Heterosexuals are vulnerable to AIDS

This letter is in resposne to two articles printed in the Daily Maine Campus on December 12, 1986

Light scattering as a Poisson process and first-passage probability

A particle entering a scattering and absorbing medium executes a random walk through a sequence of scattering events. The particle ultimately either achieves first-passage, leaving the medium, or it is absorbed. The KubelkaMunk model describes a flux of such particles moving perpendicular to the surface of a plane-parallel medium with a scattering rate and an absorption rate. The particle path alternates between the positive direction into the medium and the negative direction back towards the surface. Backscattering events from the positive to the negative direction occur at local maxima or peaks, while backscattering from the negative to the positive direction occur at local minima or valleys. The probability of a particle avoiding absorption as it follows its path decreases exponentially with the path-length λ. The reflectance of a semiinfinite slab is therefore the Laplace transform of the distribution of path-length that ends with a first-passage out of the medium. In the case of a constant scattering rate the random walk is a Poisson process. We verify our results with two iterative calculations, one using the properties of iterated convolution with a symmetric kernel and the other via direct calculation with an exponential steplength distribution. We present a novel demonstration, based on fluctuation theory of sums of random variables, that the first-passage probability as a function of the number of peaks n in the alternating path is a step-length distribution-free combinatoric expression involving Catalan numbers. Counting paths with backscattering on the real half-line results in the same Catalan number coefficients as Dyck paths on the whole numbers. Including a separate forward-scattering Poisson process results in a combinatoric expression related to counting Motzkin paths. We therefore connect walks on the real line to discrete path combinatorics

Precontractual Damages as a Result of an Irrevocable Offer – A Resolution Within the CISG

This paper is written in response to the arguments that have beenput forward by Anne Rossen, Maria Pedersen, and Thomas Neumann,titled “How far does the dynamic doctrine go? Looking for the basis ofprecontractual liability in the CISG”. On the backdrop of this paper, it isworth noting that the United Nations Convention on Contracts for theInternational Sale of Goods (CISG) is one of the most successfulinternational commercial law treaties ever devised. It has been ratified bymost of the world's important trading countries and has become atemplate for the drafting of commercial law treaties. The CISG isconsidered a self-executing treaty, as it creates a private right of action infederal court under federal law. It provides the default set of rules thatgovern contracts for the sale of goods between parties located in differentContracting States. In some cases, the CISG also addresses situations inwhich only one of the parties is located in a Contracting State.This article argues that the CISG can accommodate breaches ofprecontractual conditions through the same procedure applied to breachesof contract. It is a controversial issue but, nevertheless, it is arguable thatthe CISG can cover the internal gap via general principles embeddedwithin its four corners. For this reason, this article will look at Article16(2). In particular, the following issues will be relevant: the revoking ofan irrevocable offer; the effects of Article 4; and the effects of Articles 71-77

Building Buzz without Big Bucks

Guerrilla marketing is a means of advertising that relies more on unconventional methods and less on big budgets. The goal is typically to do something that gets the targeted market or demographic talking so that word of mouth does most of the advertising legwork. Guerilla marketing was the technique employed to promote the 2010 Information Faire and Festival, or IF2, a new event sponsored by the Libraries of the College of the Holy Cross which invited students to learn in fun and engaging ways about the many library services and resources available. The Information Faire and Festival was highly successful with attendees commenting on our enthusiasm and creative marketing strategy

Negative spatial regulation of the lineage specific CyIIIa actin gene in the sea urchin embryo

The CyIIIa·CAT fusion gene was injected into Strongylocentrotus purpuratus eggs, together with excess ligated competitor sequences representing subregions of the CyIIIa regulatory domain. In this construct, the chloramphenicol acetyltransferase (CAT) reporter gene is placed under the control of the 2300 nucleotide upstream regulatory domain of the lineage-specific CyIIIa cytoskeletal actin gene. CAT mRNA was detected by in situ hybridization in serial sections of pluteus stage embryos derived from the injected eggs. When carrier DNA lacking competitor CyIIIa fragments was coinjected with CyIIIa.CAT, CAT mRNA was observed exclusively in aboral ectoderm cells, i.e. the territory in which the CyIIIa gene itself is normally expressed (as also reported by us previously). The same result was obtained when five of seven different competitor subfragments bearing sites of DNA-protein interaction were coinjected. However, coinjection of excess quantities of either of two widely separated, nonhomologous fragments of the CyIIIa regulatory domain produced a dramatic ectopic expression of CAT mRNA in the recipient embryos. CAT mRNA was observed in gut, mesenchyme cells and oral ectoderm in these embryos. We conclude that these fragments contain regulatory sites that negatively control spatial expression of the CyIIIa gene

Diffuse fibromuscular dysplasia successfully treated with scoring balloon angioplasty in a 3-year-old boy

In children, up to 10% of the cases of arterial hypertension may be caused by a renovascular disease. The etiology of this renovascular disease is most of the time due to a fibromuscular dysplasia (FMD), which causes a noninflammatory intimal-medial fibroplasia leading to luminal compromise. Percutaneous transluminal angioplasty of FMD is a worldwide-accepted treatment modality for this serious arterial disease with, so far, good safety and long-term efficacy data. Once FMD involves several arterial compartments leading to symptoms the outcomes are poor. Herein we report the case of a 3½-year-old boy with severe arterial hypertension and abdominal angina due to a diffuse multivisceral FMD involvement, successfully managed by a percutaneous angioplasty approach using a new balloon catheter for plaque modulatio