The Case for Learned Index Structures

Indexes are models: a B-Tree-Index can be seen as a model to map a key to the position of a record within a sorted array, a Hash-Index as a model to map a key to a position of a record within an unsorted array, and a BitMap-Index as a model to indicate if a data record exists or not. In this exploratory research paper, we start from this premise and posit that all existing index structures can be replaced with other types of models, including deep-learning models, which we term learned indexes. The key idea is that a model can learn the sort order or structure of lookup keys and use this signal to effectively predict the position or existence of records. We theoretically analyze under which conditions learned indexes outperform traditional index structures and describe the main challenges in designing learned index structures. Our initial results show, that by using neural nets we are able to outperform cache-optimized B-Trees by up to 70% in speed while saving an order-of-magnitude in memory over several real-world data sets. More importantly though, we believe that the idea of replacing core components of a data management system through learned models has far reaching implications for future systems designs and that this work just provides a glimpse of what might be possible

Practising reflexivity in international law : introducing a concept and the working paper series

The field of international law is increasingly turning upon itself. For instance, there is heightened attention to its histories, to the background of the field's actors, or to the structure of international legal argument. This introduction to the concept and practice of reflexivity uses reflexivity to connect and explain these different strands of scholarship in international law. It suggests, in sum, that the field of international law is becoming more reflexive. To substantiate this view, this introduction defines the concept of reflexivity and identifies three levels of reflexive practice in the field. These levels involve turning upon (1) one’s own personal and professional situation or that of the international lawyer; (2) the situation of the field of international law; and (3) the scholarly endeavor in international law. After having situated the concept and practice of reflexivity in international legal scholarship, this introduction extracts some of the implications of its practice and highlights both its benefits and potential pitfalls. It concludes by noting that a reflexive practice may serve as a tool for international lawyers to cultivate an awareness of the contexts and constraints of the field in which they operate, and their position within it

Universal Health Care Coverage in Massachusetts: A Follow-up on the Effects on Neurosurgical Practice

Background: It has been four years since the introduction of universal health care coverage in Massachusetts. Our initial assessment performed from 2007-2008 demonstrated largely positive results. Objectives: We performed a follow-up study to assess the long term financial impact of universal health care on hospital charges associated with neurosurgical operative cases at our institution. Methods: The billing records from July 1, 2009 – June 30, 2010 were compared to those from 2007 and 2008. Records were analyzed for length of stay, case mix, patient age, hospital charge, reimbursement, and procedure. Results: Case volume increased by 31% and mean acuity increased from 2.3 to 3.1 (p \u3c 0.005). Hospital stays lengthened by 1 day (p \u3c 0.005). Payor mix changed over this time with Commonwealth Care and Medicaid comprising 2.9% and 12.4%, respectively, of neurosurgical inpatients; neither had significantly different acuity or lengths of stay. Despite an increase in case volume by 31% and significantly increased acuity in 2010, revenue increased 14% over early reform data. When volume was normalized, extrapolations of pre-reform and early reform coverage on current financials demonstrated that the change in payor mix alone had decreased revenue by 30% and 24%, respectively. When modifying 2010 financials by considering 2007 reimbursement rates and 2007 payor mix, these changes together resulted in a revenue reduction of 36%. Conclusions: Taken together, our data suggests that revenue associated with hospital charges for neurosurgical inpatients has decreased significantly since health care reform went into effect

Maternal obesity and gestational diabetes : Impact on arterial wall layer thickness and stiffness in early childhood - RADIEL study six-year follow-up

