Hasil untuk "General works"

Leonel Bixano, Tonatiuh Matos

In this work, we generalize Ernst potentials to the Einstein-Maxwell-Dilaton case and explicitly write the corresponding potential space metric. Since this metric is five-dimensional in potential space, we generalize the corresponding Newman-Penrose coefficients for this metric and compare this formalism with previous approaches to show that this formulation is very convenient for analyzing these spacetimes and finding new exact solutions. We show how to obtain old exact solutions and some new ones with very interesting properties.

Yijun Liu, Xiaokun Jin, Yunrui Zhang

Abstract Complex systems pose risks characterized by factors such as uncertainty, nonlinearity, and diversity, making traditional risk measurement methods based on a probabilistic framework inadequate. Supernetworks can effectively model complex systems, and temporal supernetworks can capture the dynamic evolution of these systems. From the perspective of network stability, supernetworks can aid in risk identification for complex systems. In this paper, an IO-SuperPageRank algorithm is proposed based on the supernetwork topological structure. This algorithm reveals network instability by calculating changes in node importance, thereby helping to identify risks in complex systems. To validate the effectiveness of this algorithm, a four-layer supernetwork composed of scale-free networks is constructed. Simulated experiments are conducted to assess the impact of changes in intralayer edge numbers, intralayer node numbers, and interlayer superedge numbers on the risk indicator IO value. Linear regression and multiple tests were used to validate these relationships. The experiments show that changes in the three network topological indicators all bring about risks, with changes in intralayer node numbers having the most significant correlation with the risk indicator IO value. Compared to traditional measures of network node centrality and connectivity, this algorithm can more accurately predict the impact of node updates on network stability. Additionally, this paper collected trade data for crude oil, chemical light oil, man-made filaments and man-made staple fibers from the UN Comtrade Database. We constructed a man-made filaments and fibers supply chain temporal supernetwork, utilizing the algorithm to identify supply chain risks from December 2020 to October 2023. The study revealed that the algorithm effectively identified risks brought about by changes in international situations such as the Russia-Ukraine war, Israel–Hamas conflict, and the COVID-19 pandemic. This demonstrated the algorithm’s effectiveness in empirical analysis. In the future, we plan to further expand its application based on different scenarios, assess risks by analyzing changes in specific system elements, and implement effective risk intervention measures.

Akintayo Eyitayo

The 2015 African Union Agenda 2063 promises “an integrated, prosperous, and peaceful Africa, driven by its own citizens.” Within its seven ambitions and several flagship projects, digital transformation and data governance are becoming key drivers of socio-economic success. Data is an economic resource and a human rights problem in the digital age, therefore adequate data protection is crucial for trust, privacy, and Africa's involvement in the global digital economy. This article investigates how Agenda 2063 prioritises data protection and cybersecurity. The African Union Convention on Cyber Security and Personal Data Protection (Malabo Convention), regional frameworks from ECOWAS, EAC, and SADC, and global regimes like the GDPR and APEC Privacy Framework are highlighted. While 39 African countries have data protection legislation and 34 have Data Protection Authorities, enforcement is patchy, with fewer than half of AU member states ratifying the Malabo Convention. Weak institutional capability, digital illiteracy, cybercrime expansion, and fragmented policy approaches are major issues. Opportunities exist: the African Continental Free Trade Area (AfCFTA) facilitates harmonised digital trade, Africa's young are a source of digital innovation, and alignment with the UN Sustainable Development Goals (SDGs) boosts global relevance. To improve cyber resilience, the report advises expediting legislative framework harmonisation, boosting institutions and public awareness, and encouraging multi-stakeholder collaboration. Agenda 2063 needs strong data protection measures to protect privacy and rights and enable inclusive, secure, and sustainable development across the continent.

