Search

We study various aspects of the Carroll limit in which the speed of light is sent to zero. A large part of this paper is devoted to the quantization of Carroll field theories. We show that these exhibit infinite degeneracies in the spectrum and may suffer from non-normalizable ground states. As a consequence, partition functions of Carroll systems are ill-defined and do not lead to sensible thermodynamics. These seemingly pathological properties might actually be a virtue in the context of flat space holography. Better defined is the Carroll $\textit{regime}$, in which we consider the leading order term in an expansion around vanishing speed of light without taking the strict Carroll limit. Such an expansion may lead to sensible notions of Carroll thermodynamics. An interesting example is a gas of massless particles with an imaginary chemical potential conjugate to the momentum. In the Carroll regime we show that the partition function of such a gas leads to an equation of state with $w=-1$. As a separate story, we study aspects of Carroll gravity and couplings to Carrollian energy-momentum tensors. We discuss many examples of solutions to Carroll gravity, including wormholes, Maxwell fields, solutions with a cosmological constant, and discuss the structure of geodesics in a Carroll geometry. The coupling of matter to Carroll gravity also allows us to derive energy-momentum tensors for hypothetical Carroll fluids from expanding relativistic fluids as well as directly from hydrostatic partition functions., Comment: 49 pages of main text and 3 appendices

We introduce two infinite sequences of entanglement monotones, which are constructed from expectation values of polynomials in the modular Hamiltonian. These monotones yield infinite sequences of inequalities that must be satisfied in majorizing state transitions. We demonstrate this for information erasure, deriving an infinite sequence of "Landauer inequalities" for the work cost, bounded by linear combinations of expectation values of powers of the modular Hamiltonian. These inequalities give improved lower bounds for the work cost in finite dimensional systems, and depend on more details of the erased state than just on its entropy and variance of modular Hamiltonian. Similarly one can derive lower bounds for marginal entropy production for a system coupled to an environment. These infinite sequences of entanglement monotones also give rise to relative quantifiers that are monotonic in more general processes, namely those involving so-called $\sigma$-majorization with respect to a fixed point full rank state $\sigma$; such quantifiers are called resource monotones. As an application to thermodynamics, one can use them to derive finite-dimension corrections to the Clausius inequality. Finally, in order to gain some intuition for what (if anything) plays the role of majorization in field theory, we compare pairs of states in discretized theories at criticality and study how majorization depends on the size of the bipartition with respect to the size of the entire chain., Comment: 47 pages, 2 figures

We present a new perspective on bulk reconstruction using Berry phases in the boundary CFT. Our parallel transport of modular Hamiltonians is associated to a trajectory in the space of states, which we obtain from the insertion of a source in the Euclidean path integral. Using a modular version of the extrapolate dictionary and the equivalence between modular flow in the boundary and the bulk, we show that the expectation value of the modular Berry curvature on the boundary agrees with an appropriately defined bulk symplectic form associated to the entanglement wedge. In addition, we derive a quantum information metric on the space of density matrices from the Berry curvature, which is related to the canonical energy in the bulk. We also explore the case where a state change reduces to a shape change, uncovering the coadjoint orbit structure of kinematic space in higher dimensions., Comment: 47 pages, 6 figures

Driven quantum systems exhibit a large variety of interesting and sometimes exotic phenomena. Of particular interest are driven conformal field theories (CFTs) which describe quantum many-body systems at criticality. In this paper, we develop both a spacetime and a quantum information geometry perspective on driven 2d CFTs. We show that for a large class of driving protocols the theories admit an alternative but equivalent formulation in terms of a CFT defined on a spacetime with a time-dependent metric. We prove this equivalence both in the operator formulation as well as in the path integral description of the theory. A complementary quantum information geometric perspective for driven 2d CFTs employs the so-called Bogoliubov-Kubo-Mori (BKM) metric, which is the counterpart of the Fisher metric of classical information theory, and which is obtained from a perturbative expansion of relative entropy. We compute the BKM metric for the universal sector of Virasoro excitations of a thermal state, which captures a large class of driving protocols, and find it to be a useful tool to classify and characterize different types of driving. For M\"obius driving by the SL(2,R) subgroup, the BKM metric becomes the hyperbolic metric on the unit disk. We show how the non-trivial dynamics of Floquet driven CFTs is encoded in the BKM geometry via M\"obius transformations. This allows us to identify ergodic and non-ergodic regimes in the driving. We also explain how holographic driven CFTs are dual to driven BTZ black holes with evolving horizons. The deformation of the black hole horizon towards and away from the asymptotic boundary provides a holographic understanding of heating and cooling in Floquet CFTs., Comment: 82 pages including references, 14 figures

