Brown-York charges at null boundaries

The Brown-York stress tensor provides a means for defining quasilocal gravitational charges in subregions bounded by a timelike hypersurface. We consider the generalization of this stress tensor to null hypersurfaces. Such a stress tensor can be derived from the on-shell subregion action of general relativity associated with a Dirichlet variational principle, which fixes an induced Carroll structure on the null boundary. The formula for the mixed-index tensor Tij takes a remarkably simple form that is manifestly independent of the choice of auxiliary null vector at the null surface, and we compare this expression to previous proposals for null Brown-York stress tensors. The stress tensor we obtain satisfies a covariant conservation equation with respect to any connection induced from a rigging vector at the hypersurface, as a result of the null constraint equations. For transformations that act covariantly on the boundary structures, the Brown-York charges coincide with canonical charges constructed from a version of the Wald-Zoupas procedure. For anomalous transformations, the charges differ by an intrinsic functional of the boundary geometry, which we explicity verify for a set of symmetries associated with finite null hyper-surfaces. Applications of the null Brown-York stress tensor to symmetries of asymptotically flat spacetimes and celestial holography are discussed.

Quantum Entanglement of Monochromatic and Non-Monochromatic Photons on a Waveguide Beam Splitter

It is well known that the waveguide beam splitter can be used as a source for the quantum entanglement of photons. The analysis of such quantum entanglement is a difficult problem even for monochromatic photons, since the system under study is multiparametric. This paper will show that quantum entanglement can be represented in a simple form not only for monochromatic photons but also for non-monochromatic ones. It will be shown that quantum entanglement for non-monochromatic photons can be very different from monochromatic photons, which can be used to create large quantum entanglement.

Delirious New Zealand

<p>Delirious New Zealand proposes an alternative parliament, one that uses walls and boundaries to navigate authority and architecture. Walls are complex, they can range from a simple form of protection against elemental conditions, through to the reinforcement of borders between two countries with emphasis and polarising effect. Whilst variable, each instance is committed to division, and both are boundaries facilitated by architecture in the form of walls. Through design led research, three phases of investigation are developed across successive scales. Presented as 'Installing Boundaries', 'Housing Politics' and 'Political Infrastructure', each design outcome forms a larger body of work referred to as the design. Shape, Threshold, and Montage are the architectural principles that determine a given walls significance investigated at each scale. These three speculative propositions are not final outcomes for what an alternative parliament should be. Instead, Delirious New Zealand explores architectural boundaries as the material interface between those who govern and those governed. Koolhaas’s observations of the Berlin Wall – pre-demise – and his publication ‘Delirious New York’ highlight the significance of the authority of an architect, and habitational authority in the realisation and reality of architecture. The significance of a given boundary wall must then consider two things. One, the architectural elements that make up the wall itself. Two, the context within which a wall operates - be that social, political, economic etc. This thesis not only examines the design outcomes as being ‘about architecture’ in the form of the design, but also uses this as a platform to discuss ‘concepts of architecture’ more broadly. Accordingly, the concept of authority and architecture is discussed throughout the production and presentation of the three scales of investigation. A final critique in the form of a design discussion concludes this thesis, at which point the final act of installing boundaries is undertaken. ‘Delirious New Zealand’ considers parliament as a programmatic and contextual provocation for the design of architectural boundaries. In doing so, the segregated inhabitants are defined as the politicians and the people. Although political in programme, this thesis is not politically motivated nor intent on acting politically.</p>

