198 research outputs found

    POINTING, ACQUISITION, AND TRACKING FOR DIRECTIONAL WIRELESS COMMUNICATIONS NETWORKS

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    Directional wireless communications networks (DWNs) are expected to become a workhorse of the military, as they provide great network capacity in hostile areas where omnidirectional RF systems can put their users in harm's way. These networks will also be able to adapt to new missions, change topologies, use different communications technologies, yet still reliably serve all their terminal users. DWNs also have the potential to greatly expand the capacity of civilian and commercial wireless communication. The inherently narrow beams present in these types of systems require a means of steering them, acquiring the links, and tracking to maintain connectivity. This area of technological challenges encompasses all the issues of pointing, acquisition, and tracking (PAT). iii The two main technologies for DWNs are Free-Space Optical (FSO) and millimeter wave RF (mmW). FSO offers tremendous bandwidths, long ranges, and uses existing fiber-based technologies. However, it suffers from severe turbulence effects when passing through long (>kms) atmospheric paths, and can be severely affected by obscuration. MmW systems do not suffer from atmospheric effects nearly as much, use much more sensitive coherent receivers, and have wider beam divergences allowing for easier pointing. They do, however, suffer from a lack of available small-sized power amplifiers, complicated RF infrastructure that must be steered with a platform, and the requirement that all acquisition and tracking be done with the data beam, as opposed to FSO which uses a beacon laser for acquisition and a fast steering mirror for tracking. This thesis analyzes the many considerations required for designing and implementing a FSO PAT system, and extends this work to the rapidly expanding area of mmW DWN systems. Different types of beam acquisition methods are simulated and tested, and the tradeoffs between various design specifications are analyzed and simulated to give insight into how to best implement a transceiver platform. An experimental test-bed of six FSO platforms is also designed and constructed to test some of these concepts, along with the implementation of a three-node biconnected network. Finally, experiments have been conducted to assess the performance of fixed infrastructure routing hardware when operating with a physically reconfigurable RF network

    Knowledge visualizations: a tool to achieve optimized operational decision making and data integration

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    The overabundance of data created by modern information systems (IS) has led to a breakdown in cognitive decision-making. Without authoritative source data, commanders’ decision-making processes are hindered as they attempt to paint an accurate shared operational picture (SOP). Further impeding the decision-making process is the lack of proper interface interaction to provide a visualization that aids in the extraction of the most relevant and accurate data. Utilizing the DSS to present visualizations based on OLAP cube integrated data allow decision-makers to rapidly glean information and build their situation awareness (SA). This yields a competitive advantage to the organization while in garrison or in combat. Additionally, OLAP cube data integration enables analysis to be performed on an organization’s data-flows. This analysis is used to identify the critical path of data throughout the organization. Linking a decision-maker to the authoritative data along this critical path eliminates the many decision layers in a hierarchal command structure that can introduce latency or error into the decision-making process. Furthermore, the organization has an integrated SOP from which to rapidly build SA, and make effective and efficient decisions.http://archive.org/details/knowledgevisuali1094545877Outstanding ThesisOutstanding ThesisMajor, United States Marine CorpsCaptain, United States Marine CorpsApproved for public release; distribution is unlimited

    Design and Application of Pan and Tilt Servo Gimbals in Pointing, Acquisition, and Tracking

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    Directional wireless communications systems are fast becoming an essential part of the world's broadband network infrastructure. When using these types of transceivers in reconfigurable networks, it becomes necessary to point them rapidly and accurately to different locations, or even to targets that may be in motion. The most efficient way of doing this is through the use of two-axis pan and tilt motion stages, also known as gimbals. This paper presents the motivation for, design and construction of, and testing of a pair of multipurpose servo gimbals, usable for both RF and laser transceivers. The gimbals are tested in terms of pointing error, movement speed, and response time. For the network portion, relink times as a function of angular rotation are examined, as well as the angular offset vs. data rate. The gimbal is also tested as part of a remote surveillance network, evaluating its ability to track moving objects

    Transformation Of Arabidopsis Thaliana For Tandem Affinity Purification Of Chloroplast Proteins