We propose a CFT definition of local observables in both the exterior and interior of bulk black holes, whenever such an interior exists. We achieve this by introducing a small microcanonical black hole as a "probe" and using its modular flow to propagate operators from the asymptotic boundary to the interior of other black holes along its worldline, elaborating on the ideas of [2009.04476]. The key conceptual advance is a CFT criterion for selecting states whose modular flow acts as geometric proper time translation in the bulk, which we dub "local equilibrium" states. Our interior reconstruction depends on the choice of code subspace but not on the specific black hole microstate and does not suffer from the "frozen vacuum" problem of other approaches. By virtue of our construction, the question of firewall typicality reduces to a technical problem we articulate and we identify a CFT correlator that is expected to signal the approach to the black hole singularity via a universal divergence. We end with comments on the utility of our framework to the quest for a quantum description of de Sitter cosmologies., Comment: 46 pages + appendices

Graphical abstract, Human epidermal stem cells initiate terminal differentiation when spreading is restricted on ECM-coated micropatterned islands, soft hydrogels or hydrogel-nanoparticle composites with high nanoparticle spacing. The effect of substrate topography, however, is incompletely understood. To explore this, primary human keratinocytes enriched for stem cells were seeded on a topographical library with over 2000 different topographies in the micrometre range. Twenty-four hours later the proportion of cells expressing the differentiation marker transglutaminase-1 was determined by high content imaging. As predicted, topographies that prevented spreading promoted differentiation. However, we also identified topographies that supported differentiation of highly spread cells. Topographies supporting differentiation of spread cells were more irregular than those supporting differentiation of round cells. Low topography coverage promoted differentiation of spread cells, whereas high coverage promoted differentiation of round cells. Based on these observations we fabricated a topography in 6-well plate format that supported differentiation of spread cells, enabling us to examine cell responses at higher resolution. We found that differentiated spread cells did not assemble significant numbers of hemidesmosomes, focal adhesions, adherens junctions, desmosomes or tight junctions. They did, however, organise the actin cytoskeleton in response to the topographies. Rho kinase inhibition and blebbistatin treatment blocked the differentiation of spread cells, whereas SRF inhibition did not. These observations suggest a potential role for actin polymerization and actomyosin contraction in the topography-induced differentiation of spread cells. Statement of Significance The epidermis is the outer covering of the skin. It is formed by layers of cells called keratinocytes. The basal cell layer contains stem cells, which divide to replace cells in the outermost layers that are lost through a process known as differentiation. In this manuscript we have developed surfaces that promote the differentiation of epidermal stem cells in order to understand the signals that control differentiation. The experimental tools we have developed have the potential to help us to devise new treatments that control diseases such as psoriasis and eczema in which epidermal stem cell proliferation and differentiation are disturbed.

This document contains detailed information on the ASReview LAB software. The latest version of the documentation can also be found on the web pagehttps://asreview.readthedocs.io/en/latest/index.html. For more information, seehttps://github.com/asreview/asreview or https://asreview.ai.&nbsp

No description supplied

This document contains detailed information for version 0.14 of the ASReview software. For more information, seehttps://github.com/asreview/asreview.&nbsp

To help researchers conduct a systematic review or meta-analysis as efficiently and transparently as possible, we designed a tool (ASReview) to accelerate the step of screening titles and abstracts. For many tasks - including but not limited to systematic reviews and meta-analyses - the scientific literature needs to be checked systematically. Currently, scholars and practitioners screen thousands of studies by hand to determine which studies to include in their review or meta-analysis. This is error prone and inefficient because of extremely imbalanced data: only a fraction of the screened studies is relevant. The future of systematic reviewing will be an interaction with machine learning algorithms to deal with the enormous increase of available text. We therefore developed an open source machine learning-aided pipeline applying active learning: ASReview. We demonstrate by means of simulation studies that ASReview can yield far more efficient reviewing than manual reviewing, while providing high quality. Furthermore, we describe the options of the free and open source research software and present the results from user experience tests. We invite the community to contribute to open source projects such as our own that provide measurable and reproducible improvements over current practice., Comment: All code for the software ASReview is available under an Apache-2.0 license at Github: https://github.com/asreview

This chapter concentrates on the measures taken by the International Maritime Organization (IMO) to prevent acts of terrorism at sea. It looks in some detail at the legal jurisdictional framework put in place by the development and adoption of the 1988 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (SUA) and its 2005 Protocols. The chapter also discusses the practical measures adopted by IMO through the International Ship and Port Facility Security (ISPS) Code aimed at improving security in ports and on ships. Finally, this chapter concludes that these measures, which are constantly under review by the relevant committees within the IMO, have put in place the necessary building blocks. What is now required is the political will on the part of IMO Member States by passing the necessary legislation or other administrative measures to implement satisfactorily these measures.

