Do President Trump’s Tweets Increase Uncertainty in the US Economy?

When President Trump tweets, does it change uncertainty in the economy? This study gathers President Trump’s tweets off his twitter accounts from October 2016 to October 2017 and classifies each of them as either negative (expected to increase uncertainty), positive (expected to decrease uncertainty) or neutral (no effect expected on uncertainty). I find that tweets with a negative sentiment were followed by an increase in uncertainty in the VIX and S&P 500 1 and 2 minutes after the tweet. Similar results were found for positive tweets. Non-neutral tweets increase trading volume in the VIX and S&P 500 by up to 200% in the hour following the tweet. Overall, this study finds that up to 2 minutes after the non-neutral tweet, investors appear to be trading based on the sentiment value of that tweet. However, after 2 minutes, investors trading strategies appear to veer away from tweet sentiment value, but trading volumes in these indices are still much higher than normal. Policy makers should be aware of this increased volatility stemming from the President’s unconventional twitter use and may suggest more conventional ways to spread new information to the financial markets

Larc: a State Collapse Theory of Quantum Measurement

This proposes a new theory of Quantum measurement; a state reduction theory in which reduction is to the elements of the number operator basis of a system, triggered by the occurrence of annihilation or creation (or lowering or raising) operators in the time evolution of a system. It is from these operator types that the acronym `LARC' is derived. Reduction does not occur immediately after the trigger event; it occurs at some later time with probability $P_t$ per unit time, where $P_t$ is very small. Localisation of macroscopic objects occurs in the natural way: photons from an illumination field are reflected off a body and later absorbed by another body. Each possible absorption of a photon by a molecule in the second body generates annihilation and raising operators, which in turn trigger a probability per unit time $P_t$ of a state reduction into the number operator basis for the photon field and the number operator basis of the electron orbitals of the molecule. Since all photons in the illumination field have come from the location of the first body, wherever that is, a single reduction leads to a reduction of the position state of the first body relative to the second, with a total probability of $m\tau_L$, where $m$ is the number of photon absorption events. Unusually for a reduction theory, the larc theory is naturally relativistic

Clearing Contamination in Large Networks

In this work, we study the problem of clearing contamination spreading through a large network where we model the problem as a graph searching game. The problem can be summarized as constructing a search strategy that will leave the graph clear of any contamination at the end of the searching process in as few steps as possible. We show that this problem is NP-hard even on directed acyclic graphs and provide an efficient approximation algorithm. We experimentally observe the performance of our approximation algorithm in relation to the lower bound on several large online networks including Slashdot, Epinions and Twitter. The experiments reveal that in most cases our algorithm performs near optimally

Residential broadband subscription demand: an econometric analysis of Australian choice experiment data

The recent roll-out of fibre-optic cable suggests that the willingness of households in passed communities to subscribe to networked services is an important issue. This paper studies the determination of the demand for network subscription. Through a discrete choice model the effect of installation and rental price on the likelihood of subscription is analysed. The logit regression is based on choice experiment (stated preference)subscription data obtained from a national survey of households. Limitations of this preliminary work and suggestions for future research are discussed.Broadband subscription demand

Transient-mediated fate determination in a transcriptional circuit of HIV

Steady-state behavior and bistability have been proposed as mechanisms for decision-making in gene circuits. However, transient gene expression has also been proposed to control cell fate with the decision arbitrated by the lifetime of the expression transient. Here, we report that transcriptional positive-feedback plays a critical role in determining HIV infected cell-fate by extending the duration of Tat expression transients far beyond what protein half-life modulation can achieve. To directly quantify feedback strength and its effects on the duration of Tat transcriptional pulses, we exploit the noise inherent to gene-expression and measure shifts in the autocorrelation of expression noise. The results indicate that transcriptional positive-feedback extends the single-cell Tat expression lifetime by ~6-fold for both minimal Tat circuits and full-length, actively-replicating HIV-1. Importantly, artificial weakening of Tat positive-feedback shortened the duration of Tat expression transients and biased the probability in favor of latency. Thus, transcriptional positive-feedback appears to modulate transient expression lifetime and thereby control cell-fate in HIV

Agglomeration, regional grants and firm location

We examine whether discretionary government grants influence the location of new plants, and how effective these incentives are in the presence of agglomeration and urbanisation externalities. We find evidence that regional industrial structure affects the location of new entrants. Firms in more agglomerated industries locate new plants near to others in the same industry. Firms are also attracted to industrially diversified locations. Foreign multinationals locate new plants near to other foreign-owned plants in the same industry. Fiscal incentives in the form of grants are found to have some effect in attracting plants to specific geographic areas eligible for such aid.Corporation tax

Examples of mirror partners arising from integrable systems

In this note we present pairs of hyperkaehler orbifolds which satisfy two different versions of mirror symmetry. On the one hand, we show that their Hodge numbers (or more precisely, stringy E-polynomials) are equal. On the other hand, we show that they satisfy the prescription of Strominger, Yau, and Zaslow (which in the present case goes back to Bershadsky, Johansen, Sadov and Vafa): that a Calabi-Yau and its mirror should fiber over the same real manifold, with special Lagrangian fibers which are tori dual to each other. Our examples arise as moduli spaces of local systems on a curve with structure group SL(n); the mirror is the corresponding space with structure group PGL(n). The special Lagrangian tori come from an algebraically completely integrable Hamiltonian system: the Hitchin system.Comment: 6 pages, in English with French summary, to appear in C. R. Acad. Sci. Paris Ser. I Math; acknowledgements and a reference adde

Taxing Corporate Income

Following Meade (1978), we reconsider issues in the design of taxes on corporate income. We outline developments in economies and in economic thought over the last thirty years, and investigate how these developments should affect the design of taxes on corporate income. We consider a number of tax systems which have been proposed, distinguishing them in two main dimensions: the definition of what is to be taxed, and where it is to be taxed. We propose that a tax levied on economic rent accruing in the corporate sector, and on a destination basis, merits serious consideration. We discuss alternative approaches, including both R-based and R+F-based flow-of-funds taxes and an ACE allowance. It is the destination basis – with border adjustments for exports and imports – which primarily distinguishes our proposals from those of Meade (1978).