1,082 research outputs found
How Do Banks Pick Safer Ventures? A Theory Relating the Importance of Risk Aversion and Collateral to Interest Margins and Credit Rationing
The paper augments the asymmetric information literature on bank lending to new ventures by focusing on the more neglected area of moral hazard; specifically the relationship between risk aversion, an entrepreneur?s wealth and the provision of collateral. The results highlight some interesting nuances which are not characteristic of the properties of models that have dominated the literature and which mainly focus on the problems of adverse selection. Contrary to models such as Evans and Jovanovic (1989) Blanchflower and Oswald (1998) our model shows that credit rationing does not necessarily have to be negatively related to an entrepreneur?s initial wealth. Our model shows that banks can use collateral as a means of affecting an entrepreneur?s risk aversion – the tactic being least effective for both very low and high wealth individuals. We show that this can cause banks to ration credit at both tails of the wealth distribution. Furthermore, we argue that credit rationing is likely to be less applicable to low wealth individuals, as a small increase in their initial wealth can have very dramatic effects on access to bank finance as it both increases the risk aversion of the borrower as well as the usual affect of raising the amount of the debt that is effectively securitized through borrower collateral. Thus, through this mechanism, low wealth individuals who can provide at least some collateral would have greater access to finance than previously supposed. The results also indicate why collateral to debt ratio need not be negatively related to interest rate margins
Evolutionary squeaky wheel optimization: a new framework for analysis
Squeaky wheel optimization (SWO) is a relatively new metaheuristic that has been shown to be effective for many real-world problems. At each iteration SWO does a complete construction of a solution starting from the empty assignment. Although the construction uses information from previous iterations, the complete rebuilding does mean that SWO is generally effective at diversification but can suffer from a relatively weak intensification. Evolutionary SWO (ESWO) is a recent extension to SWO that is designed to improve the intensification by keeping the good components of solutions and only using SWO to reconstruct other poorer components of the solution. In such algorithms a standard challenge is to understand how the various parameters affect the search process. In order to support the future study of such issues, we propose a formal framework for the analysis of ESWO. The framework is based on Markov chains, and the main novelty arises because ESWO moves through the space of partial assignments. This makes it significantly different from the analyses used in local search (such as simulated annealing) which only move through complete assignments. Generally, the exact details of ESWO will depend on various heuristics; so we focus our approach on a case of ESWO that we call ESWO-II and that has probabilistic as opposed to heuristic selection and construction operators. For ESWO-II, we study a simple problem instance and explicitly compute the stationary distribution probability over the states of the search space. We find interesting properties of the distribution. In particular, we find that the probabilities of states generally, but not always, increase with their fitness. This nonmonotonocity is quite different from the monotonicity expected in algorithms such as simulated annealing
Corruption in University Admissions and the Administrative Allocation of Scarce Goods
The Varsity Blues investigation uncovered a seamy side of university admissions. Multiple wealthy parents were indicted for securing their children s admission to selective institutions through bribery. Despite the publicity the indictments and guilty pleas received, and the public schadenfreude over the sight of celebrities being arrested, the investigation is most notable for what it did not do: it did not deploy the federal government\u27s arsenal of anti-money laundering and anti-corruption tools against the universities involved. This represents a significant missed opportunity to address the serious problems that arise from rationing access to selective institutions via opaque, easily manipulated admissions processes designed to benefit university constituencies. Without deploying the same tools used routinely against other for- and non-profit organizations, the chances for real reform are significantly reduced. We call for universities and their boards to be held to the standards applied to other institutions with respect to corruption and money laundering in their oversight of admissions programs
Legal structure and strategic regulation of intellectual property : Who pays for R&D in arts markets?
