Longer Gap Research Articles

Experimental Investigation on Vacuum Arc Behaviors Subjected to Larger Diameter Cup-Shaped and Coil-Shaped Axial Magnetic Field Electrode

In this paper, high-current vacuum arc (VA) breaking experiments in vacuum interrupters were conducted using two kinds of high-capacity (larger diameter) axial magnetic field (AMF) electrodes with contact gap distance changing from 10 to 40 mm. Triggering arc mode and fixed gap distance were adopted. Experimental results showed that during the initial diffusion stage, the arc voltage of high-current VA got a peak value. The change in high-current VA appearance would also affect the curve of arc voltage. With the increase of contact gap distance, the voltage of high-current VA increased and the VA near the anode appeared contracted, and its shape was changed from cylinder to cone. In the shorter gap distance, for cup electrodes, the plasma jets mix with each other and the arc column appears like a bright cone, whereas for coil electrodes, the plasma jets are clear and the column appears like a cylinder, and the transfer of arc appearance affects arc voltage distribution. Moreover, arc twist and rotation often occur under longer gap and higher current, which is due to the larger radial magnetic field component generated by AMF coils, and arc voltage appeared high-frequency and high-amplitude noise, and ultimately resulted in the distortion of the arc current in the current experimental conditions (lower charging voltage of capacitor).

Le diagnostic anténatal modifie-t-il la prise en charge néonatale et le devenir à 1 an des enfants suivis pour atrésie de l’œsophage de type III ?

Evaluate neonatal management and outcome of neonates with either a prenatal or a post-natal diagnosis of EA type III. Population-based study using data from the French National Register for EA from 2008to 2010. We compared children with prenatal versus post-natal diagnosis in regards to prenatal, maternal and neonatal characteristics. We define a composite variable of morbidity (anastomotic esophageal leaks, recurrent fistula, stenosis) and mortality at 1year. Four hundred and eight live births with EA type III were recorded with a prenatal diagnosis rate of 18.1%. Transfer after birth was lower in prenatal subset (32.4% versus 81.5%, P<0.001). Delay between birth and first intervention was not significantly different. Defect size (2cm vs 1.4cm, P<0.001), gastrostomy (21.6% versus 8.7%, P<0.001) and length in neonatal unit care were higher in prenatal subset (47.9days versus 33.6days, P<0.001). The composite variables were higher in prenatal diagnosis subset (38.7% vs 26.1%, P=0.044). Despite the excellent survival rate of EA, cases with antenatal detection have a higher morbidity related to the EA type (longer gap). Even if it does not modify neonatal management and 1-year outcome, prenatal diagnosis allows antenatal parental counseling and avoids post-natal transfer.

Do changes in anal sphincter anatomy correlate with anal function in women with a history of vaginal delivery?

To evaluate anal sphincter anatomy using three-dimensional ultrasonography (3-DAUS) in incontinent women with vaginal delivery, correlate anatomical findings with symptoms of fecal incontinence and determine the effect of vaginal delivery on anal canal anatomy and function. Female with fecal incontinence and vaginal delivery were assessed with Wexner's score, manometry, and 3DAUS. A control group comprising asymptomatic nulliparous was included. Anal pressure, the angle of the defect and length of the external anal sphincter (EAS), the anterior and posterior internal anal sphincter (IAS), the EAS + puborectal and the gap were measured and correlated with score. Of the 62, 49 had fecal incontinence and 13 were asymptomatic. Twenty five had EAS defects, 8 had combined EAS+IAS defects, 16 had intact sphincters and continence scores were similar. Subjects with sphincter defects had a shorter anterior EAS, IAS and longer gap than women without defects. Those with a vaginal delivery and intact sphincters had a shorter anterior EAS and longer gap than nulliparous. We found correlations between resting pressure and anterior EAS and IAS length in patients with defects. Fecal incontinence symptoms did not correlate with anal pressures and anal sphincter anatomy changes, but women with sphincter defects have shorter anterior EAS and IAS and a longer gap.

