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PubMed2003

Detection of characteristic signals from as-doped (<1 at.%) regions of silicon by transmission electron microscopy and convergent-beam electron diffraction.

Characteristic signals were detected from As-doped (< 1 at.%) regions of silicon by dark-field transmission electron microscopy and convergent-beam electron diffraction. A slight intensity increase was observed in 220 dark-field images, which may be explained by an increase of scattering amplitude due to the As doping. The doped region showed a much higher intensity in 004 dark-field images. The characteristic high intensity was observed for specimens with As concentrations of about 0.09-0.8 at.%. Convergent-beam electron diffraction patterns obtained from the As-doped region showed a characteristic rocking curve for 004 reflection. These characteristics should originate from incoherent elastically scattered electrons due to a static lattice distortion around the doped As atoms. The observed characteristics in dark-field images and rocking curves of the 004 reflection should be a good probe not only for investigating the concentration of doped atoms in Si lattice, but also for the amount of impurity and/or point defects in other crystalline materials.

Journal Article↗

PubMed1985

Promoter selectivity of E. coli RNA polymerase: analysis of the promoter system of convergently-transcribed dnaQ-rnh genes.

Promoter properties were analyzed for the convergently-overlapped E. coli genes coding for the DNA polymerase III epsilon subunit (dnaQ) and the ribonuclease H (rnh). The rates of open complex formation for a single promoter of the rnh gene and two tandem promoters of the dnaQ gene were constant whether they are located on a single DNA fragment or separated into individual fragments. The relative expression levels of these three promoters, as measured using an in vitro mixed transcription system, varied differentially depending on the concentration of RNA polymerase. At low enzyme concentrations, the downstream promoter (P2) of the dnaQ gene was utilized preferentially, but the upstream promoter (P1) was utilized as well when the enzyme concentration was increased. This indicates different physiological roles between the two dnaQ promoters. The level of rnh transcription was as low as that of dnaQ-1 RNA synthesis but the rnh promoter was utilized as well as the dnaQ P2 promoter when it was separated from the dnaQ promoters. This implies a promoter interference between the convergently transcribed genes.

Base Sequence↗

PubMed1990

The degradation of T7 DNA in converging flow.

The flow-induced degradation of T7 DNA (Molecular Size = 40 Kbp) was studied in a flow device that generates converging flow rather than simple shear flow. We discovered that the sizes of the degradation products were very broadly distributed, covering the range from 10 Kbp to 36 Kbp. An explanation for the broadness of the distribution is given based on a computer simulation of the experiment. The significance of converging flow to the routine handling of large DNA is emphasized.

Computer Simulation↗

PubMed1995

Convergent DNA synthesis: a non-enzymatic dimerization approach to circular oligodeoxynucleotides.

We report a novel convergent approach to the construction of circular DNA oligonucleotides from two smaller linear precursors. Circular DNAs 34-74 nucleotides (nt) in size are constructed non-enzymatically in a single step from two half-length oligomers. A DNA template is used to assemble the constituent parts into a triple helical complex which brings the four reactive ends together for chemical ligation with BrCN/imidazole/Ni2+. A homodimerization reaction strategy is successfully used on a small scale to construct circles 42, 58 and 74 nt in size. In addition, a heterodimerization strategy is successfully used in two cases to construct circular 34mers from different 16mer and 18mer precursors. Measurement of preparative yields for one biologically active 34mer circle shows that the dimerization strategy gives a yield higher than that from conventional cyclization and nearly as high as that for a normally synthesized linear DNA, establishing that there is not necessarily a yield penalty for circle construction. Six additional preparative circle constructions, giving conversions of approximately 33-85% from precursors to circular product, are also described. Convergent strategies allow the construction of medium and large size DNA molecules in higher yields than can be achieved by standard linear synthesis alone.

Base Sequence↗

PubMed2003

Leishmania major chromosome 3 contains two long convergent polycistronic gene clusters separated by a tRNA gene.

Leishmania parasites (order Kinetoplastida, family Trypanosomatidae) cause a spectrum of human diseases ranging from asymptomatic to lethal. The approximately 33.6 Mb genome is distributed among 36 chromosome pairs that range in size from approximately 0.3 to 2.8 Mb. The complete nucleotide sequence of Leishmania major Friedlin chromosome 1 revealed 79 protein-coding genes organized into two divergent polycistronic gene clusters with the mRNAs transcribed towards the telomeres. We report here the complete nucleotide sequence of chromosome 3 (384 518 bp) and an analysis revealing 95 putative protein-coding ORFs. The ORFs are primarily organized into two large convergent polycistronic gene clusters (i.e. transcribed from the telomeres). In addition, a single gene at the left end is transcribed divergently towards the telomere, and a tRNA gene separates the two convergent gene clusters. Numerous genes have been identified, including those for metabolic enzymes, kinases, transporters, ribosomal proteins, spliceosome components, helicases, an RNA-binding protein and a DNA primase subunit.