کیومرث اشتریان

انبوه - داده یکی از دستاوردهای مهم انقلاب فناوری اطلاعات و ارتباطات است که از حیث تأثیری که می‌تواند بر پژوهش‌های علمی بگذارد در این مقاله مورد توجه قرار گرفته است. در آنچه که به حوزه معرفت‌شناسی پژوهش‌های علمی مربوط می‌شود، دو گرایش عمده در این موضوع وجود دارد: یکی اینکه چنین پدیده‌ای به کنار گذاشتن تئوری از فرآیندهای پژوهش منجر می‌شود و دیگری در نقطه مقابل نقش تئوری‌ها را همچنان مؤثر می‌داند. انبوه - داده عبارت است از داده‌هایی که از گستره وسیعی از جریان فعالیت‌های اقتصادی، اجتماعی، زیست‌محیطی و... به‌صورت خودکار یا نیمه‌خودکار و با مشارکت فعال کاربران به وجود می‌آید. از شبکه‌های اجتماعی، وبگاه‌ها، وبلاگ‌ها، ژورنالیسم و «ردپای دیجیتال» افراد گرفته تا خدمات و تعاملات تجاری، اداری، فرهنگی، اجتماعی و... همگی عرصه‌ای پویا و گسترده را برای ایجاد انبوه - داده فراهم می‌کنند. انبوه - داده صرفاً حجم عظیم داده نیست؛ بلکه گستره وسیعی است که دارای تنوع، تکثر، سرعت، ارزش و انعطاف است. انبوه - داده زمینه دانش داده‌کاوی را فراهم کرده است که عبارت است از استخراج دانش‌های مفید از پایگاه‌های بزرگ داده یا از جریان داده‌ها که توسط روش‌های رایج، به‌دلیل گستردگی و پیچیدگی‌ آنها قابل‌مدیریت نیستند. به‌دلیل حجم بالا، تنوع و سرعت زیاد انبوه - داده فنون جدیدی برای تحلیل آنها ضروری است. انبوه - داده ویژگی لحظه‌ای بودن دارد و ازاین‌رو، مشکل زمان را در پیمایش‌ها حل می‌کند. این یکی از مهم‌ترین ویژگی‌های انبوه - داده است. انبوه- داده و علم داده -ران بحث از اگنوستیک[1] را پیش روی ما می‌گشاید. «اگنوستیک» که اساساً نوعی «لاادری‌گری» یا ندانم‌گرایی است را می‌توان در ساحت معرفت‌شناسی به علم مستقل، علم بدون پیش‌فرض، یا علم قابل انطباق تعبیر کرد. در اگنوستیک ادعا بر این است که پیش‌فرضی ازسوی پژوهشگر وجود ندارد و می‌گوید که نمی‌دانم چه چیزی هست یا نیست، درست است یا غلط، حقیقت دارد یا ندارد. این مبنایی برای ورود به عرصه دانش است. علم داده - ران نیز بر همین ادعا استوار است. ازاین‌رو، این دو مفهوم مرتبط با معرفت‌شناسی را در کنار هم آورده‌ایم. ازآنجاکه داده‌های انبوه به‌خودی‌خود و بدون فرضیه یا تئوری ممکن است ما را در پژوهش علمی یاری دهند، بنابراین راه برای اقبال به اگنوستیسم فراهم می‌شود. به‌ویژه آنکه فناوری‌ها و روش‌هایی چون داده‌کاوی، یادگیری ماشین و هوش مصنوعی امکان پردازش داده‌های انبوه و استخراج الگوها را فراهم می‌کنند. این پدیده هنوز از حیث تأثیراتی که بر معرفت‌شناسی و نظریه‌پردازی دارد به‌اندازه کافی واکاوی نظری نشده است. مقاله حاضر، در پی بحث از همین ابعاد است. روش: در این مقاله با روشی تحلیلی نخست، چارچوبی مفهومی از چند مقوله اصلی برساخته می‌شود که شامل انبوه - داده، علم داده-ران، اگنوستیسم است. این سه مفهوم اصلی با یکدیگر در علوم فناوری‌های نوین و در علوم‌اجتماعی ارتباط دارند. این چارچوب مفهومی ازآن‌رو اهمیت دارد که با ترکیب علوم‌ داده‌ای، علوم ‌محاسباتی، علوم‌اجتماعی می‌تواند مبانی پارادایمی موجود را متحول کند و به تضعیف پارادایم علوم‌تجربی (پیشارنسانس)، علوم‌نظری (پیشارایانه) و علوم ‌محاسباتی (پیشاداده انبوه) که پس از رنسانس مسلط بوده است بینجامد (کیچین، 2014). نتایج: این مقاله استدلال می‌کند که انبوه - داده ظرفیت آن را دارد که تحولی عمده را در معرفت‌شناسی علوم‌اجتماعی پدید آورد. ازسویی پدیده انبوه - داده بازیگران جدیدی را که پژوهشگران سنتی علوم‌اجتماعی نیستند، وارد توسعه علمی و معرفت‌شناسی می‌کند که شامل فناوران حوزه اطلاعات و  ارتباطات و نیز کارآفرینان اقتصادی می‌شود. ازسوی‌دیگر، نقش رشته‌های دانشگاهی و تئوری‌ها در توسعه علمی کاهش می‌یابد. علم داده- ران می‌تواند برنامه‌های پژوهشی را سامان‌دهی کند؛ به‌گونه‌ای‌که نقش نظریه‌ها و تقسیم‌بندی‌های رشته‌ای سنتی در دانشگاه را محدود