Foreign Currency for Long-Term Investors

Conventional wisdom holds that conservative investors should avoid exposure to foreign currency risk. Even if they hold foreign equities, they should hedge the currency exposure of these positions and should hold only domestic Treasury bills. This paper argues that the conventional wisdom may be wrong for long-term investors. Domestic bills are risky for long-term investors, because real interest rates vary over time and bills must be rolled over at uncertain future interest rates. This risk can be hedged by holding foreign currency if the domestic currency tends to depreciate when the domestic real interest rate falls, as implied by the theory of uncovered interest parity. Empirically this effect is important and can lead conservative long-term investors to hold more than half their wealth in foreign currency.

Investigating Hastily-Formed Collaborative Networks

This research explores both the human and technical aspects of the network centric environment in the context of a major disaster or incident of national significance. The National Incident Management System (NIMS) is viewed by the authors as a social network, and an organizational topology is developed to improve its effectiveness. A rapid Network Deployment Kit (RNDK) using commercial off the shelf (COTS) wireless networking technology is also proposed that facilitates immediate NIMS implementation. The integration of logical and technical analyses forms a comprehensive systems engineering proposal to facilitate collaboration in a net-centric environment. It is envisioned that the methodology used herein to derive and evaluate comprehensive networks proves extendable to other contexts thereby contributing to the netcentric body of knowledge

Rumination as a Mediator of Chronic Stress Effects on Hypertension: A Causal Model

Chronic stress has been linked to hypertension, but the underlying mechanisms remain poorly specified. We suggest that chronic stress poses a risk for hypertension through repeated occurrence of acute stressors (often stemming from the chronic stress context) that cause activation of stress-mediating physiological systems. Previous models have often focused on the magnitude of the acute physiological response as a risk factor; we attempt to extend this to address the issue of duration of exposure. Key to our model is the notion that these acute stressors can emerge not only in response to stressors present in the environment, but also to mental representations of those (or other) stressors. Consequently, although the experience of any given stressor may be brief, a stressor often results in a constellation of negative cognitions and emotions that form a mental representation of the stressor. Ruminating about this mental representation of the stressful event can cause autonomic activation similar to that observed in response to the original incident, and may occur and persist long after the event itself has ended. Thus, rumination helps explain how chronic stress causes repeated (acute) activation of one's stress-mediating physiological systems, the effects of which accumulate over time, resulting in hypertension risk

Determining Accuracy of Chondral Lesion Sizing Methods Prior to Surgery

Background: Osteochondral lesions of the knee may require cartilage restoration such as osteochondral allograft (OCA) transplantation or autologous chondrocyte implantation (ACI). Although MRI and arthroscopy can offer valuable information regarding lesion characteristics prior to these procedures, no study has compared the use of each in estimating the sizes of grafts used at the time of surgical correction. Hypothesis/Purpose: To compare osteochondral defect size measurements and characteristics across MRI, arthroscopy, and at the time of implantation with OCA or ACI. Study Design: Retrospective Cohort Study (Level III) Methods: Patients who underwent ACI and OCA transplantation at a single institution between 2015 and 2019 were retrospectively identified. Osteochondral lesion characteristics including size were collected preoperatively from MRI and arthroscopy and at the time of definitive open surgical intervention. Subgroup analysis was performed comparing measurement techniques depending on the corrective surgical approach used as well as depending on the mechanism of chondral injury to determine if these had any effect on the ability of arthroscopy or MRI to predict graft size. Results: Overall, 136 chondral lesions were addressed with restoration procedures in 117 patients (mean age 32.5 years). Average difference between final graft size and lesion area measured with index arthroscopy was 116 mm2, while average difference between final graft size and lesion size measured with preoperative MRI was 182 mm2 (P \u3c .001). Depending on surgical technique, measurements with MRI were more similar to final graft size when a patient underwent OCA transplantation versus ACI (P = .007). Depending on mechanism of injury, MRI measurements of lesions were closer to graft area when lesions resulted from trauma (P = .047). Conclusion: Chondral lesion size determined by preoperative MRI imaging is less accurate than arthroscopic measurements. The mechanism injury leading to chondral damage and degree of damage may influence the ability of MRI and arthroscopy to accurately measure chondral lesions and predict the final graft size used in surgical correction. Future studies may be warranted to further investigate influencing factors that alter the reliability of arthroscopy and MRI in measuring chondral lesions. Magnetic Resonanc

