Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Vita. "Part I. Analytical applications of the hanging mercury drop electrode ... the text of a paper by J.W. Ross, Jr., R.D. DeMars, and Irving Shain which was published in Analytical Chemistry, 28, 1768 (1956)." eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

This paper is an attempt to appraise the usefulness of the dropping gallium electrode (DGE) in fused LiNO3-KNO3, to compare it with the dropping mercury electrode (DME), and to study the DGE in fused LiCl-KCl.

Thesis (Ph.D.)--Boston University / The most common polagraphic electrode in use at the present time is the dropping mercury electrode (DME). There are, however, certain well-recognized disadvantages attendant on the use of the DME: (1) oxidation analysis is limited to 0.4 v.; (2) there are rather large charging currents associated with the growing drop; (3) the area of the drops, and hence the sensitivity can not be appreciably increased; (4) because of drop growth, a a spiky sort of current is obtained which introduces a reading error into the results obtained, especially at low concentrations. It can be seen that these disadvantages are largely a function either of the electrode shape and size, or of the method of electrode propagation. [TRUNCATED]

Master of Arts / Department of Economics / William F. Blankenau / This paper describes the socioeconomic determinants of school dropout for Vietnamese children aged 11-18. It seeks to answer the following two questions: 1) What is the magnitude of the dropout rate for children between the ages of 11-18 and how does this figure change over time? 2) What are the determinants that affect the decision to drop out of school? This paper is based largely on the two Vietnam Living Standard Surveys (VLSS) conducted in 2004 and 2006. A probit model is used to ascertain the major determinants affecting the probability to drop out of school. The decision to drop out of school is affected by key factors including the child’s demographic characteristics (such as age, gender, ethnicity, and regions where they are living) and the child’s household’s situation (such as income per capita, cost of schooling, household size, and parental education). In particular, age and household size have significantly positive effects on the dropout probability. The dropout rate is also shown to vary between girls and boys, but this gender gap has narrowed substantially. Minority girls face more obstacles in staying school than minority boys. The school dropout rate is also very sensitive to changes in the household’s income and cost of schooling. However, the cost of schooling has different impacts on families in different quintiles. Region is another determinant affecting child’s decision to drop out of school. Vietnam’s population is unequally distributed in 8 regions with different socio-economic conditions, and hence the dropout situation is also regionally specific. Moreover, the parents’ perception of the value of education may increase the child’s probability of school retention. Since it is difficult to measure parental attitude to schooling, the paper uses parents’ education level instead, assuming that parents who have more education will appreciate education more.

With the increase of mobile and smart device usage, the interest in dynamically forming networks is rising. One such type of network isWireless Mesh Networks (WMNs). WMNs are multi-hop networks, with a decentralised nature that can dynamically form into mesh topologies. Network Coding (NC) is a method that is used to increase the efficiency of networks by encoding and decoding data on packet level by means of an XOR operation. NC works well with WMNs because it can exploit WMNs broadcast and opportunistic listening properties. When implementing NC on WMNs the issue of security has to be taken into consideration. Dong et al. identified various security threats for intra-flow NC in WMNs. Intra-flow NC combines packets within individual flows, where the information is divided into different flows called generations, to optimize the decoding process. They identified threats for each component of intra-flow NC for WMNs. These components include forwarding node selection, data packet forwarding and acknowledgement delivery. These threats respectively for each component are wormhole attacks and link quality falsification, packet pollution and packet dropping and acknowledgementdropping, injection and delay. We identified that most security schemes focus on packet pollution attacks in NC, but not on any other threats. Packet dropping is also a major threat in networks that is not addressed. Both packet pollution and packet dropping are threats identified for the data forwarding component of WMNs. The Delayed Authentication with Random Transformations (DART) security scheme addresses packet pollution in intra-flow NC systems. The scheme is based on time asymmetry and checksums. The DART scheme only addresses packet pollution and not any of the other identified threats. The DART scheme was selected to be enhanced to also address packet dropping. To enhance the DART scheme we added additional information to the DART scheme’s checksum packets to detect malicious packet dropping nodes in the network. The information added to the checksum packet took the form of a HealthMatrix, which indicates how many packets a node has received and verified. The new scheme, called the Packet Dropping Detection (PDD) scheme collects the additional information from the checksum packets at the receiver node. The receiver sends the collected information to the source node which then uses the information to identify the malicious nodes in the network. These nodes are then removed from the network. The results show that this new scheme causes a small decrease in throughput – about 2%. The identification of malicious nodes can be used as a diagnostic tool and faulty nodes can be repaired or removed form the network. The advantage to detect malicious packet dropping nodes far outweighs this decrease in throughput. In this dissertation we investigate the effects of packet pollution and packet dropping on NC networks inWMNs. We also enhance an already existing scheme (DART) to add additional packet dropping detection security to it without a great loss in throughput. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

