bluuebunny/crossref_metadata_2025 huggingface dataset:
Previous tonsillectomy as prognostic indicator for success of uvulopalatopharyngoplasty
Authors: Mcguirt William F. , Johnson Jonas T. , Sanders Mark H.
Published: October 2006

Factors that determine a successful outcome following uvulopalatopharyngoplasty (UPPP) for obstructive sleep apnea (OSA) are not well defined. This study was undertaken to determine if prior tonsillectomy is predictive of a lower response rate to UPPP. A retrospective review of a cohort undergoing UPPP alone or in combination with nasal septoplasty for OSA was undertaken. Preoperative and postoperative polysomnograms were obtained to evaluate the severity of the OSA. The sample was a consecutive series of 79 patients with OSA. Clinical evaluation was performed by both an otolaryngologist and a pulmo‐nologist. Surgical treatment in this group of 79 patients included 52 UPPP and 27 UPPP in patients with prior tonsillectomy. Concurrent septoplasty was undertaken in 17 patients.

Criteria for outcome were based on comparison of preoperative and postoperative polysomnograms (i.e., apnea index, respiratory disturbance index change, and lowest saturation). A response to therapy was defined as a reduction in apnea index greater than 50%. A success was defined as apnea index less than 5, reduction of respiratory disturbance index greater than 50%, and nadir saturation greater than 82%. In 79 patients with OSA, 78% responded and 37% reflected therapeutic successes. Patients with history of prior tonsillectomy were less likely to have therapeutic improvement following UPPP. In 52 patients without previous tonsillectomy, 88% responded and 52% had a successful outcome. of those with previous tonsillectomy, 59% responded and 7% had a successful outcome.

The status of previous tonsillectomy is an important prognostic indicator in the success of UPPP for the treatment of OSA. We speculate that the presence of palatine tonsils allows the removal of an extra measure of oropharyngeal tissue, thereby improving the likelihood of success for UPPP.
Hemicentins Assemble on Diverse Epithelia in the Mouse
Authors: Xu Xuehong , Dong Chun , Vogel Bruce E.
Published: October 2006

Hemicentins are recently described extracellular matrix (ECM) proteins with a single ortholog in C. elegans that assembles into discrete tracks constricting broad regions of epithelial cell contact into adhesive and flexible line-shaped junctions. There are two highly conserved hemicentin genes in most vertebrate species; however, nothing is known about the function or distribution of vertebrate hemicentins. To determine the distribution of vertebrate hemicentins, we used a polyclonal antibody to stain mouse tissue and showed that hemicentins are found in the pericellular ECM of epithelial cells in a number of tissues including embryonic trophectoderm and adult skin and tongue, in addition to the ECM of some, but not all, blood vessels. Hemicentins also assemble on multiple epithelia in the eye, including cornea, lens, and retina. The pericellular localization of vertebrate hemicentins on epithelia and other cell surfaces suggests that vertebrate hemicentins, like their nematode counterpart, are secreted ECM proteins likely to have a role in the architecture of adhesive and flexible cell junctions, particularly in tissues subject to significant amounts of mechanical stress.
Patterns of Mobilization in Local Movement Organizations: Leadership and Strategy in Four National Organization for Women Chapters
Authors: Reger Jo , Staggenborg Suzanne
Published: October 2006

This article focuses on the organizational strategies of four local chapters of the National Organization for Women (NOW) across three decades. The goal is to explain differences in chapters' abilities to remain active and to survive over time by examining their overall patterns of mobilization. The authors argue that the ability to maintain organizational stability and collective action is influenced by internal organizational characteristics and strategies, such as leadership, mobilizing tactics, and organizational structure, as well as by external factors. Two of the chapters, New York City and Chicago NOW, have remained relatively stable throughout their histories and continue to survive. The other two, in Cleveland, Ohio, and Bloomington, Indiana, experienced dramatic ups and downs during their histories and ultimately declined. The authors argue that leadership and organizational choices influence these patterns of chapter mobilization.
Organizational Sectors and the Institutionalization of Job-Training Programs: Evidence from a Longitudinal National Organizations Survey
Authors: Yang Song
Published: October 2006

This study assesses the institutional impact of coercive, normative, and mimetic pressures on job-training programs and the extent to which the institutionalization of such programs is contingent upon the environment in which organizations operate. Event-history analysis of a retrospective data set (1967 to 1997) of 301 American organizations indicates that having an external human resources attorney and competing with a number of other organizations with training—two of the mimetic institutional effects—are the driving factors behind the spread of job-training programs. Furthermore, these mimetic institutional pressures exert a stronger impact on governmental organizations' choice to adopt training programs than on for-profit firms. Governmental agencies appear to be more responsive to institutional influences because, compared with for-profit firms, they are in greater need of external legitimation of their procedures and operations, one of the crucial benefits of being an institutional conformist.
Leadership Structures in Same-Sex Task Groups
Authors: Hysom Stuart J. , Johnson Cathryn
Published: October 2006