Calculation of melting/breaking of GW and OPGW strands struck by DC arc discharge simulating high energy lightning

Some metal strands of ground wire (GW) and composite fiber-optic ground wire (OPGW) are sometimes melted and broken by high energy lightning strikes. Direct current (DC) arc tests simulating high energy lightning strikes have thus been performed to obtain the melting and breaking characteristics of these strands. In this work, calculations regarding these characteristics are performed considering the transferred heat and its area from the arc to the strands. The melting/breaking characteristics of the strands are calculated for arc currents of 0.1–100kA, considering the current prescribed in the IEC standard and the measured actual lightning current. The calculation results of the strand-breaking duration depending on the arc current show good agreement with the experimental values obtained in DC arc tests. Furthermore, the calculation results show that the IEC standard testing conditions are far more severe than those in the cases of a higher current and longer gap.

Could zinc supplementation improve bone status in growth hormone (GH) deficient children?

Reduced bone mineral density (BMD) and increased fracture rate have been reported in subjects with either childhood or adult onset growth hormone (GH) deficiency (GHD), more severe in childhood onset GHD [1, 2]. A longer gap in GH replacement in adults with childhood onset GHD is associated with a lower bone mineralization and GH replacement has been suggested having a critical role in transition to adulthood to optimize bone accrual [3]. Furthermore, also a delay in starting GH replacement in GHD adults may be associated with a persistent increase in vertebral fracture risk [4]. However, many criticisms have been raised on these assumptions. Limitations of current bone imaging techniques have caused many artefacts about BMD and bone structure. Using appropriate size corrections, BMD is normal in children and adults with isolated GHD in several studies and the anabolic changes in muscle mass and strength may contribute to the observed bone changes [for critical reviews see 5, 6]. Briefly, many historical studies used T-scores in GHD children, comparing children’s BMD with adult reference data. On the other hand, when age—and sex—Z scores have been introduced for the pediatric population, height remained a confounding factor and being tall or short for age leads to a false negative or a false positive result for BMD Z-score, respectively. Since 2008, official positions of the International Society for Clinical Densitometry strongly recommend size correction for DXA measurements in the pediatric age [7]; however, no consensus exists how to correct measurements. To date, the most real effect of GHD on bone seems to be a reduction in bone volume ratio and trabecular thickness in both animal and human studies [5, 6]. Moreover, we must not forget that GH replacement causes biphasic effects on the bone remodeling with early stimulation of bone resorption followed by a sustained increase in bone formation [8]: some controversial results of published literature could be due to the time from the start of the therapy. On the other hand, it is unclear whether changes in BMD may really predict the fracture risk in patients with GHD, as well as other forms of secondary osteoporosis, being other markers of bone quality still searched. The first point in favor of the paper by Ekbote et al. [9] in this issue of Endocrine is that the Authors performed size correction for DXA bone mineral content (BMC) and bone area (BA) measurements using height. They showed that in Indian prepubertal children with isolated GHD, height adjusted BMC and BA significantly increased of 48 and 40 %, respectively, after 1 year of GH treatment. These changes were associated with an increase in height adjusted lean body mass and a decrease in height adjusted body fat. Many previous studies in childhood onset GHD, in particular in Italian and Dutch cohorts, reported an increase in BMC in the range of 2–10 %, significantly lower than that observed in the present study [5, 6]. However, it has to be emphasized that the majority of other studies did not perform any size correction. Furthermore, the population investigated in this study [9] presented a very low BMC at baseline and this aspect could have influenced the results. However, we can first speculate that when BMC is clearly reduced in GHD patients, a treatment with rhGH works in improving bone health. Bone metabolism is complex. Many factors tightly regulate BMC and bone accrual, mainly, among others, F. Prodam SCDU of Pediatrics, Department of Health Sciences, Universita del Piemonte Orientale ‘‘A. Avogadro’’, Novara, Italy

Gaps-in-noise (GIN©) test results in children with and without reading disabilities and phonological processing deficits

Objective: To determine if the gaps-in-noise (GIN©) test could differentiate children with dyslexia and significant phonological awareness deficits from a group of children with normal reading skills. Design: A prospective study of GIN test performance in two groups of children. Participants were administered routine audiological tests, a phonological processing test, and an auditory temporal resolution test (GIN test). Statistical testing was completed to determine if significant differences existed between groups on GIN test results and phonological processing measures, and to examine potential relationships between these test measures. Routine clinical analysis procedures examined the performance of the two groups from a clinical perspective. Study sample: Participants included 61 children between the ages of 8 years, 1 month and 9 years, 11 months, separated into two groups: children with dyslexia and significant phonological deficits (Group I); normal-reading peers with age-appropriate phonological skills (Group II). Results: Children in Group I showed longer gap detection (GD) thresholds and lower gap identification scores than did the children in Group II. Results of statistical and clinical testing revealed significant differences between the groups. Conclusion: An auditory temporal processing deficit is a factor to be considered in children presenting with dyslexia and phonological processing disorders.