General Neutralino NLSPs at the Early LHC

Gauge mediated supersymmetry breaking (GMSB) is a theoretically well-motivated framework with rich and varied collider phenomenology. In this paper, we study the Tevatron limits and LHC discovery potential for a wide class of GMSB scenarios in which the next-to-lightest superpartner (NLSP) is a promptly-decaying neutralino. These scenarios give rise to signatures involving hard photons, $W$'s, $Z$'s, jets and/or higgses, plus missing energy. In order to characterize these signatures, we define a small number of minimal spectra, in the context of General Gauge Mediation, which are parameterized by the mass of the NLSP and the gluino. Using these minimal spectra, we determine the most promising discovery channels for general neutralino NLSPs. We find that the 2010 dataset can already cover new ground with strong production for all NLSP types. With the upcoming 2011-2012 dataset, we find that the LHC will also have sensitivity to direct electroweak production of neutralino NLSPs.Comment: 26 page

Structural, functional, and genetic analyses of the actinobacterial transcription factor RbpA

Gene expression is highly regulated at the step of transcription initiation, and transcription activators play a critical role in this process. RbpA, an actinobacterial transcription activator that is essential in Mycobacterium tuberculosis (Mtb), binds selectively to group 1 and certain group 2 σ-factors. To delineate the molecular mechanism of RbpA, we show that the Mtb RbpA σ-interacting domain (SID) and basic linker are sufficient for transcription activation. We also present the crystal structure of the Mtb RbpA-SID in complex with domain 2 of the housekeeping σ-factor, σ(A). The structure explains the basis of σ-selectivity by RbpA, showing that RbpA interacts with conserved regions of σ(A) as well as the nonconserved region (NCR), which is present only in housekeeping σ-factors. Thus, the structure is the first, to our knowledge, to show a protein interacting with the NCR of a σ-factor. We confirm the basis of selectivity and the observed interactions using mutagenesis and functional studies. In addition, the structure allows for a model of the RbpA-SID in the context of a transcription initiation complex. Unexpectedly, the structural modeling suggests that RbpA contacts the promoter DNA, and we present in vivo and in vitro studies supporting this finding. Our combined data lead to a better understanding of the mechanism of RbpA function as a transcription activator

Analysis of Neptune's 2017 Bright Equatorial Storm

We report the discovery of a large ($\sim$8500 km diameter) infrared-bright storm at Neptune's equator in June 2017. We tracked the storm over a period of 7 months with high-cadence infrared snapshot imaging, carried out on 14 nights at the 10 meter Keck II telescope and 17 nights at the Shane 120 inch reflector at Lick Observatory. The cloud feature was larger and more persistent than any equatorial clouds seen before on Neptune, remaining intermittently active from at least 10 June to 31 December 2017. Our Keck and Lick observations were augmented by very high-cadence images from the amateur community, which permitted the determination of accurate drift rates for the cloud feature. Its zonal drift speed was variable from 10 June to at least 25 July, but remained a constant $237.4 \pm 0.2$ m s$^{-1}$ from 30 September until at least 15 November. The pressure of the cloud top was determined from radiative transfer calculations to be 0.3-0.6 bar; this value remained constant over the course of the observations. Multiple cloud break-up events, in which a bright cloud band wrapped around Neptune's equator, were observed over the course of our observations. No "dark spot" vortices were seen near the equator in HST imaging on 6 and 7 October. The size and pressure of the storm are consistent with moist convection or a planetary-scale wave as the energy source of convective upwelling, but more modeling is required to determine the driver of this equatorial disturbance as well as the triggers for and dynamics of the observed cloud break-up events.Comment: 42 pages, 14 figures, 6 tables; Accepted to Icaru