551 research outputs found
Holographically Viable Extensions of Topologically Massive and Minimal Massive Gravity?
Recently, an extension of the topologically massive gravity (TMG) in
dimensions, dubbed as minimal massive gravity (MMG), was found which is free of
the bulk-boundary unitarity clash that inflicts the former theory and all the
other known three dimensional theories. Field equations of MMG differ from
those of TMG at quadratic terms in the curvature that do not come from the
variation of an action depending on the metric alone. Here we show that MMG is
a unique theory and there does not exist a deformation of TMG or MMG at the
cubic and quartic order (and beyond) in the curvature that is consistent at the
level of the field equations. The only extension of TMG with the desired bulk
and boundary properties having a single massive degree of freedom is MMG.Comment: 10 pages, references added, almost matches the published versio
Linearization Instability for Generic Gravity in AdS
In general relativity, perturbation theory about a background solution fails
if the background spacetime has a Killing symmetry and a compact spacelike
Cauchy surface. This failure, dubbed as {\it linearization instability}, shows
itself as non-integrability of the perturbative infinitesimal deformation to a
finite deformation of the background. Namely, the linearized field equations
have spurious solutions which cannot be obtained from the linearization of
exact solutions. In practice, one can show the failure of the linear
perturbation theory by showing that a certain quadratic (integral) constraint
on the linearized solutions is not satisfied. For non-compact Cauchy surfaces,
the situation is different and for example, Minkowski space having a
non-compact Cauchy surface, is linearization stable. Here we study, the
linearization instability in generic metric theories of gravity where
Einstein's theory is modified with additional curvature terms. We show that,
unlike the case of general relativity, for modified theories even in the
non-compact Cauchy surface cases, there are some theories which show
linearization instability about their anti-de Sitter backgrounds. Recent
dimensional critical and three dimensional chiral gravity theories are two such
examples. This observation sheds light on the paradoxical behavior of vanishing
conserved charges (mass, angular momenta) for non-vacuum solutions, such as
black holes, in these theories.Comment: 31 pages, 1 figure, some grammatical typos are correcte
Linearization Instability of Chiral Gravity
Carrying out an analysis of the constraints and their linearizations on a
spacelike hypersurface, we show that topologically massive gravity has a
linearization instability at the chiral gravity limit about . We also
calculate the symplectic structure for all the known perturbative modes
(including the log-mode) for the linearized field equations and find it to be
degenerate (non-invertible) hence these modes do not approximate exact
solutions and so do not belong to the linearized phase space of the theory.
Naive perturbation theory fails: the linearized field equations are necessary
but not sufficient in finding viable linearized solutions. This has important
consequences for both classical and possible quantum versions of the theory.Comment: 6 pages, version to appear in PR
On Exact Solutions and the Consistency of 3D Minimal Massive Gravity
We show that all algebraic Type-O, Type-N and Type-D and some Kundt-Type
solutions of Topologically Massive Gravity are inherited by its holographically
well-defined deformation, that is the recently found Minimal Massive Gravity.
This construction provides a large class of constant scalar curvature solutions
to the theory. We also study the consistency of the field equations both in the
source-free and matter-coupled cases. Since the field equations of MMG do not
come from a Lagrangian that depends on the metric and its derivatives only, it
lacks the Bianchi identity valid for all non-singular metrics. But it turns out
that for the solutions of the equations, Bianchi identity is satisfied. This is
a necessary condition for the consistency of the classical field equations but
not a sufficient one, since the the rank-two tensor equations are susceptible
to double-divergence. We show that for the source-free case the
double-divergence of the field equations vanish for the solutions. In the
matter-coupled case, we show that the double-divergence of the left-hand side
and the right-hand side are equal to each other for the solutions of the
theory. This construction completes the proof of the the consistency of the
field equations.Comment: 8 page
The Relationship Between EFL Teachersā Professional Identity and Professional Autonomy
This study aims to identify 250 Turkish EFL teachersā level of professional identity and professional autonomy. This study also aims to investigate whether the results differ by gender, the school in which they work, education level and work experience. Furthermore, the study aims to identify whether there is a significant relationship between EFL teachersā professional identity and their professional autonomy. In this survey-based research, the results demonstrate that EFL teachers have a very high level of professional identity and a high level of professional autonomy, and the results differ by EFL teachersā gender, school type and work experience. Results also reveal that there was a significant, positive and moderate relationship between professional identity and professional autonomy of EFL teachers. This study suggests that the freer EFL teachers feel to make decisions in their teaching and profession, the more they can define their identity in the teaching profession
