992 resultados para Frequency stability
Resumo:
The first phase of the study of intersection lighting and accidents conducted using data from 1964 through 1971 yielded the conclusion that the installation of intersection lighting reduced the nighttime accident frequency by 52%. With this conclusion, this project (the second phase), was initiated to determine the relative benefit of a higher level of lighting as opposed to minimum lighting. Twenty pairs of intersections with similar geometrics were selected. Some lights were turned out at one intersection of each pair to produce a lighting level differential. Based on the results of this research, the lighting level of lighted rural at-grade intersections does not have a significant effect on the accident frequency. At the nineteen "reduced lighting" intersections, the number of lighted luminaires was reduced from 101 to 46 with a corresponding reduction in energy consumption of over 100,000 Kilowatt hours per year. This energy conservation measure could reduce consumption by an estimated 1,000,000 Kilowatt hours per year if initiated on more than 200 earlier primary, rural installations.
Resumo:
The Iowa D.O.T. specifications do not require 100 percent of 50 blow Marshall density (generally 94%) for field compaction. However, stabilities are determined in the Laboratory on specimens compacted to 100 percent of Marshall density. The purpose of this study is to determine the stabilities of specimens compacted to various densities which are below 100 percent of the 50 blow Marshall density.
Resumo:
It has been observed in the Laboratory that an increase in oven heating time of relatively short duration between mixing and compaction of asphaltic concrete hot mixes can have an effect on the Marshall stability results obtained. The purpose of this short investigation is to determine the effect of oven heating time on the density and stability of hot mixes.
Effect of Delay in Testing Asphalt Concrete Specimens for Marshall Stability, MLR-86-08, Draft, 1986
Resumo:
The Central Laboratory has been delaying the mix design testing of 2 1/2" X 4" Marshall specimens for stability, until the next day after molding. For example, if the mixes are made and samples molded on Friday a man would have to come in and work on Saturday to test these specimens. The reason for this is that the ASTM-01559 "Resistance to Plastic Flow of Bituminous Mixes Using Marshall Apparatus," states that "the specimens after being molded shall be carefully transferred to a smooth, flat surface and allowed to stand overnight at room temperature, before being weighed, measured and tested." The AASHTO procedure, AASHTO Designation T-245-82 "Resistance to Plastic Flow of Bituminous Mixtures using Marshall Apparatus," does not say when the specimens shall be tested for stability. The IDOT Lab. Specifications, Test Method No. Iowa 502-8 and test method No. Iowa 506-C "compacting asphaltic concrete by the Marshall Method" and "Resistance to Plastic Flow of Bituminous Mixtures Using the Marshall Apparatus," respectively, only state that the specimens shall be cooled before testing. Due to the above conflict in specifications, a number of mix samples were tested, in the Central Lab, for stability on different days. This should furnish enough information to allow us to change the procedure and to test for stability the same day molded, or be able to delay the testing for 3 days or more.
Resumo:
The objective of this project was to assess the predictive accuracy of flood frequency estimation for small Iowa streams based on the Rational Method, the NRCS curve number approach, and the Iowa Runoff Chart. The evaluation was based on comparisons of flood frequency estimates at sites with sufficiently long streamgage records in the Midwest, and selected urban sites throughout the United States. The predictive accuracy and systematic biases (under- or over-estimation) of the approaches was evaluated based on forty-six Midwest sites and twenty-one urban sites. The sensitivity of several watershed characteristics such as soil properties, slope, and land use classification was also explored. Recommendations on needed changes or refinements for applications to Iowa streams are made.
Resumo:
The aim of this work was the identification of new metabolites and transformation products (TPs) in chicken muscle from Enrofloxacin (ENR), Ciprofloxacin (CIP), Difloxacin (DIF) and Sarafloxacin (SAR), which are antibiotics that belong to the fluoroquinolones family. The stability of ENR, CIP, DIF and SAR standard solutions versus pH degradation process (from pH 1.5 to 8.0, simulating the pH since the drug is administered until its excretion) and freeze-thawing (F/T) cycles was tested. In addition, chicken muscle samples from medicated animals with ENR were analyzed in order to identify new metabolites and TPs. The identification of the different metabolites and TPs was accomplished by comparison of mass spectral data from samples and blanks, using liquid chromatography coupled to quadrupole time-of-flight (LC-QqToF) and Multiple Mass Defect Filter (MMDF) technique as a pre-filter to remove most of the background noise and endogenous components. Confirmation and structure elucidation was performed by liquid chromatography coupled to linear ion trap quadrupole Orbitrap (LC-LTQ-Orbitrap), due to its mass accuracy and MS/MS capacity for elemental composition determination. As a result, 21 TPs from ENR, 6 TPs from CIP, 14 TPs from DIF and 12 TPs from SAR were identified due to the pH shock and F/T cycles. On the other hand, 14 metabolites were identified from the medicated chicken muscle samples. Formation of CIP and SAR, from ENR and DIF, respectively, and the formation of desethylene-quinolone were the most remarkable identified compounds.
