1,306 research outputs found

    Do more banking offices mean more banking services?

    Get PDF
    An argument that recent growth in the number of banking offices (head offices plus their branches) does not necessarily mean that banking services have increased.Banks and banking - Customer services

    Magnon contribution to unidirectional spin Hall magnetoresistance

    Full text link
    We develop a model for the magnonic contribution to the unidirectional spin Hall magnetoresistance (USMR) of heavy metal/ferromagnetic insulator bilayer films. We show that diffusive transport of Holstein-Primakoff magnons leads to an accumulation of spin near the bilayer interface, giving rise to a magnoresistance which is not invariant under inversion of the current direction. Unlike the electronic contribution described by Zhang and Vignale [Phys. Rev. B 94, 140411 (2016)], which requires an electrically conductive ferromagnet, the magnonic contribution can occur in ferromagnetic insulators such as yttrium iron garnet. We show that the magnonic USMR is, to leading order, cubic in the spin Hall angle of the heavy metal, as opposed to the linear relation found for the electronic contribution. We estimate that the maximal magnonic USMR in Pt|YIG bilayers is on the order of 10βˆ’810^{-8}, but may reach values of up to 10βˆ’510^{-5} if the magnon gap is suppressed, and can thus become comparable to the electronic contribution in, e.g., Pt|Co. We show that the magnonic USMR at a finite magnon gap may be enhanced by an order of magnitude if the magnon diffusion length is decreased to a specific optimal value that depends on various system parameters.Comment: 9 pages, 7 figure

    The Growth Potential of Startups over the Business Cycle

    Get PDF
    This paper shows that employment in cohorts of US firms is strongly influenced by aggregate conditions at the time of their entry. Employment fluctuations of startups are procyclical, they persist into later years, and cohort-level employment variations are largely driven by differences in firm size, rather than the number of firms. An estimated general equilibrium firm dynamics model reveals that aggregate conditions at birth, rather than post-entry choices, drive the majority of cohort-level employment variation by affecting the share of startups with high growth potential. In the aggregate, changes in startup conditions result in large, slow-moving fluctuations in employment

    Reviving american entrepreneurship? tax reform and business dynamism

    Get PDF
    The 2017 Tax Cuts and Jobs Act slashed tax rates on business income and introduced immediate expensing of investments. Using a quantitative heterogeneous-firms model, we investigate the long-run effects of such tax reforms on firm dynamics. We find that they can substantially increase business dynamism, potentially offsetting the large decline in the U.S. startup rate observed over recent decades. This result is driven by indirect equilibrium forces: the tax reform stimulates firm entry, leading to an increase in labor demand and wages. Related to this is a large boost of the number of firms and of aggregate output, investment and employment

    Leaving More Than Money: Mediation Clauses in Estate Planning Documents

    Full text link
    When probate disputes arise, an increasing number of courts have been referring those disputes to mediation. Estate planners, however, have been less proactive about drafting wills to include mediation clauses that would anticipate estate disputes and channel them away from litigation. When a will mandates mediation, the will provides a dispute resolution mechanism designed to preserve family harmony, conserve estate assets, and avoid airing the family\u27s dirty laundry -objectives common to many testators. Mediation clauses in wills are no panacea. They are of little value to testators who exalt control over estate assets above all other concerns, and they are unlikely to bind disappointed family members whose primary claim is against the will rather than under the will. Nevertheless, compared to other alternatives frequently employed by estates lawyers (including no contest clauses), mediation clausesp resent significantp otentialf or reducing estates litigation, with its attendant financial and emotional costs

    On Max-Semistable Laws and Extremes for Dynamical Systems

    Get PDF
    Suppose [Formula: see text] is a measure preserving dynamical system and [Formula: see text] a measurable observable. Let [Formula: see text] denote the time series of observations on the system, and consider the maxima process [Formula: see text]. Under linear scaling of [Formula: see text] , its asymptotic statistics are usually captured by a three-parameter generalised extreme value distribution. This assumes certain regularity conditions on the measure density and the observable. We explore an alternative parametric distribution that can be used to model the extreme behaviour when the observables (or measure density) lack certain regular variation assumptions. The relevant distribution we study arises naturally as the limit for max-semistable processes. For piecewise uniformly expanding dynamical systems, we show that a max-semistable limit holds for the (linear) scaled maxima process

    Assessing the impact of tumor evolution on oncology drug development and commercialization

