bluuebunny/crossref_metadata_2025 huggingface dataset:
Viscoelastic Behaviour of Wood Fibres during the Hot Pressing of Medium Density Fibreboard
Authors: Houts J. van , Bhattacharyya D. , Jayaraman K.
Published: September 2004

Sufficient stress relaxation within a medium density fibreboard (MDF) mat during hot pressing is
critical for producing a panel with acceptable mechanical properties and dimensional stability.
This paper describes a series of load relaxation tests of wood fibres conducted at temperatures and
moisture contents similar to those within an MDF mat during the hot pressing process (temperatures
ranging from 80°C to 100°C with relative humidity levels ranging from 9% to 68%). The results
clearly show an increase in relaxation when either the temperature or relative humidity is increased.
The relaxation behaviour of MDF is also measured and the trends observed are
comparable to those of the wood fibres. Taguchi experimental design is employed to analyse the
effects of temperature, moisture content and initial stress on the viscoelastic behaviour of MDF.
Modeling Ovendry Softwood Resistivity Based on the Resistor Network Theory
Authors: Jiang Z.-H. , Chen Z. , Fen B.-H. , Hou Z.-Q. , Chen G.-H.
Published: September 2004

This study develops a method to theoretically calculate ovendry softwood resistance and resistivity
based on block transformation theory. The resistance of a single cell was calculated as the sum of a
combination of serial and parallel connections of the two end cell walls, four side cell walls and cell
cavity. One cell was considered as a resistor, and the wood as a network of single cell resistors. Resistance
was calculated for a group of four resistors. After several iterations, the total resistance of wood
was obtained. To test the model, experiments were conducted on Masson pine specimens. The resistances
of fifty specimens were measured and their resistivities calculated. A comparison of the theoretical
calculations and the measured results revealed a difference between the measured average resistivity
of specimens and the model calculations of less than 8%. The resistivity of softwood was
found to relate to the size of wood cells, amount of ray cells and the percentage of latewood.
Comparison of the TL-Shear Strength of Normal and Compression Wood of European Larch
Authors: Gindl W. , A.Teischinger A.
Published: September 2004

The strength of larch compression wood specimens in longitudinal shear in the radial plane was
determined and compared to normal wood. Fracture surfaces were examined with a scanning electron
microscope. Compression wood showed higher shear strength than normal wood. The difference
persisted after correction of the strength values for density. Scanning electron microscopy revealed
clear differences in the pattern of failure in normal wood compared to compression wood.
While transwall and intrawall fracture predominate in normal wood, intercell fracture at the middle
lamella occurs in compression wood. An explanation of this change in fracture behaviour is
proposed in terms of microfibril angle and lignification of the cell wall.
Comparing the Effect of Chemical and Physical Properties on Complex Electrical Impedance of Scots Pine Wood
Authors: Tiitta M. , Kainulainen P. , Harju A. M. , Venäläinen M. , Manninen A.-M. , Vuorinen M. , H.Viitanen H.
Published: September 2004

This study examined the effects of physical (moisture content, water content and wood density)
and chemical properties (concentration of phenolics and resin acids) on the electrical properties of
Scots pine (Pinus sylvesteris L.) wood specimens. Complex impedance was measured from heartwood
and sapwood specimens using frequencies between 5 kHz and 1 MHz. Significant correlation
between density and electrical properties was found at high frequencies with sapwood specimens
in which the extractive content was low. Moisture content had an effect on electrical
properties over the whole frequency range. Electrical properties of heartwood samples with high
extractive content were differently affected by the chemical and physical properties. Electrical
properties were sufficient to distinguish between the samples from the brown-rot resistant and
susceptible Scots pine trees.
The Oriented Structure of Lignin and its Viscoelastic Properties Studied by Static and Dynamic FT-IR Spectroscopy
Authors: Åkerholm M. , Salmén L.
Published: September 2004