Resumo:
The purpose of this study was to assess the spatial resolution of a computed tomography (CT) scanner with an automatic approach developed for routine quality controls when varying CT parameters. The methods available to assess the modulation transfer functions (MTF) with the automatic approach were Droege's and the bead point source (BPS) methods. These MTFs were compared with presampled ones obtained using Boone's method. The results show that Droege's method is not accurate in the low-frequency range, whereas the BPS method is highly sensitive to image noise. While both methods are well adapted to routine stability controls, it was shown that they are not able to provide absolute measurements. On the other hand, Boone's method, which is robust with respect to aliasing, more resilient to noise and provides absolute measurements, satisfies the commissioning requirements perfectly. Thus, Boone's method combined with a modified Catphan 600 phantom could be a good solution to assess CT spatial resolution in the different CT planes.
Resumo:
A simple method using liquid chromatography-linear ion trap mass spectrometry for simultaneous determination of testosterone glucuronide (TG), testosterone sulfate (TS), epitestosterone glucuronide (EG) and epitestosterone sulfate (ES) in urine samples was developed. For validation purposes, a urine containing no detectable amount of TG, TS and EG was selected and fortified with steroid conjugate standards. Quantification was performed using deuterated testosterone conjugates to correct for ion suppression/enhancement during ESI. Assay validation was performed in terms of lower limit of detection (1-3ng/mL), recovery (89-101%), intraday precision (2.0-6.8%), interday precision (3.4-9.6%) and accuracy (101-103%). Application of the method to short-term stability testing of urine samples at temperature ranging from 4 to 37 degrees C during a time-storage of a week lead to the conclusion that addition of sodium azide (10mg/mL) is required for preservation of the analytes.
Resumo:
The aim of this work was the identification of new metabolites and transformation products (TPs) in chicken muscle from Enrofloxacin (ENR), Ciprofloxacin (CIP), Difloxacin (DIF) and Sarafloxacin (SAR), which are antibiotics that belong to the fluoroquinolones family. The stability of ENR, CIP, DIF and SAR standard solutions versus pH degradation process (from pH 1.5 to 8.0, simulating the pH since the drug is administered until its excretion) and freeze-thawing (F/T) cycles was tested. In addition, chicken muscle samples from medicated animals with ENR were analyzed in order to identify new metabolites and TPs. The identification of the different metabolites and TPs was accomplished by comparison of mass spectral data from samples and blanks, using liquid chromatography coupled to quadrupole time-of-flight (LC-QqToF) and Multiple Mass Defect Filter (MMDF) technique as a pre-filter to remove most of the background noise and endogenous components. Confirmation and structure elucidation was performed by liquid chromatography coupled to linear ion trap quadrupole Orbitrap (LC-LTQ-Orbitrap), due to its mass accuracy and MS/MS capacity for elemental composition determination. As a result, 21 TPs from ENR, 6 TPs from CIP, 14 TPs from DIF and 12 TPs from SAR were identified due to the pH shock and F/T cycles. On the other hand, 14 metabolites were identified from the medicated chicken muscle samples. Formation of CIP and SAR, from ENR and DIF, respectively, and the formation of desethylene-quinolone were the most remarkable identified compounds.
Resumo:
In contrast with the low frequency of most single epitope reactive T cells in the preimmune repertoire, up to 1 of 1,000 naive CD8(+) T cells from A2(+) individuals specifically bind fluorescent A2/peptide multimers incorporating the A27L analogue of the immunodominant 26-35 peptide from the melanocyte differentiation and melanoma associated antigen Melan-A. This represents the only naive antigen-specific T cell repertoire accessible to direct analysis in humans up to date. To get insight into the molecular basis for the selection and maintenance of such an abundant repertoire, we analyzed the functional diversity of T cells composing this repertoire ex vivo at the clonal level. Surprisingly, we found a significant proportion of multimer(+) clonotypes that failed to recognize both Melan-A analogue and parental peptides in a functional assay but efficiently recognized peptides from proteins of self- or pathogen origin selected for their potential functional cross-reactivity with Melan-A. Consistent with these data, multimers incorporating some of the most frequently recognized peptides specifically stained a proportion of naive CD8(+) T cells similar to that observed with Melan-A multimers. Altogether these results indicate that the high frequency of Melan-A multimer(+) T cells can be explained by the existence of largely cross-reactive subsets of naive CD8(+) T cells displaying multiple specificities.
Resumo:
The objective of this work was to analyze the agronomic performance and chromosomal stability of transgenic homozygous progenies of soybean [Glycine max (L.) Merrill.], and to confirm the resistance of these plants against Anticarsia gemmatalis. Eleven progenies expressing cry1Ac, hpt and gusA genes were evaluated for agronomic characteristics in relation to the nontransformed parent IAS 5 cultivar. Cytogenetical analysis was carried out on transgenic and nontransgenic plants. Two out of the 11 transgenic progenies were also evaluated, in vitro and in vivo, for resistance to A. gemmatalis. Two negative controls were used in resistance bioassays: a transgenic homozygous line, containing only the gusA reporter gene, and nontransgenic 'IAS 5' plants. The presence of cry1Ac transgene affected neither the development nor the yield of plants. Cytogenetical analysis showed that transgenic plants presented normal karyotype. In detached-leaf bioassay, cry1Ac plants exhibited complete efficacy against A. gemmatalis, whereas negative controls were significantly damaged. Whole-plant feeding assay confirmed a very high protection of cry1Ac against velvetbean caterpillar, while nontransgenic 'IAS 5' plants and homozygous gusA line exhibited 56.5 and 71.5% defoliation, respectively. The presence of cry1Ac transgene doesn't affect the majority of agronomic traits (including yield) of soybean and grants high protection against A. gemmatalis.