نماید. پدیده انبوه - داده به فردگرایی روش‌شناختی  در علوم‌اجتماعی دامن می‌زند. ازاین‌رو، تجزیه‌وتحلیل سیاستی مبتنی بر ابزارهای فناوری اطلاعات  یا علوم‌اجتماعی محاسباتی  در معرض توجه بیشتری قرار گرفته است. بر‌اساس‌این، پایه‌های معرفت جدید بر درک فعالیت‌های خُرد فردی و فردگرایی روش‌شناختی بنا گذاشته می‌شود. «شناختِ ترکیبیِ فردمحور» امکان وقوع می‌یابد که حاصل سپهرهای گوناگون است. به‌‌دیگرسخن، شناخت بهتر فرد زمینه توسعه نظریه‌های فردمحور را امکان‌پذیر می‌کند. شناخت داده‌های متکثر، ضرورتاً به بی‌نیازی از نظریه نمی‌انجامد. تحلیل نظری گریبان انسان را رها نمی‌کند؛ زیرا این نظریه‌ها بخشی جداناشدنی از تجربه‌ها، سلیقه‌ها، ترجیحات و ادراکات روحی و روانی ما هستند. اما تحول اساسی اینجاست که نقش داده‌های خُردِ فردی و در مقیاس «نانورفتار» توسعه نظریه‌های فردمحور - داده‌محور را بیشتر می‌کند. به همین سان، نقش داده‌های فردی و نقش سوژه در شکل‌گیری نظریه بیش از نقش پژوهشگر - فاعلِ نظریه‌پرداز می‌شود؛ زیرا این داده‌ها به‌هرحال خود، کم‌و‌بیش سخن می‌گویند و نقش‌آفرینی بیشتری در فهم و در شکل‌گیری ذهن نظریه‌پرداز ایفا می‌کنند. نظریه‌های گوناگونی که از داده‌ها برمی‌آیند، بدینسان، از تعامل‌پذیری بیشتری برخوردارند؛ زیرا سهم هریک از عوامل و مؤلفه‌ها به‌صورت محسوس‌تری دیده شده و تصدیق می‌شود. ازاین‌رو، در نگاه نخست، زمینه برای تلفیق نظریه‌های گوناگون و شکل‌گیری کلان نظریه‌های «متناسب‌تر» بیش‌ازپیش فراهم می‌شود. به‌عنوان‌مثال، آنگاه که داده‌هایی طبقه‌بندی‌شده و شفاف از پدیده فقر و سهم ساختارها و رفتارها در آن شناسایی شود و آنگاه که داده‌هایی روشن و طبقه‌بندی‌شده از توانمندسازی انسان، از ابعاد گوناگون محیط‌زیست، از نقش سیاست دولتی در این زمینه‌ها، از عوامل مؤثر بر علم، فناوری و نوآوری در ابعاد و اجزای گوناگون و... به دست آید، زمینه برای نظریه‌پردازی‌های خُرد در هریک از این موضوعات و درنتیجه نظریه‌ای جامع فراهم می‌آید؛ البته در نگاه عمیق‌تر تحولی پارادایمی در توسعه دانش بدون رشته  فراهم می‌آورد که خود می‌تواند موجد اغتشاش نظری باشد. بحث و نتیجه‌گیری: اگرچه دقیقاً نمی‌توان گفت که نقش نظریهها پایان یافته است، اما این انقلاب وجوهی دارد که نقشی بنیانی در تغییر پارادایم دارد؛ ازطریق گسست فعالیت علمی از نظریه‌پردازی، با از بین بردن ساختار سلسلهمراتبی دانشمندان، با تضعیف ساختار رشتهای،  با توده‌ای کردن بازیگران دانش، با گسست تولید علم از زمینه رشته‌ای و از زمینه متخصصان، و با پدید آوردن دانش غیرتداومی.  تقسیم‌بندی رشته‌ای به‌دلیل غرق شدن در اقیانوسی از داده‌ها اهمیت خود را از دست داده یا اینکه حداقل متزلزل شده است. داده مستقل از رشته است و ازاین‌رو، همکاری بین‌رشته‌ای در فضای «شبه - اگنوستیکی» از علم می‌تواند بلاموضوع باشد. در علم در دست کارشناسان فنی، تکنیسین‌ها و نه ضرورتاً دانشمندان به‌صورت «آنارشیک» رشد می‌یابد. امروزه، تحولات نوآورانه‌ای در حوزه فناوری‌های نوین ازسوی جوانان (و گاه نوجوانانی)، که دوره‌های تحصیلات تکمیلی را نگذرانده‌اند، مشاهده می‌شود. مایکروسافت، اپل، فیسبوک، تلگرام، واتساپ و بسیاری دیگر ازاین‌دست توسط کسانی به عرصه نوآوری آمده‌اند که ابداع‌کنندگان اولیه اغلب «دانشمند» به معنای مصطلح نبوده‌اند و حتی گاه از دانشگاه ترک تحصیل کرده‌اند. این ابتکارات و ابداعات خود سرمنشأ رشد علم بوده‌اند. نتیجه آنکه تحول علمی از محیط آکادمی به محیط کسب‌و‌کار آمده است. علم بیش از گذشته به بازار وابسته شده است و «دینامیسم» بازار سرمنشأ «دینامیسم» علم شده است. فناوری اطلاعات چنین بستری را ازطریق تسهیل ارتباطات و ترکیب فناوری‌های گوناگون با یکدیگر زمینه جهش متقابل را فراهم کرده است و علم نه اینتردیسیپلینری است و نه دیسیپلینری بلکه بی‌دیسیپلین است و این می‌تواند کل ساختار پیشین از رنسانس به این سو را به هم زند.

