Jet Formation in the magnetospheres of supermassive black holes: analytic solutions describing energy loss through Blandford-Znajek processes

In this paper, we provide exact solutions for the extraction of energy from a rotating black hole via both the electromagnetic Poynting flux and matter currents. By appropriate choice of a radially independent poloidal function $\Lambda(\theta)$, we find solutions where the dominant outward energy flux is along the polar axis, consistent with a jet-like collimated outflow, but also with a weaker flux of energy along the equatorial plane. Unlike all the previously obtained solutions (Blandford & Znajek (1977), Menon & Dermer (2005)), the magnetosphere is free of magnetic monopoles everywhere

Executive Power: Rethinking the Modalities of Control

The Honorable Sundaresh Menon, Chief Justice of the Supreme Court of Singapore, delivered the 2018-2019 Bernstein Lecture in Comparative Law titled Executive Power: Rethinking the Modalities of Control. The Chief Justice discussed the control of executive power in Singapore as compared to other legal systems. Co-sponsored by the Center for International and Comparative Law and the Office of the Dean

From Spaghetti Bowl to Jigsaw Puzzle? Addressing the Disarray in the World Trade System

The rise of mega-regionals such as the Regional Comprehensive Economic Partnership (RCEP) and the Trans-Pacific Partnership (TPP) suggests that the world trade system is fragmenting to the point it appears more like a jigsaw puzzle than a spaghetti bowl. There are both regional and global jigsaw puzzles to be solved—in that order—to clean up the world trade system. But is this even likely? The difficulties of free trade agreement (FTA) consolidation at the regional level are well known, while piecing together the blocs around the world to form a coherent whole is even more challenging. In this context, a way forward is to return to the most widely used modality of trade liberalization—unilateral actions—but this time involving the multilateralization of preferences rather than unreciprocated reductions in tariff rates. As more and more FTAs are negotiated, preference erosion sets in, reducing the resistance of FTA partners to multilateralization. Multilateralization of preferences may then present a practical way forward in addressing the disarray in the world trade system

Verification of feature regions for stops and fricatives in natural speech

The presence of acoustic cues and their importance in speech perception have long remained debatable topics. In spite of several studies that exist in this eld, very little is known about what exactly humans perceive in speech. This research takes a novel approach towards understanding speech perception. A new method, named three-dimensional deep search (3DDS), was developed to explore the perceptual cues of 16 consonant-vowel (CV) syllables, namely /pa/, /ta/, /ka/, /ba/, /da/, /ga/, /fa/, /Ta/, /sa/, /Sa/, /va/, /Da/, /za/, /Za/, from naturally produced speech. A veri cation experiment was then conducted to further verify the ndings of the 3DDS method. For this pur- pose, the time-frequency coordinate that de nes each CV was ltered out using the short-time Fourier transform (STFT), and perceptual tests were then conducted. A comparison between unmodi ed speech sounds and those without the acoustic cues was made. In most of the cases, the scores dropped from 100% to chance levels even at 12 dB SNR. This clearly emphasizes the importance of features in identifying each CV. The results con rm earlier ndings that stops are characterized by a short-duration burst preceding the vowel by 10 cs in the unvoiced case, and appearing almost coincident with the vowel in the voiced case. As has been previously hypothesized, we con rmed that the F2 transition plays no signi cant role in consonant identi cation. 3DDS analysis labels the /sa/ and /za/ perceptual features as an intense frication noise around 4 kHz, preceding the vowel by 15{20 cs, with the /za/ feature being around 5 cs shorter in duration than that of /sa/; the /Sa/ and /Za/ events are found to be frication energy near 2 kHz, preceding the vowel by 17{20 cs. /fa/ has a relatively weak burst and frication energy over a wide-band including 2{6 kHz, while /va/ has a cue in the 1.5 kHz mid-frequency region preceding the vowel by 7{10 cs. New information is established regarding /Da/ and /Ta/, especially with regards to the nature of their signi cant confusions

Approach to self-similarity in Smoluchowski's coagulation equations

We consider the approach to self-similarity (or dynamical scaling) in Smoluchowski's equations of coagulation for the solvable kernels $K(x,y)=2$, $x+y$ and $xy$. In addition to the known self-similar solutions with exponential tails, there are one-parameter families of solutions with algebraic decay, whose form is related to heavy-tailed distributions well-known in probability theory. For K=2 the size distribution is Mittag-Leffler, and for $K=x+y$ and $K=xy$ it is a power-law rescaling of a maximally skewed $\alpha$-stable Levy distribution. We characterize completely the domains of attraction of all self-similar solutions under weak convergence of measures. Our results are analogous to the classical characterization of stable distributions in probability theory. The proofs are simple, relying on the Laplace transform and a fundamental rigidity lemma for scaling limits.Comment: Latex2e, 42 pages with 1 figur

Topics on High-Energy Elastic Hadron Scattering

We review the main results we have obtained in the area of high-energy elastic hadron scattering and presented in this series of Workshops on Hadronic Interactions. After an introduction to some basic experimental and theoretical concepts, we survey the results reached by means of four approaches: analytic models, model-independent analyses, eikonal models and nonperturbative QCD. Some of the ongoing researches and future perspectives are also outlined.Comment: 24 pages, 17 figures, typos corrected, one reference added and six references updated. Version to appear in Brazilian Journal of Physic