984 resultados para De Witt, Simeon, 1756-1834.


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Recent years have witnessed a rapid growth in the demand for streaming video over the Internet, exposing challenges in coping with heterogeneous device capabilities and varying network throughput. When we couple this rise in streaming with the growing number of portable devices (smart phones, tablets, laptops) we see an ever-increasing demand for high-definition videos online while on the move. Wireless networks are inherently characterised by restricted shared bandwidth and relatively high error loss rates, thus presenting a challenge for the efficient delivery of high quality video. Additionally, mobile devices can support/demand a range of video resolutions and qualities. This demand for mobile streaming highlights the need for adaptive video streaming schemes that can adjust to available bandwidth and heterogeneity, and can provide us with graceful changes in video quality, all while respecting our viewing satisfaction. In this context the use of well-known scalable media streaming techniques, commonly known as scalable coding, is an attractive solution and the focus of this thesis. In this thesis we investigate the transmission of existing scalable video models over a lossy network and determine how the variation in viewable quality is affected by packet loss. This work focuses on leveraging the benefits of scalable media, while reducing the effects of data loss on achievable video quality. The overall approach is focused on the strategic packetisation of the underlying scalable video and how to best utilise error resiliency to maximise viewable quality. In particular, we examine the manner in which scalable video is packetised for transmission over lossy networks and propose new techniques that reduce the impact of packet loss on scalable video by selectively choosing how to packetise the data and which data to transmit. We also exploit redundancy techniques, such as error resiliency, to enhance the stream quality by ensuring a smooth play-out with fewer changes in achievable video quality. The contributions of this thesis are in the creation of new segmentation and encapsulation techniques which increase the viewable quality of existing scalable models by fragmenting and re-allocating the video sub-streams based on user requirements, available bandwidth and variations in loss rates. We offer new packetisation techniques which reduce the effects of packet loss on viewable quality by leveraging the increase in the number of frames per group of pictures (GOP) and by providing equality of data in every packet transmitted per GOP. These provide novel mechanisms for packetizing and error resiliency, as well as providing new applications for existing techniques such as Interleaving and Priority Encoded Transmission. We also introduce three new scalable coding models, which offer a balance between transmission cost and the consistency of viewable quality.

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Platinum therapeutic agents are widely used in the treatment of several forms of cancer. Various mechanisms for the transport of the drugs have been proposed including passive diffusion across the cellular membrane and active transport via proteins. The copper transport protein Ctr1 is responsible for high affinity copper uptake but has also been implicated in the transport of cisplatin into cells. Human hCtr1 contains two methionine-rich Mets motifs on its extracellular N-terminus that are potential platinum-binding sites: the first one encompasses residues 7-14 with amino acid sequence Met-Gly-Met-Ser-Tyr-Met-Asp-Ser and the second one spans residues 39-46 with sequence Met-Met-Met-Met-Pro-Met-Thr-Phe. In these studies, we use liquid chromatography and mass spectrometry to compare the binding interactions between cisplatin, carboplatin and oxaliplatin with synthetic peptides corresponding to hCtr1 Mets motifs. The interactions of cisplatin and carboplatin with Met-rich motifs that contain three or more methionines result in removal of the carrier ligands of both platinum complexes. In contrast, oxaliplatin retains its cyclohexyldiamine ligand upon platinum coordination to the peptide.