Background and aims: Gestational diabetes (GDM) and maternal obesity are linked to weight gain in childhood and an increased risk of cardiovascular disease later in life. We assessed the effects of GDM and maternal obesity on arterial function and morphology in relation to body anthropometrics and composition in early childhood. Methods: We assessed body size and composition, blood pressure (BP), arterial morphology and stiffness in 201 pairs of obese mothers (pre-pregnancy BMI 30.7 +/- 5.6 kg/m(2), 96 with GDM) and their children at 6.1 years (SD 0.5). Results: Child BMI (z-score 0.45 +/- 0.92; p <0.001) and common carotid intima-media thickness (IMT, z-score 0.15 +/- 0.75, p=0.003) were increased compared with a healthy Finnish reference population. No associations with maternal GDM was found. Carotid IMT and pulse wave velocity were unrelated to child sex, anthropometrics, body composition, BP, as well as maternal anthropometrics and body composition. Carotid stiffness was independently predicted by second trimester fasting glucose. Child lean body mass was the strongest independent predictor for radial (RA), and brachial artery (BA) lumen diameter (LD) and BA IMT (LD: RA: r(2)=0.068, p <0.001; BA: r(2)=0.108, p <0.001; IMT: BA: r(2)=0.161, p <0.001) and carotid LD (r(2)=0.066, p <0.001). Conclusions: Children of obese mothers have increased BMI, blood pressure and carotid IMT suggesting a transgenerational effect of maternal obesity and clustering of cardiovascular risk factors in the population. Arterial dimensions were mainly predicted by child LBM, and not associated with maternal or child adiposity, or GDM. There was a weak association with maternal gestational fasting glucose and increased carotid artery stiffness.Peer reviewe

Ultra-high frequency ultrasound delineated changes in carotid and muscular artery intima-media and adventitia thickness in obese early middle-aged women

Obesity is linked to increased arterial size, carotid intima-media thickness and arterial stiffness. The effects of obesity and body composition on muscular artery intima-media and adventitia thickness has previously not been established. The aim of this study was to explore associations between carotid and muscular artery wall layer thickness with body composition and cardiovascular risk factors in early middle-aged women. This is a cross-sectional study including 199 women aged 40 +/- 4 years. Arterial lumen (LD), intima-media (IMT) and adventitia thickness (AT) were measured from carotid, brachial and radial arteries using ultra-high frequency ultrasound (22-71 MHz). Women with obesity had increased IMT in carotid (0.47 vs 0.45 mm), brachial (0.19 vs 0.17 mm) and radial arteries (0.16 vs 0.15 mm) and increased brachial AT (0.14 vs 0.13 mm). In multiple regression models all arterial LD (beta-range 0.02-0.03 mm/kg/m(2)), IMT (beta-range 0.91-3.37 mu m/kg/m(2)), AT (beta-range 0.73-1.38 mu m/kg/m(2)) were significantly associated with BMI. The IMT of all arteries were significantly associated with systolic blood pressure (beta-range 0.36-0.85 mu m/mmHg), attenuating the association between IMT and BMI (beta-range 0.18-2.24 mu m/kg/m(2)). Obese early middle-aged women have increased arterial intima media thickness and brachial artery adventitia thickness compared to non-obese counterparts. The association between BMI and intima-media thickness is partly mediated through blood pressure levels.Peer reviewe

No effect of gestational diabetes or pre-gestational obesity on 6-year offspring left ventricular function-RADIEL study follow-up

Aims We aimed to investigate associations between pre-pregnancy obesity, gestational diabetes (GDM), offspring body composition, and left ventricular diastolic and systolic function in early childhood. Methods This is an observational study, including 201 mother-child pairs originating from the Finnish Gestational Diabetes Prevention Study (RADIEL; 96 with GDM, 128 with pre-pregnancy obesity) with follow-up from gestation to 6-year postpartum. Follow-up included dyads anthropometrics, body composition, blood pressure, and child left ventricular function with comprehensive echocardiography (conventional and strain imaging). Results Offspring left ventricular diastolic and systolic function was not associated with gestational glucose concentrations, GDM, or pregravida obesity. Child body fat percentage correlated with maternal pre-pregnancy BMI in the setting of maternal obesity (r = 0.23,P = 0.009). After adjusting for child lean body mass, age, sex, systolic BP, resting HR, maternal lean body mass, pre-gestational BMI, and GDM status, child left atrial volume increased by 0.3 ml (95% CI 0.1, 0.5) for each 1% increase in child body fat percentage. Conclusions No evidence of foetal cardiac programming related to GDM or maternal pre-pregnancy obesity was observed in early childhood. Maternal pre-pregnancy obesity is associated with early weight gain. Child adiposity in early childhood is independently associated with increased left atrial volume, but its implications for long-term left ventricle diastolic function and cardiovascular health remain unknown.Peer reviewe