    Get PDF
    Thesis (S.M.)--Harvard-MIT Division of Health Sciences and Technology, 2011.Vita. Cataloged from PDF version of thesis.Includes bibliographical references (p. 91-97).This thesis investigates the commercial viability of developing and commercializing targeted oncology drugs directed at a specific tumor mutation instead of all forms and mutations of a single target. While oncologic drugs targeted to aberrant or overexpressed pro-proliferative proteins have revolutionized cancer treatment, tumors treated for long periods may mutate over time, gain resistance to these drugs and proliferate rapidly again. I hypothesize that drugs developed to inhibit specific resistant tumor genotypes can be commercially viable from a pharmaceutical manufacturer's perspective. To assess this hypothesis empirically, I construct a patient flow model in order to quantify the treatment of CML, a relatively rare and indolent hematological malignancy with extensive clinical data available and well-delineated disease phases and response criteria. To represent the rate of diagnosis, patients are "added" to the model every month, and thereafter there is a probability that a patient may either 1) become sufficiently intolerant to his drug in order to discontinue treatment, 2) fail to respond to treatment but remain in the same disease phase, 3) fail to respond to treatment and progress to the next phase of disease, or 4) adequately respond to treatment and stay on the same drug in the same phase. Patients that fail to respond (categories 2 and 3 above) have a chance of manifesting a resistance mutation that is adequately controlled by a hypothetical drug (in addition to their current treatment) but is otherwise untreatable. The aim of this analysis is to track the number of patients that accrue the chosen resistance mutation and thus would be good candidates to receive the hypothetical drug. Patient treatment rates are converted to sales figures, and are weighed against clinical development costs, timelines, and probabilities to determine the net present value (NPV) of a project to develop the hypothetical drug. In addition, parameters are varied in order to conduct a sensitivity analysis and determine the "boundary conditions" that make a drug profitable or unprofitable. To supplement the model results and confirm the model dynamics, I interviewed investment analysts, clinical oncology thoughtleaders, academic cancer researchers and clinical, commercial and regulatory personnel from drug manufacturers to gauge their opinions on the CML market and the hurdles particular to developing drugs aimed at resistant genotypes. The conclusion I reach from this analysis is that development of a specific mutation-directed therapy for resistant CML is unlikely to be profitable. Given the significantly smaller patient population, favorable conditions in pricing and clinical development would be required to make the hypothetical candidate even marginally profitable.by Joseph P. Sterk.S.M

    The carrot extracellular lipid transfer protein EP2

    Get PDF
    In many plant species embryos can develop from cultured somatic cells in a process referred to as somatic embryogenesis. Apart from their cellular origin somatic embryos develop through the same characteristic morphological stages, i.e. globular, heart and torpedo stages, observed during zygotic embryogenesis. Somatic embryos of different developmental stages can easily be obtained in large quantities, one of the main reasons for the frequent use of somatic embryogenesis as an alternative system to study plant embryogenesis.Despite the wealth of information available on both zygotic and somatic embryo development with respect to their morphology and histology, insight in the molecular events that take place during embryogenesis is still poor. The study presented in this thesis is based on the observation that the presence of a small number of (glyco)proteins secreted into media of cultured carrot cells parallels the appearance of actual somatic embryos in these cultures. The aim of this study was to clone genes encoding these proteins and to study their expression and function in relation to embryogenesis. The approach taken was to screen an expression library with antisera raised against proteins secreted by carrot cells. This screening resulted in four cDNA clones which, upon detailed analysis of the expression patterns of the corresponding genes and identification of the respective encoded proteins by immunological means, were shown to represent genes encoding proteins secreted by distinct cell types.In chapter 1 an introduction to both somatic and zygotic embryogenesis is presented, as well as an overview and classification of genes and proteins expressed in embryos that have been identified in other studies, based on their temporal expression patterns during embryo development. Chapter 2 describes the cloning of four cDNAs representing the carrot genes Extracellular Protein (EP)1, EP2, EP5 and EP6. Based on the observed close correlation of EP2 gene expression with embryo development, this gene was chosen for further study as described in chapter 3. In situ hybridization experiments revealed EP2 expression already in the 60-celled zygotic embryo, and in proembryogenic masses, the precursors of somatic embryos, and in somatic embryos. Based on its sequence homology with other extracellular non-specific lipid transfer proteins, the expression of the EP2 gene in protodermal and epidermal cells in embryos and plants, and the known coincidence of a cuticle on those cells, a role for the EP2 encoded protein was proposed in the transport of monomeric cutin precursors to sites of cutin synthesis. To support this hypothesis, the affinity of the purified EP2 protein for known cutin precursors was demonstrated in chapter 4. In chapter 5 the existing approaches to study early plant embryo development are discussed and compared with the results presented here

    On the predictability of extremes: Does the butterfly effect ever decrease?

    Get PDF
    This is the peer reviewed version of the following article: Sterk, A. E., Stephenson, D. B., Holland, M. P. and Mylne, K. R. (2015), On the predictability of extremes: Does the butterfly effect ever decrease?. Quarterly Journal of the Royal Meteorological Society, which has been published in final form at http://dx.doi.org/10.1002/qj.2627. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving: http://olabout.wiley.com/WileyCDA/Section/id-820227.html#termsThis study investigates whether or not predictability always decreases for more extreme events. Predictability is measured by the Mean Squared Error (MSE), estimated here from the difference of pairs of ensemble forecasts, conditioned on one of the forecast variables (the 'pseudo-observation') exceeding a threshold. Using an exchangeable linear regression model for pairs of forecast variables, we show that the MSE can be decomposed into the sum of three terms: a threshold-independent constant, a mean term that always increases with threshold, and a variance term that can either increase, decrease, or stay constant with threshold. Using the generalised Pareto distribution to model wind speed excesses over a threshold, we show that MSE always increases with threshold at sufficiently high threshold. However, MSE can be a decreasing function of threshold at lower thresholds but only if the forecasts have finite upper bounds. The methods are illustrated by application to daily wind speed forecasts for London made using the 24 member Met Office Global and Regional Ensemble Prediction System from 1 January 2009 to 31 May 2011. For this example, the mean term increases faster than the variance term decreases with increasing threshold, and so predictability decreases for more extreme events.Engineering and Physical Sciences Research Council (EPSRC)Netherlands Organisation for Scientific Research (NWO
    • …
    corecore