In order to define the role of lignin for stress transfer in the fiber wall, its orientation and mechanical
interaction with other cell-wall components were investigated. Polarized infrared spectra of
oriented thermomechanical pulp fiber sheets were used to determine the molecular orientation,
and dynamic infrared spectroscopy was used to study the rheology of lignin in the cell wall. The results
indicate that there is a preferred orientation of the phenyl-propane units of lignin along the
fiber axis in spruce tracheids. This implies there is an ordered structure of lignin in the secondary
wall of tracheids analogous to that of the cell-wall polysaccharides. The dynamic IR-spectra also
indicated that lignin exhibits a much more viscoelastic behavior than do the carbohydrates, a
knowledge of importance in the interpretation of transverse fiber properties.
Effect of Ozonation on Assembly of Xylans
Authors: Linder Å. , Roubroeks J. P. , Gatenholm P.
Published: September 2004

In this study the molecular structure of birch xylan was altered by ozonation. Longer ozonation
times increased the cleavage of aromatic rings in the lignin residues attached to the xylan molecules,
resulting in the formation of muconic acid derivatives and other carboxylic acid structures.
Size exclusion chromatography showed a decreasing molar mass of xylan after ozonation. The
ozonation improved xylan solubility as evidenced by the reduced amounts of aggregates in aqueous
solution. Atomic force microscopy showed increases in the sizes of the aggregates. Furthermore,
the ozonation resulted in a decreased ability of xylan to assemble into particle-like structures
on cellulose surfaces. We therefore believe that there is a relationship between xylan
aggregation in aqueous solution and the formation of xylan surface structures on cellulose.
Optimization of a Laccase-Mediator Stage for TCF Bleaching of Flax Pulp
Authors: García O. , Camarero S. , Colom J. F. , Martínez Á. T. , Martínez M. J. , Monje R. , Vidal T.
Published: September 2004

Flax pulp obtained by anthraquinone-soda pulping, resulting in a kappa number of 11.1, a viscosity of 950 ml/g and 36.7% ISO brightness, was bleached in a totally chlorine-free sequence using the enzyme laccase from the fungusPycnoporus cinnabarinusand 1-hydroxybenzotriazole (HBT) as redox mediator (stage L), followed by a hydrogen peroxide stage (P). The laccase treatment was optimized using a three-variable sequential statistical plan over the following ranges: 1–20 U/g o.d.p. (oven-dried pulp) laccase dose, 0.5–7.5% o.d.p. HBT dose and 1–24 h reaction time. The influence of these variables on several pulp properties after the P stage of the LP sequence was examined. The models defined from the results obtained predicted variations in ISO brightness, viscosity and kappa number of 57.6–74.8%,590–955 ml/g and 0–6.2, respectively. The variables most strongly influencing these pulp properties were found to be the reaction time and the enzyme dose. A compromise was adopted as regards the operating conditions in order to ensure optimum results. The study was completed by conducting a biobleaching assay in a pressurized reactor (590 kPa) to assess the effect of oxygen pressure. The high pressure level resulted in improved pulp properties by the laccase-mediator system.
Analysis of Black Wattle (Acacia mearnsii De Wild) Bark by Near Infrared Spectroscopy
Authors: Schimleck L. R. , Yazaki Y.
Published: September 2004

The analysis of two sets of Acacia mearnsii De Wild (Black Wattle) samples by near infrared
(NIR) spectroscopy is reported. Set 1 samples were characterised in terms of hot water extractives,
Stiasny value and polyflavanoid content. Set 2 samples were characterised by nine different parameters,
including tannin content. NIR spectra were obtained from the milled bark of all samples
and calibrations developed for each parameter. Calibrations developed for hot water extractives
and polyflavanoid content (set 1) gave very good coefficients of determination (R2) and performed
well in prediction. Set 2 calibrations were generally good with total and soluble solids, tannin
content, Stiasny value-2 and UV-2, all having R2 greater than 0.8. Owing to the small number of
set 2 samples, no predictions were made using the calibrations. The strong relationships obtained
for many parameters in this study indicates that NIR spectroscopy has considerable potential for
the rapid assessment of the quality of extractives in A. mearnsii bark.
Computer Aided Identification of the Moisture Transport Parameters in Spruce Wood
Authors: Koc P. , Houka M. , Štok B.
Published: September 2004

