An effective formalism for testing extensions to General Relativity with gravitational waves

The recent direct observation of gravitational waves (GW) from merging black holes opens up the possibility of exploring the theory of gravity in the strong regime at an unprecedented level. It is therefore interesting to explore which extensions to General Relativity (GR) could be detected. We construct an Effective Field Theory (EFT) satisfying the following requirements. It is testable with GW observations; it is consistent with other experiments, including short distance tests of GR; it agrees with widely accepted principles of physics, such as locality, causality and unitarity; and it does not involve new light degrees of freedom. The most general theory satisfying these requirements corresponds to adding to the GR Lagrangian operators constructed out of powers of the Riemann tensor, suppressed by a scale comparable to the curvature of the observed merging binaries. The presence of these operators modifies the gravitational potential between the compact objects, as well as their effective mass and current quadrupoles, ultimately correcting the waveform of the emitted GW.Comment: v1: 43+16 pages, 11 figures, 2 tables; v2: minor corrections; v3: minor corrections, JHEP published versio

The Impact Of Spike-Frequency Adaptation On Balanced Network Dynamics

A dynamic balance between strong excitatory and inhibitory neuronal inputs is hypothesized to play a pivotal role in information processing in the brain. While there is evidence of the existence of a balanced operating regime in several cortical areas and idealized neuronal network models, it is important for the theory of balanced networks to be reconciled with more physiological neuronal modeling assumptions. In this work, we examine the impact of spike-frequency adaptation, observed widely across neurons in the brain, on balanced dynamics. We incorporate adaptation into binary and integrate-and-fire neuronal network models, analyzing the theoretical effect of adaptation in the large network limit and performing an extensive numerical investigation of the model adaptation parameter space. Our analysis demonstrates that balance is well preserved for moderate adaptation strength even if the entire network exhibits adaptation. In the common physiological case in which only excitatory neurons undergo adaptation, we show that the balanced operating regime in fact widens relative to the non-adaptive case. We hypothesize that spike-frequency adaptation may have been selected through evolution to robustly facilitate balanced dynamics across diverse cognitive operating states

Building Maritime Security in Southeast Asia

Today’s globalized economy is intricately interconnected and is heavily dependent on maritime trade in order to sustain the movement of energy, raw materials, and finished goods. The arteries of global trade include the narrow waterways of Southeast Asia, with about a third of the world’s trade and half its oil transiting through the Straits of Malacca and Singapore alone. As China and India continue their strong growth, sea trade through the straits is expected to increase correspondingly

DESIGN, MODELING, OPTIMIZATION, AND BENCHMARKING OF INTERCONNECTS AND SCALING TECHNOLOGIES AND THEIR CIRCUIT AND SYSTEM LEVEL IMPACT

This research focuses on the future of integrated circuit (IC) scaling technologies at the device and back end of line (BEOL) level. This work includes high level modeling of different technologies and quantifying potential performance gains on a circuit and system level. From the device side, this research looks at the scaling challenges and the future scaling drivers for conventional charge-based devices implemented at the 7nm technology node and beyond. It examines the system-level performance of stacking device logic in addition to tunneling field effect transistors (TFET) and their potential as beyond-CMOS devices. Finally, this research models and benchmarks BEOL scaling challenges and evaluates proposed technological advancements such as metal barrier scaling for copper interconnects and replacing local interconnects with ruthenium. Potential impact on performance, power, and area of these interconnect technologies is quantified for fully placed and routed circuits.Ph.D

A small weak scale from a small cosmological constant

We propose a framework in which Weinberg's anthropic explanation of the cosmological constant problem also solves the hierarchy problem. The weak scale is selected by chiral dynamics that controls the stabilization of an extra dimension. When the Higgs vacuum expectation value is close to a fermion mass scale, the radius of an extra dimension becomes large, and develops an enhanced number of vacua available to scan the cosmological constant down to its observed value. At low energies, the radion necessarily appears as an unnaturally light scalar, in a range of masses and couplings accessible to fifth-force searches as well as scalar dark matter searches with atomic clocks and gravitational-wave detectors. The fermion sector that controls the size of the extra dimension consists of a pair of electroweak doublets and several singlets. These leptons satisfy approximate mass relations related to the weak scale and are accessible to the LHC and future colliders.Comment: 58 pages, 16 figure

Bijective Proofs of Gould's and Rothe's Identities

We first give a bijective proof of Gould's identity in the model of binary words. Then we deduce Rothe's identity from Gould's identity again by a bijection, which also leads to a double-sum extension of the $q$-Chu-Vandermonde formula.Comment: 4 page

School-business partnerships: the case of the UAE

© 2013, © Emerald Group Publishing Limited. Purpose – The purpose of this paper is to examine the reasons for businesses to partner with schools from the point of view of both stakeholders. Understanding the process by which schools and business entities collaborate with the goal of improving student achievement is important to ensure success and anticipate barriers. Pitfalls and keys to success are outlined. Recommendations for school and business leaders interested in forming partnerships based on lessons learned from the literature are provided. Design/methodology/approach – The paper achieves this aim by reviewing the literature on school-business partnership formation and assessment. Findings – Characteristics of successful school-business partnerships are discussed. Practical implications – Both business and education leaders will be able to assess the value and scope of such partnership arrangements and be able to determine if their current or planned endeavours encompass the identified keys to success. Originality/value – This paper concisely examines the major, practical issues involved for those interested in forming school-business partnerships and synthesizes the research on program evaluations while placing the issue in the context of current trends in corporate social responsibility programs