Showing papers by "Michael L. Nelson published in 2011"

How much of the web is archived

Abstract: The Memento Project's archive access additions to HTTP have enabled development of new web archive access user interfaces. After experiencing this web time travel, the in- evitable question that comes to mind is "How much of the Web is archived?" This question is studied by approximating the Web via sampling URIs from DMOZ, Delicious, Bitly, and search engine indexes and measuring number of archive copies available in various public web archives. The results indicate that 35%-90% of URIs have at least one archived copy, 17%-49% have two to five copies, 1%-8% have six to ten copies, and 8%-63% at least ten copies. The number of URI copies varies as a function of time, but only 14.6-31.3% of URIs are archived more than once per month.

Glycaemic index and glycaemic load of breakfast predict cognitive function and mood in school children: a randomised controlled trial.

Abstract: The macronutrient composition of a breakfast that could facilitate performance after an overnight fast remains unclear. As glucose is the brain's major energy source, the interest is in investigating meals differing in their blood glucose-raising potential. Findings vary due to unaccounted differences in glucoregulation, arousal and cortisol secretion. We investigated the effects of meals differing in glycaemic index (GI) and glycaemic load (GL) on cognition and mood in school children. A total of seventy-four school children were matched and randomly allocated either to the high-GL or low-GL group. Within each GL group, children received high-GI and low-GI breakfasts. Cognitive function (CF) and mood were measured 95–140 min after breakfast. Blood glucose and salivary cortisol were measured at baseline, before and after the CF tests. Repeated-measures ANOVA was used to identify differences in CF, mood, glucose and cortisol levels between the breakfasts. Low-GI meals predicted feeling more alert and happy, and less nervous and thirsty (P < 0·05 for each); high-GL meals predicted feeling more confident, and less sluggish, hungry and thirsty (P < 0·05 for each). High-GL (P < 0·001) and high-GI (P = 0·05) meals increased glucose levels 90 min after breakfast, and high-GI meals increased cortisol levels (P < 0·01). When baseline mood, glucose and cortisol levels were considered, low-GI meals predicted better declarative-verbal memory (P = 0·03), and high-GI meals better vigilance (P < 0·03); observed GI effects were valid across GL groups. GI effects on cognition appear to be domain specific. On balance, it would appear that the low-GI high-GL breakfast may help to improve learning, and of potential value in informing government education policies relating to dietary recommendations and implementation concerning breakfast.

The impact of the food-based and nutrient-based standards on lunchtime food and drink provision and consumption in secondary schools in England

Abstract: ObjectivesTo assess lunchtime provision of food and drink in English secondary schools and the choices and consumption of food and drink by pupils having school lunches, and to compare provision in 2011 with that in 2004.DesignCross-sectional data collected between October 2010 and April 2011. In each school, food and drink provision, including portion weights and number of portions of each item served at lunchtime, were recorded over five consecutive days. Caterers provided recipe information.SettingEngland.SubjectsA random selection of 5969 pupils having school lunches in a nationally representative sample of eighty secondary schools in England.ResultsCompared with 2004, significantly more schools in 2011 provided main dishes, vegetables and salads, water, fruit juice and other drinks on 4 or 5 d/week (P < 0·005). The number of schools offering items not permitted under the food-based standards for school food on 4 or 5 d/week fell significantly over time (P < 0·005), while the number not offering these items on any day increased significantly (P < 0·005). Meals eaten by pupils were well-balanced in relation to macronutrients.ConclusionsLunchtime food provision and consumption in secondary schools have improved considerably since 2004, following the introduction of new compulsory standards for school food in 2009. To maximise their energy and nutrient intake at lunchtime, pupils should be encouraged to select a full meal, and to take and eat more fruit and vegetables. Schools also need continued support to increase the micronutrient content of menus and recipes.

Short communicationKey differences between school lunches and packed lunches in primary schools in England in 2009.