An inverse identification method for characterization of wood sorptive properties is presented.
The method relies on a computer simulation of a real experiment, in our case a desorption experiment,
where spruce heartwood samples were dried from 27% to 8% moisture content. Three samples,
distinguished by the respective moisture flow pattern through the specimen, were investigated.
A computer aided material characterization using the so-called inverse problem identification
method was performed on the measurements. The solution of the specified inverse problem enabled
us to estimate the moisture diffusion coefficients of wood and to determine the moisture
content field in the sample simultaneously. The method is first verified on two simple cases of uniaxial
moisture flow, and then is used to characterize the diffusion coefficients on a biaxial moisture
flow sample. In the latter case some salient features of the proposed method are exhibited.
The Adjusted Dynamic Modulus of Elasticity Above the Fiber Saturation Point in Taiwania Plantation Wood by Ultrasonic-Wave Measurement
Authors: S.-Y.Wang S.-Y. , Lin C.-J. , Chiu C.-M.
Published: September 2004

In this study, the effects of moisture content and bulk density on the ultrasonic velocity of Taiwania
(Taiwania cryptomerioides Hay.) plantation wood in the longitudinal and radial directions are investigated.
The dynamic modulus of elasticity is adjusted above the fiber saturation point by a simple
method. It was observed that ultrasonic velocity tended to increase with a decrease in moisture
content, and the effect of moisture content on the ultrasonic speed below the fiber saturation point
was stronger than that above. Moreover, for this species ultrasonic speed in the longitudinal direction
decreased with increasing bulk density, while that in the radial direction increased. The correlations
between ultrasonic velocity, moisture and bulk density could be represented by a polynomial
regression model. The K value for ultrasonic wave was affected by density. The adjusted
dynamic modulus of elasticity remained fairly constant above the fiber saturation point using this
simple method. Therefore, the results obtained by the ultrasonic-wave technique should be adjusted
before estimating some physical properties of standing trees.
A Suspected Case of Abruzzo-Erickson Syndrome
Authors: Kidner Giles , Taylor James , Patton Michael A. , Taylor Nigel
Published: September 2004

The features of Abruzzo-Erickson syndrome are described. A case report of an adult female suspected to have this condition is described and illustrated. The possible link to Abruzzo-Erickson syndrome and differential diagnosis of CHARGE is discussed.
Variations in the Tensor Veli Palatini Muscle with Special Reference to Its Origin and Insertion
Authors: Abe Masato , Murakami Gen , Noguchi Makoto , Kitamura Seiichiro , Shimada Kazuyuki , Kohama Gen-iku
Published: September 2004

Objective

Previous research on the tensor veli palatini muscle (TVP) has produced conflicting descriptions of its functions and topographical relationships with other orofacial structures. The goal of this study was to describe the morphology of the TVP in a systematic and comprehensive manner.

Methods

One hundred nineteen sides of 77 human heads from donated cadavers were partially dissected under a binocular microscope. Histological examination of the hard tissue–muscle interfaces was also undertaken.

Results

There were two adjacent origins of the TVP: the cranial base origin (CB origin) and the auditory tube cartilage origin (AT origin). The CB origin always lay anterior to the AT origin and there was no septum or loose tissue between the two muscular laminae leading from these origins. The muscle fibers converged on a central tendinous plate in the muscle belly, which gradually became a common tendon that rounded the pterygoid hamulus before inserting into the palatine aponeurosis. Notably, secondary insertions were found on the maxillary tuber (33.6%) and/or in the submucosal tissue near the palatoglossal arch (37.8%). Maxillary insertions were almost exclusively associated with an AT origin that was wide as or wider than the CB origin. Histological observations confirmed that the hamulus acted purely as a pulley and suggested that a connecting band to the tensor tympani had no or few functions of an intermediate tendon.

Conclusions

The TVP appears to act as the dilator tubae and that this function can be maintained by preserving or reconstructing the maxillary insertion during push-back surgery, even if hamulotomy is necessary.
An Acoustic Study of the Temporal Characteristics of Nasalization in Children with and without Cleft Palate
Authors: Ha Seunghee , Sim Hyunsub , Zhi Minje , Kuehn David P.
Published: September 2004

Objective

The purpose of this study was to measure the oral and nasal cavity acoustic energies to determine whether temporal patterns of nasalization differentiate children with and without cleft palate and the extent to which vowel context contributes to these temporal differences.

