Geometric Hamilton-Jacobi Theory

The Hamilton-Jacobi problem is revisited bearing in mind the consequences arising from a possible bi-Hamiltonian structure. The problem is formulated on the tangent bundle for Lagrangian systems in order to avoid the bias of the existence of a natural symplectic structure on the cotangent bundle. First it is developed for systems described by regular Lagrangians and then extended to systems described by singular Lagrangians with no secondary constraints. We also consider the example of the free relativistic particle, the rigid body and the electron-monopole system.Comment: 40 page

Geometric Hamilton-Jacobi Theory for Nonholonomic Dynamical Systems

The geometric formulation of Hamilton--Jacobi theory for systems with nonholonomic constraints is developed, following the ideas of the authors in previous papers. The relation between the solutions of the Hamilton--Jacobi problem with the symplectic structure defined from the Lagrangian function and the constraints is studied. The concept of complete solutions and their relationship with constants of motion, are also studied in detail. Local expressions using quasivelocities are provided. As an example, the nonholonomic free particle is considered.Comment: 22 p

Pola Komunikasi Pemimpin Organisasi Dalam Meningkatkan Motivasi Kerja Anggota Di LPM (Lembaga Pers Mahasiswa) Inovasi Unsrat

Penelitian ini dengan judul Pola Komunikasi Pemimpin Organisasi Dalam Meningkatkan Motivasi Kerja Anggota Di LPM (lembaga pers mahasiswa) Inovasi Unsrat, dengan focus penelitian adalah : Bagaimana komunikasi pemimpin organisasi dalam aspek orientasi kerja. Kemudian tentang bagaimana komunikasi pemimpin organisasi dalam aspek orientasi hubungan. Dan juga bagaimana komunikasi pemimpin organisasi dalam aspek keefektifan. Penelitian ini menggunakan pendekatan metode kualitatif sebagai prosedur penelitian yang menghasilkan data deskriptif berupa kata-kata atau lisan dari orang-orang dan perilaku yang dapat diamati. Teori yang digunakan dalam penelitian ini adalah teori Reddin, mendapatkan hasil penelitian sebagai berikut : (1). Aspek Orientasi-Kerja. Pemimpin Organisasi di LPM Inovasi Unsrat memberikan pemahaman kepada anggota agar dapat mengerti tugas yang diberikan, serta motivasi yang dapat membuat anggota menjadi giat bekerja. Anggota juga berusaha untuk memahami dan termotivasi agar dapat bekerja dengan baik. Komunikasi yang dilakukan dalam meningkatkan motivasi kerja anggota adalah dengan menggunakan komunikasi kelompok medium group yaitu komunikasi dalam kelompok sedang lebih mudah karena dapat diorganisir dengan baik dan terarah, misalnya komunikasi antara satu bidang dengan bidang yang lain dalam organisasi. (2) Aspek Orientasi-Hubungan. Pemimpin organisasi selalu menciptakan hubungan yang baik dengan anggota, begitupun sebaliknya dengan anggota. Komunikasi antara pemimpin dan anggota dalam menciptakan hubungan yang baik dalam organisasi yaitu dengan menggunakan komunikasi antar personal yaitu komunikasi yang terjadi antar komunikator dengan komunikan secara langsung dengan cara berhadapan muka atau tidak. Komunikasi seperti ini lebih efektif karena kedua belah pihak saling melancarkan komunikasinya dan dengan feedback keduanya melaksanakan fungsi masing-masing. Untuk itu pemimpin harus mampu menyediakan waktu untuk dapat berbincang dengan para anggota, sekaligus mengatasi kendala-kendala yang menjadi pemicu keterlambatan dalam penyelesaian tugas. Hal ini juga akan memunculkan berbagai tanggapan ataupun masukkan dari para anggota, yang harus diterima oleh pemimpin organisasi. (3) Aspek Keefektifan. Setiap tugas yang diberikan tidak selalu dapat diselesaikan sesuai target dan tepat waktu, namun pemimpin selalu berusaha untuk mengupayakan agar pencapaian produksi seperti pembuatan majalah tahunan dapat terselesaikan dengan baik dan tepat waktu sesuai deadline. Tidak bisa efektif juga karena kendala yang dihadapi oleh organisasi yang menjadi faktor utama yaitu dana. Pencairan dana yang diproses melalui pengelola Gedung PKM Unsrat, bisa diproses cukup lama, karena pengecekan dilakukan dengan prosedur-prosedur yang telah ditetapkan