This article investigates contradictory findings reported in the literature concerning differences in leadership differentiation between same-sex groups. Drawing on arguments developed by Walker et al. (1996) addressing measurement validity in this literature, and on an extension in the status literature developed by Ridgeway (1988) and Fennell et al. (1978), this article develops and tests three predictions. Specifically, the authors predict greater differences in leadership differentiation between all-male and all-female groups when assessing leadership based on procedural behaviors than when assessing leadership based on influence. Also, leadership differentiation will be greater in all-male groups within a male-dominated organization, and in all-female groups within a female-dominated organization, than in all-female groups within a male-dominated organization when assessing leadership based on procedural compared with influence behaviors. Contrary to predictions, results show that all-male and all-female groups are equally likely to develop differentiated leadership structures when using procedural- and influenced-based measures. Implications of these results are discussed.
Identity and Competence: The Use of Culture in the Interpretation of Sexual Images
Authors: Armstrong Elizabeth A. , Weinberg Martin S.
Published: October 2006

Cultural sociology agrees that meanings attributed to objects vary depending upon the cultural competencies of viewers, but tends to ignore the role of identities in interpretation. This article argues that both identities and competencies influence interpretation. Through an analysis of how 307 undergraduate students at a Midwestern state university interpreted a black-and-white photograph of an individual masturbating, this article finds that assessments of the degree to which the image should be considered art and/or pornography are associated with self-reported indicators of both cultural competencies and identities. Indicators of religious and conventional identities and of training with regard to photography stand out in this regard. The intersection of the constructions of pornography and art enabled the authors to classify participants as Nonartistic Conservatives, Nonartistic Liberals, Artistic Liberals, and Artistic Conservatives and to show that interpretations are a consequence of how persons are simultaneously situated in relation to both moral and aesthetic criteria.
The Natural History of Juvenile or Subacute GM2 Gangliosidosis: 21 New Cases and Literature Review of 134 Previously Reported
Authors: Maegawa Gustavo H. B. , Stockley Tracy , Tropak Michael , Banwell Brenda , Blaser Susan , Kok Fernando , Giugliani Roberto , Mahuran Don , Clarke Joe T.R.
Published: October 2006

OBJECTIVE. Juvenile GM2 gangliosidosis is a group of inherited neurodegenerative diseases caused by deficiency of lysosomal β-hexosaminidase resulting in GM2 ganglioside accumulation in brain. The purpose of this study was to delineate the natural history of the condition and identify genotype-phenotype correlations that might be helpful in predicting the course of the disease in individual patients.

METHODS. A cohort of 21 patients with juvenile GM2 gangliosidosis, 15 with the Tay-Sachs variant and 6 with the Sandhoff variant, was studied prospectively in 2 centers. Our experience was compared with previously published reports on 134 patients. Information about clinical features, β-hexosaminidase enzyme activity, and mutation analysis was collected.

RESULTS. In our cohort of patients, the mean (±SD) age of onset of symptoms was 5.3 ± 4.1 years, with a mean follow-up time of 8.4 years. The most common symptoms at onset were gait disturbances (66.7%), incoordination (52.4%), speech problems (28.6%), and developmental delay (28.6%). The age of onset of gait disturbances was 7.1 ± 5.6 years. The mean time for progression to becoming wheelchair-bound was 6.2 ± 5.5 years. The mean age of onset of speech problems was 7.0 ± 5.6 years, with a mean time of progression to anarthria of 5.6 ± 5.3 years. Muscle wasting (10.6 ± 7.4 years), proximal weakness (11.1 ± 7.7 years), and incontinence of sphincters (14.6 ± 9.7 years) appeared later in the course of the disease. Psychiatric disturbances and neuropathy were more prevalent in patients with the Sandhoff variant than in those with the Tay-Sachs variant. However, dysphagia, sphincter incontinence, and sleep problems occurred earlier in those with the Tay-Sachs variant. Cerebellar atrophy was the most common finding on brain MRI (52.9%). The median survival time among the studied and reviewed patients was 14.5 years. The genotype-phenotype correlation revealed that in patients with the Tay-Sachs variant, the presence of R178H and R499H mutations was predictive of an early onset and rapidly progressive course. The presence of either G269S or W474C mutations was associated with a later onset of symptoms along with a more slowly progressive disease course.

CONCLUSIONS. Juvenile GM2 gangliosidosis is clinically heterogeneous, not only in terms of age of onset and clinical features but also with regard to the course of the disease. In general, the earlier the onset of symptoms, the more rapidly the disease progresses. The Tay-Sachs and Sandhoff variants differed somewhat in the frequency of specific clinical characteristics. Speech deterioration progressed more rapidly than gait abnormalities in both the Tay-Sachs variant and Sandhoff variant groups. Among patients with the Tay-Sachs variant, the HEXA genotype showed a significant correlation with the clinical course.
Pharmacokinetics of Pyridostigmine in a Child With Postural Tachycardia Syndrome
Authors: Filler Guido , Gow Robert M. , Nadarajah Renisha , Jacob Pierre , Johnson Gillian , Zhang Yan-Ling , Christians Uwe
Published: October 2006

