Investor Sentiment and Corporate Finance: Micro and Macro

We document that net equity issuance is considerably more sensitive to aggregate stock returns and Q's than to firm-level stock returns and Q's. Very similar patterns also emerge when we look at merger activity. In light of earlier work (Campbell 1991, Vuolteenaho 2002) which finds that aggregate stock returns are less informative about future cashflows than are firm-level stock returns--and thus, potentially more strongly influenced by investor sentiment--these results suggest that both equity issuance and mergers are to a significant extent driven by market-timing considerations, as opposed to by purely fundamental factors.

Aggregate Short Interest and Market Valuations

We examine some basic data on the evolution of aggregate short interest, both during the dot-com era, and at other times in history. Total short interest moves in a countercyclical fashion. For example, short interest in NASDAQ stocks actually declines as the NASDAQ index approaches its peak. Moreover, this decline does not seem to reflect a substitution away from outright short-selling and towards put options, as the ratio of put-to-call volume displays the same countercyclical tendency. The evidence suggests that: i) arbitrageurs are reluctant to bet against aggregate mispricings; and ii) short-selling does not play a particularly helpful role in stabilizing the overall stock market.

Aggregate Short Interest and Market Valuations

We examine some basic data on the evolution of aggregate short interest, both during the dot-com era, and at other times in history. Total short interest moves in a countercyclical fashion. For example, short interest in NASDAQ stocks actually declines as the NASDAQ index approaches its peak. Moreover, this decline does not seem to reflect a substitution away from outright short-selling and towards put options, as the ratio of put-to-call volume displays the same countercyclical tendency. The evidence suggests that: i) arbitrageurs are reluctant to bet against aggregate mispricings; and ii) short-selling does not play a particularly helpful role in stabilizing the overall stock market.

Universal thermodynamic bounds on nonequilibrium response with biochemical applications

Diverse physical systems are characterized by their response to small perturbations. Near thermodynamic equilibrium, the fluctuation-dissipation theorem provides a powerful theoretical and experimental tool to determine the nature of response by observing spontaneous equilibrium fluctuations. In this spirit, we derive here a collection of equalities and inequalities valid arbitrarily far from equilibrium that constrain the response of nonequilibrium steady states in terms of the strength of nonequilibrium driving. Our work opens new avenues for characterizing nonequilibrium response. As illustrations, we show how our results rationalize the energetic requirements of two common biochemical motifs.Comment: 21 pages, 15 figure

Thermodynamic bounds on ultrasensitivity in covalent switching

Switch-like motifs are among the basic building blocks of biochemical networks. A common motif that can serve as an ultrasensitive switch consists of two enzymes acting antagonistically on a substrate, one making and the other removing a covalent modification. To work as a switch, such covalent modification cycles must be held out of thermodynamic equilibrium by continuous expenditure of energy. Here, we exploit the linear framework for timescale separation to establish tight bounds on the performance of any covalent-modification switch, in terms of the chemical potential difference driving the cycle. The bounds apply to arbitrary enzyme mechanisms, not just Michaelis-Menten, with arbitrary rate constants, and thereby reflect fundamental physical constraints on covalent switching.Comment: 29 pages, 6 figure

Pests or prey? Micromammal species within an ancient anthropic environment at the Norse settlement site of Tuquoy (Westray, Orkney)

Excel file with five tables containing Tuquoy micromammal data (four tables) and references from Andrews 1990 (one table)

Expansion of the ligand knowledge base for chelating P,P-donor ligands (LKB-PP)

[Image: see text] We have expanded the ligand knowledge base for bidentate P,P- and P,N-donor ligands (LKB-PP, Organometallics2008, 27, 1372–1383) by 208 ligands and introduced an additional steric descriptor (nHe(8)). This expanded knowledge base now captures information on 334 bidentate ligands and has been processed with principal component analysis (PCA) of the descriptors to produce a detailed map of bidentate ligand space, which better captures ligand variation and has been used for the analysis of ligand properties

The value of 99mTc-MAA SPECT/CT for lung shunt estimation in 90Y radioembolization: a phantom and patient study

Abstract Background A major toxicity concern in radioembolization therapy of hepatic malignancies is radiation-induced pneumonitis and sclerosis due to hepatopulmonary shunting of 90Y microspheres. Currently, 99mTc macroaggregated albumin (99mTc-MAA) imaging is used to estimate the lung shunt fraction (LSF) prior to treatment. The aim of this study was to evaluate the accuracy/precision of LSF estimated from 99mTc planar and SPECT/CT phantom imaging, and within this context, to compare the corresponding LSF and lung-absorbed dose values from 99mTc-MAA patient studies. Additionally, LSFs from pre- and post-therapy imaging were compared. Results A liver/lung torso phantom filled with 99mTc to achieve three lung shunt values was scanned by planar and SPECT/CT imaging with repeat acquisitions to assess accuracy and precision. To facilitate processing of patient data, a workflow that relies on SPECT and CT-based auto-contouring to define liver and lung volumes for the LSF calculation was implemented. Planar imaging-based LSF estimates for 40 patients, obtained from their medical records, were retrospectively compared with SPECT/CT imaging-based calculations with attenuation and scatter correction. Additionally, in a subset of 20 patients, the pre-therapy estimates were compared with 90Y PET/CT-based measurements. In the phantom study, improved accuracy in LSF estimation was achieved using SPECT/CT with attenuation and scatter correction (within 13% of the true value) compared with planar imaging (up to 44% overestimation). The results in patients showed a similar trend with planar imaging significantly overestimating LSF compared to SPECT/CT. There was no correlation between lung shunt estimates and the delay between 99mTc-MAA administration and scanning, but off-target extra hepatic uptake tended to be more likely in patients with a longer delay. The mean lung absorbed dose predictions for the 28 patients who underwent therapy was 9.3 Gy (range 1.3–29.4) for planar imaging and 3.2 Gy (range 0.4–13.4) for SPECT/CT. For the patients with post-therapy imaging, the mean LSF from 90Y PET/CT was 1.0%, (range 0.3–2.8). This value was not significantly different from the mean LSF estimate from 99mTc-MAA SPECT/CT (mean 1.0%, range 0.4–1.6; p = 0.968), but was significantly lower than the mean LSF estimate based on planar imaging (mean 4.1%, range 1.2–15.0; p = 0.0002). Conclusions The improved accuracy demonstrated by the phantom study, agreement with 90Y PET/CT in patient studies, and the practicality of using auto-contouring for liver/lung definition suggests that 99mTc-MAA SPECT/CT with scatter and attenuation corrections should be used for lung shunt estimation prior to radioembolization.https://deepblue.lib.umich.edu/bitstream/2027.42/144504/1/13550_2018_Article_402.pd

Credit Conditions and the Cyclical Behavior of Inventories: A Case Studyof the 1981-82 Recession

This paper examines micro data on U.S. firms' inventories during different macroeconomic episodes. Much of the analysis focuses on the 1981-82 recession, a recession that was apparently precipitated by tight monetary policy. We find important cross-sectional effects in this period: firms that were "bank-dependent" were much more prone to shed inventories than their non-bank-dependent counterparts. In contrast, such cross-sectional differences are largely absent during a period of "loose" monetary policy later in the 1980s. Our findings are consistent with the view that 1) there is a bank lending channel of monetary policy transmission; 2) the lending channel is likely to be particularly important in explaining inventory fluctuations during downturns.