Massive stealth scalar fields from deformation method II: charged case

Extending the results of our previous work we construct an uniparametric class of action principles for complex scalar fields with the property that their energy momentum tensor and the electric current vanish for certain massive configurations. These {\it stealth} fields do not curve the spacetime and they do not source electromagnetic fields in spite their non-trivial degrees of freedom and $U(1)$ gauge invariance. We shall also show that the presence of these stealth fields can affect the strength of the gravity-matter and radiation-matter coupling of other massive configurations. Indeed, the energy momentum tensor of other massive (non-stealth) configurations and the electric current can be rescaled (with a stealth-mass depending factor) with respect to the predictions of the standard complex scalar field model. Hence we argue that stealth fields could be detected indirectly by means of their effects on standard configurations of matter.Comment: 13 pages. This is the second part of arXiv:1805.04621 published at Eur.Phys.J.

Outlier Mining Methods Based on Graph Structure Analysis

Outlier detection in high-dimensional datasets is a fundamental and challenging problem across disciplines that has also practical implications, as removing outliers from the training set improves the performance of machine learning algorithms. While many outlier mining algorithms have been proposed in the literature, they tend to be valid or efficient for specific types of datasets (time series, images, videos, etc.). Here we propose two methods that can be applied to generic datasets, as long as there is a meaningful measure of distance between pairs of elements of the dataset. Both methods start by defining a graph, where the nodes are the elements of the dataset, and the links have associated weights that are the distances between the nodes. Then, the first method assigns an outlier score based on the percolation (i.e., the fragmentation) of the graph. The second method uses the popular IsoMap non-linear dimensionality reduction algorithm, and assigns an outlier score by comparing the geodesic distances with the distances in the reduced space. We test these algorithms on real and synthetic datasets and show that they either outperform, or perform on par with other popular outlier detection methods. A main advantage of the percolation method is that is parameter free and therefore, it does not require any training; on the other hand, the IsoMap method has two integer number parameters, and when they are appropriately selected, the method performs similar to or better than all the other methods tested.Peer ReviewedPostprint (published version

Massive stealth scalar fields from field redefinition method

We propose an uni-parametric deformation method of action principles of scalar fields coupled to gravity which generates new models with massive stealth field configurations, i.e. with vanishing energy-momentum tensor. The method applies to a wide class of models and we provide three examples. In particular we observe that in the case of the standard massive scalar action principle, the respective deformed action contains the stealth configurations and it preserves the massive ones of the undeformed model. We also observe that, in this latter example, the effect of the energy-momentum tensor of the massive (non-stealth) field can be amplified or damped by the deformation parameter, alternatively the mass of the stealth field.Comment: 12 page

La dialéctica como enfoque filosófico en la formación del investigador en América Latina

Methodology in the training of scientific researchers has always been a complicated subject, awakening diverse academic concerns. The objective of this article is to recognize dialectics as a philosophical approach for the training of scientific researchers in Latin America. The aim is to obtain experiences, reflections on dialectical competences for the use of methodologies in research. Dialectics as a philosophical approach should be used from the undergraduate or graduate level, in the teacher-student binomial, in teaching and learning. The qualitative approach was used, privileging the deep -reflexive analysis of concepts that are part of studied contexts, from a critical- self-critical orientation, allowing approaches such as materialistic dialectics, phenomenology for the scientific method. The study was developed in consultation with new bibliography, doctoral theses, texts of different currents of philosophical and social thinking. It is concluded that, for the formation of scientific researchers, the use of philosophical approaches such as dialectics, phenomenology plus the experience assumed in reading is required, as a practice in writing in the formation of future researchers from the student seedlings. Keywords: dialectics; philosophical approach; formative research; scientific method.La metodología en formación de investigadores científicos fue siempre tema complicado, despertando diversas inquietudes académicas, el artículo tiene como objetivo reconocer la dialéctica como un enfoque filosófico para la formación del investigador científico en América Latina. Se trata de obtener experiencias, reflexiones en competencias dialécticas para la utilización de metodologías en investigación. La dialéctica como enfoque filosófico debe utilizarse desde pregrado o licenciatura, en el binomio docente – estudiante, en enseñanza y aprendizaje. Se utilizó el enfoque cualitativo, privilegiando el análisis profundo – reflexivo de conceptos que forman parte de contextos estudiados, desde una orientación critico - autocritico, permitiendo enfoques como dialéctica materialista, fenomenología para el método científico. El estudio se desarrolló en consulta a novedosa bibliografía, tesis doctorales, textos de distintas corrientes del pensar filosófico y social. Se concluye que, para la formación de investigadores científicos, se requiere la utilización de enfoques filosóficos como la dialéctica, fenomenología más la experiencia asumida en la lectura, como práctica en redacción en la formación de futuros investigadores desde los semilleros estudiantiles. Palabras claves: Dialéctica; enfoque filosófico; investigación formativa; método científico