Design

Nasal onset interval, nasal offset interval, and total nasalization duration measures were obtained from acoustic waveforms, spectrograms, and energy contours acquired using the Computerized Speech Lab (Kay Elemetrics, Lincoln Park, NJ). In addition to absolute temporal values, proportional durations of nasalization were measured to obtain information regarding the relative duration of nasalization.

Participants

Fifteen children with cleft palate exhibiting mild hypernasality and 15 children without cleft palate participated in the study. Children in both groups were between 4 and 7 years of age.

Results

Each of the three absolute measures was significantly different between the two groups of subjects and within the three vowel contexts. Children with cleft palate showed longer temporal characteristics than children without cleft palate in all three absolute measures. The three temporal variables of the high vowel contexts were generally longer than those of low vowel contexts. Regarding proportional measures, nasal offset interval ratio, and total nasalization ratio showed significant differences between the two groups.

Conclusions

Nasalization, as reflected by acoustic signals, showed different timing characteristics between children with cleft palate and without cleft palate and across vowel contexts. This suggests that the duration of nasalization reflecting temporal patterns of the oral-nasal acoustic impedance may have an influence on the perception of hypernasality.
Speech Outcome following Treatment in Cross-Linguistic Cleft Palate Studies: Methodological Implications
Authors: Hutters Birgit , Henningsson Gunilla
Published: September 2004

Objective

In cross-linguistic studies of cleft palate speech outcome following treatment, treatment is the independent variable, speech outcome is the dependent variable, and the speakers’ language background is a background variable, like sex, age, and cleft type, which must be eliminated. This article focuses on language as a background variable and how it should be treated. The methodological problems are illustrated through a presentation of two cross-linguistic speech outcome studies.

Conclusion

When speakers of different language background are included in cleft palate studies of speech outcome following treatment, speech outcome data should be based on speech units that are phonetically identical across languages. This affects the make-up of the speech material used in the study. In practice, the requirement of phonetically identical speech units may not be totally met, and detailed information regarding the interaction between the cleft condition and speech sound production is still required to fully understand how the validity of data is affected if this requirement is not met.
Abnormal Vomer Development in Human Fetuses with Isolated Cleft Palate
Authors: Hansen Lene , Nolting Dorrit , Holm Gitte , Hansen Birgit Fischer , Kjaer Inger
Published: September 2004

Objective

The aim of this study was to elucidate the prenatal human development of the vomer with emphasis on the vomeral footplate and to assess vomeral morphology in fetuses with isolated cleft palate.

Material and Methods

Nine human fetuses of which four were normal (menstrual age [MA] 13 to 21 weeks) and five with isolated cleft palate (14 to 19 weeks MA) were studied. Midaxial cranial tissue blocks from the fetuses were cut frontally in 4μm serial sections. Sections were stained with toluidine blue in 30% ethanol.

Results

From 16 weeks MA, the vomeral footplate of normal fetuses was formed from bilateral ossifications located below a U-shaped vomeral body. Later in development, an osseous connection was found between the footplate and the vomeral body. Neither bilateral areas of ossification below the vomer nor a vomeral footplate was observed in isolated cleft palate fetuses.

Conclusions

In normal fetuses, the base or footplate of the vomeral bone appears from 16 weeks MA in frontal sections. In fetuses with isolated cleft palates, with no connection between the nasal septum and the maxillary processes, this vomeral footplate does not develop in the period observed (14 to 19 weeks MA).
Cleft Palate in a Newborn with Duplication 2(q13q23)
Authors: Wenger Sharon L. , Bleigh Ona C. , Hummel Marybeth
Published: September 2004

Objectives

A preterm boy was born with multiple anomalies including cleft palate and ventricular septal defect. Chromosome analysis on a blood sample identified additional material within the long arm of chromosome 2.