Pyridostigmine has been proposed for the treatment of postural orthostatic tachycardia syndrome in adults at a dose of 60 mg twice daily, but no dosing recommendation exists for children. With the approval of our local ethics board, we tested the pharmacokinetics of pyridostigmine in 6 children with myasthenia and a pediatric index patient with severe postural orthostatic tachycardia syndrome whose condition failed all conventional therapy and who had developed significant postural hypertension. Pyridostigmine was quantified by using a validated, semiautomated, and specific high-performance liquid chromatography/tandem mass spectrometry assay in combination with online column-switching extraction and turbo electrospray ionization. The patient with postural orthostatic tachycardia syndrome showed a dose-dependent favorable response to oral pyridostigmine. Pharmacokinetic evaluation revealed a short half-life of 2.29 hours, similar to the 2.0 ± 0.63 hours in the patients with myasthenia. The patient with postural orthostatic tachycardia syndrome has subsequently been treated at a dose of 45 mg in the morning, 30 mg at lunchtime, and 15 mg at bedtime; after 9 months, there has been persistent positive effect and without additional blood pressure medication. No major adverse effects occurred. Pyridostigmine has been a safe and effective treatment modality for this child with postural orthostatic tachycardia syndrome. The short half-life suggests that dosing 3 times per day is preferable.
Evaluating the seismicity parameters of Tehran, Iran
Authors: Ghodrati Amiri G. , Motamed R. , Hashemi R. , Nouri H.
Published: October 2006

The objective of this paper is to evaluate the seismicity parameters of Tehran. These parameters are achieved using the Gutenberg–Richter method, cumulative distribution functions, and the Kijko–Sellevoll approach. First, a catalogue of earthquakes that have occurred within a radius of 200 km of Tehran is collected and processed. Aftershocks and foreshocks are ignored in the earthquake catalogue, and the main seismic events are considered in evaluating the data. In this approach the variable windows in time and location domains are employed, and the earthquakes are supposed to follow Poisson’s formulation. Subsequently, the seismicity coefficients for Gutenberg–Richter, cumulative distribution functions, and Kijko–Sellevoll methods are calculated and the magnitude–period graphs are constructed. Comparative analysis of the results shows the best accuracy for the Kijko–Sellevoll method, with the Gutenberg–Richter method providing the least precise results.
MTF measurement method for medical displays by using a bar‐pattern image
Authors: Ichikawa Katsuhiro , Kodera Yoshie , Fujita Hiroshi
Published: October 2006

Abstract— A modulation‐transfer‐function (MTF) measurement method that uses a bar‐pattern image for medical displays such as liquid‐crystal displays (LCDs) and cathode‐ray tubes (CRTs) has been investigated. A specific bar‐pattern image on the display was acquired with a high‐resolution single‐lens reflex‐type digital camera equipped with a close‐up lens. The MTF was calculated from the amplitudes of the fundamental‐frequency components, which were extracted from the profile data across the bar patterns by using Fourier analysis. Actual comparisons with the conventional line technique were performed for a medical CRT. The adequate accuracy and excellent reproducibility of the method were confirmed. Furthermore, unlike the line method, an advantageous feature which can use an input signal with sufficient amplitude was theoretically proved. Horizontal and vertical MTFs at the central position of the display area were measured up to the Nyquist frequency for several medical displays. From these measurements, this method has the capability to detect slight differences between the displays measured. This proposed method is useful in understanding and quantifying the medical display's performance due to excellent reproducibility and accuracy.
In‐field assessment of display resolution and noise: Performance evaluation of a commercial measurement system
Authors: Samei Ehsan , Cleland Esi , Roehrig Hans
Published: October 2006

Abstract— Two key metrics of image quality for high‐fidelity displays, including medical displays, are resolution and noise. Until now, these properties have been primarily measured in laboratory settings. For the first time, a system consisting of a CCD camera and analysis software has been made commercially available for measuring the resolution and noise of medical displays in a clinical setting. This study aimed at evaluating this new product in terms of accuracy and precision. In particular, the project involved the measurement of the modulation transfer function (MTF) and the signal‐to‐noise ratio (SNR) of two medical imaging displays, one cathode‐ray tube (CRT) display and one liquid‐crystal display (LCD) using this camera/software system. To assess the system's precision, measurements were made multiple times at the same setting. To check for accuracy, the results were compared with published values of the MTF and noise for the same displays. The performance of the system was also ascertained as a function of the focus setting of the camera. The results indicated that for the LCD, when the camera is focused within ±0.6 mm of the optimum focus setting, the MTF values lie within approximately 14% of the best focus MTF at the Nyquist frequency and 11% of the optimum overall sharpness (∫ MTF2 df). Similar results were obtained in the horizontal and vertical directions. For the CRT, this focus produced vertical and horizontal MTF values at the Nyquist frequency within 15.2% and 61.2% of the optimum focus MTF, respectively. The figures in terms of overall sharpness were 3.0% and 0.7%. The results for the noise measurements showed a repeatability of 3% for the LCD and 13% for the CRT and a relative (but not absolute) magnitude of the noise between the two displays reflective of prior measurements. Overall, the measurement system yielded reasonably precise resolution and noise results for both display devices. The accuracy was traceable to published results only for the MTF and for relative level of display noise with differences in the absolute magnitude of noise between current and prior measurements attributed to variations in the non‐standard techniques applied for display noise measurements.
Noise estimation and reduction on five medical liquid‐crystal displays
Authors: Fan Jiahua , Roehrig Hans , Sundareshan Malur K. , Krupinski Elizabeth A.
Published: October 2006

