258 resultados para Interference screw
Resumo:
This paper investigates the impact of carrier frequency offset (CFO) on Single Carrier wireless communication systems with Frequency Domain Equalization (SC-FDE). We show that CFO in SC-FDE systems causes irrecoverable channel estimation error, which leads to inter-symbol-interference (ISI). The impact of CFO on SC-FDE and OFDM is compared in the presence of CFO and channel estimation errors. Closed form expressions of signal to interference and noise ratio (SINR) are derived for both systems, and verified by simulation results. We find that when channel estimation errors are considered, SC-FDE is similarly or even more sensitive to CFO, compared to OFDM. In particular, in SC-FDE systems, CFO mainly deteriorates the system performance via degrading the channel estimation. Both analytical and simulation results highlight the importance of accurate CFO estimation in SC-FDE systems.
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This paper reviews some aspects of calcium phosphate chemistry since phosphate in juice is an important parameter in all sugar juice clarification systems. It uses basic concepts to try and explain the observed differences in clarification performance obtained with various liming techniques. The paper also examines the current colorimetric method used for the determination of phosphate in sugar juice. In this method, a phosphomolybdate blue complex formed due to the addition of a dye is measured at 660 nm. Unfortunately, at this wavelength there is interference of the colour arising from within the juice and results in the underestimation of the amount of soluble inorganic phosphate content of juice. It is suggested that phosphate analysis be conducted at the higher wavelength of 875 nm where the interference of the juice colour is minimised.
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This study, to elucidate the role of des(1-3)IGF-I in the maturation of IGF-I,used two strategies. The first was to detect the presence of enzymes in tissues, which would act on IGF-I to produce des(1-3)IGF-I, and the second was to detect the potential products of such enzymic activity, namely Gly-Pro-Glu(GPE), Gly-Pro(GP) and des(l- 3)IGF-I. No neutral tripeptidyl peptidase (TPP II), which would release the tripeptide GPE from IGF-I, was detected in brain, urine nor in red or white blood cells. The TPPlike activity which was detected, was attributed to a combined action of a dipeptidyl peptidase (DPP N) and an aminopeptidase (AP A). A true TPP II was, however, detected in platelets. Two purified TPP II enzymes were investigated but they did not release GPE from IGF-I under a variety of conditions. Consequently, TPP II seemed unlikely to participate in the formation of des(1-3)IGF-I. In contrast, an acidic tripeptidyl peptidase activity (TPP I) was detected in brain and colostrum, the former with a pH optimum of 4.5 and the latter 3.8. It seems likely that such an enzyme would participate in the formation of des( 1-3 )IGF-I in these tissues in vitro, ie. that des(1-3)IGF-I may have been produced as an artifact in the isolation of IGF-I from brain and colostrum in acidic conditions. This contrasts with suggestions of an in vivo role for des(1-3)IGF-I, as reported by others. The activity of a dipeptidyl peptidase N (DPP N) from urine, which should release the dipeptide GP from IGF-I, was assessed under a variety of conditions and with a variety of additives and potential enzyme stimulants, but there was no release of GP. The DPP N also exhibited a transferase activity with synthetic substrates in the presence of dipeptides, at lower concentrations than previously reported for other acceptors or other proteolytic enzymes. In addition, a low concentration of a product,possibly the tetrapeptide Gly-Pro-Gly-Leu, was detected with the action of the enzyme on IGF-I in the presence of the dipeptide Gly-Leu. As part of attempts to detect tissue production of des(1-3)IGF-I, a monoclonal antibody (MAb ), directed towards the GPE- end ofiGF-I was produced by immunisation with a 10-mer covalently attached to a carrier protein. By the use of indirect ELISA and inhibitor studies, the MAb was shown to selectively recognise peptides with anNterminal GPE- sequence, and applied to the indirect detection of des(1-3)IGF-I. The concentration of GPE in brain, measured by mass spectrometry ( MS), was low, and the concentration of total IGF-I (measured by ELISA with a commercial polyclonal antibody [P Ab]) was 40 times higher at 50 nmol/kg. This also, was not consistent with the action of a tripeptidyl peptidase in brain that converted all IGF-I to des(1-3)IGF-I plus GPE. Contrasting ELISA results, using the MAb prepared in this study, suggest an even higher concentration of intact IGF-I of 150 nmollkg. This would argue against the presence of any des( 1-3 )IGF-I in brain, but in turn, this indicates either the presence of other substances containing a GPE amino-terminus or other cross reacting epitope. Although the results of the specificity studies reported in Chapter 5 would make this latter possibility seem unlikely, it cannot be completely excluded. No GP was detected in brain by MS. No GPE was detected in colostrum by capillary electrophoresis (CE) but the interference from extraneous substances reduced the detectability of GPE by CE and this approach would require further, prior, purification and concentration steps. A molecule, with a migration time equal to that of the peptide GP, was detected in colostrum by CE, but the concentration (~ 10 11mo/L) was much higher than the IGF-I concentration measured by radio-immunoassay using a PAb (80 nmol/L) or using a Mab (300-400 nmolL). A DPP IV enzyme was detected in colostrum and this could account for the