1,450 research outputs found

    Resectable Pediatric Nonrhabdomyosarcoma Soft Tissue Sarcoma: Which Patients Benefit from Adjuvant Radiation Therapy and How Much?

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    It remains unclear which children and adolescents with resected nonrhabdomyosarcoma soft tissue sarcoma (NRSTS) benefit from radiation therapy, as well as the optimal dose, volume, and timing of radiotherapy when used with primary surgical resection. This paper reviews the sparse literature from clinical trials and retrospective studies of resected pediatric NRSTS to discern local recurrence rates in relationship to the use of radiation therapy

    Effects of low sampling rate in the digital data-transition tracking loop

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    This article describes the performance of the all-digital data-transition tracking loop (DTTL) with coherent and noncoherent sampling using nonlinear theory. The effects of few samples per symbol and of noncommensurate sampling and symbol rates are addressed and analyzed. Their impact on the probability density and variance of the phase error are quantified through computer simulations. It is shown that the performance of the all-digital DTTL approaches its analog counterpart when the sampling and symbol rates are noncommensurate (i.e., the number of samples per symbol is an irrational number). The loop signal-to-noise ratio (SNR) (inverse of phase error variance) degrades when the number of samples per symbol is an odd integer but degrades even further for even integers

    A comparison of full-spectrum and complex-symbol combining techniques for the Galileo S-band mission

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    Full-spectrum combining (FSC) and complex-symbol combining (CSC) are two antenna-arraying techniques being considered for the Galileo spacecraft's upcoming encounter with Jupiter. This article describes the performance of these techniques in terms of symbol signal-to-noise ratio (SNR) degradation and symbol SNR loss. It is shown that both degradation and loss are approximately equal at low values of symbol SNR but diverge at high SNR values. For the Galileo S-band (2.2 to 2.3 GHz) mission, degradation provides a good estimate of performance as the symbol SNR is typically below -5 dB. For the following arrays - two 70-m antennas, one 70-m and one 34-m antenna, one 70-m and two 34-m antennas, and one 70-m and three 34-m antennas - it is shown that FSC has less degradation than CSC when the subcarrier and symbol window-loop bandwidth products are above 3.0, 10.0, 8.5, and 8.2 mHz at the symbol rate of 200 sym/sec, and above 1.2, 4.5, 4.0, and 3.5 mHz at a symbol rate of 400 sym/sec, respectively. Moreover, for an array of four 34-m antennas, FSC has less degradation than CSC when the subcarrier and symbol window-loop bandwidth products are above 0.32 mHz at the symbol rate of 50 sym/sec and above 0.8 mHz at the symbol rate of 25 sym/sec

    Tnt1 retrotransposon tagging of STF in Medicago truncatula reveals tight coordination of metabolic, hormonal and developmental signals during leaf morphogenesis

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    Tnt1 (transposable element if Nicotiana tabaccum cell type 1) is one of the very few active LTR retrotransposons used for gene tagging in plants. In the model legume Medicago truncatula, Tnt1 has been effectively used as a gene knock-out tool to generate several very useful mutants. stenofolia (stf) is such a mutant identified by Tnt1 insertion in a WUSCHEL-like homeobox transcription factor. STF is required for blade outgrowth, leaf vascular patterning and female reproductive organ development in barrel medic and woodland tobacco. Using transcript profiling and metabolite analysis, we uncovered that mutant leaves are compromised in steady-state levels of multiple phytohormones, sugar metabolites and derivatives including flavonoids and polyamines. In the lam1 mutant (caused by deletion of the STF ortholog in Nicotiana sylvestris), while glucose, fructose, mannose, galactose, myo-inositol and aromatic aminoacids are dramatically reduced, sucrose is comparable to wild-type levels, and glutamine, proline, putrescine, nicotine and sorbitol are highly increased. We demonstrated that both stf and lam1 mutants accumulate reduced levels of free auxin and ABA in their leaves, and ectopic expression of STF in tobacco leads to auxin and cytokinin overproduction phenotypes including formation of tumors on the roots and crown. These data suggest that STF mediated integration of metabolic and hormonal signals are required for lateral organ morphogenesis and elaboration

    Investigation of phase-separated electronic states in 1.5µm GaInNAs/GaAs heterostructures by optical spectroscopy