With the increase of mobile and smart device usage, the interest in dynamically forming networks is rising. One such type of network isWireless Mesh Networks (WMNs). WMNs are multi-hop networks, with a decentralised nature that can dynamically form into mesh topologies. Network Coding (NC) is a method that is used to increase the efficiency of networks by encoding and decoding data on packet level by means of an XOR operation. NC works well with WMNs because it can exploit WMNs broadcast and opportunistic listening properties. When implementing NC on WMNs the issue of security has to be taken into consideration. Dong et al. identified various security threats for intra-flow NC in WMNs. Intra-flow NC combines packets within individual flows, where the information is divided into different flows called generations, to optimize the decoding process. They identified threats for each component of intra-flow NC for WMNs. These components include forwarding node selection, data packet forwarding and acknowledgement delivery. These threats respectively for each component are wormhole attacks and link quality falsification, packet pollution and packet dropping and acknowledgementdropping, injection and delay. We identified that most security schemes focus on packet pollution attacks in NC, but not on any other threats. Packet dropping is also a major threat in networks that is not addressed. Both packet pollution and packet dropping are threats identified for the data forwarding component of WMNs. The Delayed Authentication with Random Transformations (DART) security scheme addresses packet pollution in intra-flow NC systems. The scheme is based on time asymmetry and checksums. The DART scheme only addresses packet pollution and not any of the other identified threats. The DART scheme was selected to be enhanced to also address packet dropping. To enhance the DART scheme we added additional information to the DART scheme’s checksum packets to detect malicious packet dropping nodes in the network. The information added to the checksum packet took the form of a HealthMatrix, which indicates how many packets a node has received and verified. The new scheme, called the Packet Dropping Detection (PDD) scheme collects the additional information from the checksum packets at the receiver node. The receiver sends the collected information to the source node which then uses the information to identify the malicious nodes in the network. These nodes are then removed from the network. The results show that this new scheme causes a small decrease in throughput – about 2%. The identification of malicious nodes can be used as a diagnostic tool and faulty nodes can be repaired or removed form the network. The advantage to detect malicious packet dropping nodes far outweighs this decrease in throughput. In this dissertation we investigate the effects of packet pollution and packet dropping on NC networks inWMNs. We also enhance an already existing scheme (DART) to add additional packet dropping detection security to it without a great loss in throughput. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

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Syftet med vår studie är att genom fokusgruppsintervjuer belysa hur rektorer anser att de organiserar specialpedagogens uppdrag och hur denna organisering påverkar specialpedagogens funktion i skolan. Vi har valt att tillämpa ett organisationsteoretiskt perspektiv då vi menar att organiseringen av uppdraget är det som till största del påverkar arbetsuppgifterna. Särskilt fokus lägger vi på begreppen sensemaking och tool-dropping, vilka kort kan förklaras som att specialpedagogens funktion är meningsskapande för alla i verksamheten och hur verktyget specialpedagog kan och bör användas. Studien har relevans för det specialpedagogiska området då rektors kunskap om specialpedagogens kompetens har betydelse för vilka arbetsuppgifter specialpedagogen tilldelas. Vi har använt oss av en hermeneutisk ansats då vi tolkar rektorernas svar för att förstå hur de resonerar. Studiens empiriska material är insamlat med hjälp av fokusgruppsintervjuer. Resultatet visar att specialpedagogens uppdrag fortfarande är otydligt för såväl rektorer som för lärare, vilket påverkar både specialpedagogens mandat och arbetsuppgifter. Det framkommer också att i talet om specialpedagogens funktion i skolan är rektorerna överens och samstämmiga i vilka huvudsakliga arbetsuppgifter en specialpedagog ska ha, men att inte alla lyckas omvandla detta i praktiken. I diskussionen lyfter vi vikten av att rektorer skapar en genomarbetad och klart uttalad arbetsbeskrivning som är väl förankrad hos både specialpedagog och lärare, som ett led i att stärka och förtydliga specialpedagogens uppdrag på skolorna.

A primary challenge in wireless networks is to use available resources efficiently so that the Quality of Service (QoS) is satisfied while maximizing the throughput of the network. Among different resource allocation strategies, power and spectrum allocations have long been regarded as efficient tools to mitigate interference and improve the throughput of the network. Also, achieving a low transmission delay is an important QoS requirement in buffer-limited networks, particularly for users with real-time services. For these networks, too much delay results in dropping some packets. Therefore, the main challenge in networks with real-time services is to utilize an efficient power allocation scheme so that the delay is minimized while achieving a high throughput. This dissertation deals with these problems in distributed wireless networks.