Animals↗

PubMed2006

Collision events between RNA polymerases in convergent transcription studied by atomic force microscopy.

Atomic force microscopy (AFM) has been used to image, at single molecule resolution, transcription events by Escherichia coli RNA polymerase (RNAP) on a linear DNA template with two convergently aligned lambda(pr) promoters. For the first time experimentally, the outcome of collision events during convergent transcription by two identical RNAP has been studied. Measurement of the positions of the RNAP on the DNA, allows distinction of open promoter complexes (OPCs) and elongating complexes (EC) and collided complexes (CC). This discontinuous time-course enables subsequent analysis of collision events where both RNAP remain bound on the DNA. After collision, the elongating RNAP has caused the other (usually stalled) RNAP to back-track along the template. The final positions of the two RNAP indicate that these are collisions between an EC and a stalled EC (SEC) or OPC (previously referred to as sitting-ducks). Interestingly, the distances between the two RNAP show that they are not always at closest approach after 'collision' has caused their arrest.

DNA↗

PubMed1996

Influence of the mechanism of regurgitation on the quantification of mitral regurgitation by the proximal flow convergence method and the jet area method.

In 84 patients mitral regurgitation was quantified by angiography. The mechanism of regurgitation was determined by echocardiography (organic, n = 54, functional, n = 30). The radii of the proximal isovelocity surface areas in the flow convergence region for 28 and 41 cm.s-1 blood flow velocity and the area and length of the regurgitant jet were measured using colour flow Doppler imaging. The radii of the proximal isovelocity surface areas correlated more closely with the angiographic grade than the jet parameters irrespective of the mechanism of regurgitation. In more than 90% of the patients, grades I-II mitral regurgitation were correctly differentiated from grades III-IV by means of the radii of the proximal isovelocity surface areas. Using the jet parameters, the differentiation was correct in 50-90% of the patients depending on the mechanism of regurgitation. The jet area method particularly failed to identify grades III-IV organic mitral regurgitation due to a high prevalence of eccentric jets in these patients. It is concluded that the proximal flow convergence method was suitable for the quantification of mitral regurgitation irrespective of the mechanism of mitral regurgitation. On the other hand, the value of the jet area method depended largely on the regurgitation mechanism.

Adult↗

PubMed2004

Functional convergence in hydraulic architecture and water relations of tropical savanna trees: from leaf to whole plant.

Functional convergence in hydraulic architecture and water relations, and potential trade-offs in resource allocation were investigated in six dominant neotropical savanna tree species from central Brazil during the peak of the dry season. Common relationships between wood density and several aspects of plant water relations and hydraulic architecture were observed. All species and individuals shared the same negative exponential relationship between sapwood saturated water content and wood density. Wood density was a good predictor of minimum (midday) leaf water potential and total daily transpiration, both of which decreased linearly with increasing wood density for all individuals and species. With respect to hydraulic architecture, specific and leaf-specific hydraulic conductivity decreased and the leaf:sapwood area ratio increased more than 5-fold as wood density increased from 0.37 to 0.71 g cm(-3) for all individuals and species. Wood density was also a good predictor of the temporal dynamics of water flow in stems, with the time of onset of sap flow in the morning and the maximum sap flow tending to occur progressively earlier in the day as wood density increased. Leaf properties associated with wood density included stomatal conductance, specific leaf area, and osmotic potential at the turgor loss point, which decreased linearly with increasing wood density. Wood density increased linearly with decreasing bulk soil water potential experienced by individual plants during the dry season, suggesting that wood density was greatest in individuals with mostly shallow roots, and therefore limited access to more abundant soil water at greater depths. Despite their taxonomic diversity and large intrapopulation differences in architectural traits, the six co-occurring species and their individuals shared similar functional relationships between all pairs of variables studied. Thus, rather than differing intrinsically in physiological responsiveness, the species and the individuals appeared to have distinct operating ranges along common physiological response curves dictated by plant architectural and structural features. The patterns of water uptake and access to soil water during the dry season appeared to be the main determinant of wood density, which constrained evolutionary options related to plant water economy and hydraulic architecture, leading to functional convergence in the neotropical savanna trees studied.

