Inhibition of hydroxyapatite growth by osteopontin phosphopeptides

Biominerals often possess features such as size, shape and crystallinity that are distinct from their abiotically formed equivalents. Organisms are known to achieve this by regulating the crystal growth process. To understand the specific structural features of the phosphoprotein osteopontin (OPN) responsible for its inhibition of hydroxyapatite (HAP) growth, we used a constant-composition seeded-growth assay. In addition to testing the HAP growth-inhibiting effects of the highly phosphorylated bovine milk OPN and the nonphosphorylated rat recombinant OPN, we have also tested the effects of synthetic peptides corresponding to amino acids 220-235 (pSHEpSTEQSDAIDpSAEK) and amino acids 65-80 (pSHDHMDDDDDDDDDGD) of rat bone OPN. OPN220-235 was synthesized in triphosphorylated (P3) and nonphosphorylated (P0) forms; OPN65-80 was synthesized in monophosphorylated (P-OPAR) and nonphosphorylated (OPAR) forms. Also studied was poly-L-aspartic acid (poly-Asp) of 11 kDa. Highly acidic and phosphorylated peptides/proteins were observed to be the most potent inhibitors of HAP growth. The 50% inhibitory concentrations measured were: poly-Asp, 1.45 pg/ml; P- OPAR, 1.65 pg/ml; milk OPN, 1.94 pg/ml; P3, 2.03 pg/ml; OPAR, 2.47 pg/ml; recombinant OPN, 5.23 pg/ml; and P0, \u3e75 pg/ml. The thermodynamics of OPN and OPN-sequence-derived peptides adsorbing onto the surface of HAP was probed using isothermal titration calorimetry. At 37°C, adsorption of all strong inhibitors is characterized by an endothermic enthalpy that rapidly diminishes to zero when HAP surface coverage approached 10%. The free energy o f adsorption is dominated by large positive entropy change, likely resulting from the liberation of water molecules from the HAP surface. It appears that negative charge, whether contributed by phosphorylated or acidic residues, is a prerequisite for the entropically driven adsorption to and growth inhibition of HAP

The Relevance of Short Sales to the Maltese Stock Market

The paper discusses the possible effects of short sales on the operation of a very small stock market such as the Maltese one. After studying the basic mechanics of short selling procedures, the paper reviews the salient literature with particular reference to how short sales may enhance informational efficiency and their relationship with liquidity. The paper proceeds by examining these relationships in the context of the Maltese securities market. The study reveals that short sales may be desirable on the Maltese stock market for enhancing price efficiency and liquidity, yet a more formal framework for conducting such transactions is required. In addition, short positions may be particularly risky in the context of the Maltese stock market, due to low liquidity levels.Short Sales, Malta Stock Exchange, Liquidity

Overview of the blood transfusion policy in preterms on the Neonatal Intensive Care Unit

Preterm infants on the Neonatal Intensive Care Unit receive a greater number of red cell transfusions than any other hospitalised group. Over the past twenty years research has focused on setting standards to determine when it is necessary to transfuse packed cells in this cohort, whilst exploring the use of red cell growth factors and other substrates judiciously in order to reduce and/or avoid red cell transfusions and limit donor exposure. One hundred and eighty-one blood transfusions were administered to 106 preterms less than 35 weeks gestation on the NICU during 2009 in Malta. The median (range) volume of blood used from each bag supplied by the Blood Transfusion Department was 25.8mls (10-50mls), the rest of which was discarded. Risk factors for transfusion included Extremely Low Birth Weight (less than 1kg) and a gestation of less than 30 weeks. The blood transfusion guidelines presently in use on the local NICU were reviewed and compared with more restrictive guidelines on other units and suggestions made to reduce transfusions in line with these guidelines. A reduction in transfusion aliquots provided for neonates to just 50mls from the customary 250mls in a dedicated single-donor programme will safeguard limited health resources and minimise donor exposure.peer-reviewe

Do fantasy books lead to the occult? The challenge of Harry Potter and the Lord of the Rings

