Optimization of Spatial Joins Using Filters

When viewing present-day technical applications that rely on the use of database systems, one notices that new techniques must be integrated in database management systems to be able to support these applications efficiently. This paper discusses one of these techniques in the context of supporting a Geographic Information System. It is known that the use of filters on geometric objects has a significant impact on the processing of 2-way spatial join queries. For this purpose, filters require approximations of objects. Queries can be optimized by filtering data not with just one but with several filters. Existing join methods are based on a combination of filters and a spatial index. The index is used to reduce the cost of the filter step and to minimize the cost of retrieving geometric objects from disk. In this paper we examine n-way spatial joins. Complex n-way spatial join queries require solving several 2-way joins of intermediate results. In this case, not only the profit gained from using both filters and spatial indices but also the additional cost due to using these techniques are examined. For 2-way joins of base relations these costs are considered part of physical database design. We focus on the criteria for mutually comparing filters and not on those for spatial indices. Important aspects of a multi-step filter-based n-way spatial join method are described together with performance experiments. The winning join method uses several filters with approximations that are constructed by rotating two parallel lines around the object

Nature and Grace in Bavinck

This paper is Dr. Al Wolters’ “translation of twenty pages from Dr. Jan Veenhof’s dissertation on Bavinck, titled Revelatie en Inspiratie.” Dr. Veenhof succeeded G. C. Berkouwer in the chair for dogmatic theology at the Free University in Amsterdam, then went on to teach at the universities of Basel and Bern and for one semester at Calvin Theological Seminary. As emeritus, he is still involved in theological and pastoral work

Implementing Dried Blood Spot sampling in transplant patient care

Dosing of immunossuppressive drugs used for transplant patients’ allograft rejection prevention is based on blood drug levels. This requires transplant patient to frequently provide a venous blood sample in the hospital. The Dried Blood Spot (DBS) method enables patient home sampling by means of collecting drops of fingerprick blood on a sampling card. This card can be sent to the laboratory by mail. From this DBS sample, blood drug levels can be measured. The purpose of the DBS method is to reduce patient burden and societal costs. In this thesis entitled ‘Implementing Dried Blood Spot sampling in transplant patient care’, a description is given how to successfully implement the DBS method. The analytical method should be fast, robust and meet all criteria of relevant guidelines. In addition, DBS-specific parameters should be validated. The DBS method should be tested in a clinical validation study where DBS results are compared to results from paired venous samples. In practice, providing a DBS sample is not easy. A checklist was developed which enables objective judgment of DBS sample quality. In addition, an app was developed enabling patients to determine the quality of a DBS by means of taking a photo of the sample. We found that the logistics concerning the sending and analysis of DBS samples are very critical to achieve a successful implementation. We also found that a novel home sampling technique involving fingerprick blood sampling on a volumetric tip was inferior to the DBS method regarding both sample quality and interchangeability with venous blood results

The Archives of Old Assyrian Traders: their Nature, Functions and Use

This contribution deals with the archives of Old Assyrian traders (originating from the city-state of Assur on the Tigris) from the first centuries of the second millennium BC, found in their houses in the lower town of the ancient Anatolian city of Kanesh, which is excavated since 1948 by Turkish archaeologists. The now more than 23.000 cuneiform tablets discovered there, belonging to at least 60 different merchants’ archives, constitute the most detailed and extensive written evidence on overland trade before the early Middle Ages. After providing general information on the traders, their business and their archives (kept in sealed “strong-rooms”), a more detailed analysis is preceded (§ 2) by distinguishing the various situations in which traders lived and worked in Kanesh – seniors or young men, with or without their family, some also with a house in another trading town in Anatolia - and the impact this had on their relations with their mother-city and on the nature and number of written records in their archives. In § 3 a brief sketch is given of the self-governing, corporate Assyrian merchant community, called “kārum Kanesh” (its location and archives have not yet been discovered), run by its main members. As an extension of the government of the city of Assur and head of the colonial network in Anatolia it played a vital role in performing administrative (it kept accounts, organized general accounting sessions and could impose rules), commercial (organizing collective operations and dealing with the local palace and ruler) and judicial tasks (as court of law), whose impact on the activities of the traders is reflected by their archives. In § 4 the three main categories into which the records may be distinguished are described: a large variety of letters, legal documents (contracts and judicial records) and memorandums, lists and short notes, whose functions the long § 5 analyzes. Three functions, which may overlap, are distinguished. Firstly (§ 5.1) as means of communication, mainly by letters, essential for the success of the caravan system and the contacts between people - relatives, business partners, authorities - in Assur and the colonies, notably with personnel and relatives traveling or temporarily settled elsewhere in Anatolia. Secondly (§ 5.2) as aid to memory, letters, testimonies, memorandums and lists, to keep track of the many, often complex and valuable transactions, especially investments and credit operations, to monitor due dates and dun defaulting debtors. And thirdly (§ 5.3) as evidence, especially “valid” records, that is those in sealed envelopes, both contracts and agreements and a variety of usually sworn depositions and testimonies, which resulted from and were used in private summonses, mediation, arbitration or formal lawsuits. The latter could take place in kārum Kanesh and in Assur, before the City Assembly, headed by the ruler of Assur, which resulted in verdicts and official letters. Credit operations in particular generated many evidentiary records, most of them in order to provide creditors with various securities and specific facilities, such as a “payment contract” (with a defaulting debtor) and a kind of “bearer’s cheques”. Paragraph 6 investigates the role of “copies” and “duplicates”, both of letters and “valid records”, made to serve multiple addressees of letters, to provide business partners and co-witnesses with essential data (e.g. to dun defaulting debtors and to prepare for lawsuits), and to keep evidence available when originals were sent overland. The final § 7 analyzes the various ways in which records were classified, by subject matter, persons involved, the nature of the texts (e.g. letters, debt-notes, and sealed or unsealed records), and stored in the archives. This was usually on shelves along the walls or in various types of frequently sealed containers (wooden boxes, baskets, leather bags and jars) or as sealed packets, whose contents could be identified by inscribed bullae that served as labels. Letters of absent traders who ask wives or friends to retrieve records from their archives and write about the transport of groups of tablets provide interesting information. Unfortunately the archaeological record about the discovery of the tablets usually is too general, because their exact find-spots and numbers are rarely mentioned, which makes it impossible to distinguish valid, current records, from old files, no longer in use and possibly stored in jars. The informative value of the bullae, often separated from the tablets to which they belonged and published separately, is also not exploited. The resulting picture, mainly based on the textual information, shows a rather practical way of classification in various types of easily distinguishable groups and files in different “containers”, but many details remain unclear