Brazil↗

PubMed1997

Survival after colon cancer 1973-1990 in Sweden. Convergence between catchment areas.

OBJECTIVE: The objective of the study is to analyze the temporal trends in relative survival among patients with colon cancer in catchment areas of hospitals of different categories and regions in Sweden. BACKGROUND: In Sweden, cancer of the colon is the second most common type of cancer in women and the third most common in men, afflicting approximately 3000 individuals annually. During the past decades, survival has improved, but it is not clear what factors have contributed to this development. Changes in the natural history of the disease, altered alimentary habits, advances in diagnosis, and treatment have been suggested. The effects of centralized care still are debated. METHOD: Longitudinal observational study of relative survival of all patients with colon cancer from 1973 to 1993 in Sweden (n = 41,700) by period of diagnosis and hospital category of primary catchment area was conducted. Multivariate analyses of relative hazards of any interaction between length of follow-up, period of diagnosis, hospital category of the primary catchment area, age at diagnosis, and region were performed. RESULTS: Relative survival in patients with colon cancer improved substantially from 1973 through 1990. The prognosis in patients from primary catchment areas of regional-university hospitals did not change during this period, and the prognostic improvement was noted only in county and local hospital areas, where survival approached that of regional hospitals. Although new management regimens may have been introduced unevenly, improved perioperative care best explains this convergence. Low-incidence regions showed the lowest survival, but this improved with time, although not significantly. CONCLUSIONS: Although survival in patients with colon cancer improved and convergence between different catchment area categories was seen, a large initial gap as well as a remaining difference may warrant future monitoring to ensure equal prognosis, irrespective of domicile.

Aged↗

PubMed2004

Viscerovisceral convergence of urinary bladder and colorectal inputs to lumbosacral spinal neurons in rats.

Extracellular potentials of single L6-S2 spinal neurons were recorded in pentobarbital anesthetized male rats. The urinary bladder was catheterized through the fundus and filled with warm saline for urinary bladder distension (UBD, 0.5-2.0 ml, 20 s). Colorectal distension (CRD) was produced by distending a latex balloon with air (20-80 mmHg, 20 s). Of 171 deeper neurons examined for responses to UBD and CRD, 49 (29%) neurons responded to both UBD and CRD; whereas 6/42 (14%) superficial neurons (depth < 0.3 mm) responded to both organs. Of 55 viscerovisceral convergent neurons, 25 (45%) neurons were excited by both UBD and CRD; the remainder exhibited multiple patterns of excitation and inhibition. In conclusion, responses of superficial and deeper lumbosacral spinal neurons to convergent inputs from urinary bladder and colon suggested that these neurons might contribute to the cross-talk that occurs between visceral organs.

Animals↗

PubMedDate not supplied

Evaluating instruments for quality: testing convergent validity of the consumer emergency care satisfaction scale.

Having reliable and valid instruments is a necessity for nurses and others measuring concepts such as patient satisfaction. The purpose of this article is to describe the use of convergence to test the construct validity of the Davis Consumer Emergency Care Satisfaction Scale (CECSS). Results indicate convergence of the CECSS with the Risser Patient Satisfaction Scale and 2 single-item visual analogue scales, therefore supporting construct validity. Persons measuring patient satisfaction with nurse behaviors in the emergency department can confidently use the CECSS.

Adolescent↗

PubMed1995

Convergence or divergence of male and female physicians' hours of work and income.

This article verifies if the increase in the percentage of women in the medical profession led to the convergence of male and female physicians' hours of work as well as income. Active physicians in Quebec in 1978 were compared to the ones in 1988. Data were obtained from the computerized files of the Quebec Corporation of Physicians and the Régie d'assurance-maladie du Quebec. Despite the increasing representation of women in the medical profession, gender differences in hours worked and income remained. However, results also showed a tendency toward a convergence in total hours of work, more behavioral variation among women physicians and some behavioral change among men. The experience of the past should thus not be used as the basis for projections of future physician productivity or for medical manpower planning purposes without a careful analysis of trends in behavioral changes.

Adult↗

PubMed1977

Stereoscopic localization with the eyes asymmetrically converged.