Maxime De Sousa, Aurélien Barrau, Killian Martineau

The issue of consistency is crucial in quantum gravity. It has recently been intensively addressed for effective symmetry-reduced models. In this article, we exhaustively study the anomaly freedom of effective loop quantum cosmology with generalized holonomy corrections, considering loop correction of the constraints at the perturbative order. We pedagogically explain why, although the holonomy correction -- including the details of the chosen scheme -- applied on the background part of the constraints is crucial, it becomes irrelevant when implemented on perturbative expansions, in the sense that all consequences are "absorbed" in the counter-terms used for the regularization. The possibility of closing the algebra of constraints without counter-terms is also studied. It is argued that, although enforcing a first-class algebra is a strong requirement, this can be achieved in several different ways, often overlooked, which generates ambiguities on the restriction of the form of the generalized holonomy correction. Those ambiguities are examined in details, leading to the conclusion that the consistency of the effective theory for cosmological perturbations, especially when considering scalar modes, cannot be achieved without counter-terms. We also take the opportunity of this work to clarify, as much as possible, all the required steps so that future works have a clear material at disposal. In particular, a highly detailed calculation of all the brackets is provided, emphasizing the (usually implicit) assumptions, hypotheses and manipulations required to ensure the closure of the algebra. Prospects for future works are underlined.

Sabrina Coelho Alves, Vanessa de Monteiro Ribeiro de Camargo, Edvaldo Gonçalves de Amorim et al.

O saneamento precário é um fator de risco às doenças de veiculação hídrica (DVH), cuja transmissão é fecal-oral. Várias doenças são agravadas ao contato com insalubres ambientais. Segundo a Unicef, a diarreia, uma doença de veiculação hídrica, é a segunda maior causa de mortes em crianças abaixo de 5 anos de idade no mundo. A Portaria de Potabilidade do Ministério da Saúde estabelece que a potabilidade da água de consumo se dá na ausência de coliformes totais e termotolerantes. Objetiva-se comparar a qualidade higiênico-sanitária da água de consumo em duas comunidades no Vale do Paraíba/SP (a primeira, em Guaratinguetá; a segunda, em São José dos Campos), carentes em saneamento. Na primeira, coletaram-se 20 amostras residenciais e na segunda, 17 amostras (residenciais, da mina e do caminhão de distribuição). Na primeira, que possui tratamento de água, não se encontrou contaminação; na segunda, carente neste recurso, houve contaminação em 71% das amostras. Em conclusão, enfatiza-se a importância do tratamento da água, que se constitui um fator de proteção à população e, ainda, deve-se considerar como necessária a implementação de políticas de monitoramento e controle dos lançamentos de esgoto in natura no rio Paraíba do Sul, bem como políticas que minimizem a vulnerabilidade socioambiental evidenciada em comunidades como as estudadas no presente trabalho

