V-like formations in flocks of artificial birds

We consider flocks of artificial birds and study the emergence of V-like formations during flight. We introduce a small set of fully distributed positioning rules to guide the birds' movements and demonstrate, by means of simulations, that they tend to lead to stabilization into several of the well-known V-like formations that have been observed in nature. We also provide quantitative indicators that we believe are closely related to achieving V-like formations, and study their behavior over a large set of independent simulations

H\"older mean applied to Anderson localization

The phase diagram of correlated, disordered electron systems is calculated within dynamical mean-field theory using the H\"older mean local density of states. A critical disorder strength is determined in the Anderson-Falicov-Kimball model and the arithmetically and the geometrically averages are found to be just particular means used respectively to detect or not the Anderson localization. Correlated metal, Mott insulator and Anderson insulator phases, as well as coexistence and crossover regimes are analyzed in this new perspective.Comment: 6 pages, 6 figures: Phys. Rev. B 76, 035111 (2007

KAJIAN YURIDIS TERHADAP PENGELOLAAN KAWASAN KONSERVASI SUMBER DAYA ALAM DI TANGKOKO DAN DUA SUDARA DITINJAU DARI LINGKUNGAN HIDUP SERTA ASPEK PIDANANYA

Tujuan dilakukannya penelitian ini adalah untuk mengetahui bagaimana ketentuan-ketentuan hukum pidana yang dapat dijadikan dasar perlindungan terhadap Kawasan Konservasi Sumber Daya Alam Hayati daN Bagaimana perlindungan dari aspek hukum pidana terhadap Kawasan Tangkokodan Duasudara. Dengan menggunakan metode penelitian yuridis normatif, maka dapat disimpulkan: 1. Pasal 98 ayat (1) Undang-undang Nomor 32 Tahun 2009, unsur “melawan hukum” disebutkan secara tegas dalam rumusan tindak pidana.  Dengan demikian unsur “melawan hukum” merupakan unsur tertulis dalam Pasal 98 ayat (1) ini.  Dengan demikian dalam pasal ini tidak ada masalah berkenaan dengan perbedaan pendapat antara ajaran melawan hukum yang formal dan ajaran melawan hukum yang material. 2. Undang-undang Nomor 32 Tahun 2009 tentang Perlindungan dan Pengelolaan Lingkungan Hidup telah memberikan perhatian yang besar terhadap konservasi sumber daya alam hayati, hal ini terlihat dalam Pasal 10 ayat (2) yang memberikan ketentuan rencana perlindungan bahwa pengelolaan lingkungan hidup wajib dilakukan secara terpadu dengan penataan ruang, perlindungan sumber daya alam nonhayati, perlindungan sumber daya buatan, konservasi sumber daya alam hayati dan ekosistemnya, cagar budaya, keanekaragaman hayati dan perubahan iklim. Kata kunci: Pengelolaan kawasan, konservasi, sumber daya alam

Fast gates for ion traps by splitting laser pulses

We present a fast phase gate scheme that is experimentally achievable and has an operation time more than two orders of magnitude faster than current experimental schemes for low numbers of pulses. The gate time improves with the number of pulses following an inverse power law. Unlike implemented schemes which excite precise motional sidebands, thus limiting the gate timescale, our scheme excites multiple motional states using discrete ultra-fast pulses.We use beam-splitters to divide pulses into smaller components to overcome limitations due to the finite laser pulse repetition rate. This provides gate times faster than proposed theoretical schemes when we optimize a practical setup

Comparative advantage of potato production in seven regions of South Africa

The focus of this research was to investigate the comparative advantage of the potato industry in seven potato production regions in South Africa. Potatoes are the most important vegetable crop produced in South Africa. In 2008 it contributed more than 40% to the total production of vegetables in South Africa and it accounted for more than 20% of the value of all fresh produce sold on all the major national fresh produce markets. This study uses the Resource Cost Ratio (RCR) methodology that provides an explicit indication of the efficiency with which production alternatives uses domestic resources to generate or save foreign exchange. The Nominal Protection Ratio (NPR) and Effective Protection Coefficient (EPC) were also calculated. The results show that current policies that affects the input market for potato production in South Africa is constraining the potato industry. This was confirmed by the results obtained from the NPR and EPC analysis, and the size of the policy distortions was shown through the calculation of market and economic profitability. If current policies prevail potato production in the Eastern Free State will not have a comparative advantage, but in the absence of such policies all production regions have a comparative advantage.Crop Production/Industries,