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    Matrix attachment region-binding filament-like protein 1 (MFP1) is part of a chloroplast protein complex that interacts with the thylakoid membrane and chloroplast DNA. The proteins in this complex need to be identified in order to determine the complex’s function. Mechanisms such as tandem affinity purification can be used to identify the proteins that interact with MFP1. The purpose of this project is to use Agrobacterium tumefaciens to transform an MFP1-TAP expression construct into MFP1-knockout mutant Arabidopsis thaliana plants via floral dipping. The genotype of the mutants was confirmed via polymerase chain reactions (PCR). The success of the transformation was also confirmed via PCR. The goal of this project is to generate MFP1-TAP plants to purify protein complexes and identify the proteins that interact with MFP

    A new method for determining of extensions and restrictions of information systems.

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    Abstract. The aim of the paper is presentation of some results that concern consistent extensions and consistent restrictions of information systems and decision systems. It is possible to determine them on the base of knowledge contained in rules generated from a given information (decision) system. The paper presents a way of consistent extensions and consistent restrictions determining, different from the one mentioned above. The paper contains also the definitions of notions of strict consistent extension (restriction) system and a necessary and sufficient condition for the existence of them for information (decision) system

    Using Student Ambassadors to Relay Themes from Changing the Conversation in Engineering First Year Seminars

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    This paper describes the efforts at a large mid-Atlantic university to integrate themes from Changing the Conversation into First Year Seminars. Changing the Conversation, a 2008 book by the National Academy of Engineering, found that both male and female students were more attracted to messages describing engineering in terms relating to societal impact, such as the phrases, Engineering makes a world of difference and Engineering is essential to our health, happiness, and safety. Although the research was conducted with younger students, the potential for using these themes in the undergraduate curricula could have the potential to impact persistence in engineering, especially for female students or those from other underrepresented groups. The purpose of the initiative described in the paper, which uses engineering students from a group called the Engineering Ambassadors to relay these messages in freshmen level courses, is to impact student perceptions of engineering and to provide information to students that will be critical in making career decisions. In the Fall of 2011, a pilot program was launched in two sections of a Chemical Engineering First Year Seminar. Engineering Ambassadors made four separate visits to each section, focusing on the following topics: 1) An overview of College of Engineering Majors, 2) Options within Chemical Engineering, 3) Student experiences in the College of Engineering, and 4) How to be a successful engineering student. Woven through each presentation were themes from Changing the Conversation, focusing on how engineers are essential to health, happiness and safety. The students were mentored by a faculty member whose background is in Communication. The quality of student presentations was high, utilizing the assertion-evidence method of slide design. Data was collected to determine whether the following project objectives were met: 1) Students in the First Year Seminars will have a greater understanding of the possible careers in engineering as well as the engineering majors; and 2) Students will be more likely to define engineering in terms associated with health, happiness, and safety. The data showed that the students had a very positive reaction to the Engineering Ambassador visits, although a larger sample size would be necessary to more clearly understand the impact

    Sexual dimorphism in socioeconomic differences regarding the risk factors, symptomatology and management of patients with stable coronary artery disease in Poland

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    Background: Relationships between socioeconomic status (SES) and the risk factors, applied treatment and outcomes of patients with coronary artery disease (CAD) have been demonstrated in Western European countries, however analogous evidence is missing from Eastern and Central European countries. The aim of the study was to investigate SES gradients regarding the risk factors, symptoms and management of patients with stable CAD in Poland, separately in men and women. Methods: We analyzed the data of 2,593 participants of the RECENT study. SES was assessed based on the level of education attainment: university, secondary school or primary school. Results: Socioeconomic differences in risk profile were most markedly seen in women: lower the education, higher body mass index (p < 0.01), systolic and diastolic blood pressure (p < 0.05), resting heart rate (p < 0.01), and greater prevalence of heart failure (p < 0.05) and dyslipidemia (p < 0.05). Importantly, smoking habit was the most frequent in women who graduated from univer­sity (p < 0.01). In men, socioeconomic gradients were only seen within resting heart rate (p < 0.01), LDL cholesterol level (p < 0.05) and smoking habit (p < 0.05). In both genders, better education was associated with less severe symptoms of angina and more frequent use of statins (p < 0.05). Conclusions: SES stratified based on education level differentiates patients with stable CAD in Poland regarding their risk profile, symptom control and the use of statins. Sexual dimorphism is found mainly within SES gradients regarding the prevalence of risk factors