Resumo:
Summary Background: Percutaneous transluminal coronary angioplasty (PTCA) is an effective and minimally invasive treatment for angina pectoris, but its impact on patient's quality of life has not been extensively studied with specific questionnaires. Methods: Over a 6 month period, ail patients suffering from angina, planned for elective PTCA, and available for a 6 months follow-up, were included in the study. The specific "Seattle Angina Questionnaire" (SAQ) was administered the day before and 6 months after PTCA. The decision to implant a coronary stent was left to the cardiologist in charge of the procedure. Results: 112 patients were initially included (39 PTCA and 62 PTCA with stent im-plantation). There was no difference in gender, age, angina severity and type of coronary lesion between the two groups. Follow-up at 6 months was available for 101 patients (90%). Quality of life was dramatically improved in 4 of 5 SAQ dimensions (physical limitation, angina stability, angina frequency, disease perception, p <0.001). Only treatment satisfaction was worse at follow-up then before the procedure (p = 0.03), in particular satisfaction with received explanations, belief that everything possible was donc to treat angina, and global satisfaction. A stent implantation had no impact on these results. Conclusions: PTCA for ischaemic cardiac disease improved not only physical abilities, but also quality of life dramatically. Dissatisfaction with treatment could be corrected with better information during follow-up. SAQ is easy to use and could be selected as a monitoring instrument. Résumé Contexte: Le traitement de l'angine de poitrine par angioplastie coronaire transluminale per-cutanée (PTCA) est efficace et peu invasif, mais son impact sur la qualité de vie des patients a été relativement peu étudié avec des questionnaires spécifiques. Méthode: Durant 6 mois, tous les patients souffrant d'une angine de poitrine pour qui une PTCA élective était envisagée, et qui étaient disponibles pour un suivi à 6 mois ont été inclus dans l'étude. Le questionnaire spécifique «Seattle Angina Questionnaire» (SAQ) a été utilisé le jour avant et 6 mois après la procédure. La décision d'implanter un stent était laissée au cardiologue au moment de la procédure. Résultats: 112 patients ont été initialement inclus. Trente-neuf d'entre eux ont été traités avec une PTCA, et 62 avec une PTCA et l'implantation de stent. Il n'y avait pas de différence de sexe, d'âge, de sévérité de l'angine de poitrine, et de type de lésion coronaire entre les deux groupes. Un suivi à 6 mois a été possible pour 101 patients (90% de la cohorte initiale). La qualité de vie a été améliorée de façon spectaculaire dans 4 des 5 dimensions du SAQ (limites physiques, stabilité de l'angor, fréquence de l'angor, perception de l'angor, p <0,001). Seule, la satisfaction avec le traitement était pire lors du suivi qu'avant l'intervention (p = 0,03), en particulier la satisfaction avec les explications reçues, la conviction que tous les moyens avaient été utilisés pour le traitement, et la satisfaction globale. L'implantation d'un stent n'a eu aucun impact sur ces résultats.
Resumo:
Background: Data on the frequency of extraintestinal manifestations (EIM) in Crohnʼs disease (CD) and ulcerative colitis (UC) are scarce. Goal: to evaluate prevalences, forms of EIM and risk factors in a large nationwide IBD cohort. Methods: Data from validated physician enrolment questionnaires of the adult Swiss IBD cohort were analyzed. Logistic regression models were used to identify EIM risk factors. Results: 950 patients were included, 580 (61%) with CD (mean age 43yrs) and 370 (39%) with UC (mean age 49yrs), of these, 249 (43%) of CD and 113 (31%) of UC patients had one to 5 EIM. The following EIM were found: arthritis (CD 33%, UC 21%), aphthous stomatitis (CD 10%, UC 4%), uveitis (CD 6%, UC 4%), erythema nodosum (CD 6%, UC 3%), ankylosing spondylitis (CD 6%, UC 2%), psoriasis (CD 2%, UC 1%), pyoderma gangrenosum (CD and UC each 2%), primary sclerosing cholangitis (CD 1%, UC 4%). Logistic regression in CD identified the following items as risk factors for ongoing EIM: active disease (OR 1.95, 95% CI 1.17-3.23, P=0.01), positive IBD family history (OR 1.77, 95% CI 1.07-2.92, P=0.025). No risk factors were identified in UC patients. Conclusions: EIM are a frequent problem in CD and UC patients. Active disease and positive IBD family history are associated with ongoing EIM in CD patients. Identification of EIM prevalence and associated risk factors may result in increased awareness for this problem and thereby facilitate their diagnosis and management.