A Comparative Numerical Study on GEM, MHSP and MSGC

In this work, we have tried to develop a detailed understanding of the physical processes occurring in those variants of Micro Pattern Gas Detectors (MPGDs) that share micro hole and micro strip geometry, like GEM, MHSP and MSGC etc. Some of the important and fundamental characteristics of these detectors such as gain, transparency, efficiency and their operational dependence on different device parameters have been estimated following detailed numerical simulation of the detector dynamics. We have used a relatively new simulation framework developed especially for the MPGDs that combines packages such as GARFIELD, neBEM, MAGBOLTZ and HEED. The results compare closely with the available experimental data. This suggests the efficacy of the framework to model the intricacies of these micro-structured detectors in addition to providing insight into their inherent complex dynamical processes

Simulation of Three Dimensional Electrostatic Field Configuration in Wire Chambers : A Novel Approach

Three dimensional field configuration has been simulated for a simple wire chamber consisting of one anode wire stretched along the axis of a grounded square cathode tube by solving numerically the boundary integral equation of the first kind. A closed form expression of potential due to charge distributed over flat rectangular surface has been invoked in the solver using Green's function formalism leading to a nearly exact computation of electrostatic field. The solver has been employed to study the effect of several geometrical attributes such as the aspect ratio ($\lambda = \frac{l}{d}$, defined as the ratio of the length $l$ of the tube to its width $d$) and the wire modeling on the field configuration. Detailed calculation has revealed that the field values deviate from the analytic estimates significantly when the $\lambda$ is reduced to 2 or below. The solver has demonstrated the effect of wire modeling on the accuracy of the estimated near-field values in the amplification region. The thin wire results can be reproduced by the polygon model incorporating a modest number of surfaces ($\geq 32$) in the calculation with an accuracy of more than 99%. The smoothness in the three dimensional field calculation in comparison to fluctuations produced by other methods has been observed.Comment: Revised version submitted to Elsevier Science including some more near-field calculation

The Textiles traded by the Assyrians in Anatolia (19th-18th Centuries BC)

International audienceThe cuneiform private archives from Kaniš, dated to the beginning of the 2nd millennium B.C., belonged to Assyrian merchants who traded many textiles between their home city Aššur and central Anatolia. The numerous terms linked to textiles cited by these tablets have been extensively studied by K. Veenhof in 1972. Since then, thousands of texts have been published and deciphered, which have supplied so many new data that a new analysis is desirable. Of those exported to Anatolia, many were imported in Aššur, others were produced in Aššur or somewhere in northern Mesopotamia. In addition the Assyrian traded textiles which were produced in Anatolia. This implies that the textiles had different origins and that their names come from different languages. Most of them occur only in the Old Assyrian dialect and the overlap with the Old Babylonian vocabulary is limited.Archaeology has not produced any remains of textiles, which means that we have to try to identify them on the basis of the designations, their combinations and the context in which they occur, which most of the time is not helpful (enumerations, lists…). This means that the researcher is faced with at least three main tasks:1. Establish the origin of the textiles (Southern Mesopotamia, Aššur, Northern Mesopotamia, Anatolia) and their material2. Make a distinction between untailored textiles or ready-to-wear garments and understand their categorisation3. Analyse their nature and functions on the basis of the various qualifications (quality, price, size, weight, colour, finishing…