Delirious New Zealand

<p>Delirious New Zealand proposes an alternative parliament, one that uses walls and boundaries to navigate authority and architecture. Walls are complex, they can range from a simple form of protection against elemental conditions, through to the reinforcement of borders between two countries with emphasis and polarising effect. Whilst variable, each instance is committed to division, and both are boundaries facilitated by architecture in the form of walls. Through design led research, three phases of investigation are developed across successive scales. Presented as 'Installing Boundaries', 'Housing Politics' and 'Political Infrastructure', each design outcome forms a larger body of work referred to as the design. Shape, Threshold, and Montage are the architectural principles that determine a given walls significance investigated at each scale. These three speculative propositions are not final outcomes for what an alternative parliament should be. Instead, Delirious New Zealand explores architectural boundaries as the material interface between those who govern and those governed. Koolhaas’s observations of the Berlin Wall – pre-demise – and his publication ‘Delirious New York’ highlight the significance of the authority of an architect, and habitational authority in the realisation and reality of architecture. The significance of a given boundary wall must then consider two things. One, the architectural elements that make up the wall itself. Two, the context within which a wall operates - be that social, political, economic etc. This thesis not only examines the design outcomes as being ‘about architecture’ in the form of the design, but also uses this as a platform to discuss ‘concepts of architecture’ more broadly. Accordingly, the concept of authority and architecture is discussed throughout the production and presentation of the three scales of investigation. A final critique in the form of a design discussion concludes this thesis, at which point the final act of installing boundaries is undertaken. ‘Delirious New Zealand’ considers parliament as a programmatic and contextual provocation for the design of architectural boundaries. In doing so, the segregated inhabitants are defined as the politicians and the people. Although political in programme, this thesis is not politically motivated nor intent on acting politically.</p>

Simple representation of the quantum entanglement of coupled harmonic oscillators in terms of the reflection coefficient

Quantum entanglement of coupled harmonic oscillators is frequently applied in quantum and non-linear physics, molecular chemistry and biophysics, which is why its study is of a great interest for modern physics. In this work a quantum entanglement of a coupled harmonic oscillator in a simple form was found. This simple form is presented as a single parameter – reflection coefficient R. All parameters of the studied system are included in the R coefficient. It is shown that the derivation of the expression can have applications in quantum optics, in particular in quantum metrology.

One-loop masses of Neumann-Dirichlet open strings and boundary-changing vertex operators

We derive the masses acquired at one loop by massless scalars in the Neumann-Dirichlet sector of open strings, when supersymmetry is spontaneously broken. It is done by computing two-point functions of “boundary-changing vertex operators” inserted on the boundaries of the annulus and Möbius strip. This requires the evaluation of correlators of “excited boundary-changing fields,” which are analogous to excited twist fields for closed strings. We work in the type IIB orientifold theory compactified on T2× T4/ℤ2, where $$ \mathcal{N} $$ N = 2 supersymmetry is broken to $$ \mathcal{N} $$ N = 0 by the Scherk-Schwarz mechanism implemented along T2. Even though the full expression of the squared masses is complicated, it reduces to a very simple form when the lowest scale of the background is the supersymmetry breaking scale M3/2. We use our results to analyze in this regime the stability at the quantum level of the moduli fields arising in the Neumann-Dirichlet sector. This completes the study of ref. [32], where the quantum masses of all other types of moduli arising in the open- or closed-string sectors are derived. Ultimately, we identify all brane configurations that produce backgrounds without tachyons at one loop and yield an effective potential exponentially suppressed, or strictly positive with runaway behavior of M3/2.

EDUKASI SAINS TEKNOLOGI “PERAN NANOTEKNOLOGI DALAM KEHIDUPAN” MELALUI BUKU CERITA BERGAMBAR UNTUK ANAK USIA DINI DI INDONESIA