Xiaojiong Ding, Lei Wang, Lingshuai Kong

Based on qualitative and quantitative data collected from an investigation of the flagship National Teacher Training Project (NTTP) in China, this study compares the impacts of teacher professional development (PD) programs located at different distances from the participants’ workplaces. The study argues that local and nonlocal programs play different roles in teacher PD. While local programs are conducive to teachers’ mastery of context-specific knowledge and skills that are directly connected to subject teaching, nonlocal programs are crucial for teachers’ continuous professional development in the long term. The two types of programs are supplementary to each other, and teachers need access to both types of programs.

Mary Awusi, David Addae, Olivia Adwoa Tiwaa Frimpong Kwapong

The question of women's legislative underrepresentation is an enduring problem which continues to garner considerable scholarly attention all over the world. Whereas the burgeoning literature on the subject has largely focused on impediments to gender parity in representation in parliament, the interest of this paper is somewhat different. In an effort to make an original contribution to the discourse, the starting point of this paper is the argument that women can be politically empowered to achieve greater representation in parliament. Consequently, in this paper – which draws on empowerment theory as theoretical lens – we present a snapshot of the views of 22 women parliamentarians from Ghana, with the aim to exploring empowerment strategies for attaining greater gender parity in representation in the legislature. They emphasize the importance of affirmative action policies, funding, inclusive political party structures, education, and societal re-socialisation in addressing women's legislative underrepresentation in Ghana. These findings may have some important implications for the nature and scope of interventions targeted at women for the purpose of promoting an inclusive political environment.

Abhay Ashtekar, Adrián del Río, Marc Schneider

The big bang and the Schwarzschild singularities are space-like. They are generally regarded as the "final frontiers" at which space-time ends and general relativity breaks down. We review the status of such space-like singularities from three increasingly more general perspectives. They are provided by (i) A reformulation of classical general relativity motivated by the Belinskii, Khalatnikov, Lifshitz conjecture on the behavior of the gravitational field near space-like singularities; (ii) The use of test quantum fields to probe the nature of these singularities; and, (iii) An analysis of the fate of these singularities in loop quantum gravity due to quantum geometry effects. At all three levels singularities turn out to be less menacing than one might a priori expect from classical general relativity. Our goal is to present an overview of the emerging conceptual picture and suggest lines for further work. In line with the \emph{Introduction to Current Research} theme, we have made an attempt to make it easily accessible to all researchers in gravitational physics.

Giuseppe Francesco Gori, Patrizia Lattarulo, Marco Mariani

Decentralised government levels are often entrusted with the management of public works and required to ensure well-timed infrastructure delivery to their communities. We investigate whether monitoring the activity of local procuring authorities during the execution phase of the works they manage may expedite the infrastructure delivery process. Focussing on an Italian regional law which imposes monitoring by the regional government on "strategic" works carried out by local buyers, we draw causal claims using a regression-discontinuity approach, made unusual by the presence of multiple assignment variables. Estimation is performed through discrete-time survival analysis techniques. Results show that monitoring does expedite infrastructure delivery.

Lucía Ramos, Jorge Novo, José Rouco et al.

The fundus of the eye is the only part of the human body that allows a direct non-invasive observation of the circulatory system. Retinal vascular tortuosity presents a valuable potential for diagnostic and treatment purposes of relevant vascular and systemic diseases. This work presents a computational metric for the tortuosity characterization that combines mathematical representations of the vessel segments with anatomical properties of the fundus image such as the vessel caliber, the distance to the optic disc, the distance to the fovea and the distinction between arteries and veins. The evaluation of the prognostic performance shows that the incorporation of the domain-related information allows a reliable characterization of the retinal vascular tortuosity that provides a better representation of the expert perception.

