Stimulated Raman adiabatic passage-like protocols for amplitude transfer generalize to many bipartite graphs

Adiabatic passage techniques, used to drive a system from one quantum state into another, find widespread application in physics and chemistry. We focus on techniques to spatially transport a quantum amplitude over a strongly coupled system, such as STImulated Raman Adiabatic Passage (STIRAP) and Coherent Tunnelling by Adiabatic Passage (CTAP). Previous results were shown to work on certain graphs, such as linear chains, square and triangular lattices, and branched chains. We prove that similar protocols work much more generally, in a large class of (semi-)bipartite graphs. In particular, under random couplings, adiabatic transfer is possible on graphs that admit a perfect matching both when the sender is removed and when the receiver is removed. Many of the favorable stability properties of STIRAP/CTAP are inherited, and our results readily apply to transfer between multiple potential senders and receivers. We numerically test transfer between the leaves of a tree, and find surprisingly accurate transfer, especially when straddling is used. Our results may find applications in short-distance communication between multiple quantum computers, and open up a new question in graph theory about the spectral gap around the value 0.Comment: 17 pages, 3 figures. v2 is made more mathematical and precise than v

Why would plant species become extinct locally if growing conditions improve?

wo assumptions underlie current models of the geographical ranges of perennial plant species: 1. current ranges are in equilibrium with the prevailing climate, and 2. changes are attributable to changes in macroclimatic factors, including tolerance of winter cold, the duration of the growing season, and water stress during the growing season, rather than to biotic interactions. These assumptions allow model parameters to be estimated from current species ranges. Deterioration of growing conditions due to climate change, e.g. more severe drought, will cause local extinction. However, for many plant species, the predicted climate change of higher minimum temperatures and longer growing seasons means, improved growing conditions. Biogeographical models may under some circumstances predict that a species will become locally extinct, despite improved growing conditions, because they are based on an assumption of equilibrium and this forces the species range to match the species-specific macroclimatic thresholds. We argue that such model predictions should be rejected unless there is evidence either that competition influences the position of the range margins or that a certain physiological mechanism associated with the apparent improvement in growing conditions negatively affects the species performance. We illustrate how a process-based vegetation model can be used to ascertain whether such a physiological cause exists. To avoid potential modelling errors of this type, we propose a method that constrains the scenario predictions of the envelope models by changing the geographical distribution of the dominant plant functional type. Consistent modelling results are very important for evaluating how changes in species areas affect local functional trait diversity and hence ecosystem functioning and resilience, and for inferring the implications for conservation management in the face of climate change

Concepto de equilibrio y no-equilibrio en los modelos genéticos forestales: los enfoques de la población