Scientific literacy is the main key to face challenges in the 21st century to solve problems in everyday life such as water and food, energy, disease, and climate change. Lack of understanding of 'what is nano', the foundation of various disciplines, widely used jargons, and various scientific terms that are difficult to understand, make nanotechnology difficult to be accepted by the wider community. However, this can be overcome by simplifying these complex concepts and presenting them in an interesting way. Media such as story books, infographic posters, interactive videos can be used to explain complex concepts in a simple form. Abroad, there are many story books that raise the concept of nanotechnology and present it in a simple and interesting way. Therefore, the form of picture story books for early childhood and elementary schools can be an effective delivery medium for the concept of nanotechnology.Keywords: education, early children, role of nanotechnology, story books AbstrakLiterasi sains merupakan kunci utama untuk menghadapi berbagai tantangan pada abad 21 untuk memecahkan masalah dalam kehidupan sehari-hari seperti air dan makanan, energi, penyakit, dan perubahan iklim. Hal ini juga berdampak terhadap kurangnya pengetahuan masyarakat Indonesia terhadap teknologi yang berkembang saat ini, salah satunya nanoteknologi. Kurangnya pemahaman tentang ‘apa itu nano’, fondasi dari macam-macam disiplin ilmu, jargon-jargon yang banyak dipergunakan, dan berbagai istilah ilmiah yang sulit dipahami, menyebabkan nanoteknologi sulit diterima oleh masyarakat luas. Namun, hal ini bisa diatasi dengan penyederhanaan konsep-konsep rumit ini dan menyajikannya dengan cara yang menarik. Hal ini sudah banyak dilakukan oleh bidang ilmu lain. Media seperti, buku cerita, poster infografis, video interaktif dapat digunakan untuk menjelaskan konsep rumit dalam bentuk yang sederhana. Di luar negeri sudah banyak buku cerita yang mengangkat konsep nanoteknologi dan menyajikannya secara sederhana dan menarik. Oleh karena itu, bentuk buku cerita bergambar untuk anak usia dini dan sekolah dasar dapat menjadi media penyampaian yang efektif untuk konsep nanoteknologi.Kata kunci: anak usia dini, buku cerita, peran nanoteknologi, pendidikan

Mathematical Modelling to Determine the Greatest Height of Trees

This study aimed to analyse the critical height of a column whose weight varies vertically in order to obtain a simple scaling law for a tree where the weight distribution considered. We modelled trees as cantilevers that were fixed to the ground and formulated a self-buckling problem for various weight distributions. A formula for calculating the critical height was derived in a simple form that did not include special functions. We obtained a theoretical clarification of the effect of the weight distribution of heavy columns on the buckling behaviour. A widely applicable scaling law for trees was obtained. We found that an actual tree manages to distribute the weight of its trunk and branches along its vertical extent in a manner that adequately secures its critical height. The method and findings of this study are applicable to a wide range of fields, such as the simplification of complicated buckling problems and the study of tree shape quantification.

A review of the ecology, genetics, evolution, and magnetosome –induced behaviours of the magnetotactic bacteria

The discovery of magnetosome and magnetotaxis in its most simple form in the magnetotactic bacteria (MTB) had created the tremendous impetus. MTB, spanning multiple phyla, are distributed worldwide, and they form the organelles called magnetosomes for biomineralization. Eight phylotypes of MTB belong to Alphaproteobacteria and Nitrospirae. MTB show preference for specific redox and oxygen concentration. Magnetosome chains function as the internal compass needle and align the bacterial cells passively along the local geomagnetic field (GMF). The nature of magnetosomes produced by MTB and their phylogeny suggest that bullet-shaped magnetites appeared about 3.2 billion years ago with the first magnetosomes. All MTB contains ten genes in conserved mamAB operon for magnetosome chain synthesis of which nine genes are conserved in greigite-producing MTB. Many candidate genes identify the aero-, redox-, and perhaps phototaxis. Among the prokaryotes, the MTB possess the highest number of O2-binding proteins. Magnetofossils serve as an indicator of oxygen and redox levels of the ancient environments. Most descendants of ancestral MTB lost the magnetosome genes in the course of evolution. Environmental conditions initially favored the evolution of MTB and expansion of magnetosome-formation genes. Subsequent changes in atmospheric oxygen concentration have led to changes in the ecology of MTB, loss of magnetosome genes, and evolution of nonMTB.