•The self-healing concept in polymers is presented and its state-of-the-art discussed.•Concepts to implement intrinsic healing in polymers are introduced.•The effect of polymer architecture on the ...intrinsic self-healing character of polymers is discussed.
Intrinsic and extrinsic self-healing strategies can be employed to mitigate the effects of local damage in order to (partially) restore a lost property or functionality and to avoid premature catastrophic failure of the whole system.
It is well known that polymer architecture has a crucial influence on mechanical, physical and thermal properties. However, the effect of polymer architecture on the healing capabilities of self-healing polymers has not yet been studied in detail. This paper addresses the effect of polymer architecture on the intrinsic healing character of polymeric materials using different reversible chemistries and aims at highlighting the need for more studies on this particular topic.
UCell is an R package for evaluating gene signatures in single-cell datasets. UCell signature scores, based on the Mann-Whitney U statistic, are robust to dataset size and heterogeneity, and their ...calculation demands less computing time and memory than other available methods, enabling the processing of large datasets in a few minutes even on machines with limited computing power. UCell can be applied to any single-cell data matrix, and includes functions to directly interact with Seurat objects. The UCell package and documentation are available on GitHub at https://github.com/carmonalab/UCell.
A
bstract
We compute all the tree-level contributions to the Wilson coefficients of the dimension-six Standard-Model effective theory in ultraviolet completions with general scalar, spinor and vector ...field content and arbitrary interactions. No assumption about the renormalizability of the high-energy theory is made. This provides a complete ultraviolet/infrared dictionary at the classical level, which can be used to study the low-energy implications of any model of interest, and also to look for explicit completions consistent with low-energy data.
Recent extinctions often resulted from humans retaliating against wildlife that threatened people's interests or were perceived to threaten current or future interests. Today's subfield of ...human‐wildlife conflict and coexistence (HWCC) grew out of an original anthropocentric concern with such real or perceived threats and then, starting in the mid‐1990s, with protecting valued species from people. Recent work in ethics and law has shifted priorities toward coexistence between people and wild animals. To spur scientific progress and more effective practice, we examined 4 widespread assumptions about HWCC that need to be tested rigorously: scientists are neutral and objective about HWCC; current participatory, consensus‐based decisions provide just and fair means to overcome challenges in HWCC; wildlife threats to human interests are getting worse; and wildlife damage to human interests is additive to other sources of damage. The first 2 assumptions are clearly testable, but if they are entangled can become a wicked problem and may need debunking as myths if they cannot be disentangled. Some assumptions have seldom or never been tested and those that have been tested appear dubious, yet the use of the assumptions continues in the practice and scholarship of HWCC. We call for tests of assumptions and debunking of myths in the scholarship of HWCC. Adherence to the principles of scientific integrity and application of standards of evidence can help advance our call. We also call for practitioners and interest groups to improve the constitutive process prior to decision making about wildlife. We predict these steps will hasten scientific progress toward evidence‐based interventions and improve the fairness, ethics, and legality of coexistence strategies.
Mitos y Suposiciones sobre el Conflicto y la Coexistencia entre el Humano y la Fauna
Resumen
Casi todas las extinciones recientes han resultado de las represalias que los humanos han realizado en contra de la fauna que amenaza o que ha sido percibida como una amenaza para intereses humanos actuales o futuros. Hoy en día, la disciplina de conflicto y coexistencia humano – fauna (HWCC, en inglés), surgió de la original preocupación antropocéntrica por las amenazas reales o percibidas y después, a partir de mediados de la década de 1990, por la preocupación de proteger a las especies valoradas por el los humanos. Trabajos recientes de ética y leyes han modificado sus prioridades hacia la coexistencia entre las personas y la fauna silvestre. Para estimular el progreso científico y una práctica más efectiva, examinamos cuatro suposiciones generalizadas sobre el HWCC que necesitan ser evaluadas rigurosamente: los científicos son neutrales y objetivos con el HWCC; las decisiones participativas actuales basadas en consensos proporcionan medios justos y razonables para sobreponerse a los retos del HWCC; las amenazas de la fauna hacia los intereses humanos cada vez son peores; y el daño causado por la fauna a los intereses humanos es aditivo a otras fuentes de daño. Las primeras dos suposiciones son claramente evaluables, pero si se entrelazan, pueden convertirse en un serio problema y necesitarían ser desacreditadas como mitos si no se pueden desenlazar. Algunas suposiciones nunca o rara vez han sido evaluadas y aquellas que sí lo han sido parecen ser dudosas. A pesar de esto, el uso de las suposiciones continua en la práctica y en la academia del HWCC. La adhesión a los principios de integridad científica y la aplicación de estándares de evidencia pueden ayudar a promover nuestra petición. También hacemos un llamado a los practicantes y a los grupos de interés para que mejoren el proceso constitutivo previo a la toma de decisiones sobre la fauna. Pronosticamos que estos pasos a seguir apresurarán el progreso científico hacia intervenciones basadas en evidencia y mejorarán la imparcialidad, ética y legalidad de las estrategias de coexistencia.