We derive necessary and sufficient conditions for large $N$ conformal field theories to have a universal free energy and an extended range of validity of the higher-dimensional Cardy formula. These constraints are much tighter than in two dimensions and must be satisfied by any conformal field theory dual to Einstein gravity. We construct and analyze symmetric product orbifold theories on $\mathbb{T}^d$ and show that they only realize the necessary phase structure and extended range of validity if the seed theory is assumed to have a universal vacuum energy., 32 pages + appendices

We revisit certain aspects of thermalization in 2D CFT. In particular, we consider similarities and differences between the time dependence of correlation functions in various states in rational and non-rational CFTs. We also consider the distinction between global and local thermalization and explain how states obtained by acting with a diffeomorphism on the ground state can appear locally thermal, and we review why the time-dependent expectation value of the energy-momentum tensor is generally a poor diagnostic of global thermalization. Since all 2D CFTs have an infinite set of commuting conserved charges, generic initial states might be expected to give rise to a generalized Gibbs ensemble rather than a pure thermal ensemble at late times. We construct the holographic dual of the generalized Gibbs ensemble and show that, to leading order, it is still described by a BTZ black hole. The extra conserved charges, while rendering $c < 1$ theories essentially integrable, therefore seem to have little effect on large-$c$ conformal field theories., 25 pages

Die Abteilung Ganzheitliche Bilanzierung GaBi wurde 1989 am Institut für Kunststoffprüfung und Kunststoffkunde IKP an der Universität Stuttgart gegründet. 2006 wechselte sie an den Lehrstuhl für Bauphysik LBP unter der Leitung von Prof. Dr.-Ing. Klaus Sedlbauer und ist seit 2008 auch am Fraunhofer-Institut für Bauphysik IBP angesiedelt. Die Arbeitsschwerpunkte der Abteilung stellen die Ganzheitliche Bilanzierung und Nachhaltigkeitsanalyse von Produkten, Prozessen sowie Dienstleistungen über den gesamten Lebenszyklus dar. Bei Ökobilanzen (Life Cycle Assessment, LCA) als Teilelement der Ganzheitlichen Bilanzierung werden ökologische Aspekte analysiert. Darüber hinaus werden in der Abteilung auch ökonomische, soziale und technische Einflussfaktoren untersucht. Die Entwicklung nachhaltiger Produkte und Prozesse ist auch Ausdruck der persönlichen Motivation der GaBi-Mitarbeiterinnen und -Mitarbeiter. Öffentliche Auftraggeber und Industrieunternehmen erhalten durch die Nachhaltigkeitsanalyse eine Entscheidungsunterstützung. Neben der Ganzheitlichen Bilanzierung werden in der Abteilung auch neue Methoden zur Nachhaltigkeitsbewertung sowie entsprechende Datenbanken entwickelt. Das breitgefächerte Wissen des interdisziplinären Teams sowie die langjährige und tiefgreifende Erfahrung mit Nachhaltigkeitsanalysen zeichnet die Abteilung GaBi aus.

It’s that sense of unease when you step out of the airport terminal building and onto the streets of Kathmandu. Or the moment when you open the door to your new office to see unfamiliar faces waiting for you. Step out of your comfort zone and discover how exciting, thrilling and liberating it can be: a new world is waiting for you. This book is about stepping out of the comfort zone of your own scientific discipline and about exposing yourself to something new. Embrace all the scientific disciplines that build modern-day biomaterials research, in the cultural hotpot of materiomics. Don’t let the jargon and three-letter abbreviations of cell biology hold you back, nor the abracadabra of statistical models, nor the Latin terms for body parts and diseases. Learn a new language and a whole new culture is waiting for you. The compilation of this book was initiated after an exciting conference termed ‘High throughput screening of biomaterials: shaping a new research area’, held beside the Amsterdam canals in April 2011. The meeting was attended by 50 selected scientists from all over the globe and across all the disciplines of biomaterials research, and the format of the conference took away that sense of unease. Chemists talked to clinicians, biologists listened to information scientists, engineers brainstormed with policy makers. We decided to bring this open and inviting atmosphere to the public through this book. Therefore, each chapter contains a tutorial on the topic for non-experts, gives an overview of the current status of that field and discusses how this technology will further shape the future of materiomics. The result of this exciting journey is presented here and was made possible only with the help of all the authors and those who contributed to the organization of the conference (Anouk Mentink), the editing of the book (Ruben Burer) or the chapters (Kristen Johnson). We hope that this book will be a scientific passport which lets you travel across the border of your discipline and helps you to learn to appreciate that of others. You won’t be disappointed. Enjoy your journey!