Setting

The newborn was in the neonatal intensive care unit requiring tertiary care during his 22 days of life.

Results

A supplementary fluorescent in situ hybridization test was performed to confirm the extra chromosomal material was chromosome 2. Parents’ chromosomes were normal, indicating a de novo duplication of 2q13q23.

Conclusion

Comparison of this case with those in the literature suggests involvement of cleft palate of cases with duplication of 2q13.
Digital Three-Dimensional Photogrammetry: Evaluation of Anthropometric Precision and Accuracy Using a Genex 3D Camera System
Authors: Weinberg Seth M. , Scott Nicole M. , Neiswanger Katherine , Brandon Carla A. , Marazita Mary L.
Published: September 2004

Objective

To determine the precision and accuracy of facial anthropometric measurements obtained through digital three-dimensional (3D) photogrammetry.

Design

Nineteen standard craniofacial measurements were repeatedly obtained on 20 subjects by two independent observers, using calipers and 3D photos (obtained with a Genex 3D camera system), both with and without facial landmarks labeled. Four different precision estimates were then calculated and compared statistically across techniques. In addition, mean measurements from 3D photos were compared statistically with those from direct anthropometry.

Results

In terms of measurement precision, the 3D photos were clearly better than direct anthropometry. In almost all cases, the 3D photo with landmarks labeled had the highest overall precision. In addition, labeling landmarks prior to taking measurements improved precision, regardless of method. Good congruence was observed between means derived from the 3D photos and direct anthropometry. Statistically significant differences were noted for seven measurements; however, the magnitude of these differences was often clinically insignificant (< 2 mm).

Conclusions

Digital 3D photogrammetry with the Genex camera system is sufficiently precise and accurate for the anthropometric needs of most medical and craniofacial research designs.
A Comparison of Oral-Nasal Balance Patterns in Speakers who are Categorized as “Almost but Not Quite” and “Sometimes but Not Always”
Authors: Jones David L. , Morris Hughlett L. , Van Demark Duane R.
Published: September 2004

Objective

The purpose of this study was to determine whether amplitude or temporal patterns of oral-nasal balance differentiate speakers with cleft palate who are classified as belonging to the “almost but not quite” (ABNQ) and “sometimes but not always” (SBNA) subgroups of marginal velopharyngeal inadequacy.

Design

The nasal accelerometric vibrational index (NAVI) was used to measure amplitude and temporal aspects of oral-nasal balance during the productions of oral and nasal syllables, words, and sentences. NAVI measures obtained include mean amplitude, time integral (area under the curve), duration, rise time, and fall time.

Setting

Tertiary care center for patients with cleft palate–craniofacial anomalies.

Participants

Seventeen patients with repaired cleft palate who were assigned by perceptual assessment to the ABNQ subgroup and 17 patients who were assigned to the SBNA subgroup.

Results

No differences were found between the ABNQ and SBNA subgroups with regard to patterns of nasalization. Further analysis as a function of level of production and phonetic context revealed no differences between the subgroups.

Conclusions

Although clinicians may report perceived differences in the resonance patterns of speakers who fall within the category of marginal velopharyngeal inadequacy, further division into the ABNQ and SBNA subgroups has yet to be validated.
Development and Clinical Usage of a Motion Analysis System for the Face: Preliminary Report
Authors: Mishima Katsuaki , Yamada Tomohiro , Fujiwara Kumiko , Sugahara Toshio
Published: September 2004

Objective

To evaluate the motion of the face and jaw of patients with cleft lip and palate, facial palsy, and in patients after reconstruction, a motion-analyzing system was developed. The aim of this article was to investigate the accuracy of this system and the possibility of clinical application.

Methods

Markers of 1 to 2 mm were placed on the face, and motion images were obtained by three digital video cameras controlled by a synchronizer and recorded on digital video tape. The image was processed on a personal computer. The markers were automatically tracked across the image sequences, and their three-dimensional coordinates were then calculated.

Main Outcome Measures

System accuracy was investigated using a positioning actuator with high accuracy and a known object. In three patients with bilateral cleft lip and palate, lip pursing was analyzed using the aforesaid method.