The environment is changing and so are forests, in their functioning, in species composition, and in the species’ genetic composition. Many empirical and process-based models exist to support forest management. However, most of these models do not consider the impact of environmental changes and forest management on genetic diversity nor on the rate of adaptation of critical plant processes. How genetic diversity and rates of adaptation depend on management actions is a crucial next step in model development. Modelling approaches of genetic and demographic processes that operate in forests are categorized here in two classes. One approach assumes equilibrium conditions in phenotype and tree density, and analyses the characteristics of the demography and the genetic system of the species that determine the rate at which that equilibrium is attained. The other modelling approach does not assume equilibrium conditions and describes both the ecological —and genetic processes to analyse how environmental changes result in selection pressures on functional traits of trees and the consequences of that selection for tree— and ecosystem functioning. The equilibrium approach allows analysing the recovery rate after a perturbation in stable environments, i.e. towards the same pre-perturbation stable state. The nonequilibrium approach allows, in addition to the equilibrium approach, analysing consequences of ongoing environmental changes and forest management, i.e. non-stationary environments, on tree functioning, species composition, and genetic composition of the trees in forest ecosystem. In this paper we describe these two modelling approaches and discuss advantages and disadvantages of them and current knowledge gaps.El ambiente está cambiando así como los bosques, en su funcionamiento, en la composición de especies, y en la composición genética de la especie. Existen muchos modelos empíricos y basados en procesos para apoyar al manejo forestal. Sin embargo, la mayoría de estos modelos no tienen en cuenta el impacto de los cambios ambientales y la gestión forestal sobre la diversidad genética ni sobre la tasa de adaptación a los procesos críticos de la planta. Cómo la diversidad genética y la tasa de adaptación dependerá de las acciones de gestión es un paso futuro decisivo en el desarrollo de los modelos. Los enfoques de modelización de los procesos genéticos y demográficos que operan en los bosques se clasifican en dos clases. Un enfoque asume las condiciones de equilibrio en el fenotipo y la densidad de árboles, y analiza las características de la demografía y el sistema genético de las especies que determinan la velocidad a la que se alcanza ese equilibrio. El otro enfoque de modelización no asume las condiciones de equilibrio y describe tanto los procesos ecológicos y genéticos para analizar cómo los cambios ambientales influyen en la presión de selección en características funcionales de los árboles y en las consecuencias de esta selección para el árbol y el funcionamiento de los ecosistemas. El enfoque de equilibrio permite analizar la tasa de recuperación después de una perturbación en un entorno estable, es decir, hacia el mismo estado que antes de la perturbación estable. El enfoque de no-equilibrio permite, además del enfoque de equilibrio, el análisis de las consecuencias de los actuales cambios del medio ambiente y la ordenación forestal, es decir, ambientes no estacionarios, en el funcionamiento de árboles, la composición de especies, y la composición genética de los árboles en el ecosistema forestal. En este trabajo se describen estos dos métodos de modelización y se discuten las ventajas y desventajas de ellos y las lagunas actuales de conocimientos

How Do Technologies Affect How We See and Treat Animals? Extending Technological Mediation Theory to Human-animal Relations

Human practices in which animals are involved often include the application of technology: some farmed animals are for example milked robotically or monitored by smart technologies, laboratory animals are adapted to specific purposes through the application of biotechnologies, and pets have their own social media accounts. Animal ethicists have raised concerns about some of these practices, but tend to assume that technologies are just neutral intermediaries in human-animal relations. This paper questions that assumption and addresses how technologies might shape human-animal relations in non-neutral ways. Building on the technological mediation approach, it proposes that technologies can influence human-animal relations by amplifying and reducing certain aspects of animals in human perception or by inviting and inhibiting certain actions towards animals. The paper next considers, in two concretizing steps, how this theoretical starting point can enrich ethical discussions on technology and human-animal relations. First, it shows how the technological mediation approach can help to conceptualize a main concern that has been raised regarding the impact of technologies on human-animal relations, namely the concern that animals might be ‘instrumentalized’ or ‘objectified’ in certain technological practices. Second, it considers how this approach can guide investigations of how particular technologies might affect human-animal relations, taking genetic selection technologies as used in livestock breeding as a case. The paper closes by briefly reviewing the prospects and challenges for the application of the technological mediation approach to human-animal relations, thus sketching directions for future research

Immune Checkpoint Inhibitor-related Pancreatitis:A Case Series, Review of the Literature and an Expert Opinion

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of various malignancies, but are associated with serious adverse events like pancreatitis. Current guidelines are limited to the first step in treating acute ICI-related pancreatitis with steroids but lack treatment advices for steroid dependent pancreatitis. We describe a case series of 3 patients who developed ICI-related pancreatitis with chronic features such as exocrine insufficiency and pancreatic atrophy at imaging. Our first case developed after treatment with pembrolizumab. The pancreatitis responded well after discontinuation of immunotherapy but imaging showed pancreatic atrophy and exocrine pancreatic insufficiency persisted. Cases 2 and 3 developed after treatment with nivolumab. In both, pancreatitis responded well to steroids. However during steroid tapering, pancreatitis recurred and the latter developed exocrine pancreatic insufficiency and pancreatic atrophy at imaging. Our cases demonstrate resemblances with autoimmune pancreatitis based on clinical and imaging findings. In line, both diseases are T-cell mediated and for autoimmune pancreatitis azathioprine is considered as maintenance therapy. Guidelines of other T-cell mediated diseases like ICI-related hepatitis suggest tacrolimus. After adding tacrolimus in case 2 and azathioprine in case 3, steroids could be completely tapered and no new episodes of pancreatitis have occurred. These findings support the idea that the treatment modalities for other T-cell mediated diseases are worthwhile options for steroid dependent ICI-related pancreatitis.</p