The paper addresses the issue of who pays for the cost of creating artistic works and other forrns of intellectual property. It examines the effect of current legal structure on regulatory performance in markets for intellectual property; specifically the effects of sequential and partial regulation. These entail the regulation of multiple market intellectual property on a "market-by-market" basis (sequential régulation) where the performance in other markets for the same intellectual property is taken as given (partial regulation). The analysis demonstrates that this form of regulation is sub-optimal and creates an incentive for copyright and antitrust, laws to be employed strategically by consumers, firms and regulators. In particular, it creates an incentive to use domestic regulation as an international stratégie device. The theoretical exposition is augmented by an analysis of two regulatory decisions relating to the US market for music performance rights which reflect the stratégie implications of partial and sequential regulation.Strategie regulation, copyright, music performance rights
Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers
Distance events in Athletics include cross country, 10,000-m track race, half-marathon and marathon road races, and 20- and 50-km race walking events over different terrain and environmental conditions. Race times for elite performers span ∼26 min to >4 hr, with key factors for success being a high aerobic power, the ability to exercise at a large fraction of this power, and high running/walking economy. Nutrition-related contributors include body mass and anthropometry, capacity to use fuels, particularly carbohydrate (CHO) to produce adenosine triphosphate economically over the duration of the event, and maintenance of reasonable hydration status in the face of sweat losses induced by exercise intensity and the environment. Race nutrition strategies include CHO-rich eating in the hours per days prior to the event to store glycogen in amounts sufficient for event fuel needs, and in some cases, in-race consumption of CHO and fluid to offset event losses. Beneficial CHO intakes range from small amounts, including mouth rinsing, in the case of shorter events to high rates of intake (75–90 g/hr) in the longest races. A personalized and practiced race nutrition plan should balance the benefits of fluid and CHO consumed within practical opportunities, against the time, cost, and risk of gut discomfort. In hot environments, prerace hyperhydration or cooling strategies may provide a small but useful offset to the accrued thermal challenge and fluid deficit. Sports foods (drinks, gels, etc.) may assist in meeting training/race nutrition plans, with caffeine, and, perhaps nitrate being used as evidence-based performance supplements
C.H.A.M.P. Families : Description and Theoretical Foundations of a Paediatric Overweight and Obesity Intervention Targeting Parents-A Single-Centre Non-Randomised Feasibility Study.
Childhood obesity represents a significant global health challenge, and treatment interventions are needed. The purpose of this paper is to describe the components and theoretical model that was used in the development and implementation of a unique parent-focussed paediatric overweight/obesity intervention. C.H.A.M.P. Families was a single-centre, prospective intervention offered to parents of children aged between 6⁻14 years with a body mass index (BMI) ≥85th percentile for age and sex. The intervention included: (1) eight group-based (parent-only) education sessions over 13-weeks; (2) eight home-based activities; and (3) two group-based (family) follow-up support sessions. The first section of the manuscript contains a detailed description of each intervention component, as well as an overview of ongoing feasibility analyses. The theoretical portion details the use of evidence-based group dynamics principles and motivational interviewing techniques within the context of a broader social cognitive theory foundation. This paper provides researchers with practical examples of how theoretical constructs and evidence-based strategies can be applied in the development and implementation of parent-focussed paediatric obesity interventions. Given the need for transparent reporting of intervention designs and theoretical foundations, this paper also adds to the areas of implementation science and knowledge translation research
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Amphotericin forms an extramembranous and fungicidal sterol sponge.