Results and Conclusions

The mean differences from the known values to the distances between the tracked sample points and to the mobile distances of the sample points per frame were 0.24 to 0.36 mm and 0.02 to 0.05 mm, respectively. Both results were similar regardless of the mobile speed or direction. In five repeated measurements, the mean differences from the known values as for the distances and the mobile speed ranged from 0.19 to 0.38 mm and from 0.00 to 0.07 mm, respectively. Examination of three patients with bilateral cleft lip and palate indicated the possibility that lip movement could be successfully analyzed using the present system.
Lacrimoauriculodentodigital Syndrome with Cleft Lip/Palate and Renal Manifestations
Authors: Ramirez Dorian , Lammer Edward J.
Published: September 2004

Objective

To describe the largest family reported with the lacrimoauriculodentodigital (LADD) syndrome.

Design

A family study of eight individuals with LADD syndrome.

Setting

Pediatric Clinical Research Center at Oakland Children's Hospital.

Patients

Eight individuals in a four-generation family.

Main Outcome Measure

A diagnosis of LADD syndrome was determined by the presence of one or more of the characteristic lacrimal duct, auricular, dental, or digital malformations. Tear function and orofacial clefting were also considered in the final diagnosis of LADD syndrome.

Results

Affected family members had the characteristic features of LADD syndrome, including cup-shaped ears; lacrimal duct obstruction; and dental, forearm, and digit malformations. In addition to the cardinal features of LADD syndrome, the proband was born with cleft lip and palate. The mother and sister of the proband have hydronephrosis, a rare feature of the disorder. Family members also have features not previously described in LADD syndrome, including vesicoureteral reflux, recurrent urinary tract infections, camptodactyly, distal thumb symphalangism, and a bicornuate uterus.

Conclusions

The findings suggest that the presence of vesicoureteral reflux and recurrent urinary tract infections should be evaluated in LADD syndrome patients and that the distinction of LADD syndrome from ectrodactyly-ectodermal dysplasia and clefting syndrome by the absence of clefting may need to be reconsidered.
Rehabilitation of a Patient with Cleft Lip and Palate with an Extremely Edentulous Atrophied Posterior Maxilla Using Zygomatic Implants: Case Report
Authors: Pham Anh Viet , Abarca Marcelo , De Mey Albert , Malevez Chantal
Published: September 2004

Objective

This case report describes the clinical and surgical management of a patient with a unilateral alveolar cleft and associated extremely atrophied totally edentulous maxilla.

Method

Two zygomatic implants and four endosseous oral implants were placed under general anesthesia in a compromised maxilla to rehabilitate a 33-year-old patient with cleft lip and palate. The two specially designed zygomatic implants were utilized to avoid the need for bone grafting in the patient. The final prosthetic rehabilitation was an esthetic and functional maxillary overdenture prosthesis supported by implants.

Results

Preliminary results have shown how dental prostheses supported by endosseous implants in grafted alveolar cleft are a reliable possibility in the dental rehabilitation of this malformation.

Conclusion

The use of zygomatic implants may be considered a reliable alternative to more resource-demanding techniques such as bone grafting in patients with cleft palate.
A Cephalometric Evaluation of Lower Lip in Patients with Unilateral Cleft Lip and Palate
Authors: Ufuk Toygar T. , Okan Akçam M. , Arman Ayça
Published: September 2004

Objective

The aim of this study was to evaluate cephalometrically the lower lip position and area of patients with unilateral cleft lip and palate (UCLP) comparatively with Class I skeletodental normal subjects.

Patients

Lateral cephalometric and hand-wrist radiographs obtained from 24 patients with UCLP (mean age 12.86 years), along with 20 normal individuals (mean age 12.33 years) used as a control group, were examined.

Design

In addition to standard cephalometric dentofacial variables, lower lip area (superior, middle, inferior) was also measured using a digital planimeter on the lateral cephalograms.

Results

The superior and middle part of the lower lip areas were significantly smaller (p < .05) in the UCLP group, compared to the control group. The inferior and total lower lip areas of patients with UCLP were found to be significantly smaller than controls. The labiomental angle was also smaller (38.79 degrees).