Alexander Igorevich Pavlenko

Purpose. The article is devoted to the topical problem within the framework of the modern anthropocentric paradigm in linguistics, i.e. the problem of understanding the original text by a translator, in particular, the poetic text. The subjects of analysis are understanding and interpretation, considered as components of the translation process and as its result. The author aims to make a terminological distinction between the above-mentioned concepts as well as highlight the stages of the translation process, taking into account the distinction; formulate the basics of an adequate understanding and interpretation of poetry. Method or methodology of the work. The basis of the research is the general scientific methods of analysis and synthesis. The analysis was employed in singling out the types of understanding, on the basis of which the three-phase model of the translation process was synthesized. Results. The author points out the possibility of considering understanding in translation studies as a process of identifying the meanings of a literary work and as a result of mental perception of the text. Interpretation is defined as one of the types of understanding during which the “intersection of two autonomous horizons” of the sender and the recipient occurs. Based on these statements, understanding and interpretation are singled out as the first and the second stage of the three-phase translation process respectively. The following aspects are defined as foundations of an adequate understanding and interpretation of the poetic text: the translator’s consideration of the emotional aspect while reading the literary work and the necessity to be objective; analysis of the literary work in the context of both the past and the present; accounting for the individual personality of the author; consideration of the literary work within the framework of all the works of its creator; the implementation of the lexical-semantic analysis of the literary work. Practical implications. The results of the study can be applied in the field of theory and practice of literary translation and in poetic text analysis.

Ricardo Sánchez Garrafa

Antonio Ariño Villarroya

El movimiento open es el conjunto de luchas protagonizadas por individuos, foros, organizaciones e instituciones de muy diverso tipo que postulan una visión abierta, inclusiva y participativa de internet y de los bienes digitales. Consta de seis ramas fundamentales en función del campo sobre el que operan: el software, la comunicación científica, los materiales educativos, la creación cultural, la producción maker y la neutralidad de la red. Este artículo ofrece una visión sintética del movimiento, de sus características y aportaciones fundamentales.

Mary Arseneau, Emery Terrell

Victorian poet Christina Rossetti (1830–1894) was frequently troubled by poor health, and her mid-life episode of life-threatening illness (1870–1872) when she suffered from Graves’ disease provides an illuminating case study of the ways that illness can be reflected in poetry and prose. Rossetti, her family, and her doctors understood Graves’ disease as a heart condition; however, Rossetti’s writing reflects a different paradigm, presenting themes of self-attack and a divided self that uncannily parallel the modern understanding of Graves’ disease as autoimmune in nature. Interestingly, these creative representations reflect an understanding of this disease process that Rossetti family documents and the history of Victorian medicine demonstrate Rossetti could not have been aware of. When the crisis had passed, Rossetti’s writing began to include new rhetoric and imagery of self-acceptance and of suffering as a means of spiritual improvement. This essay explores the parallels between literary and somatic metaphors: Rossetti’s body and art are often simultaneously “saying„ the same thing, the physical symptoms expressing somatically the same dynamic that is expressed in metaphor and narrative in Rossetti’s creative writing. Such a well-documented case history raises questions about how writing may be shaped by paradigms of illness that are not accessible to the conscious mind.

Jose Beltrán Jiménez, Konstantinos F. Dialektopoulos

We revisit the field content and consistency of the New General Relativity family of theories. These theories are constructed in a geometrical framework with a flat and metric-compatible connection, so the affine structure is entirely determined by the torsion. The action is given by a local and parity-preserving quadratic form of the torsion with three free parameters. It is well-known that a special choice of parameters gives an equivalent to General Relativity and that the spectrum of the general linear theory around Minkowski contains an additional 2-form field. It has been suggested that the viability of these theories at linear order requires the 2-form field to feature a gauge symmetry so that it describes a massless Kalb-Ramond field. In this work we revisit these previous results and compute the cubic interactions. We also obtain the decoupling limit of the theories and show that the required gauge symmetry for the 2-form at linear order cannot be extended to higher orders. This signals towards a pathological behaviour of these theories and singles out the equivalent of General Relativity as the only consistent New General Relativity theory with a stable Minkowski background that includes gravity.