Analisis Sinkronisasi RPJMD Kabupaten Karawang Tahun 2021-2026 dengan Rencana Strategis Dinas Pariwisata dan Kebudayaan Kabupaten Karawang Tahun 2021-2026
The Regional Medium Term Development Plan (abbreviated as RPJMD) is an elaboration of the regional head's vision, mission and program which contains goals, targets, strategies, policy direction, regional development and regional finance, as well as regional apparatus programs accompanied by an indicative funding framework for the period of time 5 (five) years prepared by the Regional Government. Regional development planning must be in line with national priorities and national strategic targets, so the preparation of regional development plans is coordinated, synergized and harmonized by regional officials. This research aims to analyze the synchronization between the Medium-Term Regional Development Plan for Karawang Regency for 2021-2026 and the Strategic Plan for the Karawang Regency Tourism and Culture Office for 2021-2026. This research uses literature review techniques to find references that are relevant to the research topic. Researchers analyze topics by collecting information from various sources such as books, journals, articles, trusted websites, and so on online to produce writing. The research results show that synchronization between the Karawang Regency RPJMD and the Tourism Office Strategic Plan with Karawang Regency Culture has occurred. This can be seen from the aspects of strategic issues, goals, targets, strategies and policy directions which are interrelated and coordinated.Rencana Pembagunan Jangka Menengah Daerah (RPJMD) adalah penjabaran dari visi, misi, dan program kepala daerah yang memuat tujuan, sasaran, strategi, arah kebijakan, pembangunan daerah dan keuangan daerah, serta program perangkat daerah yang disertai dengan kerangka pendanaan bersifat indikatif untuk jangka waktu 5 (lima) tahun yang disiapkan oleh Pemerintah Daerah. Perencanaan pembangunan daerah harus sejalan dengan prioritas nasional dan target strategis nasional, maka dalam penyusunan rencana pembangunan daerah dikoordinasikan, disinergikan dan diharmonisasikan oleh perangkat daerah. penelitian ini bertujuan untuk menganalisis sinkronisasi antara Rencana Pembangunan Jangka Menengah Daerah Kabupaten Karawang tahun 2021-2026 dengan Rencana Strategis Dinas Pariwisata dan Kebudayaan Kabupaten Karawang tahun 2021-2026. Penelitian ini menggunakan teknik kajian literatur untuk menemukan rujukan yang relevan dengan topik penelitian. Peneliti menganalisis topik dengan mengumpulkan informasi dari berbagai sumber seperti buku, jurnal, artikel, web terpercaya, dan sebagainya secara daring untuk menghasilkan suatu tulisan. Hasil Penelitian menunjukkan bahwa sinkronisasi antara RPJMD Kabupaten Karawang dengan Renstra Dinas Pariwisata dengan Kebudayaan Kabupaten Karawang telah terjadi. hal ini terlihat dari aspek isu strategis, tujuan, sasaran, strategi, dan arah kebijakan yang saling terkait dan terkoordinasi
Application of soft computing techniques for the prediction of the air permeability property of fabrics
Zrakopropusnost tkanine je mjerilo brzine protoka zraka kroz tkaninu kod zadanog tlaka. Ona je vrlo znaÄajna za svojstva udobnosti tkanina za izradu odjeÄe. Svrha istraživanja je primjena simulacije neizrazite logike i umjetne neuronske mreže za procjenu zrakopropusnosti lanenih tkanina. Za tu svrhu upotrijebljeno je 11 razliÄitih lanenih tkanina i njihova osnovna fizikalna svojstva koja su ocijenjena: duljinska masa preÄe, koeficijent uvijanja, povrÅ”inska masa tkanine, gustoÄa tkanine i svojstvo propusnosti zraka. Svojstvo zrakopropusnosti lanenih tkanina predviÄeno je upotrebom modela neizrazite logike (FL) i umjetne neuronske mreže (ANN) pomoÄu parametara koji djeluju na propusnost zraka prema literaturi. PredviÄanja metoda ANN i FL usporeÄena su s eksperimentalnim rezultatima. Prema rezultatima uoÄeno je da modeli ANN i FL daju izlazne rezultate koji su bliži eksperimentalnim rezultatima. MeÄutim, ustanovljeno je da je uspjeÅ”nost procjene metode ANN bolja nego kod modela FL.The air permeability of a fabric is the measure of the air flow rate through the fabric under a given pressure. It has a great significance on the fabric comfort related properties of clothing. The target of the study is the application of fuzzy logic and artificial neural network simulation for the estimation of the air permeability of the linen woven fabrics. For this aim, eleven different linen woven fabrics were used and their basic physical properties such as; yarn linear density, twist coefficient, fabric unit weight, fabric thickness and air permeability properties were evaluated. The air permeability property of linen fabrics was predicted by using Fuzzy Logic (FL) and Artificial Neural Network (ANN) models using the parameters which are effective on air permeability according to the literature. The predictions of ANN and FL methods compared with experimental results. According to the results, it was seen that ANN and FL models give outputs closer to experimental results, but the estimation success of ANN method was found better than the FL model
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