Detecting genomic indel variants with exact breakpoints in single- and paired-end sequencing data using SplazerS

The reliable detection of genomic variation in resequencing data is still a major challenge, especially for variants larger than a few base pairs. Sequencing reads crossing boundaries of structural variation carry the potential for their identification, but are difficult to map. Here we present a method for 'split' read mapping, where prefix and suffix match of a read may be interrupted by a longer gap in the read-to-reference alignment. We use this method to accurately detect medium-sized insertions and long deletions with precise breakpoints in genomic resequencing data. Compared with alternative split mapping methods, SplazerS significantly improves sensitivity for detecting large indel events, especially in variant-rich regions. Our method is robust in the presence of sequencing errors as well as alignment errors due to genomic mutations/divergence, and can be used on reads of variable lengths. Our analysis shows that SplazerS is a versatile tool applicable to unanchored or single-end as well as anchored paired-end reads. In addition, application of SplazerS to targeted resequencing data led to the interesting discovery of a complete, possibly functional gene retrocopy variant. SplazerS is available from http://www.seqan.de/projects/ splazers. Supplementary data are available at Bioinformatics online.

Breast cancer risk in relation to the interval between menopause and starting hormone therapy.

BackgroundAlthough breast cancer risk is greater in users of estrogen–progestin than estrogen-only formulations of menopausal hormonal therapy, reports on their effects have been somewhat inconsistent. We investigated whether the timing of these therapies affected breast cancer incidence.MethodsA total of 1 129 025 postmenopausal UK women provided prospective information on hormonal therapy use and other factors relevant for breast cancer risk. We used Cox regression to estimate adjusted relative risks (RRs) of breast cancer in hormonal therapy users vs never users and calculated standardized incidence rates. All statistical tests were two-sided.ResultsDuring 4.05 million woman-years of follow-up, 15 759 incident breast cancers occurred, with 7107 in current users of hormonal therapy. Breast cancer incidence was increased in current users of hormonal therapy, returning to that of never users a few years after use had ceased. The relative risks for breast cancer in current users were greater if hormonal therapy was begun before or soon after menopause than after a longer gap (Pheterogeneity < .001, for both estrogen-only and estrogen-progestin formulations). Among current users of estrogen-only formulations, there was little or no increase in risk if use began 5 years or more after menopause (RR = 1.05, 95% confidence interval [CI] = 0.89 to 1.24), but risk was statistically significantly increased if use began before or less than 5 years after menopause (RR = 1.43, 95% CI = 1.35 to 1.51). A similar pattern was observed among current users of estrogen–progestin formulations (RR = 1.53, 95% CI = 1.38 to 1.70, and RR = 2.04, 95% CI = 1.95 to 2.14, respectively). At 50–59 years of age, annual standardized incidence rates for breast cancer were 0.30% (95% CI = 0.29% to 0.31%) among never users of hormone therapy and 0.43% (95% CI = 0.42% to 0.45%) and 0.61% (95% CI = 0.59% to 0.64%), respectively, among current users of estrogen-only and estrogen–progestin formulations who began use less than 5 years after menopause.ConclusionsThere was substantial heterogeneity in breast cancer risk among current users of hormonal therapy. Risks were greater among users of estrogen–progestin than estrogen-only formulations and if hormonal therapy started at around the time of menopause than later.

Delayed Operating Room Availability Significantly Impacts The Total Hospital Costs Of An Urgent Surgical Procedure

Background Financial pressures drive efforts to optimize hospital resource use, but inefficiencies occur in systems as volume nears total capacity. We examined how operating room use impacts efficiency and costs of treating an urgent surgical condition. Methods A retrospective review of patients who underwent appendectomy for appendicitis at a single hospital from 2004 to 2009 was performed. Patient demographics, operative characteristics, pathologic diagnoses, hospital time intervals, and costs were analyzed. Gap time (time from case booking to surgery start) was used to measure operating room availability. Results In all, 453 patients met inclusion criteria. Longer gap times were associated with increased hospital-based costs. A gap time of greater than 2 h was associated with 39% higher costs to the hospital, which could not be accounted for by any single cost center. The patients in the 2 groups had similar medical and surgical complexity, as well as similar clinical outcomes and hospital duration of stay. Gap times were greatest during peak elective operating room activity (7 am to 11 pm ); however, the total hospital costs were not related to the time of day of the case. Conclusion A short delay in operating room availability for urgent cases is associated with significantly increased total hospital costs. Our data suggest this finding is attributable to inefficient care when the operating room volume nears total capacity.