    BRAF<sup>V600E</sup>-mutated serrated colorectal neoplasia drives transcriptional activation of cholesterol metabolism

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    Abstract BRAF mutations occur early in serrated colorectal cancers, but their long-term influence on tissue homeostasis is poorly characterized. We investigated the impact of short-term (3 days) and long-term (6 months) expression of Braf V600E in the intestinal tissue of an inducible mouse model. We show that Braf V600E perturbs the homeostasis of intestinal epithelial cells, with impaired differentiation of enterocytes emerging after prolonged expression of the oncogene. Moreover, Braf V600E leads to a persistent transcriptional reprogramming with enrichment of numerous gene signatures indicative of proliferation and tumorigenesis, and signatures suggestive of metabolic rewiring. We focused on the top-ranking cholesterol biosynthesis signature and confirmed its increased expression in human serrated lesions. Functionally, the cholesterol lowering drug atorvastatin prevents the establishment of intestinal crypt hyperplasia in Braf V600E -mutant mice. Overall, our work unveils the long-term impact of Braf V600E expression in intestinal tissue and suggests that colorectal cancers with mutations in BRAF might be prevented by statins

    The distribution of proenkephalin-derived peptides in the central nervous system of turtles

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    The present study was carried out to examine if peptides similar to the various opioid peptide products of mammalian proenkephalin are present in the turtle central nervous system and to determine their distribution. Antisera against several enkephalin peptides were used: (1) leucine-enkephalin (LENK), (2) methionine-enkephalin (MENK), (3) methionine-enkephalin-arg 6 -phe 7 (MERF), (4) methionine-enkephalin-arg 6 -gly 7 -leu 8 (MERGL), (5) Peptide E (PEPE), and (6) BAM22P. Their specificity and cross-reactivity were carefully examined. The results indicated that LENK, MENK, and MERF (or highly similar peptides) are present in the turtle central nervous system, and that a peptide showing immunological similarity to BAM22P and PEPE also appeared to be present. In contrast, MERGL did not appear to be present. The distributions of the immunoreactive labeling for LENK, MENK, MERF, BAM22P, and PEPE were indistinguishable, and double-label studies showed that LENK, MERF, and BAM22P were colocalized within individual neurons and fibers. Although all of the above substances were observed in the same cell groups, there was some regional variation, in terms of which enkephalin peptide appeared to be most abundant. The distributions of these enkephalin peptides were very similar to those previously described in mammals and birds. Enkephalin was more abundant in the basal ganglia than in overlying telencephalic regions. Within the basal ganglia, enkephalin was present in striatal neurons and fibers and in pallidal fibers, thereby suggesting the existence of an enkephalinergic striatopallidal projection. Sensory relay nuclei of the thalamus were generally poor in enkephalinergic fibers, whereas the hypothalamus was rich in enkephalinergic neurons and fibers. Enkephalinergic neurons and fibers were present in the midbrain central gray. As is true of neurons of the nucleus spiriformis lateralis of the avian pretectum, the neurons of the homologous cell group in turtles, the dorsal nucleus of the posterior commissure of the pretectum, were found to contain enkephalin and have an enkephalinergic projection to the deep layers of the ipsilateral tectum. Enkephalinergic neurons and fibers were also abundant in the entry zones of the trigeminal nerve and dorsal root fibers of the spinal cord. The present results indicate that: (1) consistent with previously published biochemical studies (Lindberg and White, '86), proenkephalin in reptiles is similar in structure to that of mammals and, with the exception of MERGL, gives rise to similar or identical enkephalin peptides, and (2) the enkephalin peptides are found in many of the same systems of reptilian brain as mammalian and avian brain, and, therefore, may play a role in similar functions (e.g., basal ganglia motor functions) as in mammals and birds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50034/1/902590106_ftp.pd
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