Analisa QS VPN MPLS TE (Traffic Engineering) pada Aplikasi Video Streaming

ABSTRAKSI: Perkembangan sistem komunikasi saat ini mampu mengembangkan sistem jaringan untuk membawa berbagai jenis trafik seperti voice, video, dan data dimana besar paketnya berbeda-beda. Untuk mengetahui kelayakan dan kualitas sistem komunikasi ini perlu dilakukan penilaian terhadap QoS(Quality of Service jaringan). Banyak pertimbangan yang perlu diperhatikan dalam mendapat nilai kualitas yang baik pada jaringan. Pengadaan bandwith yang besar merupakan salah satu alternatif, namun hal ini menjadi tidak efektif karena trafik yang dilewatkan tidak secara terus menerus memiliki nilai trafik yang besar. Untuk meningkatkan kinerja jaringan yang dapat dilakukan antara lain differential service, resource reservation protocol (RSVP), multi protocol label switching (MPLS), dan penggunaan manajemen routing.Salah satu teknologi jaringan yang berkembang adalah MPLS, teknologi ini memiliki metode forwarding malalui suatu jaringan dengan menggunakan informasi dalam label yang dilekatkan pada paket IP. Dengan menggunakan ruting OSPF yang diterapkan pada jaringan MPLS, diharapkan mampu member peningkatan terhadap nilai QoS. Contoh layanan yang disediakan oleh MPLS adalah VPN (Virtual Private Network). Layanan ini mengimplementasikan sebuah jaringan pada infrastruktur jaringan yang lebih besar yang menyediakan jasa sewa dan keamanan pada jaringan tersebut.Penambahan fungsi Traffic Engineering dapat mengefisienkan MPLS VPN. Dengan MPLS-TE VPN, sebelum paket dikirimkan terdapat mekanisme untuk melihat kondisi jaringan terlebih dahulu, bagaimana kondisi bandwidth-nya, apakah kondisi link tersebut penuh atau tidak, setelah itu barulah dilakukan mekanisme pemilihan rute terbaik berdasarkan kondisi jalur tersebut.Dalam tugas akhir ini dilakukan analisa seberapa besar pengaruh MPLS-TE pada VPN terhadap performansi QoS jaringan serta membandingkannya dengan VPN yang hanya menggunakan MPLS untuk trafik video dengan trafik background yang besarnya bervariasi. Parameter performansi QoS jaringan yang dianalisa tu delay, jitter, packet loss, dan troughput.Kata Kunci : MPLS, MPLS TE, MPLS TE VPN, OSPF, delay, jitter, packet loss, throughputABSTRACT: Today‟s communication system growth is able to develop network system to carry various traffic such as voice, video, and data with different packet size each. In order to find out this communication system ability and quality,it need to evaluate the QoS (Quality of Service) of network. Many considerations that need to be observe in order to get good quality in the network. Provide more bandwidth is one of many alternative, but this is not increase network effetivity, because traffic which across the network is not always big. Increase network performance is able by doing improvement such as differentiated service, resource reservation protocol, multiprotocol label switching, and routing management. One of network technology growth is MPLS, this technology has forwarding method across another network using information in label which is stick on IP packet. By using OSPF routing in MPLS network, MPLS is expected to increase network QoS. One of MPLS service is VPN (Virutal Private Network). This service implement a network across another network which is bigger and usually provide rent and security service to provide that network. Traffic engineering is an extension that is able to make VPN MPLS more efficient. By using VPN MPLS TE, befor packet deliver to destination there is a mechanism to evalulat network condition, how is the bandwidth condition, wether link is full or not, then do the route mechanism. This project do analysis about how much MPLS TE affected VPN QoS performance and compare it with VPN that only using MPLS with video traffic and background traffic which has variated length. Network QoS performance parameter which will be analized is delay, jitter, packet loss, and throughput.Keyword: MPLS, MPLS TE, MPLS TE VPN, OSPF, delay, jitter, packet loss, throughpu