Abstract— Liquid‐crystal displays (LCDs) are replacing cathode‐ray tube (CRT) displays as primary diagnostic viewing devices in clinics. They exhibit higher spatial noise than CRTs, which can interfere with diagnosis and reduce the efficiency especially when subtle abnormalities are presented. A study by the authors on LCD spatial noise has recently been reported. A high‐quality CCD camera was used to acquire images from the LCD. Noise properties were estimated from the digital‐camera images. Then, an error‐diffusion‐based operation was applied to reduce the display spatial noise. This paper presents the noise estimation and reduction results on five different medical‐grade LCDs using the same study protocol. These five different LCDs vary in terms of matrix size, pixel size, pixel structure, and vendors. The purpose of this work is to demonstrate that the LCD spatial‐noise estimation and reduction scheme proposed earlier by the authors is valid, robust, and necessary for various medicalgrade LCDs used in clinics today.
Black‐level offset: Characterization and correction
Authors: Besuijen Jacobus
Published: October 2006

Abstract— The correct setting of the black level is an important step in the (re)calibration of an electronic display. This study looks at the consequences of black‐level offset, the possibilities for display characterization with offset, offset correction, and the ability of average untrained users to visually correct the black‐level setting with the contrast and brightness controls on the display. In an experiment, 32 subjects were asked to optimally set the black level according to two types of instructions (short and extensive, between subjects) under two levels of illumination (low and office, between subjects) for two types of displays (CRTs and LCDs, within subjects). Most subjects were not able to set the black level near optimal for either display, with any combination of instruction and illumination level. The LCD did not have an optimal black level. For the CRT, optimal black level did not provide minimal differences with the sRGB standard tone reproduction curve.
Calibration of diagnostic monitors: Theoretical determination of optimal luminance settings
Authors: Båth Magnus , Sund Patrik , Ungsten Linda , Månsson Lars Gunnar
Published: October 2006

Abstract— Common practice today is to calibrate diagnostic monitors according to the gray‐scale standard display function (GSDF) described in DICOM part 14. However, the GSDF is based on the assumption of variable adaptation of the human‐visual system (HVS). It is well known that the HVS adapts to the average quantity of light falling on the retina, so‐called fixed adaptation. For the luminance setting of a monitor, the effect of fixed adaptation is of interest. The wider the luminance range of the monitor, the larger the number of available just‐noticeable differences (JNDs). However, at the same time, the sensitivity of the HVS to the average contrast change is decreased since it occurs at a luminance level further away from the adaptation luminance. A computer program was therefore written which takes the effect of the fixed adaptation into account by determining the number of effective JNDs for a given luminance setting of a monitor. The probability of detecting each change in presentation value is then calculated from the distribution of effective JNDs. Based on the assumptions implemented in the program, it is shown that for monitors calibrated according to the GSDF, the optimal luminance setting for visualizing the image information in the best possible way is to use the entire available luminance range.
Generation of low‐contrast sinusoidal test patterns on a high‐brightness display
Authors: Sund Patrik , Båth Magnus , Ungsten Linda , Månsson Lars Gunnar
Published: October 2006

Abstract— By using a technique of addressing individual subpixels, low‐contrast sinusoidal test patterns were generated on a high‐brightness color LCD. Detection tasks were performed using 2AFC experiments, and the value obtained for the contrast threshold was found to agree well with previously published data. As long as the shape of the pattern was close to sinusoidal, a good correlation was found between pattern contrast and detection rate. The influence of the eye‐adaptation luminance level was studied and compared to the f‐factor published by Barten. Luminance non‐uniformities in the background did not cause any significant change in the detection threshold.
Guiding principles for high‐quality moving picture in LCD TVs
Authors: Yamamoto T. , Sasaki S. , Igarashi Y. , Tanaka Y.
Published: October 2006

Abstract— The moving‐picture quality of several LCD modules was evaluated by using the quantitative parameter, normalized blurred edge width (N‐BEW), or the N‐BEW value normalized by time (N‐BET), measured and calculated by the developed time‐sequence‐image integration system which has taken LCD‐response characteristics and human‐vision characteristics into consideration. The quality of several LCD TVs is also discussed by using subjective evaluation and the unified quantitative parameter moving‐picture response time (MPRT), which is based on N‐BEW. According to the experimental and calculated results, it is clear that the value of N‐BET can express moving‐picture quality, which depends on the liquid‐crystal response time and the hold‐type character of LCDs. Also, it is confirmed that the value of MPRT can express the moving‐picture quality by comparison with subjective evaluation. The target values of MPRT and N‐BET for the motion‐blur‐less picture are deduced by extrapolating the subjective evaluation results. Then, guidelines to improve the moving picture quality are demonstrated.
HD motion‐picture evaluation method for overdrive technology in the frequency domain
Authors: Okumura Haruhiko , Baba Masahiro , Taira Kazuki , Okumura Makiko
Published: October 2006