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    We report on the comparative electronic state characteristics of particular GaInNAs/GaAs quantum well structures that emit near 1.3 and 1.5 µm wavelength at room temperature. While the electronic structure of the 1.3 µm sample is consistent with a standard quantum well, the 1.5 µm sample demonstrate quite different characteristics. By using photoluminescence sPLd excitation spectroscopy at various detection wavelengths, we demonstrate that the macroscopic electronic states in the 1.5 µm structures originate from phase-separated quantum dots instead of quantum wells. PL measurements with spectrally selective excitation provide further evidence for the existence of composition-separated phases. The evidence is consistent with phase segregation during the growth leading to two phases, one with high In and N content which accounts for the efficient low energy 1.5 µm emission, and the other one having lower In and N content which contributes metastable states and only emits under excitation in a particular wavelength range

    Residual and suppressed-carrier arraying techniques for deep-space communications

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    Three techniques that use carrier information from multiple antennas to enhance carrier acquisition and tracking are presented. These techniques in combination with baseband combining are analyzed and simulated for residual and suppressed-carrier modulation. It is shown that the carrier arraying using a single carrier loop technique can acquire and track the carrier even when any single antenna in the array cannot do so by itself. The carrier aiding and carrier arraying using multiple carrier loop techniques, on the other hand, are shown to lock on the carrier only when one of the array elements has sufficient margin to acquire the carrier on its own

    Computer simulation results for PCM/PM/NRZ receivers in nonideal channels

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    This article studies, by computer simulations, the performance of deep-space telemetry signals that employ the pulse code modulation/phase modulation (PCM/PM) technique, using nonreturn-to-zero data, under the separate and combined effects of unbalanced data, data asymmetry, and a band-limited channel. The study is based on measuring the symbol error rate performance and comparing the results to the theoretical results presented in previous articles. Only the effects of imperfect carrier tracking due to an imperfect data stream are considered. The presence of an imperfect data stream (unbalanced and/or asymmetric) produces undesirable spectral components at the carrier frequency, creating an imperfect carrier reference that will degrade the performance of the telemetry system. Further disturbance to the carrier reference is caused by the intersymbol interference created by the band-limited channel

    Developing a framework for a district-based information management system for mental health care in the Western Cape

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    Philosophiae Doctor - PhDA review of the literature has shown that there is a lack of mental health information on which to base planning of mental health services and decisions concerning programme development for mental health services. Several studies have indicated that the use of an evidence-based health information system (HIS) reduces inappropriate clinical practices and promotes the quality of health care services. This study was aimed at developing a framework for a district-based mental health information management system, utilising the experiences of health care providers and caregivers about a district mental health information system (DMHIS). Activity Theory was used as the philosophical foundation of the information system for the study. A qualitative approach was employed using semi-structured individual interviews, Focus Group Discussions (FGDs), systematic review and document analysis. The intervention research design and development model of Rothman and Thomas (1994) was used to guide the study, which was conducted in the Cape Town Metropole area of the Western Cape. A purposive, convenient sampling method was employed to select study participants. Ethical clearance for the study was obtained from the University of the Western Cape, and permission to use the health facilities from the Department of Health. The data collection process involved 62 individual interview participants, from mental health nurses to district health managers, health information clerks, and patient caregivers/families and persons with stable mental conditions. Thirteen caregivers took part in the FGDs. Document review was conducted at three community mental health centres. The data were analysed manually using content analysis. Core findings of the interviews were lack of standardized information collection tools and contents for mental health, information infrastructure, capacity building, and resources. Information processing in terms of collection, compiling, analysing, feedback, access and sharing information were the major problems. Results from document analysis identified inconsistencies and inaccuracies of information recording and processing, which in turn affected the quality of information for decision making. Results from the systematic review identified five functional elements: organizational structure; information infrastructure; capacity building; inputs, process, output and feedback; and community and stakeholders’ participation in the design and implementation of a mental health information system (MHIS). The study has contributed a framework for a DMHIS based on the findings of the empirical and systematic review. It is recommended that there is a need to establish a HIS committee at district health facility level for effective implementation of the framework and quality information processing. There is a need to ensure that staffs have adequate knowledge and skills required for effective implementation of an information system. It is recommended that higher education institutions include a course on HISs in their curriculum. It is suggested that the South African Mental Health Policy be reviewed to include an MHIS and ensure involvement of the community and stakeholders in this system as well as adequate budget allocation
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