Abstract: Objective: To compare the key differences between school lunches and packed lunches as consumed in a nationally representative sample of primary schools, 6–8 months after the nutrient-based standards for school lunch became mandatory. Design: Data on 6580 pupils’ school lunches and 3422 pupils’ packed lunches were collected between February and April 2009 from pupils attending primary schools in England. Fieldwork was conducted over five consecutive school days. Fieldworkers randomly selected ten pupils taking a school lunch and five pupils bringing a packed lunch each day at each school, and recorded and weighed all food and drink items consumed, as well as any leftovers. Setting: A nationally representative sample of 136 state-maintained primary schools in England. Subjects: A total of 10 002 pupils aged 4–12 years. Results: Mean intakes of protein, fat, saturated fat and vitamin C from both types of lunch met the nutrient-based standards. Pupils taking school lunches on average consumed significantly more protein, NSP, vitamin A, folate and Zn and less fat, saturated fat, non-milk extrinsic sugars (NMES), Na, Ca, vitamin C and Fe than pupils taking packed lunches. Energy intakes were low in both groups. Conclusions: Packed lunches were less likely to accord with food-based or nutrientbased standards than school lunches. Higher levels of Na, NMES, fat and percentage energy from saturated fat emphasise the difficulties associated with optimising nutrient intakes from packed lunches.

Children's lunchtime food choices following the introduction of food-based standards for school meals: observations from six primary schools in Sheffield.

Abstract: Objective To describe the lunchtime choices and nutritional intake of primary-school-aged children in England 4 months after the introduction of interim food-based standards for school lunches. Design Cross-sectional 2 d weighed food records collected in January and February 2007. Setting Six primary schools in Sheffield, England. Subjects One hundred and twenty-three pupils aged 8–10 years. Results Vegetables (81 % v . 8 %) and cakes and biscuits (43 % v . 23 %) were chosen more frequently by pupils consuming a school lunch, while fruit (40 % v . 36 %), meat products (18 % v . 14 %), confectionery (72 % v . 0 %), savoury snacks (69 % v . 0 %) and drinks not meeting the school food standards (40 % v . 0 %) were chosen more often by pupils eating a packed lunch. Mean energy intake was lower in the school lunch group compared with the packed lunch group (1402 ( sd 573) v . 2192 ( sd 619), P = 0·005). Nutrient density (per MJ energy) was significantly better in school meals for key nutrients including protein (9·8 ( sd 2·7) v . 6·3 ( sd 1·9) g), fat (7·4 ( sd 2·7) v . 10·6 ( sd 2·8) g), NSP (2·8 ( sd 1·3) v . 1·1 ( sd 0·4) g), vitamin A (151·3 ( sd 192·8) v . 69·1 ( sd 55·6) μg), folate (29·6 ( sd 11·6) v . 17·0 ( sd 7·0) μg), iron (1·3 ( sd 0·3) v . 0·9 ( sd 0·3) mg) and zinc (1·1 ( sd 0·4) v . 0·7 ( sd 0·3) mg). Conclusions Schools were largely compliant with the interim food-based standards for school meals 4 months after their introduction. Within the context of the new standards, children taking a school lunch are more likely to eat a more nutritious lunch, in terms of less high-fat/salt/sugar foods and nutrient density. The introduction of nutrient-based standards is warranted. Efforts to improve the lunchtime intake of children taking a packed lunch are also required.

Nutrient-based standards for school lunches complement food-based standards and improve pupils' nutrient intake profile.

Abstract: Following concerns about the nutritional content of school lunches and the increased prevalence of overweight and obesity in the UK, changes to the standards of school meals were made. From September 2008, all primary schools in England were required, by law, to be fully compliant with the new food-based standards (FBS) and nutrient-based standards (NBS) for school lunches. The aim of the present survey was to evaluate the introduction of the NBS for school lunches on the nutritional profile of food and drink items provided by schools and chosen by pupils at lunchtime. A nationally representative sample of 6696 pupils from 136 primary schools in England aged 3-12 years and having school lunches was recruited. Data were collected on lunchtime food and drink provision at each school and on pupil food and drink choices at lunchtime. Caterers also provided planned menus, recipes and other cooking information. Compliance with both the FBS and NBS was then assessed. Results show that even when the FBS was met, many schools did not provide a school lunch that met the NBS as well. The average school lunch eaten was significantly lower in fat, saturated fat and Na in schools that met both the FBS and NBS for school lunches compared with schools that met only the FBS. Change in school lunch policy has contributed to improvements in pupils' choices and the nutritional profile of foods selected at lunchtime.