摘要
近代发生的物种灭绝许多是因为人类对威胁其利益, 或是主观认为会威胁其当下或未来利益的野生动物进行的报复。目前人兽冲突与共存 (human‐wildlife conflict and coexistence, HWCC) 子领域起源于最初以人类为中心对这些真实或感知中的威胁的关注, 随后自二十世纪九十年代中期起, 开始考虑保护有价值的物种不受人类威胁。近期伦理学和法律方面的工作已将重点转向人与野生动物的共存。为了促进科学进步和更有效的实践, 我们检验了四个有关 HWCC 普遍流传但需要严格检验的假设: 科学家对 HWCC 持客观中立的态度; 目前参与性的、基于共识的决策为克服 HWCC 中的挑战提供了公正公平的手段; 野生动物对人类利益的威胁越来越严重; 野生动物对人类利益的损害可以与其它来源的损害累加。最后两个假设明显可以检验, 但它们如果相互关联就可能成为一个棘手难题, 不能彼此理清的话则会发展为谬见, 需要得到揭露。还有一些假设很少或从未被检验过, 而那些已经被检验过的假设也显得可疑, 但 HWCC 的实践和学术研究中仍然在使用这些假设。我们呼吁在 HWCC 的学术研究中检验假设、消除谬见。而坚持科学诚信的原则和证据标准的应用有助于推动我们的呼吁。我们还呼吁实践者和利益团体在改进流程后再进行有关野生动物的决策。我们预计这些做法将推动以证据为基础的干预措施的科学进展, 并提高共存策略的公平性、道德性和合法性。 【翻译: 胡怡思; 审校: 聂永刚】
Article impact statement: Progress in the scholarship and practice of human‐wildlife conflict and coexistence requires rigorous tests of four fundamental assumptions.
M dwarfs are the most numerous stars in the Galaxy. They are characterized by strong magnetic activity. The ensuing high-energy emission is crucial for the evolution of their planets and the eventual ...presence of life on them. We systematically study the X-ray and ultraviolet emission of a subsample of M dwarfs from a recent proper-motion survey, selecting all M dwarfs within 10 pc to obtain a nearly volume-limited sample (∼90 per cent completeness). Archival ROSAT, XMM-Newton and GALEX data are combined with published spectroscopic studies of Hα emission and rotation to obtain a broad picture of stellar activity on M dwarfs. We make use of synthetic model spectra to determine the relative contributions of photospheric and chromospheric emission to the ultraviolet flux. We also analyse the same diagnostics for a comparison sample of young M dwarfs in the TW Hya association (∼10 Myr). We find that generally the emission in the GALEX bands is dominated by the chromosphere but the photospheric component is not negligible in early-M field dwarfs. The surface fluxes for the Hα, near-ultraviolet, far-ultraviolet and X-ray emission are connected via a power-law dependence. We present here for the first time such flux-flux relations involving broad-band ultraviolet emission for M dwarfs. Activity indices are defined as flux ratio between the activity diagnostic and the bolometric flux of the star in analogy to the Ca ii
R′HK index. For given spectral type, these indices display a spread of 2-3 dex which is largest for M4 stars. Strikingly, at mid-M spectral types, the spread of rotation rates is also at its highest level. The mean activity index for fast rotators, likely representing the saturation level, decreases from X-rays over the FUV to the NUV band and Hα, i.e. the fractional radiation output increases with atmospheric height. The comparison to the ultraviolet and X-ray properties of TW Hya members shows a drop of nearly three orders of magnitude for the luminosity in these bands between ∼10 Myr and few Gyr age. A few young field dwarfs (<1 Gyr) in the 10-pc sample bridge the gap indicating that the drop in magnetic activity with age is a continuous process. The slope of the age decay is steeper for the X-ray than for the UV luminosity.
Single-cell RNA sequencing (scRNA-seq) has revealed an unprecedented degree of immune cell diversity. However, consistent definition of cell subtypes and cell states across studies and diseases ...remains a major challenge. Here we generate reference T cell atlases for cancer and viral infection by multi-study integration, and develop ProjecTILs, an algorithm for reference atlas projection. In contrast to other methods, ProjecTILs allows not only accurate embedding of new scRNA-seq data into a reference without altering its structure, but also characterizing previously unknown cell states that "deviate" from the reference. ProjecTILs accurately predicts the effects of cell perturbations and identifies gene programs that are altered in different conditions and tissues. A meta-analysis of tumor-infiltrating T cells from several cohorts reveals a strong conservation of T cell subtypes between human and mouse, providing a consistent basis to describe T cell heterogeneity across studies, diseases, and species.