GP, derived from substrates other than IGF-1. Based on the differential results of the two antibody assays, there was no indication of the presence of des(1-3)IGF-I in brain or colostrum. In the absence of any enzyme activity directed towards the amino terminus of IGF-I and the absence any potential products, IGF-I, therefore, does not appear to "mature" via des(1-3)IGF-I in the brain, nor in the neutral colostrum. In spite of these results which indicate the absence of an enzymic attack on IGF-I and the absence of the expected products in tissues, the possibility that the conversion of IGF-I may occur in neutral conditions in limited amounts, cannot be ruled out. It remains possible that in the extracellular environment of the membrane, a complex interaction of IGF-I, binding protein, aminopeptidase(s) and receptor, produces des(1- 3)IGF-I as a transient product which is bound to the receptor and internalised.
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Defining the precise promoter DNA sequence motifs where nuclear receptors and other transcription factors bind is an essential prerequisite for understanding how these proteins modulate the expression of their specific target genes. The purpose of this chapter is to provide the reader with a detailed guide with respect to the materials and the key methods required to perform this type of DNA-binding analysis. Irrespective of whether starting with purified DNA-binding proteins or somewhat crude cellular extracts, the tried-and-true procedures described here will enable one to accurately access the capacity of specific proteins to bind to DNA as well as to determine the exact sequences and DNA contact nucleotides involved. For illustrative purposes, we primarily have used the interaction of the androgen receptor with the rat probasin proximal promoter as our model system.
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Melanoma is one of the most aggressive cancers affecting humans. Although early melanomas are curable with surgical excision, metastatic melanomas are associated with high mortality. The mechanism of melanoma development, progression, and metastasis is largely unknown. In order to uncover genes unique to melanoma cells, we used high-density DNA microarrays to examine the gene expression profiles of metastatic melanoma nodules using benign nevi as controls. Over 190 genes were significantly overexpressed in metastatic melanomas compared with normal nevi by at least 2-fold. One of the most abundantly expressed genes in metastatic melanoma nodules is osteopontin (OPN). Immunohistochemistry staining on tissue microarrays and individual skin biopsies representing different stages of melanoma progression revealed that OPN expression is first acquired at the step of melanoma tissue invasion. In addition, blocking of OPN expression by RNA interference reduced melanoma cell numbers in vitro. Our observations suggest that OPN may be acquired early in melanoma development and progression, and may enhance tumor cell growth in invasive melanoma.
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Leukocytes are critical effectors of inflammation and tumor biology. Chemokine-like factors produced by such inflammatory sites are key mediators of tumor growth that activate leukocytic recruitment and tumor infiltration and suppress immune surveillance. Here we report that the endocrine peptide hormone, relaxin, is a regulator of leukocyte biology with properties important in recruitment to sites of inflammation. This study uses the human monocytic cell line THP-1 and normal human peripheral blood mononuclear cells to define a novel role for relaxin in regulation of leukocyte adhesion and migration. Our studies indicate that relaxin promotes adenylate cyclase activation, substrate adhesion, and migratory capacity of mononuclear leukocytes through a relaxin receptor LGR7-dependent mechanism. Relaxin-stimulated cAMP accumulation was observed to occur primarily in non-adherent cells. Relaxin stimulation results in increased substrate adhesion and increased migratory activity of leukocytes. In addition, relaxin-stimulated substrate adhesion resulted in enhanced chemotaxis to monocyte chemoattractant protein-1. These responses in THP-1 and peripheral blood mononuclear cells are relaxin dose-dependent and proportional to cAMP accumulation. We further demonstrate that LGR7 is critical for mediating these biological responses by use of RNA interference lentiviral short hairpin constructs. In summary, we provide evidence that relaxin is a novel leukocyte stimulatory agent with properties affecting adhesion and chemomigration
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Railway signaling facilitates two main functions, namely, train detection and train control, in order to maintain safe separations among the trains. Track circuits are the most commonly used train detection means with the simple open/close circuit principles; and subsequent adoption of axle counters further allows the detection of trains under adverse track conditions. However, with electrification and power electronics traction drive systems, aggravated by the electromagnetic interference in the vicinity of the signaling system, railway engineers often find unstable or even faulty operations of track circuits and axle counting systems, which inevitably jeopardizes the safe operation of trains. A new means of train detection, which is completely free from electromagnetic interference, is therefore required for the modern railway signaling system. This paper presents a novel optical fiber sensor signaling system. The sensor operation, field setup, axle detection solution set, and test results of an installation in a trial system on a busy suburban railway line are given.