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BACKGROUND: In newly diagnosed patients with Hodgkin lymphoma (HL) the effect of doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD)-related neutropenia on chemotherapy delivery is poorly documented. The aim of this analysis was to assess the impact of chemotherapy-induced neutropenia (CIN) on ABVD chemotherapy delivery in HL patients. STUDY DESIGN: Data from two similarly designed, prospective, observational studies conducted in the US and the EU were analysed. One hundred and fifteen HL patients who started a new course of ABVD during 2002-2005 were included. The primary objective was to document the effect of neutropenic complications on delivery of ABVD chemotherapy in HL patients. Secondary objectives were to investigate the incidence of CIN and febrile neutropenia (FN) and to compare US and EU practice with ABVD therapy in HL. Pooled data were analysed to explore univariate associations with neutropenic events. RESULTS: Chemotherapy delivery was suboptimal (with a relative dose intensity < or = 85%) in 18-22% of patients. The incidence of grade 4 CIN in cycles 1-4 was lower in US patients (US 24% vs. EU 32%). Patients in both the US and the EU experienced similar rates of FN across cycles 1-4 (US 12% vs. EU 11%). Use of primary colony-stimulating factor (CSF) prophylaxis and of any CSF was more common in the US than the EU (37% vs. 4% and 78% vs. 38%, respectively). The relative risk (RR) of dose delays was 1.54 (95% confidence interval [CI] 1.08-2.23, p = 0.036) for patients with vs. without grade 4 CIN and the RR of grade 4 CIN was 0.35 (95% CI 0.12-1.06, p = 0.046) for patients with vs. without primary CSF prophylaxis. CONCLUSIONS: In this population of HL patients, CIN was frequent and FN occurrence clinically relevant. Chemotherapy delivery was suboptimal. CSF prophylaxis appeared to reduce CIN rates.

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Medical journals and other sources do not show evidence that cholera occurred in Haiti before 2010, despite the devastating effect of this disease in the Caribbean region in the 19th century. Cholera occurred in Cuba in 1833-1834; in Jamaica, Cuba, Puerto Rico, St. Thomas, St. Lucia, St. Kitts, Nevis, Trinidad, the Bahamas, St. Vincent, Granada, Anguilla, St. John, Tortola, the Turks and Caicos, the Grenadines (Carriacou and Petite Martinique), and possibly Antigua in 1850-1856; and in Guadeloupe, Cuba, St. Thomas, the Dominican Republic, Dominica, Martinique, and Marie Galante in 1865-1872. Conditions associated with slavery and colonial military control were absent in independent Haiti. Clustered populations, regular influx of new persons, and close quarters of barracks living contributed to spread of cholera in other Caribbean locations. We provide historical accounts of the presence and spread of cholera epidemics in Caribbean islands.

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OBJECTIVES: To assess the performance of WHO's "Guidelines for care at the first-referral level in developing countries" in an area of intense malaria transmission and identify bacterial infections in children with and without malaria. DESIGN: Prospective study. SETTING: District hospital in Muheza, northeast Tanzania. PARTICIPANTS: Children aged 2 months to 13 years admitted to hospital for febrile illness. MAIN OUTCOME MEASURES: Sensitivity and specificity of WHO guidelines in diagnosing invasive bacterial disease; susceptibility of isolated organisms to recommended antimicrobials. RESULTS: Over one year, 3639 children were enrolled and 184 (5.1%) died; 2195 (60.3%) were blood slide positive for Plasmodium falciparum, 341 (9.4%) had invasive bacterial disease, and 142 (3.9%) were seropositive for HIV. The prevalence of invasive bacterial disease was lower in slide positive children (100/2195, 4.6%) than in slide negative children (241/1444, 16.7%). Non-typhi Salmonella was the most frequently isolated organism (52/100 (52%) of organisms in slide positive children and 108/241 (45%) in slide negative children). Mortality among children with invasive bacterial disease was significantly higher (58/341, 17%) than in children without invasive bacterial disease (126/3298, 3.8%) (P<0.001), and this was true regardless of the presence of P falciparum parasitaemia. The sensitivity and specificity of WHO criteria in identifying invasive bacterial disease in slide positive children were 60.0% (95% confidence interval 58.0% to 62.1%) and 53.5% (51.4% to 55.6%), compared with 70.5% (68.2% to 72.9%) and 48.1% (45.6% to 50.7%) in slide negative children. In children with WHO criteria for invasive bacterial disease, only 99/211(47%) of isolated organisms were susceptible to the first recommended antimicrobial agent. CONCLUSIONS: In an area exposed to high transmission of malaria, current WHO guidelines failed to identify almost a third of children with invasive bacterial disease, and more than half of the organisms isolated were not susceptible to currently recommended antimicrobials. Improved diagnosis and treatment of invasive bacterial disease are needed to reduce childhood mortality.