Glycemic Index and Glycemic Load Used in Combination to Characterize Metabolic Responses of Mixed Meals in Healthy Lean Young Adults

Abstract: Background: Glycemic index (GI) and glycemic load (GL) have been independently assessed with regard to their metabolic effects and their associations with disease risk. Because a low-GI high-carbohydrate and a high-GI low-carbohydrate food/meal can produce the same GL, we propose that these 2 concepts should be used in conjunction to characterize the carbohydrate quality of mixed meals.Objective: The aim of this study was to measure postprandial glucose, insulin, and cortisol responses of meals differing in both GI and GL over a period of 3 hours (every 15 minutes for the first hour, and every 30 minutes subsequently), and to investigate the validity of methods of calculating GI and GL by measuring the cumulative incremental area under the curve (iAUC) for glucose and insulin (0–2 hours and 2–3 hours postprandially).Methods: A total of 10 healthy lean young adults (5 males, 5 females) participated. Breakfast meals were designed to differ in terms of GI and GL based on a 2 × 2 grid with a single elaboratio...

Rediscovering missing web pages using link neighborhood lexical signatures

Abstract: For discovering the new URI of a missing web page, lexical signatures, which consist of a small number of words chosen to represent the "aboutness" of a page, have been previously proposed. However, prior methods relied on computing the lexical signature before the page was lost, or using cached or archived versions of the page to calculate a lexical signature. We demonstrate a system of constructing a lexical signature for a page from its link neighborhood, that is the "backlinks", or pages that link to the missing page. After testing various methods, we show that one can construct a lexical signature for a missing web page using only ten backlink pages. Further, we show that only the first level of backlinks are useful in this effort. The text that the backlinks use to point to the missing page is used as input for the creation of a four-word lexical signature. That lexical signature is shown to successfully find the target URI in more than half of the test cases.

Music Video Redundancy and Half-Life in YouTube

Abstract: YouTube is the largest, most popular video digital library in existence, and is quite possibly the most popular digital library regardless of format type. Furthermore, music videos are one of the primary applications of YouTube. Based on our experiences of linking to music videos in YouTube, we observed that while any single URI had a short half-life, music videos were always available at another URI. For this study we collected 1291 music videos and found that very few had zero or one copies in YouTube at any given time, and some had several thousand copies at any given time. Furthermore, individual URIs had a half-life of anywhere from 9 to 18 months, depending on the publication date and remaining commercial potential.

Find, new, copy, web, page - tagging for the (re-)discovery of web pages

Abstract: The World Wide Web has a very dynamic character with resources constantly disappearing and (re-)surfacing. A ubiquitous result is the "404 Page not Found" error as the request for missing web pages. We investigate tags obtained from Delicious for the purpose of rediscovering such missing web pages with the help of search engines. We determine the best performing tag based query length, quantify the relevance of the results and compare tags to retrieval methods based on a page's content. We find that tags are only useful in addition to content based methods. We further introduce the notion of "ghost tags", terms used as tags that do not occur in the current but did occur in a previous version of the web page. One third of these ghost tags are ranked high in Delicious and also occurred frequently in the document which indicates their importance to both the user and the content of the document.

Using the web infrastructure for real time recovery of missing web pages

Abstract: Given the dynamic nature of the World Wide Web, missing web pages, or "404 Page not Found" responses, are part of our web browsing experience. It is our intuition that information on the web is rarely completely lost, it is just missing. In whole or in part, content often moves from one URI to another and hence it just needs to be (re-)discovered. We evaluate several methods for a "just-in-time" approach to web page preservation. We investigate the suitability of lexical signatures and web page titles to rediscover missing content. It is understood that web pages change over time which implies that the performance of these two methods depends on the age of the content. We therefore conduct a temporal study of the decay of lexical signatures and titles and estimate their half-life. We further propose the use of tags that users have created to annotate pages as well as the most salient terms derived from a page's link neighborhood. We utilize the Memento framework to discover previous versions of web pages and to execute the above methods. We provide a workflow including a set of parameters that is most promising for the (re-)discovery of missing web pages. We introduce Synchronicity, a web browser add-on that implements this workflow. It works while the user is browsing and detects the occurrence of 404 errors automatically. When activated by the user Synchronicity offers a total of six methods to either rediscover the missing page at its new URI or discover an alternative page that satisfies the user's information need. Synchronicity depends on user interaction which enables it to provide results in real time.