Effects of Auxiliary Electrode Width in AC Plasma Display Panels With Auxiliary Electrodes

We investigated the effects of changing the width of the auxiliary electrode in an ac plasma display panel including centrally located auxiliary electrodes between the sustain electrodes, based on analyses of the discharge mode. A panel with auxiliary electrodes was driven by pulse waveforms that included auxiliary pulses applied to the auxiliary electrode immediately after every sustain pulse. The discharge modes are changed consecutively from mode 1 to mode 3-2 when the sustain or auxiliary pulse voltages are increased, which can be characterized as follows: 1) only the sustain pulse discharges are generated in mode 1; 2) one of a pair of the auxiliary pulse discharges is additionally generated in mode 2; and 3) the other auxiliary pulse discharge is also generated in mode 3-1 and mode 3-2. Distribution of the discharge mode changes in accordance with the width of the auxiliary electrode (the focus is on modes 1 and 2 because these modes are effective modes); as the auxiliary electrode is narrowed, the range of mode 1 becomes wide and the range of mode 2 becomes narrow. The wide range of mode 1 is attributed to the fact that the discharge of the auxiliary pulse is suppressed due to a longer gap between the sustain and auxiliary electrodes. The narrow range of mode 2 is caused by the discharge of the auxiliary pulse less affecting the discharge of the sustain pulse. Since the auxiliary electrode provides less of a decrease in the number of wall charges on the sustain electrodes, the voltage margin is improved for the case of the narrow auxiliary electrode. The luminous efficacy is mostly improved in mode 1 for the case of the narrow auxiliary electrode due to the auxiliary pulse with a higher voltage generating a larger number of space charges, as well as in mode 2 for the case of the wide auxiliary electrode due to a short electrode gap rendering a great number of wall charges decreasing.

Technology Assessment of a Novel High-Yield Lithographic Technique for Sub-15-nm Direct Nanotransfer Printing of Nanogap Electrodes

We have demonstrated direct nanoscale transfer printing (nTP) of PdAu lines from a hard mold onto a hard substrate at room temperature without employing any flexible buffer layers or organic adhesion promoters or release agent layers. PdAu was evaporated onto the mold surface, and a Ti layer was deposited on top of the PdAu layer. By pressing the mold against a Si/SiO2 substrate, the PdAu/Ti sandwich structure was directly transferred onto the SiO2 surface. The molds used in these experiments were GaAs/AlGaAs sandwich structures fabricated by molecular beam epitaxy that we cleaved and selectively etched afterwards in order to generate 3-D grating structures with nanometer resolution on their edges. We fabricated positive multiline molds with different aspect ratios, linewidths between 15 and 100 nm, and spacings between lines ranging from 5 to 70 nm. We also fabricated negative single-line molds with a positive supporting structure comprising a single 16-nm-wide groove feature. The experiments revealed that direct hard-on-hard transfer of nanoscale structures from a mold onto a substrate can be used to fabricate PdAu gaps with widths down to 9 nm. We also performed electronic measurements on transfer patterns and demonstrated that transferred structures can be used as electrodes, which are electrically isolated by these gaps. Since isolation characteristics of gaps improved with decreasing gap length, we partitioned longer gap segments into multiple shorter ones by focused ion beam lithography and conventional optical lithography in combination with wet chemical or plasma etching of the mold or the substrate, respectively. In this paper, we give a detailed description of all technological aspects of the developed direct nTP technique, including mold preparation, patterning efficiency, short reduction techniques, and yield.