\Lambda-buildings and base change functors

We prove an analog of the base change functor of \Lambda-trees in the setting of generalized affine buildings. The proof is mainly based on local and global combinatorics of the associated spherical buildings. As an application we obtain that the class of generalized affine building is closed under ultracones and asymptotic cones. Other applications involve a complex of groups decompositions and fixed point theorems for certain classes of generalized affine buildings.Comment: revised version, 29 pages, to appear in Geom. Dedicat

Modelos para el apoyo a la gestión forestal bajo un ambiente cambiante

Forests are experiencing an environment that changes much faster than in at least the past several hundred years. In addition, the abiotic factors determining forest dynamics vary depending on its location. Forest modeling thus faces the new challenge of supporting forest management in the context of environmental change. This review has focused on three types of models that are used in forest management: empirical, process-based and hybrid models. Recent approaches might lead to the applicability of empirical models under changing environmental conditions, such as (i) the dynamic state-space approach, or (ii) the development of productivity-environment relationships. 25 process-based models in use in Europe were analyzed in terms of its structure, inputs and outputs having in mind a forest management perspective. Two paths for hybrid modeling were distinguished: (i) coupling of EMs and PBMs by developing signal-transfer environment-productivity functions; (ii) hybrid models with causal structure including both empirical and mechanistic components. Several gaps of knowledge were identified for the three types of models reviewed. The strengths and weaknesses of the three model types differ and all are likely to remain in use. There is a trade-off between how little data the models need for calibration and simulation purposes, and the variety of input-output relationships that they can quantify. PBMs are the most versatile, with a wide range of environmental conditions and output variables they can account for. However, PBMs require more data making them less applicable whenever data for calibration are scarce. The EMs, on the other hand, are easier to run as they require much less prior information, but their simplicity makes them less reliable in the context of environmental changes. These different deficiencies of PBMs and EMs suggest that hybrid models may be a good compromise, but a more extensive testing of these models is required in practice.Los bosques están experimentando un ambiente que cambia más rápidamente que en, al menos, varios cientos de años en el pasado. Además, los factores abióticos que determinan la dinámica forestal varían dependiendo de su localización. La modelización forestal, por tanto, se enfrenta al nuevo reto de apoyar la gestión forestla en el contexto del cambio climático. Esta revisión se enfoca en tres tipos de modelos que se usan en gestión forestal: empíricos, basados en procesos e híbridos. Las aproximaciones reciente pueden conducir a la aplicabilidad de los modelos empíricos bajo condiciones de cambio ambiental, tales como (i) aproximaciones de la dinámica de estado-espacio, o (ii) el desarrollo de relaciones de productividad-ambiente. Se han analizado 25 modelos basados en proceso que están en uso en Europa en términos de su estructura, entradas y salidas teniendo en cuenta una perspectiva de gestión forestal. Se han distinguido dos pasos para modelos híbridos: (i) acoplamiento de modelos EM y PBM mediante el desarrollo de funciones de transferencia de señal ambiente-productividad; (ii) modelos híbridos con una estructura causal incluyendo tanto componentes empíricos como mecanicistas. Se han identificado varias lagunas de conocimiento para los tres tipos de modelos revisados. Las fortalezas y debilidades de los tres tipos de modelos difieren y es probable que se sigan utilizando. Hay un compromiso entre la cantidad mínima de información necesaria para la calibración y la simulación, y la variedad de relaciones input-output que pueden cuantifiar. Los modelos PBM requieren más datos, haciéndolos menos aplicables cuando los datos para la calibración son escasos. Los modelos EM, por otra parte, son más fáciles de correr puesto que requieren mucha menos información previa, pero la representación agregada de los efectos ambientales los hace menos fiables en el contexto del cambio climático. Las distintas desventajas de los modelos PBM y EM sugieren que los modelos híbridos pueden ser un buen compromiso, pero se requiere una mayor evaluación práctica de estos modelos