lL) en comparación al grupo control (494,71 ± 54,99 f.lL). Además, se encontró una tendencia a una mayor duración de la motilidad de los espermatozoides con la utilización de la hormona GnRH-a durante un tiempo de almacenaje de 60 min, mientras que en el grupo control las diferencias se presentaron a los JO min de almacenaje, con respecto al tiempo inicial para ambos grupos. Los restantes parámetros medidos: densidad espermática, espermatocríto, motilidad espermática y capacidad fecundante no presentaron diferencias significativas por el uso de GnRH-a. Los result~dos que se expresan en esta tesis son un paso fundamental para conocer la biología reproductiva enmachos de P. adspersus, así como en el manejo de gametos para el desarrollo de su cultivo en forma integral.In this work milt from captive juvenile Paralichthys adspersus males was characterized under several quality parameters. In addition, the effect of the analog gonadotropin releasing hormone factor (GnRH-a, [des-Gly10 , D-Ala6]-LHRH etylamide) in the milt quality was evaluated in a group of those specimens. The :fish population was divided in two groups: control (non-treated) and induced. The latter group was intraperitonialy injected with adose of20 J.lg ofGnRH-a per Kg of:fish at the different dates. The following parameters were evaluated three days after the hormone injection: total volume of extracted semen, spermatocrit, spermatic motility after O, 30, 60 90, and 120 min storage at 4°C, fecundating capacity with 20 and 50 J.lL semen in 200 J.lL total volume ofroe for both groups, and basic morphology in the control group. The results show a significant increase in the total volume of extracted milt for the GnRH-a induced groups (619,18 ± 46,79 J.lL) as compared with the control (494,71 ± 54,99 J.lL). A tendency to a longer motility time for the spermatozoon was found for the GnRH-a treated group at a storage time of 60 min, while in the control groups differences where detected at a storage time of 30 min. All other evaluated parameters (spermatic density, spermatocrit, spermatic motility, and fecundating capacity) showed no differences between the two groups. The work presented in this thesis is a fundamental step towards the understanding of the reproductive biology of P. adspersus males, as well as for the handling ofthe gametes in an appropriate and comprehensive way

A Simple Distribution Energy Tariff under the Penetration of DG

In a scenario where distributed generation infrastructure is increasing, the impact of that integration on electricity tariffs has captured particular attention. As the distribution sector is mainly regulated, tariff systems are defined by the authority. Then, tariffs must be simple, so the methodology, criteria, and procedures can be made public to ensure transparency and responsiveness of the customers to price signals. In the aim of simplicity, tariff systems in current practices mostly consist of volumetric charges. Hence, the reduction of the energy purchased from the distribution network jeopardizes the ability of the tariff system to ensure recovery of the total regulated costs. Although various works have captured this concern, most proposals present significant mathematical complexity, contrasting with the simplicity of current practices and limiting its regulatory applicability. This work develops a tariff system that captures the basic elements of distribution systems, trying to maintain the simplicity of current practices, ensuring recovery of the total regulated cost under the penetration of distributed generation, and incentivizing through price signals operational efficiency. A simulation will be presented to discuss numerical results

Impact of cumulative incarceration and the post‐release period on syringe‐sharing among people who inject drugs in Tijuana, Mexico: a longitudinal analysis

Background and aimsSyringe-sharing among people who inject drugs, which can occur during incarceration and post-release, has been linked with increased risk of blood-borne infections. We aimed to investigate the cumulative effect of repeated incarceration and the post-release period on receptive syringe-sharing.DesignOngoing community-based cohort, recruited through targeted sampling between 2011 and 2012 with 6-month follow-ups.SettingTijuana, Mexico.ParticipantsSample of 185 participants (median age 35 years; 67% female) with no history of incarceration at study entry, followed to 2017.MeasurementsCumulative incarceration and post-release period were constructed from incarceration events reported in the past 6 months for each study visit. Receptive syringe-sharing in the past 6 months was assessed as a binary variable. We used logistic regression with generalized estimating equations to examine the association between cumulative incarceration events and the post-release period with receptive syringe-sharing over time. Missing data were handled through multiple imputation.FindingsAt baseline, 65% of participants engaged in receptive syringe-sharing in the prior 6 months. At follow-up, 150 (81%) participants experienced a total of 358 incarceration events [median = 2, interquartile range (IQR) = 1-3]. The risk of receptive syringe-sharing increased with the number of repeated incarcerations. Compared with never incarcerated, those with one incarceration had 1.28 [95% confidence interval (CI) = 0.97-1.68] higher adjusted odds of syringe-sharing; two to three incarcerations, 1.42 (95% CI = 1.02-1.99) and more than three incarcerations, 2.10 (95% CI = 1.15-3.85). Participants released within the past 6 months had 1.53 (95% CI = 1.14-2.05) higher odds of sharing syringes compared with those never incarcerated. This post-release risk continued up to 1.5 years post-incarceration (adjusted odds ratio = 1.41, 95% CI = 1.04-1.91), but then waned.ConclusionsA longitudinal community cohort study among people who inject drugs suggested that the effects of incarceration on increased injecting risk, measured through syringe-sharing, are cumulative and persist during the post-release period

Modelling the contribution of incarceration and public health oriented drug law reform to HCV transmission and elimination among PWID in Tijuana, Mexico

BackgroundIncarceration is associated with increased risk of hepatitis C virus (HCV) among people who inject drugs (PWID). Mexico's previous attempt in implementing a public health-oriented drug law reform resulted in minimal impact on incarceration among PWID. However, implementation of reforms alongside Mexico's HCV elimination program has the potential to reshape the HCV epidemic among PWID in the next decade. We use data from a cohort of PWID in Tijuana, Mexico, to inform epidemic modeling to assess the contribution of incarceration and fully implemented drug reform on HCV transmission and elimination among PWID.MethodsWe developed a dynamic, deterministic model of incarceration, HCV transmission and disease progression among PWID. The model was calibrated to data from Tijuana, Mexico, with 90% HCV seroprevalence among 10,000 PWID. We estimated the 10-year population attributable fraction (PAF) of incarceration to HCV incidence among PWID and simulated, from 2022, the potential impact of the following scenarios: 1) decriminalization (80% reduction in incarceration rates); 2) fully implemented drug law reform (decriminalization and diversion to opiate agonist therapy [OAT]); 3) fully implemented drug law reform with HCV treatment (direct-acting antivirals [DAA]). We also assessed the number DAA needed to reach the 80% incidence reduction target by 2030 under these scenarios.ResultsProjections suggest a PAF of incarceration to HCV incidence of 5.4% (95% uncertainty interval [UI]:0.6-11.9%) among PWID in Tijuana between 2022-2032. Fully implemented drug reforms could reduce HCV incidence rate by 10.6% (95%UI:3.1-19.2%) across 10 years and reduce the number of DAA required to achieve Mexico's HCV incidence reduction goal by 14.3% (95%UI:5.3-17.1%).ConclusionsAmong PWID in Tijuana, Mexico, incarceration remains an important contributor to HCV transmission. Full implementation of public health-oriented drug law reform could play an important role in reducing HCV incidence and improve the feasibility of reaching the HCV incidence elimination target by 2030