Local covariant quantum field theory over spectral geometries

A framework which combines ideas from Connes' noncommutative geometry, or spectral geometry, with recent ideas on generally covariant quantum field theory, is proposed in the present work. A certain type of spectral geometries modelling (possibly noncommutative) globally hyperbolic spacetimes is introduced in terms of so-called globally hyperbolic spectral triples. The concept is further generalized to a category of globally hyperbolic spectral geometries whose morphisms describe the generalization of isometric embeddings. Then a local generally covariant quantum field theory is introduced as a covariant functor between such a category of globally hyperbolic spectral geometries and the category of involutive algebras (or *-algebras). Thus, a local covariant quantum field theory over spectral geometries assigns quantum fields not just to a single noncommutative geometry (or noncommutative spacetime), but simultaneously to ``all'' spectral geometries, while respecting the covariance principle demanding that quantum field theories over isomorphic spectral geometries should also be isomorphic. It is suggested that in a quantum theory of gravity a particular class of globally hyperbolic spectral geometries is selected through a dynamical coupling of geometry and matter compatible with the covariance principle.Comment: 21 pages, 2 figure

The Casimir force in noncommutative Randall-Sundrum models

In this paper we study the effect of spacetime noncommutativity in the 5-dimensional Randall-Sundrum brane worlds on the Casimir force acting on a pair of parallel plates. We show that the presence of a noncommutative scale length affects the nature of the Casimir force for small plate separation. Using accurate experimental bounds for the Casimir force in parallel plate geometry, we find an upper bound for the noncommutative cutoff of the order of $10^{3}$ TeV, and that the size of the interbrane distance in RSI model is approximately given by $kR\lesssim20.5$ and $kR\lesssim18.4$ for $k=10^{19}$ GeV and $k=10^{16}$GeV, respectively.Comment: 20 pages, 5 figures, accepted for publication in Phys. Rev.

Chaos in computer performance

Modern computer microprocessors are composed of hundreds of millions of transistors that interact through intricate protocols. Their performance during program execution may be highly variable and present aperiodic oscillations. In this paper, we apply current nonlinear time series analysis techniques to the performances of modern microprocessors during the execution of prototypical programs. Our results present pieces of evidence strongly supporting that the high variability of the performance dynamics during the execution of several programs display low-dimensional deterministic chaos, with sensitivity to initial conditions comparable to textbook models. Taken together, these results show that the instantaneous performances of modern microprocessors constitute a complex (or at least complicated) system and would benefit from analysis with modern tools of nonlinear and complexity science

Hard TeV spectra of blazars and the constraints to the IR intergalactic background

Recent gamma-ray observations of the blazar 1ES 1101-232 (redshift z=0.186) reveal that the unabsorbed TeV spectrum is hard, with spectral index $\alpha \lesssim 0.5$ [$F(\nu) \propto \nu^{-\alpha}$]. We show that simple one-zone synchrotron self-Compton model can explain such hard spectra if we assume a power law energy distribution of the emitting electrons with a relatively high minimum energy. In this case the intrinsic TeV spectrum can be as hard as $F(\nu)\propto \nu^{1/3}$, while the predicted X-ray spectrum can still be much softer. The observations of 1ES 1101-232 can therefore be reconciled with relatively high intensities of the infrared background, even if some extreme background levels can indeed be excluded. We show that the other TeV sources (Mrk 421, Mrk 501 and PKS 2155-304) can be interpreted in the same framework, with a somewhat larger minimum energy.Comment: 5 pages, 3 figures, accepted for publication as a letter in MNRA

Aspects of noncommutative Lorentzian geometry for globally hyperbolic spacetimes

Connes' functional formula of the Riemannian distance is generalized to the Lorentzian case using the so-called Lorentzian distance, the d'Alembert operator and the causal functions of a globally hyperbolic spacetime. As a step of the presented machinery, a proof of the almost-everywhere smoothness of the Lorentzian distance considered as a function of one of the two arguments is given. Afterwards, using a $C^*$-algebra approach, the spacetime causal structure and the Lorentzian distance are generalized into noncommutative structures giving rise to a Lorentzian version of part of Connes' noncommutative geometry. The generalized noncommutative spacetime consists of a direct set of Hilbert spaces and a related class of $C^*$-algebras of operators. In each algebra a convex cone made of self-adjoint elements is selected which generalizes the class of causal functions. The generalized events, called {\em loci}, are realized as the elements of the inductive limit of the spaces of the algebraic states on the $C^*$-algebras. A partial-ordering relation between pairs of loci generalizes the causal order relation in spacetime. A generalized Lorentz distance of loci is defined by means of a class of densely-defined operators which play the r\^ole of a Lorentzian metric. Specializing back the formalism to the usual globally hyperbolic spacetime, it is found that compactly-supported probability measures give rise to a non-pointwise extension of the concept of events.Comment: 43 pages, structure of the paper changed and presentation strongly improved, references added, minor typos corrected, title changed, accepted for publication in Reviews in Mathematical Physic