Abstract— In this paper, the development of an advanced level‐adaptive overdrive (A‐LAO) method applicable to a full‐HD LC projector with 1.84 Mpixels, which reduced the gray‐level response time to less than 16 msec, is introduced. In addition, it is shown that a response of less than 8 msec can be achieved by combining the A‐LAO method with a frame interpolation method (120‐Hz refresh). A new motion‐picture evaluation method using frequency‐domain analysis, in other words, perceived bandwidth instead of the conventional time‐domain‐analysis response time evaluation, is reported.
Dynamic gamma: Application to LCD motion‐blur reduction
Authors: Feng Xiao‐fan , Pan Hao , Daly Scott
Published: October 2006

Abstract— A metric, “dynamic gamma,” to quantitatively evaluate the dynamic temporal response of an LCD device is proposed. Dynamic gamma, associated with 2‐D plots, is more suitable for quantitatively characterizing the dynamic characteristics of an LC panel. The dynamic gamma metric was applied to improve the temporal response of LCDs. From dynamic gamma data, overdrive tables can be derived. Dynamic gamma can also be used to evaluate the effectiveness of overdrive. With a second‐order dynamic gamma, the performance of different overdrive algorithms can be quantitatively assessed. The dynamic gamma metric was also applied to backlight flashing and developed a time adaptive overdrive algorithm. The new algorithm reduces the ghosting artifact due to the timing mismatch between LCD driving and backlight flashing. Experimental results from a simulated tracking camera confirms the advantages of the new algorithm designed using dynamic gamma.
Method for predicting motion artifacts in matrix displays
Authors: Teunissen Kees , Zhang Yuning , Li Xiaohua , Heynderickx Ingrid
Published: October 2006

Abstract— A method is proposed to measure and characterize motion artifacts in matrix displays. By using a fast, V(λ)‐corrected photodiode and a data‐acquisition system, accurate measurements of the temporal luminance behavior (step response) are recorded. The motion artifacts of LCDs and PDP displays are predicted from these measurements using the properties of the human‐visual system. The method is validated with perceptual evaluation experiments, for which a new evaluation protocol is established. In the end, new measures are proposed to quantify the motion‐rendering performance of these matrix displays.
Heritability of the Main Agronomic Traits of Taro
Authors: Quero‐García José , Ivancic Anton , Letourmy Philippe , Feldmann Philippe , Molisale Tari , Lebot Vincent
Published: October 2006

The increase of production of an important root crop such as taro [Colocasia esculenta (L.) Schott, Araceae] implies the development of new varieties through an efficient breeding scheme. The breeding of new taro cultivars is a complex process which requires experience, adequate genetic resources, and reliable data about inheritance of crucial agronomic traits. To obtain these data, 2‐yr heritability taro trials were conducted in Vanuatu with 42 full‐sib families of variable sizes. In the first clonal generation (C1), a fully randomized complete block design was planted with plots of 16 datum plants. During the second clonal generation (C2), parents were included with their offspring in two alpha incomplete block designs with elementary plots of 12 and 4 datum plants, respectively. Both family and narrow‐sense heritabilities were higher for the number of suckers and dry matter content than for corm weight or its components (corm length and width). A high percentage of valuable hybrids were observed among a small number of families. These results, combined with the moderately high family heritability values for several traits, recommend the creation of a small number of large full‐sib families when working with a narrow genetic base and the creation of numerous small full‐sib families when dealing with a broad genetic base.
Evaluation of Soybean Cultivars with the Rps1k Gene for Partial Resistance or Field Tolerance to Phytophthora sojae
Authors: Ferro C. R. , Hill C. B. , Miles M. R. , Hartman G. L.
Published: October 2006

Phytophthora root rot, caused by Phytophthora sojae Kaufmann and Gerdeman, primarily attacks the roots of soybean [Glycine max (L.) Merr.] plants. Partial resistance and field tolerance in 14 commercial glyphosate [N‐(phosphonomethyl)glycine] tolerant soybean cultivars with the Rps1k resistance gene were studied. Partial resistance to compatible P. sojae races 28 and 30 was evaluated by the agar layer technique. Relative to the percentage of the control, all of the commercial cultivars with the Rps1k had reductions in top mass and plant height that were not significantly different from the partial resistant check ‘Conrad’ that had 83% top mass and 77% plant height reduction; two of the 14 commercial cultivars had significantly lower root mass (28 and 31% lower) than Conrad (84%). In addition, there was no significant difference in disease ratings (root or whole plant) of the 14 commercial cultivars with the Rps1k compared with Conrad. Field tolerance, studied in six field experiments at Urbana, IL, during 2002–2004, was identified when there were no significant differences between the yield of inoculated treatments with or without mefenoxam [methyl N‐(methoxyacetyl)‐N‐(2,6‐xylyl)‐d‐alaninate] fungicide seed treatment or between inoculated and noninoculated treatments. There were no significant cultivar × inoculation × fungicide treatment interactions found in any of the field experiments, and a significant cultivar × inoculation treatment interaction was found in only one field experiment. Therefore, most of the cultivars appeared to be tolerant to P. sojae It should be noted that field tolerance was not distinguished from partial resistance in the field component of this study.
Genetic Variation among Canada Wildrye Accessions from Midwest USA Remnant Prairies for Biomass Yield and other Traits
Authors: Vogel K. P. , Hopkins A. A. , Moore K. J. , Johnson K. D. , Carlson I. T.
Published: October 2006