When the eyes fixate a point in the median plane of the head, the physical surface to which the stereoscopic disparities of "nearer" and "farther" points are referred is the so-called frontal plane horopter. When, however, a point is fixated with the eyes in asymmetrical convergence, the horopter is now rotated with respect to the objective normal plane--that is, the surface that is normal to the direction of gaze. This rotation is believed to pose a problem with veridical stereoscopic localization. It has, therefore, been postulated that in asymmetrical convergence some physiological compensation takes place in order to preserve accurate stereoscopic perception. Some experimental evidence apparently supports this view. The logic of the arguments and the experiments are critically assessed with the conclusion that there is little evidence of any visual modification, nor would any seem likely. A reinterpretation of the stereoscopic axes of reference does occur, but this can be accounted for purely by innervational factors, the visual aspects remaining unchanged.

Afterimage↗

PubMed1983

Zone of zero-associated phoria in patients with convergence insufficiency.

The zone of zero-associated phoria (ZZAP) was determined for patients with convergence insufficiency. The ZZAP for these patients differs from that of asymptomatic patients. It is concluded that the ZZAP may be used as a supplemental test to help the clinician detect convergence insufficiency and possibly other binocular deficiencies.

Accommodation, Ocular↗

PubMed1983

Reduction of asthenopia in patients with convergence insufficiency after fusional vergence training.

Seven patients with convergence insufficiency and related asthenopia underwent automated fusional convergence training. A matched-subjects control group crossover design was used to reduce placebo effects. All patients showed significant increases in vergence ranges with concurrent marked reduction of symptoms after training. All patients showed a flattening of and an increase in the base-out portion of their fixation disparity curve. Our results demonstrated the effectiveness of fusional vergence training in reducing asthenopia in these patients. Subsequent accommodation and vergence training using traditional orthoptic procedures yielded further reduction of asthenopia, as well as an increase in the base-out fusional range.

Adolescent↗

PubMed1984

Classification criterion for success in the treatment of convergence insufficiency.

Using data collected from a retrospective study of the records of 110 patients diagnosed as having convergence insufficiency, a model has been developed which allows the classification of a patient into one of two categories of success (total or partial/none) on the basis of an initial examination. The subjects were treated with orthoptics and classified into either the total success group (no objective or subjective visual difficulties) or the partial/no success group. Stepwise discriminant analysis was used in the data reduction phase in which 6 of 14 possible variables were selected which best explained the variation in the degree of success. These six variables were: (1) the AC/A ratio; (2) the negative vergence blur value at 40 cm; (3) the recovery value of the positive vergences at 6 m; (4) the break value of the positive vergence at 6 m; (5) the amplitude of accommodation; and (6) the frequency of the deviation. Subjects were more likely to be successful when 1, 2 and 3 were high, 4 and 5 were low, and the deviation was latent. Discriminant analysis using these six variables allowed 25 of 33 (76%) of the patients to be correctly classified in terms of their success. The application of the model for classifying patients with convergence insufficiency is presented and briefly discussed.

Accommodation, Ocular↗

PubMed1984

Convergence insufficiency.

A retrospective study of 110 subjects with convergence insufficiency has been completed. Their mean age was 19.9 years. There were 72 females and 38 males in the group. The clinical profiles of these subjects were examined before and after a standard orthoptic treatment regimen. Over the course of treatment, the near angle of deviation, the AC/A ratio, a portion of the negative vergence values, all the positive vergence values, the nearpoint of convergence, and the amplitude of accommodation were found to have changed in a statistically significant manner. The importance of these findings is discussed.

Accommodation, Ocular↗

PubMed2003

Assessment of the convergent validity of pain intensity in the Pain Sensory Tool.

The purpose of this study was to examine the convergent validity of the Pain Sensory Tool with the Poker Chip Tool. Both tools were used to assess children's pain intensity (ages 5 to 14 years). A total of 104 hospitalized Taiwanese children with acute pain were asked to participate in this study. All children were required to use both the Pain Sensory Tool and the Poker Chip Tool to measure their pain. The results of Pearson correlation revealed a coefficient of.79 to.88. The convergent validity of the Pain Sensory Tool with the Poker Chip Tool was therefore supported. No significant differences in preferences of using the PST and the PCT were found by age group and sex. The findings of this study also demonstrated that the Poker Chip Tool can be used to measure Taiwanese children's pain intensity. In addition, the Pain Sensory Tool and the Poker Chip Tool were reliable instruments to measure pain intensity of Taiwanese children (ranged from 5 to 14 years of age). However, 27 % of five-year-old children failed to understand the instructions of the PST although these children were dropped from the study. This raises concerns about the validity of the PST for five-year-old children. It is not clear whether these five-year-old children were outliers or whether the PST is difficult for younger children. The authors suggested duplicating this study and specifying the five-year-old age group for the validity test.

Acute Disease↗