Albert Huber

In the present work, the spin-coefficient formalism of Newman and Penrose is used to formulate geometric constraints for the existence of Kerr-Schild groups, i.e. continuous groups of generalized Kerr-Schild transformations. In addition, by characterizing the geometric structure of the deformed Einstein tensor of the generalized Kerr-Schild class, restrictions are imposed on the existence of apparent conservation laws in generic spacetimes, which are defined via considering special Kerr-Schild currents whose associated Kerr-Schild vector fields coincide with timelike Killing vector fields of pairs of stationary background geometries. The feasibility of the derived conditions is demonstrated by considering concrete, suitably simple models of generalized Kerr-Schild spacetimes.

Dede Sujana

Polytechnic as a higher educational institution trains students to be capable of becoming independent human. It is also responsible for equipping students with competence to compete in the workplace. Sport serves as a means of character and life skills development in students. It is well supported by the infrastructure management in Polytechnic.  Based on the formulation of the problem mentioned above, the general purpose of this study is to determine the effect of infrastructure management on sports development in the State Polytechnic of Bandung. This study employed quantitative approach with survey method to obtain data from questionnaires and physical fitness test. The participants of the study are 77 students from two state polytechnics in Bandung. The result from data processing and analysis showed that 95.7% of sports participation rate is influenced by infrastructure management and the rest of 4.35 is influenced by other unexplainable variables, which means that facility and infrastructure management give positive influence on sports participation.   In addition, other results showed that 93.0% of physical fitness figures are influenced by infrastructure management and 7.0% is influenced by other unexplainable variable, which means that infrastructure gives significant influence on physical fitness. It shows that if sports infrastructure is managed well, then it will greatly influence sports development.

Victor Climent, Julián Porras Bulla

Object: To analyse the framework within which the informal labour market operates and the social implications of this market by conducting a case study of sub-Saharan scrap metal waste pickers – chatarreros – in the city of Barcelona. Design/methodology: The study compares and contrast theoretical findings drawn from the literature about informal work and the social and living conditions of Barcelona’s chatarreros. Our primary data are collected from twelve interviews (ten with scrap metal waste pickers and two with neighbourhood leaders) and from ethnographic fieldwork conducted between February and August 2013. Contributions / results: Barcelona, in common with many other cities in the northern hemisphere, has experienced a growth in informal work directly linked to the tourism sector, the city’s main economic activity. This growth was especially marked in the Great Recession (2008-2015). Traditionally, informal workers have been systematically ignored, recognition being saved solely for those legally or formally employed. But the major economic changes of the last 20 years have led to the transformation of labour markets and to the segmentation and precarisation of work, and with it the growth of the informal sector. Here, we analyse three elements that are critical for understanding this sector: recognition of work, its capitalisation and the relation between the individual and work. Limitations: This study, for reasons of space, limits itself to an examination of one group of informal workers in Barcelona, namely the chatarreros; however, there are many other groups that are worthy of study, including, the city’s street vendors, and street artists: buskers, living statues, caricaturists, etc. Originality/added value: The study serves to fill the gap in knowledge regarding the reality of informal work and its social consequences. Specifically, it facilitates understanding of the theoretical concept of informality, illustrating, by means of a case study of informal recyclers or scrap metal waste pickers, the economic and social condition of informal immigrant workers characterised by poverty, discrimination, disembeddedness and subsistence.

Francisco das Chagas Mariz Fernandes

Simultaneamente burocrática e anárquica, sob tensões de uma estruturação matricial com ancoragem entre centralização e descentralização, a organização educacional Instituto Federal abrange múltiplas dimensões e imagens, demanda articulações fracas para funcionar adequadamente, e estruturalmente, enquadra-se e pode ser igualado, em termos de parâmetros, à configuração de uma Estrutura Divisionalizada (MINTZBERG, 1995). O campo de tensões e de relações de forças que se cria entre a administração central, a gestão multicampi e as comunidades escolares, na maioria do tempo de estabilidade, advinda de consensos e acomodações, oportunizam, também, instabilidades e conflitos. Essa imagem é coerente com a compreensão exposta por Weick (1976) de que em contraste com a imagem predominante de que elementos em organizações são acoplados através de ligações densas e apertadas, na prática, esses elementos são, apenas, fracamente conectados uns aos outros, ou seja, constituem-se em um “sistema debilmente articulado”.