Connectivity Damage to a Graph by the Removal of an Edge or a Vertex

Abstract: The approach of quantifying the damage inflicted on a graph in Albert, Jeong and Barabasi's (AJB) report "Error and Attack Tolerance of Complex Networks" using the size of the largest connected compo- nent and the average size of the remaining components does not capture our intuitive idea of the damage to a graph caused by disconnections We evaluate an alternative metric based on average inverse path lengths (AIPLs) that better fits our intuition that a graph can still be reasonably functional even when it is disconnected We compare our metric with AJB's using a test set of graphs and report the differences AJB's report should not be confused with a report by Crucitti et al with the same name Based on our analysis of graphs of different sizes and types, and using various numerical and statistical tools; the ratio of the average inverse path lengths of a connected graph of the same size as the sum of the size of the fragments of the disconnected graph can be used as a metric about the damage of a graph by the removal of an edge or a node This damage is reported in the range (0,1) where 0 means that the removal had no effect on the graph's capability to perform its functions A 1 means that the graph is totally dysfunctional We exercise our metric on a collection of sample graphs that have been subjected to various attack profiles that focus on edge, node or degree betweenness values We believe that this metric can be used to quantify the damage done to the graph by an attacker, and that it can be used in evaluating the positive effect of adding additional edges to an existing graph

Synchronicity: automatically rediscover missing web pages in real time

Abstract: Missing web pages (pages that return the 404 "Page Not Found" error) are part of the browsing experience. The manual use of search engines to rediscover such pages can be frustrating and unsuccessful. We introduce Synchronicity, a Mozilla Firefox add-on that supports the Internet user in (re-)discovering missing web pages in real time.

An Evaluation of Link Neighborhood Lexical Signatures to Rediscover Missing Web Pages

Abstract: For discovering the new URI of a missing web page, lexical signatures, which consist of a small number of words chosen to represent the "aboutness" of a page, have been previously proposed. However, prior methods relied on computing the lexical signature before the page was lost, or using cached or archived versions of the page to calculate a lexical signature. We demonstrate a system of constructing a lexical signature for a page from its link neighborhood, that is the "backlinks", or pages that link to the missing page. After testing various methods, we show that one can construct a lexical signature for a missing web page using only ten backlink pages. Further, we show that only the first level of backlinks are useful in this effort. The text that the backlinks use to point to the missing page is used as input for the creation of a four-word lexical signature. That lexical signature is shown to successfully find the target URI in over half of the test cases.

Comparison between school lunches and packed lunches in secondary schools

Abstract: In order to improve the quality of food provided in secondary schools, food-based standards (FBS) and nutrient-based standards (NBS) were introduced in 2007 and 2009, respectively. The standards do not apply to packed lunches but schools are encouraged to have a packed lunch policy. Research in primary schools comparing the nutrient intakes of pupils who consume either a school lunch or a packed lunch has shown that, on average, pupils who consume a school lunch typically have a more favourable intake of key nutrients, to date no similar comparison has been carried out in secondary schools. In 2008, the School Food Trust studied the effect in secondary schools of improving school food and the meal experience on pupil’s postprandial behaviour in the classroom. Ethical approval was obtained from Kings College London Research Ethics Committee. Lunchtime food and drink choices of pupils consuming either a school lunch or a packed lunch were recorded at eleven secondary schools. Portion sizes were either weighed or estimated by weighing duplicate portions of foods provided at the schools. Leftovers were weighed to calculate the amount of each food eaten by each child. Baseline data from this study were used to compare mean energy and nutrient intakes from school lunches and packed lunches.

Persistent annotations deserve new URIs

Abstract: Some digital libraries support annotations, but sharing these annotations with other systems or across the web is difficult because of the need of special applications to read and decode these annotations. Due to the frequent change of web resources, the annotation's meaning can change if the underlying resources change. This project concentrates on minting a new URI for every annotation and creating a persistent and independent archived version of all resources. Users should be able to select a segment of an image or a video to be part of the annotation. The media fragment URIs described in the Open Annotation Collaboration data model can be used, but in practice they have limits, and they face the lack of support by the browsers. So in this project the segments of images, and videos can be used in the annotations without using media fragment URIs.