Canada wildrye (Elymus canadensis L.) and Virginia wildrye (Elymus virginicus L.), which are native to the USA, were collected from remnant Midwest prairies. The objectives of this study were to determine the genetic variability among the collected accessions for biomass yield and other traits, determine the extent of genotype × environment interactions for these traits across Midwest environments, and to determine the relationship between the geographical location of the collection site and evaluation sites for these accessions for plant biomass yield which can be used as a measure of adaptation. Seed collected from six Midwest states was bulked by collection site to form individual accessions. Space transplanted evaluation nurseries were established at Mead, NE, Ames, IA, and West Lafayette, IN, and accessions were evaluated on a plot basis for 2 yr. There was significant genetic variation among accessions for post‐heading forage yield, heading date, height, pre‐heading in vitro dry matter digestibility (IVDMD) and crude protein (CP) concentration, and post‐heading CP concentration. Strain × location (S × L) interaction effects were only significant for post‐heading IVDMD and height indicating that for the other traits, the relative ranking of the strains was similar at all three locations over the two evaluation years. Regression analyses of the effect of distance of the collection site from the evaluation site (direct, east or west, and north or south) on biomass yield were largely nonsignificant or had very low R2 values. These regression results along with the nonsignificant S × L effects from the analysis of variance indicate that longitudinal or latitudinal adaptation gradients for plant biomass yield are lacking for Canada wildrye accessions from Midwest prairies. All but five of the Canada wildrye accessions had higher biomass yield than the only released cultivar, Mandan, indicating that this germplasm can be used to develop improved cultivars that should be adapted to the region represented by the collection and evaluation sites.
Genotype–Environment Analysis of Parameters Describing Water Uptake in Natto Soybean
Authors: Cober E. R. , Frégeau‐Reid J. A. , Butler G. , Voldeng H. D.
Published: October 2006

The amount of water absorbed following a defined soaking period has been studied in natto soybean [Glycine max (L.) Merr.], but there are no reports of studies of the rate or rapidity of water uptake. This study was conducted to examine the suitability of several water uptake parameters, which define the speed and amount of water absorbed, for analysis of variance and to determine the extent of genotype, environment, and genotype × environment interaction effects on water uptake parameters. Two larger‐seeded checks and 14 natto lines were grown at six locations in 1996 and 1997. Water uptake observations were taken at 0, 1, 3, 6, and 24.5 h using seed from individual plots. The exponential rise to a maximum equation, Y = a[1 − exp(−bX)], was fitted for each plot. The parameters a at 16 h (a16) and b, best fit the assumptions for analysis of variance. Genotype, year × location, genotype × year, and genotype × location × year effects were significant for these parameters. Location effects were significant for a16 but not for b Year and genotype × location effects were not significant. In this study, genotype × environment effects were relatively unimportant, while the main effect of genotype was more important. The b parameter provides additional information compared with the use of a16 alone. Heritability estimates for water uptake parameters (a16, H = 0.36 ± 0.16; b, H = 0.42 ± 0.46) were low to moderate on a plot basis. It seems possible to select for both rapid and high final water uptake in natto soybean.
Genetic Resistance to Mycosphaerella pinodes in 558 Field Pea Accessions
Authors: Zhang Roger , Hwang Sheau‐Fang , Chang Kan‐Fa , Gossen Bruce D. , Strelkov Stephen E. , Turnbull George D. , Blade Stanford F.
Published: October 2006

Comprehensive assessments of germplasm collections of field pea (Pisum sativum L.) have failed to identify any accessions that are highly resistant to Mycosphaerella blight, caused by Mycosphaerella pinodes In the present study, the broad‐sense heritability of resistance to M. pinodes was studied on 558 pea genotypes in a detached‐leaf assay and in field trials over 2 yr. In addition, analysis of covariance in disease reaction between the two assessment methods was examined. Only a few genotypes displayed relatively high levels of resistance, and as expected, no complete resistance was observed. The pattern of differences in reaction to M. pinodes among the genotypes demonstrates that resistance is quantitative and moderately heritable. Broad‐sense heritability was higher in the detached‐leaf assays than in the field trials, likely because of more environmental variance in the field. Covariance between repetitions of the detached leaf assays was not significant but was significant between the field tests. This indicates that detached‐leaf assessments are more reliable for assessment of large numbers of accessions.
Milling and Baking Quality of Low Phytic Acid Wheat
Authors: Guttieri M. J. , Peterson K. M. , Souza E. J.
Published: October 2006