The Impact of Methodological Approach on Cost Findings in Comparison of Epoetin Alfa with Darbepoetin Alfa

Two erythropoiesis-stimulating agents (ESAs), epoetin alfa and darbepoetin alfa, are approved for the treatment of chemotherapy-induced anemia in patients with cancer. Randomized controlled trials indicate that the drugs are similarly efficacious, but that the duration of clinical benefit (DCB) ranges from 2 to 7 days for epoetin alfa and from 7 to 21 days for darbepoetin alfa, depending on dose. Given equivalent efficacy, payers are increasingly interested in understanding the cost differences for these 2 drugs. To examine the impact of different methodological approaches on the cost comparison between epoetin alfa and darbepoetin alfa users, with cancer from a payer perspective. Episodes of care (episode) were constructed for cancer patients treated with ESAs, using MarketScan claims data. Episodes started with the first ESA claim and ended on the last ESA claim or the claim before a 42-day or longer gap in ESA therapy. Each episode was augmented with an estimated DCB based on the last dose in the episode. Cost was reimbursed amount observed in the claims database. Adjusted weekly cost was estimated using generalized linear models to control for difference in clinical and demographic differences across epoetin alfa and darbepoetin alfa episodes. Episodes were created in 324 darbepoetin alfa and 342 epoetin alfa users. Darbepoetin alfa users tended to be younger, had more comorbidities, and had advanced cancer (all p < 0.001). After accounting for DCB, the average weekly cost of darbepoetin alfa was significantly lower than that of epoetin alfa ($619 vs $940; p < 0.001). After multivariate adjustment, darbepoetin alfa had lower costs than epoetin alfa in the base case and all alternative approaches. To reduce the risk of potential bias, DCB and different patient characteristics should be taken into account when using retrospective claims data to conduct cost comparisons between agents that have significant differences in dosing schedule.

The Impact of Methodological Approach on Cost Findings in Comparison of Epoetin Alfa with Darbepoetin Alfa

Background/Objective: There is interest in longer acting therapies with extended dosing schedules as a mechanism to improve patient compliance and/or decrease health resource utilization (in the case of therapies administered in physician offices/clinics). Based on randomized controlled trial (RCTs) data, the duration of clinical benefit (DCB) of Epoetin alfa (EA) ranges from 2–7 days depending on dose and darbepoetin alfa (DA) ranges from 7–21 days. Comparison of weekly cost between DA and EA in claims data analysis may not be valid if their estimated DCBs are not taken into account. Thus the objective of this study was to use a case study to examine the costs of epoetin alfa (EA) and darbepoetin alfa (DA), 2 erythropoiesis stimulating agents (ESAs), for cancer patients with anemia due to cancer, chemotherapy or radiation treatment.Methods: The MarketScan Research Database, a large national claims database, was used to build EA and DA treatment episodes among patients with a cancer diagnosis on at least 2 medical or facility claims, with no diagnoses indicating chronic renal disease, and with at least 1 EA or DA medical or pharmacy claim. Claims were from patients who were continuously enrolled for benefits during the 6-month period from January-June 2005. Base-case average weekly costs were calculated, with the episode of care (EOC) being the number of days from first date of service for an ESA claim to the last date of service for an ESA claim or until there was a 42-day or longer gap in ESA therapy. Each episode was augmented with an estimated duration of clinical benefit calculated from the last dose administered in the EOC. DCB estimates were based on the results of randomized controlled trials: EA doses <35,000 units =2 days and >=35,000 units =7 days; DA doses <=100 mcg =7 days, 101–299 mcg =14 days, and >=300 mcg =21 days. Cost was reimbursed amount observed in the claims database.Results: Analysis-of-variance (ANOVA) models estimated an adjusted average weekly cost controlling for difference in clinical/demographic differences across EA and DA users. Younger patients, those with more comorbidities, and those with advanced cancer, were found to have increased likelihood of DA use (all P<0.001). After accounting for DCB, the average weekly dose across all episodes was 43,113 units for EA and 94 mcg for DA; the average weekly cost of DA was significantly lower than that of EA ($561 vs. $983, P<0.001). Sensitivity tests on patient selection criteria, length of follow-up period, and definitions of average weekly cost and dose had minimal impact on findings, while changes were more dramatic when different DCB rules were applied. DA had lower costs than EA in all sensitivity analyses except when single dose episodes were excluded and no DCB adjustment was incorporated. With ANOVA adjustment to equalize the population characteristics, estimated average weekly cost was $647 for DA and $833 for EA in the base case..Conclusion: Failure to adjust for differences in patient demographic and clinical characteristics between users of EA and DA can result in misleading comparisons. Cost calculations are sensitive to incorporating the assumption of duration of clinical benefit and the decision to drop and/or retain single dose episodes. To reduce the risk of potential bias, these factors should be taken into account when using retrospective claims data to conduct cost comparisons between agents that have significant differences in dosing schedule.