Scope: High-throughput screening (HTS) is carried out on two- (2D) and three-dimensional (3D) materials, with hundreds to thousands of conditions at various size scales. When hits are successfully found in HTS systems, upscaling to clinically relevant surfaces needs to be performed to validate whether the identified material and functionality can be replicated on the macroscale. In doing so, parameters such as surface chemistry, topography and sample dispensing must be controlled to maintain reproducibility. Here, we discuss the methods harnessed to replicate chemical and topographical features from the nano- to the macroscale in 2D and 3D systems. Technologies to control cell adhesion and 3D scaffold fabrication are introduced and discussed in terms of their potential for HTS. Basic upscaling principles: HTS is a highly automated process that tests small amounts of large numbers of compounds for a desired function. In the previous chapters of this book, the general principles behind material chemistry and resulting physico-chemical properties, combinatorial chemistry, microfabrication technologies and development of tools to perform biological assays on HTS platforms have been described. These elements partly return here, where basic principles of polymer chemistry and surface topographies are introduced in the context of facing the technological challenges to upscale selected candidates to larger surfaces or medical devices with complex curved shapes. In addition, the basic principles behind implant fabrication technologies and precise cell deposition are discussed to illustrate the steps required to assimilate HTS into clinically relevant 3D systems.

Scope: High-throughput and combinatorial research on biomaterials aims at the rapid development of new materials and the establishment of structure–function relationships. Therefore, knowledge of the chemistry of each material and its impact on physical properties is essential to understand the effect on its function as a biomaterial. A tutorial on basic physical and chemical properties of (polymeric) materials highlights these features and can be found in the first part of this chapter. The second part gives an overview of relevant techniques that can be used to screen these material properties in high throughput. In addition, several examples are described in which these methods are used to develop structure–function relationships between material properties and biological performance. Basic principles: physical and chemical properties of polymeric biomaterials: Chemistry is a constant factor from which the performance of most (polymeric) biomaterials can be predicted, but this extrapolation becomes less obvious when numerous materials are mixed in huge combinatorial libraries. Therefore, researchers are becoming increasingly involved in high-throughput material research when successful correlations between biological performance and physico-chemical material properties are to be made. This accelerating trend can be extracted from many studies where high-throughput technologies are successfully applied to measure physical properties and biological performance of many different polymeric biomaterials. Physical properties such as hardness, topography and hydrophilicity are known to be important parameters in the biological evaluation of materials, because they allow or block the adhesion of biological compounds which is required to allow cell-spreading, migration, proliferation and differentiation. These properties are naturally different for every material or combination of materials, and relate primarily to the variable properties on the chemical level (molecular structure, functional groups and degradation). Therefore, the chemistry of a biomaterial directly contributes to its interaction with biological environments.

The ability to regenerate and repair tissues and organs – using science and engineering to supplement biology – continuously intrigues and inspires those hoping that the frailty of our bodies can be ultimately avoided. From ancient times, a surprising range of unnatural materials have been used to (partially) substitute human tissues for medicinal purposes. For example, in the era of the Incas (c. 1500), moulded materials such as gold and silver were used for the ‘surgical’ repair of cranial defects. In addition, archaeological findings reveal a wide range of materials, such as bronze, wood and leather, being used to replace and repair parts of the human body. Continuous refinement led to the first evidence of materials successfully implanted inside the body, reportedly used to repair a bone defect in the seventeenth century (see Further Reading). Even earlier than this, the relationships between anatomy (i.e. structure) and function of living systems had been explored by Leonardo da Vinci and Galileo Galilei, who were among the first few to apply fundamental science to biological systems. In the current age of technology, new materials for biomedical and clinical application have undergone a modern Renaissance, resulting in a surge in design and successful application (1–5). The concepts of tissue repair and substitution are constantly improving and becoming more accessible, as proven for example by the widespread occurrence (and popular approval) of total hip and knee replacements. But rather than replacement with synthetic analogues, can biological tissue(s) be directly engineered?