For over 50 years, amphotericin has remained the powerful but highly toxic last line of defense in treating life-threatening fungal infections in humans with minimal development of microbial resistance. Understanding how this small molecule kills yeast is thus critical for guiding development of derivatives with an improved therapeutic index and other resistance-refractory antimicrobial agents. In the widely accepted ion channel model for its mechanism of cytocidal action, amphotericin forms aggregates inside lipid bilayers that permeabilize and kill cells. In contrast, we report that amphotericin exists primarily in the form of large, extramembranous aggregates that kill yeast by extracting ergosterol from lipid bilayers. These findings reveal that extraction of a polyfunctional lipid underlies the resistance-refractory antimicrobial action of amphotericin and suggests a roadmap for separating its cytocidal and membrane-permeabilizing activities. This new mechanistic understanding is also guiding development of what are to our knowledge the first derivatives of amphotericin that kill yeast but not human cells
Survey for Transiting Extrasolar Planets in Stellar Systems. II. Spectrophotometry and Metallicities of Open Clusters
We present metallicity estimates for seven open clusters based on
spectrophotometric indices from moderate-resolution spectroscopy. Observations
of field giants of known metallicity provide a correlation between the
spectroscopic indices and the metallicity of open cluster giants. We use \chi^2
analysis to fit the relation of spectrophotometric indices to metallicity in
field giants. The resulting function allows an estimate of the target-cluster
giants' metallicities with an error in the method of \pm0.08 dex. We derive the
following metallicities for the seven open clusters: NGC 1245,
[m/H]=-0.14\pm0.04; NGC 2099, [m/H]=+0.05\pm0.05; NGC 2324, [m/H]=-0.06\pm0.04;
NGC 2539, [m/H]=-0.04\pm0.03; NGC 2682 (M67), [m/H]=-0.05\pm0.02; NGC 6705,
[m/H]=+0.14\pm0.08; NGC 6819, [m/H]=-0.07\pm0.12. These metallicity estimates
will be useful in planning future extra-solar planet transit searches since
planets may form more readily in metal-rich environments.Comment: 38 pages, including 12 figures. Accepted for publication in A
A Geometric Formulation of Quantum Stress Fields
We present a derivation of the stress field for an interacting quantum system
within the framework of local density functional theory. The formulation is
geometric in nature and exploits the relationship between the strain tensor
field and Riemannian metric tensor field. Within this formulation, we
demonstrate that the stress field is unique up to a single ambiguous parameter.
The ambiguity is due to the non-unique dependence of the kinetic energy on the
metric tensor. To illustrate this formalism, we compute the pressure field for
two phases of solid molecular hydrogen. Furthermore, we demonstrate that
qualitative results obtained by interpreting the hydrogen pressure field are
not influenced by the presence of the kinetic ambiguity.Comment: 22 pages, 2 figures. Submitted to Physical Review B. This paper
supersedes cond-mat/000627
Experience-Dependent Effects of Muscimol-Induced Hippocampal Excitation on Mnemonic Discrimination
Memory requires similar episodes with overlapping features to be represented distinctly, a process that is disrupted in many clinical conditions as well as normal aging. Data from humans have linked this ability to activity in hippocampal CA3 and dentate gyrus (DG). While animal models have shown the perirhinal cortex is critical for disambiguating similar stimuli, hippocampal activity has not been causally linked to discrimination abilities. The goal of the current study was to determine how disrupting CA3/DG activity would impact performance on a rodent mnemonic discrimination task. Rats were surgically implanted with bilateral guide cannulae targeting dorsal CA3/DG. In Experiment 1, the effect of intra-hippocampal muscimol on target-lure discrimination was assessed within subjects in randomized blocks. Muscimol initially impaired discrimination across all levels of target-lure similarity, but performance improved on subsequent test blocks irrespective of stimulus similarity and infusion condition. To clarify these results, Experiment 2 examined whether prior experience with objects influenced the effect of muscimol on target-lure discrimination. Rats that received vehicle infusions in a first test block, followed by muscimol in a second block, did not show discrimination impairments for target-lure pairs of any similarity. In contrast, rats that received muscimol infusions in the first test block were impaired across all levels of target-lure similarity. Following discrimination tests, rats from Experiment 2 were trained on a spatial alternation task. Muscimol infusions increased the number of spatial errors made, relative to vehicle infusions, confirming that muscimol remained effective in disrupting behavioral performance. At the conclusion of behavioral experiments, fluorescence in situ hybridization for the immediate-early genes Arc and Homer1a was used to determine the proportion of neurons active following muscimol infusion. Contrary to expectations, muscimol increased neural activity in DG. An additional experiment was carried out to quantify neural activity in naïve rats that received an intra-hippocampal infusion of vehicle or muscimol. Results confirmed that muscimol led to DG excitation, likely through its actions on interneuron populations in hilar and molecular layers of DG and consequent disinhibition of principal cells. Taken together, our results suggest disruption of coordinated neural activity across the hippocampus impairs mnemonic discrimination when lure stimuli are novel
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