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The extinction of the giant tortoises of the Seychelles Archipelago has long been suspected but is not beyond doubt. A recent morphological study of the giant tortoises of the western Indian Ocean concluded that specimens of two native Seychelles species survive in captivity today alongside giant tortoises of Aldabra, which are numerous in zoos as well as in the wild. This claim has been controversial because some of the morphological characters used to identify these species, several measures of carapace morphology, are reputed to be quite sensitive to captive conditions. Nonetheless, the potential survival of giant tortoise species previously thought extinct presents an exciting scenario for conservation. We used mitochondrial DNA sequences and nuclear microsatellites to examine the validity of the rediscovered species of Seychelles giant tortoises. Our results indicate that the morphotypes suspected to represent Seychelles species do not show levels of variation and genetic structuring consistent with long periods of reproductive isolation. We found no variation in the mitochondrial control region among 55 individuals examined and no genetic structuring in eight microsatellite loci, pointing to the survival of just a single lineage of Indian Ocean tortoises.

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At the end of the sixteenth century, Germany had become one of the most active centers of early Baroque music, and therefore Austro-German music came to dominate Western music. An investigation of violin works written during this period reveals the ways in which Austro-German compositions are extraordinary contributions to the violin repertoire. This research warranted further study and performance of these works in order to determine what influence these composers had on the violin repertoire as a whole. For my dissertation recital project, I trace the history of works for violin focusing the violin concerto repertoire in particular. A genre which remained popular throughout the century, the nineteenth-century concerto served primarily as a vehicle for virtuosic display of the violin and piano as never before. For my research I studied and performed works selected from the Baroque through the Romantic period in three recorded recitals with collaborative pianists Ilya Sinaisky, Sun-ha Yun, and Seyon Lee at the Gildenhorn Recital Hall, Clarice Smith Performing Arts Center. I selected particularly prominent pieces which represent the work of significant composers from each period. The composers discussed include Johann Sebastian Bach (1685-1750), owing to the fact that his works are the culmination of the Baroque era during the first half of the eighteenth century; from the Classical period, Wolfgang Amadeus Mozart (1756-1791) all of whom emerged mixing German and Italian traditions into his own style, and Ludwig van Beethoven (1770-1827), the bridge composer between the Classical and the Romantic periods; Romantic composers, Franz Schubert (1979-1828), Johannes Brahms (1833-1897), Robert Schumann (1810-1856), Felix Mendelssohn (1809-1847), and Max Bruch (1838-1920), all who tended to mix Classic and Romantic elements. As a violinist, I learned that their own original sound, rich harmonies and unique expression made these works worthy of becoming masterpieces. I have relished the opportunity for musical and professional growth in exploring these substantial compositions.

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BACKGROUND: Dislocation remains a difficult problem in total hip arthroplasty. Large-diameter femoral heads may lower the incidence of dislocation by enhancing the jump distance and decreasing impingement, but their performance against small-diameter heads has not been assessed. This study compared the mid-term radiographic and functional outcomes of two matched cohorts of patients undergoing total hip arthroplasty who had a high pre-operative risk for dislocation and who received either small-diameter (26- or 28-millimeters) or large-diameter (≥36-millimeters) femoral heads. METHODS: All patients who received large-diameter heads (≥36-millimeter) between 2002 and 2005, and who had pre-operative risk factors for dislocation, were identified in the institution's joint registry. Forty-one patients (52 hips) who received large-diameter heads were identified, and these patients were matched to 48 patients (52 hips) in the registry who received small-diameter femoral heads. RESULTS: At mean final follow-up of 62 months (range, 49 to 101 months), both groups achieved excellent functional outcomes as measured by Harris Hip scores, with slightly better final scores in the large-diameter group (90 vs. 83 points). No patient showed any radiographic signs of loosening. No patient dislocated in the large-diameter femoral head group; the smaller-diameter group had a greater rate of dislocation (3.8%, 2 out of 52). CONCLUSIONS: Large-diameter femoral head articulations may reduce dislocation rates in patients who have a high pre-operative risk for dislocation while providing the same functional improvements and safety as small-diameter bearings.