We embed spherical Rindler space -- a geometry with a spherical hole in its center -- in asymptotically AdS spacetime and show that it carries a gravitational entropy proportional to the area of the hole. Spherical AdS-Rindler space is holographically dual to an ultraviolet sector of the boundary field theory given by restriction to a strip of finite duration in time. Because measurements have finite durations, local observers in the field theory can only access information about bounded spatial regions. We propose a notion of Residual Entropy that captures uncertainty about the state of a system left by the collection of local, finite-time observables. For two-dimensional conformal field theories we use holography and the strong subadditivity of entanglement to propose a formula for Residual Entropy and show that it precisely reproduces the areas of circular holes in AdS3. Extending the notion to field theories on strips with variable durations in time, we show more generally that Residual Entropy computes the areas of all closed, inhomogenous curves on a spatial slice of AdS3. We discuss the extension to higher dimensional field theories, the relation of Residual Entropy to entanglement between scales, and some implications for the emergence of space from the RG flow of entangled field theories., Comment: v3: minor typos corrected

After a stroke, many people experience difficulties to selectively activate muscles. As a result many patients move the affected arm in stereotypical patterns. Shoulder abduction is often accompanied by elbow flexion, reducing the ability to extend the elbow. This involuntary coupling reduces the patient's active range of motion. Gravity compensation reduces the activation level of shoulder abductors which limits the amount of coupled elbow flexion. As a result, stroke patients can instantaneously increase their active range of motion [1]. The objective of the present study is to examine whether training in a gravity compensated environment can also lead to an increased range of motion in an unsupported environment. Parts of this work have been presented at EMBC2009, Minneapolis, USA.

We previously demonstrated that cAMP-mediated protein kinase A (PKA) activation induces in vitro osteogenesis and in vivo bone formation by human mesenchymal stem cells (hMSCs). To analyze the species-specific response of this phenomenon and to translate our findings into a clinical trial, suitable animal models and cell lines are desirable. In this report, we assessed whether PKA plays a similar proosteogenic role played by two commonly used PKA activators—N6,2′-O-dibutyryl-cAMP (db-cAMP) and 8-bromo cAMP (8b-cAMP)—in a number of model systems. To this end, we treated MC3T3-E1 cells, mouse calvarial osteoblasts, mouse MSCs, and rat MSCs with cAMP. We demonstrate that cAMP inhibits osteogenesis in rodent cell types, evidenced by inhibition of osteogenic markers such as alkaline phosphatase (ALP), osteocalcin (BGLAP), and collagen type 1 (COL1A1). In support of this, ex vivo–cultured mouse calvaria exposed to db-cAMP showed a reduction in bone volume. Interestingly, cAMP even stimulated adipogenic differentiation in rat MSCs. Taken together, our data demonstrate that cAMP inhibits osteogenesis in vitro and bone formation ex vivo in rodent models in contrast to our earlier findings in hMSCs. The species discrepancy in response to various osteogenic signals is a critical need to be tested in clinically relevant models to translate the fundamental findings in lower species level to clinical applications.

Publisher Summary This chapter defines stem cells and their properties. It identifies the major differences between embryonic and adult stem cells. Stem cells can be defined by two properties: the ability to make identical copies of themselves and the ability to form other cell types of the body. These properties are also referred to as “stemness.” Stem cells may potentially provide an unlimited supply of cells that can form any of the hundreds of specialized cells in the body. It is because of these properties that stem cells are an interesting cell source for tissue engineers. Stem cells can be divided into two main groups: embryonic and adult or somatic stem cells. Embryonic stem cells are responsible for embryonic and fetal development and growth. In the human body, adult stem cells are responsible for growth, tissue maintenance and regeneration and repair of diseased or damaged tissue. Embryonic stem cells do not exist in the body. When cells are isolated from the inner cell mass of the blastocyst, they can be massively expanded in the laboratory, while maintaining their pluripotency. Adult stem cells are undifferentiated cells, which reside in differentiated tissues.

Tissue engineering aims at replacing or regenerating tissues lost due to diseases or traumas (Langer and Vacanti, 1993). However, mimicking in vitro the physiological complexity of vascularized tissue is a major obstacle, which possibly contributes to impaired healing in vivo. In higher organisms, native features including the vascular network, the lymphatic networks and interstitial flow promote both mass transport and organ development. Attempts to mimic those features in engineered tissues will lead to more clinically relevant cell-based therapies. Aside from current strategies promoting angiogenesis from the host, an alternative concept termed prevascularization is emerging. It aims at creating a biological vasculature inside an engineered tissue prior to implantation. This vasculature can rapidly anastamose with the host and enhances tissue survival and differentiation. Interestingly, growing evidence supports a role of the vasculature in regulating pattern formation and tissue differentiation. Thus, prevascularized tissues also benefit from an intrinsic contribution of their vascular system to their development. From those early attempts are emerging a body of principles and strategies to grow and maintain, in vitro, those self-assembled biological vascular networks. This could lead to the generation of engineered tissues of more physiologically relevant complexity and improved regenerative potential.