This article tries to show whether the fantastical and magical elements in literary fiction such as Harry Potter and Lord of the Rings might be a bad influence and an introduction to the occult for children and young adults. The authors conducted a study to find out whether young readers are able to distinguish between fact and fantasy.peer-reviewe

cwl_eval : An evaluation tool for information retrieval

We present a tool (“cwl_eval”) which unifies many metrics typically used to evaluate information retrieval systems using test collections. In the C/W/L framework metrics are specified via a single function which can be used to derive a number of related measurements: Expected Utility per item, Expected Total Utility, Expected Cost per item, Expected Total Cost, and Expected Depth. The C/W/L framework brings together several independent approaches for measuring the quality of a ranked list, and provides a coherent user model-based framework for developing measures based on utility (gain) and cost.Here we outline the C/W/L measurement framework; describe the cwl_eval architecture; and provide examples of how to use it. We provide implementations of a number of recent metrics, including Time Biased Gain, U-Measure, Bejewelled Measure, and the Information Foraging Based Measure, as well as previous metrics such as Precision, Average Precision, Discounted Cumulative Gain, Rank-Biased Precision, and INST. By providing state-of-the-art and traditional metrics within the same framework, we promote a standardised approach to evaluating search effectiveness

Building economic models and measures of search

Economics provides an intuitive and natural way to formally represent the costs and benefits of interacting with applications, interfaces and devices. By using economic models it is possible to reason about interaction, make predictions about how changes to the system will affect behavior, and measure the performance of people's interactions with the system. In this tutorial, we first provide an overview of relevant economic theories, before showing how they can be applied to formulate different ranking principles to provide the optimal ranking to users. This is followed by a session showing how economics can be used to model how people interact with search systems, and how to use these models to generate hypotheses about user behavior. The third session focuses on how economics has been used to underpin the measurement of information retrieval systems and applications using the C/W/L framework (which reports the expected utility, expected total utility, expected total cost, and so on) - and how different models of user interaction lead to different metrics. We then show how information foraging theory can be used to measure the performance of an information retrieval system - connecting the theory of how people search with how we measure it. The final session of the day will be spent building economic models and measures of search. Here sample problems will be provided to challenge participants, or participants can bring their own

Laryngeal lymphoma : the high and low grades of rare lymphoma involvement sites

The larynx is an extremely rare site of involvement by lymphomatous disease.We present two cases of isolated laryngeal high-grade and another low-grade lymphoma, together with a literature review of laryngeal lymphoma management.peer-reviewe

The Relevance of Short Sales to the Maltese Stock Market

This paper outlines the main concepts behind short selling activities and explores their relevance to a smaller stock market in the context of Maltese securities. While short sales have desirable properties, especially with respect to pricing efficiency, formal and informal restrictions may hinder this function. Short sale activity may be particularly risky in the context of the Maltese market, due to its low liquidity level. Short sales on their own may not be sufficient to enhance liquidity levels on this market

The Relevance of Short Sales to the Maltese Stock Market

This paper outlines the main concepts behind short selling activities and explores their relevance to a smaller stock market in the context of Maltese securities. While short sales have desirable properties, especially with respect to pricing efficiency, formal and informal restrictions may hinder this function. Short sale activity may be particularly risky in the context of the Maltese market, due to its low liquidity level. Short sales on their own may not be sufficient to enhance liquidity levels on this market

Measuring the utility of search engine result pages : an information foraging based measure

Web Search Engine Result Pages (SERPs) are complex responses to queries, containing many heterogeneous result elements (web results, advertisements, and specialised “answers”) positioned in a variety of layouts. This poses numerous challenges when trying to measure the quality of a SERP because standard measures were designed for homogeneous ranked lists. In this paper, we aim to measure the utility and cost of SERPs. To ground this work we adopt the C/W/L framework which enables a direct comparison between different measures in the same units of measurement, i.e. expected (total) utility and cost. Within this framework, we propose a new measure based on information foraging theory, which can account for the heterogeneity of elements, through different costs, and which naturally motivates the development of a user stopping model that adapts behaviour depending on the rate of gain. This directly connects models of how people search with how we measure search, providing a number of new dimensions in which to investigate and evaluate user behaviour and performance. We perform an analysis over 1000 popular queries issued to a major search engine, and report the aggregate utility experienced by users over time. Then in an comparison against common measures, we show that the proposed foraging based measure provides a more accurate reflection of the utility and of observed behaviours (stopping rank and time spent)