Factors influencing diagnosis delay in children with Tourette syndrome

Background Tourette syndrome (TS) is a chronic disorder characterized by motor and vocal tics. Previous studies reported a substantial lag period between disease onset and diagnosis ranging from 3 to 11.9 years. Aims To determine the lag period and factors associated with diagnosis delay of TS. Methods All files of 185 children with TS attending one neuropediatric unit in Jerusalem were reviewed. Lag time between disease onset, according to DSM criteria, and diagnosis was determined and the contributions of the disease course, comorbidities and epidemiological factors were assessed. Results A relatively short lag to diagnosis following the onset of diagnosable TS was documented (mean 13.2±15.9 months, median 6 months). A relatively longer gap was associated with older age at TS onset ( r=0.161, p<0.05) and vocal tics as the first manifestation rather than motor or combined motor and vocal tics (mean=20.3+16.3 months vs 11.9+16.5 and 12.6+15.2, respectively, p<0.05). A relatively shorter gap was associated with tic severity ( r=0.13, p<0.05) and presence of comorbid obsessive–compulsive disorder (OCD) (9.5+14.7 months vs. 14.1+16 without OCD, p<0.05). Conclusions Lag time to diagnosis is relatively short in our population. Factors associated with a shorter lag (early age of TS onset, motor tics as the first manifestation, greater tics severity and the presence of OCD) may be perceived as disruptive, prompting patient and families to seek medical care. Conversely, vocal tics as the first manifestation, associated with a longer lag, may be misdiagnosed as features of common pediatric conditions, thus delaying diagnosis.

Anal canal anatomy showed by three-dimensional anorectal ultrasonography

Demonstrate precisely the anatomic configuration of the anal canal and the length and thickness of the anal sphincters using three-dimensional (3-D) anorectal ultra-sonography in both genders. Twelve normal volunteer males and 14 females, with a mean age of 52.4 and 50.3 years, respectively, were prospectively enrolled in this study. All individuals from both groups were submitted to anorectal ultra-sonography. The anal canal was analyzed, measuring the length and thickness of the external anal sphincter (EAE), internal anal sphincter (IAS), puborectalis muscle (PR) and the gap (distance from the anterior EAS to the anorectal junction) in the midline longitudinal (ML) and transverse (MT) planes, and the results were compared between quadrants and genders. The distribution of sphincter muscles is asymmetric in both genders. The anterior upper anal canal is an extension of the rectal wall with all layers clearly identified. The anterior IAS is formed in the distal upper anal canal and is significantly shorter in female than in male in all quadrants. The anterior IAS length is shorter than the posterior and lateral in both genders. The anterior EAS length is significantly shorter (2.2 cm) and the gap is longer (1.2 cm) in female than in male (3.4 cm) (0.7 cm) (p < 0.05), respectively. The posterior and lateral EAS-PR is significant longer in males (3.6 cm) (3.9 cm) than in females (3.2 cm) (3.5 cm) (p < 0.05), respectively. The lateral EAS-PR is significant longer than the posterior part in both genders. The anterior IAS is significantly thicker in males (0.19 cm) than in females (0.12 cm) (p = 0.04). 3-D anal endosonography enabled measurement of the different anatomical structures of the anal canal and demonstrated its asymmetrical configuration. The shorter anterior EAS and IAS associated with a longer gap could justify the higher incidence of pelvic floor dysfunction in females, especially fecal incontinence and anorectocele with rectal intussusception.

Pigeons’ memory for sequences of light flashes when gap duration is an unreliable discriminative cue

In Experiment 1, pigeons were trained with a 1-sec dark and a 1-sec houselight-illuminated delay interval to discriminate between sequences of two and four flashes of light (feeder illumination). The sequences could be discriminated on the basis of the number of flashes, the number of gaps, or the duration of the gap between flashes. A choose-few bias was obtained at extended dark delays, but not at extended illuminated delays. Pigeons appeared to confuse long dark delays with the longer gap between flashes on few-sample trials. In Experiment 2, additional sample sequences were included that made gap duration an unreliable cue for discriminating between the few and many samples. A significant choose-many bias was obtained at extended dark delay intervals, but no biased forgetting was found at extended illuminated delays. The pigeons appeared to discriminate light flash sequences by relying on multiple temporal features of a sequence rather than using an event switch to count flashes. The biased-forgetting effects observed appear to be due to instructional ambiguity that results from the similarity of the delay interval to features of the flash sequences.