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When performing in opera, a singer portrays a character. A libretto is used as the principal resource for the research. Music can also reveal insights into the composer’s ideas regarding characterization. This performance dissertation examines how musical devices such as genre, texture, meter, melody, instrumentation and form can be used to inform choices of characterization. Three roles from diverse operas were examined and performed. The first role, Estelle Oglethorpe in Later the Same Evening (2007) by John Musto (b 1954) was performed November 15, 16, 17, 18 2007. The second role, Dorabella in Così fan tutte (1789) by Wolfgang Amadeus Mozart (1756-1791) was performed April 20, 25, 27, 2008. The third role, Olga in Eugene Onegin (1878) by Pyotr Ilyich Tchaikovsky (1840-1893) was performed on April 19, 2009. All operas were presented by the University of Maryland Opera Studio at the Ina and Jack Kay Theater in the Clarice Smith Performing Arts Center, University of Maryland College Park. DVD recordings of all performances can be found in the University of Maryland library system.

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Variation, or the re-working of existing musical material, has consistently attracted the attention of composers and performers throughout the history of Western music. In three recorded recitals at the University of Maryland School of Music, this dissertation project explores a diverse range of expressive possibilities for violin in seven types of variation form in Austro-German works for violin from the 17th through the 20th centuries. The first program, consisting of Baroque Period works, performed on period instrument, includes the divisions on “John come kiss me now” from The Division Violin by Thomas Baltzar (1631 – 1663), constant bass variations in Sonate Unarum Fidium by Johann Heinrich von Schmelzer (1623 – 1680), arbitrary variation in Sonata for Violin and Continuo in E Major, Op. 1, No. 12 “Roger” by George Friedrich Händel (1685 – 1759), and French Double style, melodic-outline variation in Partita for Unaccompanied Violin in B Minor by Johan Sebastian Bach (1685 – 1750). Theme and Variations, a popular Classical Period format, is represented by the Sonata for Piano and Violin in G Major K. 379 by Wolfgang Amadeus Mozart (1756 – 1791) and Sonata for Violin and Piano in A Major, Op. 47 No. 9 the “Kreutzer” by Ludwig van Beethoven (1770 – 1827). Fantasy for Piano and Violin in C Major D. 934 by Franz Schubert (1797 – 1828) represents the 19th century fantasia variation. In these pieces, the piano and violin parts are densely interwoven, having equal importance. Many 20th century composers incorporated diverse types of variations in their works and are represented in the third recital program comprising: serial variation in the Phantasy for Violin and Piano Op.47 of Arnold Schoenberg (1874 – 1951); a strict form of melodic-outline variation in Sonate für Violine allein, Op. 31, No. 2 of Paul Hindemith (1895 – 1963); ostinato variation in Johan Halvorsen’s (1864 – 1935) Passacaglia for Violin and Viola, after G. F. Handel’s Passacaglia from the Harpsichord Suite No. 7 in G Minor. Pianist Audrey Andrist, harpsichordist Sooyoung Jung, and violist Dong-Wook Kim assisted in these performances.

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The Fantasy, as the term suggests, is a genre that composers have found congenial for exploring innovative and imaginative processes. Works in this genre are numerous in the solo piano literature, and extend even to works for piano and orchestra and to chamber music with piano. I was curious to explore how a specific genre of music maintained similar characteristics but evolved over time. A fantasy is primed to be inventive and I wanted to see how composers from different eras and backgrounds would handle their material in this genre. I have learned that composers worked through formal developments while making innovations within this genre. The heart of my dissertation is presented through the recording project. Because ofthe abundance ofpiano fantasies, many works had to be excluded from this project for time's sake. On two compact discs, I have recorded approximately two hours of solo piano music. I have included some shorter fantasies to magnify significant developments from era to era, country to country, and composer to composer. The first disc has recordings of eighteenth and nineteenth-century fantasies: Chromatic Fantasy and Fugue, BWV 903 by J.S. Bach (1685-1750); Fantasia inC major, H. XVII, 4 by Franz Joseph Haydn (1732-1809); Fantasy inc minor, K. 475 by Wolfgang Amadeus Mozart (1756- 1791); Fantasia inf-sharp minor, Op. 28 by Felix Mendelssohn (1809-1847); and Polonaise-Fantaisie in A-flat major, Op. 61 by Frederic Chopin (1810-1849). On the second disc I have included mid-19th, 20th and 2151-century piano fantasies: Fantasy and Fugue on the Theme B-A-C-H by Franz Liszt (1811-1886); Fantasia Baetica by Manuel de Falla (1876-1946); Three Fantasies by William Bergsma (1921-1994); Fantasy, Aria and Fugue by Frederic Goossen (1927-2011); and Piano Fantasy ("Wenn ich einmal sol! scheiden") by Richard Danielpour (b. 1956). The accompanying document includes program notes for each of the pieces recorded. They were recorded on a Steinway "D" in Dekelboum Concert Hall at the University of Maryland by Antonino D'Urzo ofOpusrite Productions. This document is available in the Digital Repository at the University of Maryland and the CO's are available through the Library System at the University of Maryland.

