Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

Introduction to applied mathematics

Abstract: Introduction to applied mathematics , Introduction to applied mathematics , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

A maximum-entropy-inspired parser

Abstract: We present a new parser for parsing down to Penn tree-bank style parse trees that achieves 90.1% average precision/recall for sentences of length 40 and less, and 89.5% for sentences of length 100 and less when trained and tested on the previously established [5, 9, 10, 15, 17] "standard" sections of the Wall Street Journal treebank. This represents a 13% decrease in error rate over the best single-parser results on this corpus [9]. The major technical innovation is the use of a "maximum-entropy-inspired" model for conditioning and smoothing that let us successfully to test and combine many different conditioning events. We also present some partial results showing the effects of different conditioning information, including a surprising 2% improvement due to guessing the lexical head's pre-terminal before guessing the lexical head.

Influence of Estrogen Plus Progestin on Breast Cancer and Mammography in Healthy Postmenopausal Women: The Women's Health Initiative Randomized Trial

Abstract: ContextThe Women's Health Initiative trial of combined estrogen plus progestin was stopped early when overall health risks, including invasive breast cancer, exceeded benefits. Outstanding issues not previously addressed include characteristics of breast cancers observed among women using hormones and whether diagnosis may be influenced by hormone effects on mammography.ObjectiveTo determine the relationship among estrogen plus progestin use, breast cancer characteristics, and mammography recommendations.Design, Setting, and ParticipantsFollowing a comprehensive breast cancer risk assessment, 16 608 postmenopausal women aged 50 to 79 years with an intact uterus were randomly assigned to receive combined conjugated equine estrogens (0.625 mg/d) plus medroxyprogesterone acetate (2.5 mg/d) or placebo from 1993 to 1998 at 40 clinical centers. Screening mammography and clinical breast examinations were performed at baseline and yearly thereafter.Main Outcome MeasuresBreast cancer number and characteristics, and frequency of abnormal mammograms by estrogen plus progestin exposure.ResultsIn intent-to-treat analyses, estrogen plus progestin increased total (245 vs 185 cases; hazard ratio [HR], 1.24; weighted P<.001) and invasive (199 vs 150 cases; HR, 1.24; weighted P = .003) breast cancers compared with placebo. The invasive breast cancers diagnosed in the estrogen plus progestin group were similar in histology and grade but were larger (mean [SD], 1.7 cm [1.1] vs 1.5 cm [0.9], respectively; P = .04) and were at more advanced stage (regional/metastatic 25.4% vs 16.0%, respectively; P = .04) compared with those diagnosed in the placebo group. After 1 year, the percentage of women with abnormal mammograms was substantially greater in the estrogen plus progestin group (716 [9.4%] of 7656) compared with placebo group (398 [5.4%] of 7310; P<.001), a pattern which continued for the study duration.ConclusionsRelatively short-term combined estrogen plus progestin use increases incident breast cancers, which are diagnosed at a more advanced stage compared with placebo use, and also substantially increases the percentage of women with abnormal mammograms. These results suggest estrogen plus progestin may stimulate breast cancer growth and hinder breast cancer diagnosis.

Scalar timing in memory.

Abstract: A recent report of ours’ proposed an information-processing account of temporal generalization. The account posited a clock process, which was the basic time measurement device, and working and reference memory for storing the output of the clock either temporarily or relatively permanently. Records of time intervals in working and reference memory were then compared using a binary decision process, which dictated responding or not responding. The analysis concentrated on a relativistic Weber’s law property of the data from temporal generalization, and the constraints this property imposed on sources of variance in the information-processing stages. Our purpose here is to summarize that work and generalize the model in two ways: First we consider several sources of variance operating simultaneously. The original analysis demonstrated that if only one source of variance is present, it must be a scalar source, that is, it must result in a variable memory for which variance increases with the square of the mean.’ In the generalized account proposed here, we will develop the conclusion that scalar sources dominate in some time ranges, while other sources may dominate in others. These ideas are then applied to two additional timing tasks with different characteristics.