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Prospective clinical case series of 100 patients receiving thoracoscopic anterior scoliosis correction surgery. The objective was to evaluate the relationship between clinical outcomes of thoracoscopic anterior scoliosis surgery and deformity correction using the Scoliosis Research Society (SRS) outcomes instrument questionnaire. The surgical treatment of scoliosis is quantitatively assessed in the clinic using radiographic measures of deformity correction, as well as the rib hump, but it is important to understand the extent to which these quantitative measures correlate with self-reported improvements in patients’ quality of life following surgery. A series of 100 consecutive adolescent idiopathic scoliosis patients received a single anterior rod via a thoracoscopic approach at the Mater Children’s Hospital, Brisbane, Australia. Patients completed SRS outcomes questionnaires pre-operatively and at 24 months post-operatively. There were 94 females and 6 males with a mean age of 16.1 years. The mean Cobb angle improved from 52º pre-operatively to 25º post-operatively (52%) and the mean rib hump improved from 16º to 8º (51%). The mean total SRS score for the cohort was 99.4/120. None of the deformity related parameters in the multiple regression were significant. However, patients with the lowest post-operative major Cobb angles reported significantly higher SRS scores than those with the highest post-operative Cobb angles, but there was no difference on the basis of rib hump correction. There were no significant differences between patients with either rod fractures or screw-related complications compared to those without complications.
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Through international agreement to the United Nations Framework Convention on Climate Change and the Kyoto Protocol the global community has acknowledged that climate change is a global problem and sought to achieve reductions in global emissions, within a sufficient timeframe, to avoid dangerous anthropogenic interference with the climate system. The sheer magnitude of emissions reductions required within such an urgent timeframe presents a challenge to conventional regulatory approaches both internationally and within Australia. The phenomenon of climate change is temporally and geographically challenging and it is scientifically complex and uncertain. The purpose of this paper is to analyse the current Australian legal response to climate change and to examine the legal measures which have been proposed to promote carbon trading, energy efficiency, renewable energy, and carbon sequestration initiatives across Australia. As this paper illustrates, the current Australian approach is clearly ineffective and the law as it stands overwhelmingly inadequate to address Australia’s emissions and meet the enormity of the challenges posed by climate change. Consequently, the government should look towards a more effective legal framework to achieve rapid and urgent transformations in the selection of energy sources, energy use and sequestration initiatives across the Australian community.
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Most research on numerical development in children is behavioural, focusing on accuracy and response time in different problem formats. However, Temple and Posner (1998) used ERPs and the numerical distance task with 5-year-olds to show that the development of numerical representations is difficult to disentangle from the development of the executive components of response organization and execution. Here we use the numerical Stroop paradigm (NSP) and ERPs to study possible executive interference in numerical processing tasks in 6–8-year-old children. In the NSP, the numerical magnitude of the digits is task-relevant and the physical size of the digits is task-irrelevant. We show that younger children are highly susceptible to interference from irrelevant physical information such as digit size, but that access to the numerical representation is almost as fast in young children as in adults. We argue that the developmental trajectories for executive function and numerical processing may act together to determine numerical development in young children.