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BACKGROUND: Small molecule inhibitors of histone deacetylases (HDACi) hold promise as anticancer agents for particular malignancies. However, clinical use is often confounded by toxicity, perhaps due to indiscriminate hyperacetylation of cellular proteins. Therefore, elucidating the mechanisms by which HDACi trigger differentiation, cell cycle arrest, or apoptosis of cancer cells could inform development of more targeted therapies. We used the myelogenous leukemia line K562 as a model of HDACi-induced differentiation to investigate chromatin accessibility (DNase-seq) and expression (RNA-seq) changes associated with this process. RESULTS: We identified several thousand specific regulatory elements [~10 % of total DNase I-hypersensitive (DHS) sites] that become significantly more or less accessible with sodium butyrate or suberanilohydroxamic acid treatment. Most of the differential DHS sites display hallmarks of enhancers, including being enriched for non-promoter regions, associating with nearby gene expression changes, and increasing luciferase reporter expression in K562 cells. Differential DHS sites were enriched for key hematopoietic lineage transcription factor motifs, including SPI1 (PU.1), a known pioneer factor. We found PU.1 increases binding at opened DHS sites with HDACi treatment by ChIP-seq, but PU.1 knockdown by shRNA fails to block the chromatin accessibility and expression changes. A machine-learning approach indicates H3K27me3 initially marks PU.1-bound sites that open with HDACi treatment, suggesting these sites are epigenetically poised. CONCLUSIONS: We find HDACi treatment of K562 cells results in site-specific chromatin remodeling at epigenetically poised regulatory elements. PU.1 shows evidence of a pioneer role in this process by marking poised enhancers but is not required for transcriptional activation.

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El trabajo trata de mostrar los logros en el aprendizaje de la matemática –área de Geometría– a través del contenido transversal Educación para la gestión de riesgos y la conciencia ambiental, usando recursos tecnológicos como Google Maps y Google Earth. El tema desarrollado para tal fin fue el problema sismológico en el Perú. Finalmente, se señalan temas de geometría involucrados, así como temas anexos a través del uso de contenidos de Estadística, Geografía y Ciencias Naturales. La experiencia se hizo con un grupo de 50 alumnas del Tercer año de Educación Secundaria de una escuela pública del Perú.

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Background: With the spread of pyrethroid resistance in mosquitoes, the combination of an insecticide (carbamate or organophosphate) with a repellent (DEET) is considered as a promising alternative strategy for the treatment of mosquito nets and other relevant materials. The efficacy of these mixtures comes from the fact that they reproduce pyrethroid features and that positive interactions occur between insecticides and repellent. To better understand the mechanisms involved and assess the impact of detoxifying enzymes (oxidases and esterases) in these interactions, bioassays were carried out in the laboratory against the main dengue vector Aedes aegypti. Methods: Topical applications of DEET and propoxur (carbamate), used alone or as a mixture, were carried out on female mosquitoes, using inhibitors of the two main detoxification pathways in the insect. PBO, an inhibitor of multi-function oxidases, and DEF, an inhibitor of esterases, were applied one hour prior to the main treatment. Results: Results showed that synergism between DEET and propoxur disappeared in the presence of PBO but not with DEF. This suggests that oxidases, contrary to esterases, play a key role in the interactions occurring between DEET and cholinesterase inhibitors in mosquitoes. Conclusion: These findings are of great interest for the implementation of "combination nets" in the field. They support the need to combine insecticide with repellent to overcome insecticide resistance in mosquitoes of public health importance.