Conclusions

The results suggest that the lower lip of patients with UCLP is smaller, retruded, and curved, with a deep labiomental sulcus, compared with normal individuals during puberty. Therefore, practitioners should focus not only on the upper lip of patients with UCLP but also should consider the lower lip as it was found distinct from normal individuals during puberty.
Heterostyly: speciation within a species
Authors: Sakai Shoko , Toquenaga Yukihiko
Published: September 2004

Almost all organisms in nature show nonrandom mating to different degrees. Two extreme results of nonrandom mating are speciation and sexual differentiation. Heterostyly is a form of sexual differentiation considered to have evolved to resolve conflicts between male and female functions of hermaphrodite flowers. Our study examines necessary and sufficient conditions for establishment of heterostyly using a configuration individual‐based model. Previous models assume invasion of a mutant phenotype into a population with monomorphic wild phenotype. In contrast, our model demonstrates that heterostyly can be established from a population with continuous phenotypic variation, a proposition that requires simpler assumptions than the previous hypotheses. Results of our simulation show that genetic linkage between stigma and anther heights is essential for establishment of heterostyly. Dominance effects on the genes for stamen or stigma heights are not necessary, but they promote evolution of heterostyly. Probability of evolution of heterostyly also depends on the functional relationship between stigma–anther distance and strength of sexual interference, and the distance and probability of pollen deposition success. Parallelity and difference between speciation and sexual differentiation are also discussed.
Positioning the genome within the nucleus
Authors: Verschure Pernette J.
Published: September 2004

Abstract Higher eukaryotic genomes contain both housekeeping genes and genes of which the expression is restricted to a defined time and space. It is well established that a correlation exists between structural organization of the genome and gene expression control. The functional mechanisms underlying this correlation are still poorly understood. Here I describe several observations that are the basis of present concepts of genome organization and nuclear architecture related to functionality. Regarding the relationship between positioning and disturbed cell functionality, I describe observations showing that the proximity of selected gene loci is statistically correlated with their propensity for oncogenic translocations as well as observations of patterns occurring in neurodegenerative disorders where unstable repeats are translated into an expanded polyglutamine tract. Such observations underscore the importance to understand how genetic perturbations lead to the global reorganization of nuclear architecture, chromatin structure and widespread changes in gene expression.
Spectral absorption of solar radiation by aerosols during ACE‐Asia
Authors: Bergstrom R. W. , Pilewskie P. , Pommier J. , Rabbette M. , Russell P. B. , Schmid B. , Redemann J. , Higurashi A. , Nakajima T. , Quinn P. K.
Published: September 2004

As part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia), the upward and downward spectral solar radiant fluxes were measured with the Spectral Solar Flux Radiometer (SSFR), and the aerosol optical depth was measured with the Ames Airborne Tracking Sunphotometer (AATS‐14) aboard the Center for Interdisciplinary Remotely‐Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. In this paper, we examine the data obtained for two cases: a moderately thick aerosol layer, 12 April, and a relatively thin aerosol case, 16 April 2001. On both days, the Twin Otter flew vertical profiles in the Korean Strait southeast of Gosan Island. For both days we determine the aerosol spectral absorption of the layer and estimate the spectral aerosol absorption optical depth and single‐scattering albedo. The results for 12 April show that the single‐scattering albedo increases with wavelength from 0.8 at 400 nm to 0.95 at 900 nm and remains essentially constant from 950 to 1700 nm. On 16 April the amount of aerosol absorption was very low; however, the aerosol single‐scattering albedo appears to decrease slightly with wavelength in the visible region. We interpret these results in light of the two absorbing aerosol species observed during the ACE‐Asia study: mineral dust and black carbon. The results for 12 April are indicative of a mineral dust‐black carbon mixture. The 16 April results are possibly caused by black carbon mixed with nonabsorbing pollution aerosols. For the 12 April case we attempt to estimate the relative contributions of the black carbon particles and the mineral dust particles. We compare our results with other estimates of the aerosol properties from a Sea‐Viewing Wide Field‐of View Sensor (SeaWiFS) satellite analysis and aerosol measurements made aboard the Twin Otter, aboard the National Oceanic and Atmospheric Administration Ronald H. Brown ship, and at ground sites in Gosan and Japan. The results indicate a relatively complicated aerosol mixture of both industrial pollution (including black carbon) and mineral dust. This underscores the need for careful measurements and analysis to separate out the absorption effects of mineral dust and black carbon in the east Asia region.
A demonstration of the capabilities of multisatellite observations of oceanic lightning
Authors: Boeck W. L. , Suszcynsky D. M. , Light T. E. , Jacobson A. R. , Christian H. J. , Goodman S. J. , Buechler D. E. , Guillen J. L. L.
Published: September 2004