Quantum-state transfer in staggered coupled-cavity arrays

We consider a coupled-cavity array, where each cavity interacts with an atom under the rotating-wave approximation. For a staggered pattern of inter-cavity couplings, a pair of field normal modes each bi-localized at the two array ends arise. A rich structure of dynamical regimes can hence be addressed depending on which resonance condition between the atom and field modes is set. We show that this can be harnessed to carry out high-fidelity quantum-state transfer (QST) of photonic, atomic or polaritonic states. Moreover, by partitioning the array into coupled modules of smaller length, the QST time can be substantially shortened without significantly affecting the fidelity.Comment: 12 pages, 8 figure

Infall models of Class 0 protostars

We have carried out radiative transfer calculations of infalling, dusty envelopes surrounding embedded protostars to understand the observed properties of the recently identified ``Class 0'' sources. To match the far-infrared peaks in the spectral energy distributions of objects such as the prototype Class 0 source VLA 1623, pure collapse models require mass infall rates \sim10^{-4}\msunyr$^{-1}$. The radial intensity distributions predicted by such infall models are inconsistent with observations of VLA 1623 at sub-mm wavelengths, in agreement with the results of Andre et al. (1993) who found a density profile of $\rho \propto r^{-1/2}$ rather than the expected $\rho \propto r^{-3/2}$ gradient. To resolve this conflict, while still invoking infall to produce the outflow source at the center of VLA 1623, we suggest that the observed sub-mm intensity distribution is the sum of two components: an inner infall zone, plus an outer, more nearly constant-density region. This explanation of the observations requires that roughly half the total mass observed within 2000 AU radius of the source lies in a region external to the infall zone. The column densities for this external region are comparable to those found in the larger Oph A cloud within which VLA 1623 is embedded. The extreme environments of Class 0 sources lead us to suggest an alternative or additional interpretation of these objects: rather than simply concluding with Andre et al. that Class 0 objects only represent the earliest phases of protostellar collapse, and ultimately evolve into older ``Class I'' protostars, we suggest that many Class 0 sources could be the protostars of very dense regions. (Shortened)Comment: 22 pages, including 3 PostScript figures, accepted for publication in The Astrophysical Journa

Non-invasive brain stimulation therapies

Noninvasive brain stimulation therapies are a promising field for the development of new protocols for the treatment of neuropsychiatric disorders. They are based on the stimulation of neural networks with the intent of modeling their synaptic activity to adequate levels. For this, it is necessary to precisely determine which networks are related to which brain functions, and the normal activation level of each of these networks, so that it is possible to direct the stimulation to the affected networks in order to induce the desired effects. These relationships are under intense investigation by the scientific community, and will contribute to the advancement of treatments by neurostimulation, with the emergence of increasingly accurate and effective protocols for different disorders. Currently, the most used techniques are Transcranial Direct Current Stimulation and Transcranial Magnetic Stimulation, with the most common applications being for treating Major Depressive Disorder. The advancement of research in this field may determine new target networks for stimulation in the treatment of other disorders, extending the application of these techniques and also our knowledge about brain functioning.As terapias biológicas não invasivas se apresentam como um campo promissor para o desenvolvimento de novos protocolos de tratamento de transtornos neuropsiquiátricos. Elas se baseiam na estimulação de redes neurais com intuito de modular sua atividade sináptica para níveis adequados. Para isso, é necessário a determinação precisa de quais redes estão relacionadas a quais funções cerebrais, e do nível de ativação normal de cada uma dessas redes, para que então seja possível direcionar a estimulação às redes afetadas a fim de induzir os efeitos desejados. Essas relações estão sob intensa investigação pela comunidade científica, e vão contribuir para o avanço dos tratamentos por neuroestimulação, com o surgimento de protocolos cada vez mais precisos e efetivos para diferentes transtornos. Atualmente, as técnicas mais utilizadas são a Estimulação Transcraniana por Corrente Contínua e a Estimulação Magnética Transcraniana, sendo a aplicação mais comum no tratamento do Transtorno Depressivo Maior. O avanço das pesquisas possivelmente determinará novas redes alvo para estimulação no tratamento de outros transtornos, estendendo a aplicação dessas técnicas e também do nosso conhecimento sobre o funcionamento cerebral