Discharge characteristics of a new ACPDP structure using Thick-Film Ceramic Sheet technology

— We have proposed a counterelectrode PDP structure in which the sustain and scan electrodes are embedded face to face in the ribs by applying Thick-Film Ceramic Sheet technology. An advantage of the counterelectrode PDP is low discharge voltage, which does not depend on the dielectric thickness. A positive column is observed at a longer gap, and the luminous efficacy reaches 3.7 lm/W at Ne-30%Xe at a 450-μm discharge gap.

14.2: Discharge Characteristics of a New Structure AC-PDP Using Thick Film Ceramic Sheet Technology

We have proposed a counter-electrode PDP, in which sustain and scan electrodes are embedded face-to-face by applying Thick Film Ceramic Sheet technology. An advantage of the counter-electrode PDP is low discharge voltage, which does not depend on dielectric thickness. A positive column is observed at a longer gap, and the luminous efficacy reaches to 3.7 lm/W at Ne-30%Xe and 450um discharge gap.

Dynamics of Gapped DNA Recognition by Human Polymerase β

Kinetics of human polymerase beta binding to gapped DNA substrates having single stranded (ss) DNA gaps with five or two nucleotide residues in the ssDNA gap has been examined, using the fluorescence stopped-flow technique. The mechanism of the recognition does not depend on the length of the ssDNA gap. Formation of the enzyme complex with both DNA substrates occurs by a minimum three-step reaction, with the bimolecular step followed by two isomerization steps. The results indicate that the polymerase initiates the association with gapped DNA substrates through the DNA-binding subsite located on the 8-kDa domain of the enzyme. This first association step is independent of the length of the ssDNA gap and is characterized by similar rate constants for both examined DNA substrates. The subsequent, first-order transition occurs at the rate of approximately 600-1200 s(-1). This is the major docking step accompanied by favorable free energy changes in which the 31-kDa domain engages in interactions with the DNA. The 5'-terminal PO(4)(-) group downstream from the primer is not a specific recognition element of the gap. However, the phosphate group affects the enzyme orientation in the complex with the DNA, particularly, for the substrate with a longer gap.

Incorporation, Relative Homoplasy, and Effect of Gap Characters in Sequence-Based Phylogenetic Analyses

Phylogenetic analysis of nucleotide and amino acid sequences requires the alignment of homologous sequences. The alignment procedure often requires the insertion of gaps, putatively corresponding to insertion or deletion events, which can be coded as phylogenetic characters. As a general class of phylogenetic characters, gaps have variously been suggested to be reliable (e.g., Lloyd and Calder, 1991; Van Dijk et al., 1999) or unreliable (e.g., Golenberg et al., 1993; Ford et al., 1995). This difference in opinion, coupled with the lack of a well-supported method for the coding of gaps, has led to a diversity of approaches by which gaps have been treated in, or excluded from, tree searches (Gonzalez, 1996). In an earlier paper we presented two methods, termed simple and complex indel coding, in which all gaps (excluding leading and trailing gaps, which are generally artifacts) can be coded from aligned sequence-based matrices (Simmons and Ochoterena, 2000). Simple indel coding, which is used in this study, is implemented by coding all gaps that have different 5' or 3' termini as separate presence/absence characters. Whenever a gap is being coded and the region it spans is completely included within the span of another gap, those sequences having the longer gap (i.e., one that extends to or beyond both the 5' and 3' termini of the gap being coded) are scored as inapplicable for the gap character being coded. Some have suggested on theoretical and empirical grounds that longer gaps are better phylogenetic characters than shorter gaps. Lloyd and Calder (1991) argued that multiresidue gaps are reliable phylogenetic characters because indels are unlikely to be repeated in the exact same position with the same length and sequence (for insertions); indels of different lengths at the same position are recognized as separate events. Similarly, van Ham et al. (1994) suggested that, based on the relative levels of homoplasy in the intergenic spacer between trnL and trnF, gaps longer than two positions are reliable phylogenetic characters. In this paper we assess the relative levels of homoplasy of gap and base characters from a selection of 38 published sequence-based matrices. We determine the potential phylogenetic information included in gap characters and the extent to which inclusion of gap characters alters the gene tree topology and branch support values. We also test the assertion that longer gaps are better phylogenetic characters than shorter gaps.