Self‐healing polymers can significantly extend the service life of materials and structures by autonomously repairing damage. Intrinsic healing holds great promise as a design strategy to mitigate ...the risks of damage by delaying or preventing catastrophic failure. However, experimentally resolving the microscopic mechanisms of intrinsic repair has proven highly challenging. This work demonstrates how optical micromechanical mapping enables the quantitative imaging of these molecular‐scale dynamics with high spatiotemporal resolution. This approach allows disentangling delocalized viscoplastic relaxation and localized cohesion‐restoring rebonding processes that occur simultaneously upon damage to a self‐healing polymer. Moreover, frequency‐ and temperature‐dependent imaging provides a way to pinpoint the repair modes in the relaxation spectrum of the quiescent material. These results give rise to a complete picture of autonomous repair that will guide the rational design of improved self‐healing materials.
A new multiple‐scattering‐based optical technique illuminates the molecular motions via which self‐healing polymers can spontaneously and autonomously restore damage. This method allows the construction of 4D micromechanical maps of repair, in situ and spanning five decades of frequency. The complex interplay of diverse dynamics at the origin of self‐healing can thus be quantitatively unraveled.
One-loop effective lagrangians after matching del Aguila, F.; Kunszt, Z.; Santiago, J.
The European physical journal. C, Particles and fields,
04/2016, Letnik:
76, Številka:
5
Journal Article
Recenzirano
Odprti dostop
We discuss the limitations of the covariant derivative expansion prescription advocated to compute the one-loop Standard Model (SM) effective lagrangian when the heavy fields couple linearly to the ...SM. In particular, one-loop contributions resulting from the exchange of both heavy and light fields must be explicitly taken into account through matching because the proposed functional approach alone does not account for them. We review a simple case with a heavy scalar singlet of charge
-
1
to illustrate the argument. As two other examples where this matching is needed and this functional method gives a vanishing result, up to renormalization of the heavy sector parameters, we re-evaluate the one-loop corrections to the T-parameter due to a heavy scalar triplet with vanishing hypercharge coupling to the Brout–Englert–Higgs boson and to a heavy vector-like quark singlet of charged 2 / 3 mixing with the top quark, respectively. In all cases we make use of a new code for matching fundamental and effective theories in models with arbitrary heavy field additions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Summary
STACAS is a computational method for the identification of integration anchors in the Seurat environment, optimized for the integration of single-cell (sc) RNA-seq datasets that ...share only a subset of cell types. We demonstrate that by (i) correcting batch effects while preserving relevant biological variability across datasets, (ii) filtering aberrant integration anchors with a quantitative distance measure and (iii) constructing optimal guide trees for integration, STACAS can accurately align scRNA-seq datasets composed of only partially overlapping cell populations.
Availability and implementation
Source code and R package available at https://github.com/carmonalab/STACAS; Docker image available at https://hub.docker.com/repository/docker/mandrea1/stacas_demo.
Cyclooxygenases are a group of heme-containing isozymes (namely Cox-1 and Cox-2) that catalyze the conversion of arachidonic acid to largely bioactive prostaglandins (PGs). Cox-1 is the ubiquitous ...housekeeping enzyme, and the mitogen-inducible Cox-2 is activated to cause inflammation. Interestingly, Cox-2 is constitutively expressed in the brain at the postsynaptic dendrites and excitatory terminals of the cortical and spinal cord neurons. Neuronal Cox-2 is activated in response to synaptic excitation to yield PGE
2
, the predominant Cox-2 metabolite in the brain, which in turn stimulates the release of glutamate and neuronal firing in a retrograde fashion. Cox-2 is also engaged in the metabolism of new endocannabinoids from 2-arachidonoyl-glycerol to modulate their actions at presynaptic terminals. In addition to these interactions, the induction of neuronal Cox-2 is coupled to the trans-synaptic activation of the dopaminergic mesolimbic system and some serotoninergic receptors, which might contribute to the development of emotional behavior. Although much of the focus regarding the induction of Cox-2 in the brain has been centered on neuroinflammation-related neurodegenerative and psychiatric disorders, some evidence also suggests that Cox-2 release during neuronal signaling may be pivotal for the fine tuning of cortical networks to regulate behavior. This review compiles the evidence supporting the homeostatic role of neuronal Cox-2 in synaptic transmission and plasticity, since neuroinflammation is originally triggered by the induction of glial Cox-2 expression. The goal is to provide perspective on the roles of Cox-2 beyond neuroinflammation, such as those played in memory and anxiety, and whose evidence is still scant.
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