Low phytic acid (LPA) wheat (Triticum aestivum L.) is one approach to improving nutritional quality of wheat by reducing the major storage form of phosphorus and increasing the level of inorganic phosphorus, which is more readily absorbed by humans and other monogastric animals. Milling and baking quality evaluations were conducted on hard red, hard white, and soft white spring wheat grain from field trials to evaluate the effects of the LPA genotype on the end‐use quality of wheat. In hard wheat backgrounds, the LPA genotypes were not associated with detrimental effects on flour protein concentration, dough mixing properties, or bread loaf volume. LPA wheats had consistent, substantial increases (up to 0.93 g kg−1) in flour ash concentration relative to wild‐type (WT) wheats. Higher flour ash in WT wheats is often a sign of higher aluerone and bran fragments which are visually evident in dulling of Asian noodles color. However, initial alkaline noodle brightness (L* = 86.8–87.5) from hard white LPA flours was at least as high as from hard white wild‐type flours (L* = 86.1–87.9). LPA genotypes have demonstrated a significant redistribution of minerals from the bran to the endosperm; this redistribution of minerals most likely caused the increase in flour ash rather than greater partitioning of bran into the flour. In the soft wheat background, LPA genotypes had greater sodium carbonate and sucrose SRC (31 and 43 g kg−1 greater than wild type, respectively), suggesting that LPA wheats milled with greater apparent starch damage and/or pentosan content than WT sib lines.
Genotypic Variation for Shoot N Concentration and Response to Water Deficits in Soybean
Authors: King C. Andy , Purcell Larry C.
Published: October 2006

For soybean [Glycine max (L.) Merr.], reports differ as to the degree to which accumulation of shoot biomass and N are inhibited by water deficit (WD). Our first objective was to evaluate responses of shoot biomass and shoot N to WD for soybean genotypes from diverse genetic backgrounds. The second objective was to determine if the severity of WD affected the response of N accumulation relative to biomass accumulation among genotypes. In a 2‐yr field study of 15 genotypes, shoot N concentrations ranged from 25 to 33 mg N kg−1 for plants from well‐watered (WW) treatments harvested around 60 d after planting, and N2 fixation accounted for 68% of the N accumulated. Following a 16‐ to 22‐d WD period, shoot N concentrations were similar to that of WW plants for genotypes with low WW N concentrations but decreased for genotypes with high WW N. As a result, the shoot N concentration range among genotypes decreased following WD stress. In a greenhouse study where essentially all of the plant N accumulated was from N2 fixation, shoot N concentration increased across a range of WD levels for six genotypes with low WW N concentrations but decreased for two genotypes with high WW N. These results indicate that changes in shoot N concentration in response to WD depend on both the inherent N concentration of a given genotype and the severity of the WD stress.
A Mutation in a 3‐Keto‐Acyl‐ACP Synthase II Gene is Associated with Elevated Palmitic Acid Levels in Soybean Seeds
Authors: Aghoram Karthik , Wilson Richard F. , Burton Joseph W. , Dewey Ralph E.
Published: October 2006

Palmitic acid is the major saturated fatty acid component of soybean [Glycine max (L.) Merr.] oil, typically accounting for approximately 11% of total seed oil content. Several genetic loci have been shown to control the seed palmitate content of soybean. One such locus, fap2, mediates an elevated seed palmitate phenotype. Previous biochemical studies indicated that the fap2 locus is associated with a reduction in the activity of 3‐keto‐acyl‐ACP synthase II (KAS II), an enzyme that initiates the elongation of palmitoyl‐ACP to stearoyl‐ACP in the plastid. The objective of the present research was to define the molecular basis by which the fap2 locus increases seed palmitate levels. We isolated two closely related, yet unique KAS II cDNAs, designated GmKAS IIA and GmKAS IIB, from soybean cultivar Century (Fap2, Fap2) and its derivative high palmitate germplasm C1727 (fap2, fap2). The GmKAS IIB cDNAs recovered from Century and C1727 were identical. In contrast, a single base‐pair substitution was found in the GmKAS IIA gene from C1727 versus Century which converted a tryptophan codon into a premature stop codon, a mutation that would be predicted to render the encoded enzyme nonfunctional. Knowledge of the DNA sequence polymorphism led to the development a facile, robust cleavage amplified polymorphic sequence (CAPS) marker that readily distinguishes the mutant GmKAS IIA gene. This marker faithfully associated with a second independent germplasm line bearing the fap2 locus, and thus may be useful in breeding programs that target the development of high palmitate soybean cultivars.
Dependence, Tests for
Authors: Hollander Myles
Published: October 2006

This paper is designed to provide a sound introduction for a reasonably well informed reader who is, however, not a specialist in tests for dependence. The paper contains references to many tests but emphasizes the parametric test of independence based on Pearson's sample correlation coefficient*rand certain nonparametric tests based on ranks. The ranks tests are generally preferable to the test based onrin that they have wider applicability, are much less sensitive to outlying observations, are exact under mild assumptions that do not require an underlying bivariate normal* population, and have good efficiency (power) properties.
Binomial Distribution: Sample Size Estimation
Authors: Grevstad Nels
Published: October 2006

The need to estimate the sample size parameternin the binomial distribution arises in many practical problems, such as estimating wildlife population sizes based on sample counts. Attempts to find reasonable estimators can be traced back to the early 1900s, when the method of moments estimator was proposed. But the method of moments estimator, as well as the maximum likelihood estimator, suffers serious shortcomings in terms of performance, not the least of which is a highly unstable behavior. Following a few examples and a brief history of the problem, this entry details some of the difficulties that arise when estimatingn, and presents the results of attempts that have been made to overcome those difficulties either by modifying the method of moments or maximum likelihood estimator, or adopting a Bayesian approach.
Concave and Log‐Concave Distributions
Authors: Sengupta Debasis
Published: October 2006