STRATEGI DIPLOMASI PUBLIK INDONESIA-MALAYSIA-THAILAND GROWTH TRIANGLE (IMT-GT) DALAM MENINGKATKAN SEKTOR PARIWISATA HALAL DI ASIA TENGGARA

This research aims at discussing the public diplomacy strategy of the Indonesia-Malaysia-Thailand Growth Triangle (IMT-GT) in promoting the halal tourism sector in Southeast Asia. This qualitative eserach used the document studies technique, which involved analyzing secondary data obtained from books, journals, websites, and reports. The data analysis techniques include data reduction, data presentation, and data interpretation. The research utilizes the concept of public diplomacy, which has three dimensions: news management, strategic communication, and relationship building, as well as international cooperation through Trilateral. The public diplomacy strategy implemented by IMT-GT for news management includes utilizing technology and mass media such as official websites, Instagram, YouTube, Twitter, Facebook, and creating a smartphone application to facilitate Muslim tourists in their travel and worship activities. The communication strategy is carried out by establishing the Halal Tourism Acceleration Team (TP3H), Working Groups on Halal Products (WGHAPASS), and the Halal Science Center of Chulalongkorn (HASCI). Relationship building is done through conducting training programs such as the Indonesia Muslim Travel Index (IMTI), the Malaysia International Halal Showcase (MIHAS), and the Thailand International Halal Expo (TIHEX). Through the Trilateral international cooperation between Indonesia, Malaysia, and Thailand, the halal industry in these three countries is growing and becoming more competitive at the global level

Comunidades y robustez en redes complejas reales y sintéticas

Tesis (Doctor en Física)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación, 2022.El estudio de las redes complejas, sistemas cuya estructura está regida por una compleja red de interacciones, es un área activa de investigación multidisciplinaria. Este campo ha recibido un gran impulso en los últimos años debido a la disponibilidad de una cantidad masiva de datos y a la existencia de recursos computacionales que permiten llevar a cabo los análisis estadísticos requeridos. Redes complejas extensas pueden encontrarse en una gran cantidad de sistemas naturales y artificiales, tales como sistemas físicos, biológicos, sociales, infraestructuras tecnológicas, etc. El aporte de la física a esta temática viene de la mano de la mecánica estadística, cuyas herramientas han facilitado el estudio de la estructura, la dinámica y la evolución de las redes complejas, brindando un marco teórico adecuado para el estudio cualitativo y cuantitativo de estos sistemas. La caracterización estadística de la estructura de las redes complejas se aborda desde diversos enfoques. Entre ellos hay dos que se destacan por la información que aportan y por las implicancias prácticas que ofrecen. Por una parte, la caracterización de estructuras modulares o comunidades es importante para entender la funcionalidad de las redes. Por otra parte, el estudio de la resiliencia de las redes ante fallas o ataques dirigidos es de gran utilidad para comprender cómo pueden generarse redes con un funcionamiento robusto. Curiosamente, estos dos conceptos –la existencia de comunidades y robustez de las redes– están íntimamente relacionados, y su estudio presenta grandes desafíos, dada la complejidad de los cálculos y análisis necesarios para su abordaje. En esta tesis estudiamos la existencia de comunidades en redes de jugadores de ajedrez utilizando la base de datos de partidas más extensa disponible, en su momento, en el mundo. Realizamos una caracterización general de las mismas y observamos una fuerte correlación entre las comunidades y el nivel de juego de los jugadores. En lo que respecta a las fallas y/o ataques analizamos redes sintéticas, tales como grafos de Erdös-Rényi y redes planares de Delaunay. Caracterizamos la robustez de las mismas mediante el estudio de transiciones de percolación, utilizando las herramientas de análisis de los fenómenos críticos y extensas simulaciones numéricas. Observamos que las transiciones varían de manera cualitativa de acuerdo con el tipo de red y con la estrategia de ataque empleada. En particular, observamos que algunos ataques generan transiciones similares a las encontradas en procesos de percolación explosiva.The study of complex networks, systems whose structure is governed by a complex interaction network, is an active multidisciplinary field of research in which physics has had a prevailing role. This field has received great impulse during the last years because of the availability of a massive amount of data and the existence of computational resources that allow to perform the required statistical analysis. Extensive complex networks can be found in a large variety of natural and artificial systems, such as physical, biological, and social systems, technological infrastructures, etc. Given the importance of these systems, investigations exploring the structure, dynamics and evolution of complex networks has raised the interest of the physics community, as tools coming from statistical mechanics, as well as from other fields of physics, are fundamental and have a direct application in the analysis and comprehension of such systems. The statistical characterization of the structure of complex networks is addressed from different approaches. Among them there are two that stand because of the information they give and because of the practical applications they allow. On one side, the characterization of modular structures or communities is important to understand the functionality of networks. On the other side, the study of the resiliency of networks against failures or targeted attacks gives relevant information on how to develop robust networks. Interestingly, these two concepts --the existence of communities and the robustness of networks-- are closely related, and their study presents big challenges, given the complexity of the calculations and analysis required to address them. In this thesis we studied the existence of communities in networks of chess players using the largest available database, at the moment, on the world. We performed a general characterization of the networks, observing a strong correlation between communities and player skill level. In terms of failures and targeted attacks, we studied synthetic random networks, such as Erdös-Rényi graphs and Delaunay triangulations. We characterized their robustness through the study of percolation transitions, using tools from critical phenomena and extensive numerical simulations. We observed that the transitions vary in a qualitative manner depending on the type of network and the attack strategy. In particular, we found that certain attacks generate transitions similar to those encountered in processes of explosive percolation.Fil: Almeira, Nahuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina

Preparación, caracterización y propiedades de nanohilos magneticos bimetálicos

Tesis (Lic. en Física)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2021.Para este trabajo nos propusimos fabricar y estudiar arreglos de nanohilos bimetálicos de Fe-Ni con un enfoque en sus propiedades magnéticas. Produjimos tres muestras con composiciones que rondan la del Permalloy, una aleación rica en Ni (Fe25Ni75) muy conocida en el mundo, usando la técnica de electrodeposición de iones en membranas de alúmina porosa previamente fabricadas en nuestro laboratorio. Mediante microscopía electrónica de barrido estudiamos la morfología y por difracción de rayos x la microestructura de las muestras fabricadas. Analizamos las propiedades magnéticas a partir de los ciclos de histéresis conseguidos por medio de magnetometría de muestra vibrante a temperatura ambiente, variando el ángulo entre el eje longitudinal de los nanohilos y el campo aplicado. Las muestras presentaron la misma fase cristalina desordenada (Fe en una matriz de Ni), coercitividades y remanencias bajas, gran contribución de la anisotropía de forma dada por la geometría de los nanohilos (alta relación de aspecto), suficiente energía dipolar para competir con la anisotropía de forma y un máximo de susceptibilidad diferencial en campos magnéticos positivos que sólo pudo ser explicado por medio de una estructura magnética remanente metaestable formada por dominios de tipo vórtice que son producto de la competencia entre la anisotropía de forma y la interacción dipolar entre nanohilos.The aim of this work is to prepare and study Fe-Ni bimetallic nanowire arrays focusing on their magnetic properties. We produced three samples with compositions around that of Permalloy, a widely-known, Ni-rich alloy (Fe25Ni75), using the electrodeposition technique into nanoporous alumina membranes previously manufactured in our laboratory. We studied the morphology of the samples using scanning electron microscopy and their microstructure by x-ray diffraction. We analyze the magnetic properties from the hysteresis cycles measured with a vibrating sample magnetometer at room temperature, varying the angle between the longitudinal axis of the nanowires and the applied field. We obtained the same disordered phase (Fe in a Ni matrix), low coercivities and remanences, an important contribution of shape anisotropy given by the geometry of the nanowires (high aspect ratio), dipolar interaction enough to compensate for the shape anisotropy and a maximum in differential susceptibility in positive magnetic fields could only be explained through a metastable remanent magnetic structure formed by vortex-type domains that result from a competition between shape anisotropy and the dipolar interaction between nanowires.Fil: Almeira, Joaquín. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina

Makna Pendapatan bagi Mahasiswa Akuntansi

Pendapatan sangat bermanfaat bagi semua masyarakat tentunya mahasiswa yang sedang menempuh Pendidikan. Mahasiswa menggunakan pendapatan tersebut untuk keperluan kuliah seperti biaya makan, dan biaya kendaraan. Tujuan dari penelitian ini adalah untuk menggali  makna mengenai pendapatan bagi mahasiswa S1 Akuntansi dan mengetahui kegunaan dari pendapatan yang telah diperoleh mahasiswa. Penelitian ini merupakan penelitian kualitatif dengan metode fenomenologi. Data dalam penelitian ini diperoleh dengan melakukan wawancara dengan para narasumber yang merupakan seorang mahasiswa akuntansi. Hasil penelitian yang didapatkan adalah para mahasiswa S1 Akuntansi UPNVJ mengetahui makna pendapatan