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The Elaborated Intrusion (EI) theory of desire posits that visual imagery plays a key role in craving. We report a series of experiments testing this hypothesis in a drug addiction context. Experiment 1 showed that a mental visual imagery task with neutral content reduced cigarette craving in abstaining smokers, but that an equivalent auditory task did not. The effect of visual imagery was replicated in Experiment 2, which also showed comparable effects of non-imagery visual working memory interference. Experiment 3 showed that the benefit of visual over auditory interference was not dependent upon imagery being used to induce craving. Experiment 4 compared a visuomotor task, making shapes from modeling clay, with a verbal task (counting back from 100), and again showed a benefit of the visual over the non-visual task. We conclude that visual imagery supports craving for cigarettes. Competing imagery or visual working memory tasks may help tackle craving in smokers trying to quit.
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Corepressors play a crucial role in negative gene regulation and are defective in several diseases. BCoR is a corepressor for the BCL6 repressor protein. Here we describe and functionally characterize BCoR-L1, a homolog of BCoR. When tethered to a heterologous promoter, BCoR-L1 is capable of strong repression. Like other corepressors, BCoR-L1 associates with histone deacetylase (HDAC) activity. Specifically, BCoR-L1 coprecipitates with the Class II HDACs, HDAC4, HDAC5, and HDAC7, suggesting that they are involved in its role as a transcriptional repressor. BCoR-L1 also interacts with the CtBP corepressor through a CtBP-interacting motif in its amino terminus. Abrogation of the CtBP binding site within BCoR-L1 partially relieves BCoR-L1-mediated transcriptional repression. Furthermore, BCoR-L1 is located on the E-cadherin promoter, a known CtBP-regulated promoter, and represses the E-cadherin promoter activity in a reporter assay. The inhibition of BCoR-L1 expression by RNA-mediated interference results in derepression of E-cadherin in cells that do not normally express E-cadherin, indicating that BCoR-L1 contributes to the repression of an authentic endogenous CtBP target.
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Background: Alcohol craving is associated with greater alcohol-related problems and less favorable treatment prognosis. The Obsessive Compulsive Drinking Scale (OCDS) is the most widely used alcohol craving instrument. The OCDS has been validated in adults with alcohol use disorders (AUDs), which typically emerge in early adulthood. This study examines the validity of the OCDS in a nonclinical sample of young adults. Methods: Three hundred and nine college students (mean age of 21.8 years, SD = 4.6 years) completed the OCDS, Alcohol Use Disorders Identification Test (AUDIT), and measures of alcohol consumption. Subjects were randomly allocated to 2 samples. Construct validity was examined via exploratory factor analysis (n = 155) and confirmatory factor analysis (n = 154). Concurrent validity was assessed using the AUDIT and measures of alcohol consumption. A second, alcohol-dependent sample (mean age 42 years, SD 12 years) from a previously published study (n = 370) was used to assess discriminant validity. Results: A unique young adult OCDS factor structure was validated, consisting of Interference/Control, Frequency of Obsessions, Alcohol Consumption and Resisting Obsessions/Compulsions. The young adult 4-factor structure was significantly associated with the AUDIT and alcohol consumption. The 4 factor OCDS successfully classified nonclinical subjects in 96.9% of cases and the older alcohol-dependent patients in 83.7% of cases. Although the OCDS was able to classify college nonproblem drinkers (AUDIT <13, n = 224) with 83.2% accuracy, it was no better than chance (49.4%) in classifying potential college problem drinkers (AUDIT score ≥13, n = 85). Conclusions: Using the 4-factor structure, the OCDS is a valid measure of alcohol craving in young adult populations. In this nonclinical set of students, the OCDS classified nonproblem drinkers well but not problem drinkers. Studies need to further examine the utility of the OCDS in young people with alcohol misuse.
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Magneto-rheological (MR) fluid damper is a semi-active control device that has recently received more attention by the vibration control community. But inherent nonlinear hysteresis character of magneto-rheological fluid dampers is one of the challenging aspects for utilizing this device to achieve high system performance. So the development of accurate model is necessary to take the advantage their unique characteristics. Research by others [3] has shown that a system of nonlinear differential equations can successfully be used to describe the hysteresis behavior of the MR damper. The focus of this paper is to develop an alternative method for modeling a damper in the form of centre average fuzzy interference system, where back propagation learning rules are used to adjust the weight of network. The inputs for the model are used from the experimental data. The resulting fuzzy interference system is satisfactorily represents the behavior of the MR fluid damper with reduced computational requirements. Use of the neuro-fuzzy model increases the feasibility of real time simulation.