This article deals with the context, scope, properties, applications and inference of concave and log‐concave distribution functions. These two classes of distributions are compared and contrasted with other related classes. It is shown that such distributions can arise from a variety of situations. Characterizations as well as closure and other properties of these classes are reviewed. Discrete versions of these classes and relation with their continuous counterparts are discussed. Implications of log‐concavity of a distribution function in various fields are mentioned. Sharp inequalities for the concave and log‐concave distribution functions having support on the positive real line are provided. Literature on estimation of concave distribution functions is briefly reviewed.
Delta Method, Infinite Dimensional
Authors: Römisch Werner
Published: October 2006

The infinite‐dimensional delta method including higher order and set‐valued variants is presented. The relevant underlying material on weak convergence, Hadamard directional derivatives and on hyperspaces of closed sets is discussed. Some examples of Hadamard directional differentiable functions and of the delta method, including M‐estimation, are given.
Markov Models, Hidden
Authors: MacDonald Iain L. , Zucchini Walter
Published: October 2006

Hidden Markov models are a class of models in which, conditional on an underlying and unobserved Markov process, the observations are independent. We outline here the main characteristics of such models, describe maximum likelihood and Bayesian approaches to parameter estimation, and list some applications.
Step‐Stress Testing
Authors: Gouno Evans
Published: October 2006

Step‐stress accelerated life test have been studied at least since the 1950s. The strategy consists in testing items successively under different levels of stresses. The main advantage of this strategy is to overcome the issue of selecting the proper level of stress that generates enough failures to make inference in classical accelerated life test where the stress is constant. It reduces test time and the variability of the failure times. Various types of data are obtained from step‐stress tests. According the nature of the basic assumptions, different statistical techniques can be used. The following work gives an overview of various approaches to handle step‐stress accelerated life test data.
Margin of Error
Authors: Vidakovic Brani
Published: October 2006

Margin of Error is a half of the length of a 95% confidence interval.
Ceres Plots
Authors: Berk Kenneth N. , Booth David E.
Published: October 2006

In a multiple linear regression, it is assumed that the dependence on each of the predictors is linear. The partial residual plot has been available as a diagnostic, but it can fail if there are nonlinear relationships among the predictors. The Mallows augmented partial residual plot is effective even if there are quadratic relationships among the predictors. Dennis Cook developed the CERES plot to show a curve in the relationship of the dependent variable to a predictor, in spite of any nonlinear relationships among the predictors.
Correlation, Weighted
Authors: Shieh Grace S.
Published: October 2006

Testing the equality of two population correlation coefficients when the data are bivariate normal and Pearson correlation coefficients are used as estimates of the population parameters is a straightforward procedure covered in many introductory statistics courses. The coefficients are converted using Fisher's z‐transformation with standard errors (N‐3)‐1/2. The two transformed values are then compared using a standard normal procedure. When data are not bivariate normal, Spearman's correlation coefficient rho is often used as the index of correlation. Comparison of two Spearman rhos is not as well documented. Three approaches were investigated using Monte Carlo simulations. Treating the Spearman coefficients as though they were Pearson coefficients and using the standard Fisher's z‐transformation and subsequent comparison was more robust with respect to Type I error than either ignoring the nonnormality and computing Pearson coefficients or converting the Spearman coefficients to Pearson equivalents prior to transformation.
Cure Model
Authors: Baker Stuart G.
Published: October 2006

A cure model is useful for modeling survival when a fraction of subjects who receive an intervention are known to be “cured” immediately while only some of the remaining subjects survive. Parameters can be estimated using the method of maximum likelihood.
Elliptically Contoured Distributions
Authors: Fang Kai‐Tai
Published: October 2006

The elliptically contoured distribution (ECD for short) is a class of multivariate distributions that are considered as an extension of the multivariate normal distributions. In this entry, we introduce a historical perspective, basic properties, and subclasses of the ECD. The estimation of parameters of an ECD implies the study of elliptical matrix distributions. A brief review on elliptical matrix distributions is given. Some applications of ECD are discussed.
Gamma‐Minimax Inference
Authors: Ruggeri Fabrizio
Published: October 2006

Γ‐minimax theory deals with the problem of selecting decision rules under partial prior information on the distribution of the unknown parameter. The selected rule is the one minimizing the supremum of the payoff (Bayes and regret risk in a frequentist approach, and posterior expected loss and regret in a Bayesian one) over the priors in Γ.
Kotz‐Type Distribution
Authors: Kotz Samuel , Nadarajah Saraless
Published: October 2006

The Kotz‐type distribution and some of its properties are discussed.
Signal Processing, Selection Approach in
Authors: Chen Pinyuen , Panchapakesan S.
Published: October 2006

This article considers selection and ranking goals and techniques in studying the problems of simultaneous detection of signals at several sites and also estimating the number of signals.
Bootstrap
Authors: Datta Somnath
Published: October 2006

Bootstrap methods, also known as resampling, have become a major component of modern statistical tools. Since the seminal paper by Efron [18], a large body of literature has evolved covering theoretical, methodological, and application aspects of this technology. This article provides a rather brief description of Efron's original proposal and its various generalizations and extensions to more complex data structures.