We have examined lightning flashes in five nighttime, oceanic thunderstorms, which were jointly observed by Tropical Rainfall Measuring Mission (TRMM) and Fast On‐Orbit Recording of Transient Events (FORTE). The multiplicity of instruments on board these satellites presents a multiphenomenological snapshot view of oceanic nighttime convection. Data are available for five oceanic storms with a total of 40 flashes. The independent optical imagers on each satellite establish the flash locations. The relative fraction of Lightning Imaging Sensor (LIS)–detected optical pulses that were also observed by the FORTE/photodiode detector varied from 0% for LIS range less than 104 J sr−1 m−2 μm−1 to 100% for LIS range greater than 106 μJ−1 sr−1 m−2 μm−1. The FORTE/VHF data sometimes allow estimation of the VHF source emissions heights and identification of individual discharge processes as positive or negative, in‐cloud or cloud‐to‐ground. These observations reinforce the concepts that the VHF pulses are produced by a breakdown process, while the optical pulses are the result of current flow.
Artificial neural network ensembles and their application in pooled flood frequency analysis
Authors: Shu Chang , Burn Donald H.
Published: September 2004

Recent theoretical and empirical studies show that the generalization ability of artificial neural networks can be improved by combining several artificial neural networks in redundant ensembles. In this paper, a review is given of popular ensemble methods. Six approaches for creating artificial neural network ensembles are applied in pooled flood frequency analysis for estimating the index flood and the 10‐year flood quantile. The results show that artificial neural network ensembles generate improved flood estimates and are less sensitive to the choice of initial parameters when compared with a single artificial neural network. Factors that may affect the generalization of an artificial neural network ensemble are analyzed. In terms of the methods for creating ensemble members, the model diversity introduced by varying the initial conditions of the base artificial neural networks to reduce the prediction error is comparable with more sophisticated methods, such as bagging and boosting. When the same method for creating ensemble members is used, combining member networks using stacking is generally better than using simple averaging. An ensemble size of at least 10 artificial neural networks is suggested to achieve sufficient generalization ability. In comparison with parametric regression methods, properly designed artificial neural network ensembles can significantly reduce the prediction error.
Application of the multiscale finite element method to flow in heterogeneous porous media
Authors: Ye Shujun , Xue Yuqun , Xie Chunhong
Published: September 2004

The multiscale finite element method is applied in this paper to simulate groundwater flow in heterogeneous porous media. The method can efficiently capture the large‐scale behavior of the solution without resolving all the small‐scale features by constructing the multiscale finite element base functions that are adaptive to the local property of the differential operator. Both multiscale finite element method and conventional finite element method are applied to five 2‐D and two 3‐D groundwater flow problems, including a 2‐D steady flow problem with continuous coefficients, a 2‐D steady flow with gradual change in coefficients, a 2‐D transient flow with gradual change in coefficients, a 2‐D steady flow problem with an abrupt change in coefficients, a 2‐D transient flow problem with an abrupt change in coefficients, and a 3‐D steady and a 3‐D transient flow problem with gradual change in coefficients in the horizontal direction and with abrupt change in the vertical direction, respectively. The applications demonstrate the main advantages of the multiscale finite element method, i.e., significantly reducing computational efforts and improving the accuracy of the solutions.
Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes
Authors: Dror Ishai , Berkowitz Brian , Gorelick Steven M.
Published: September 2004

The effects of air injection on flow through porous media were explored in a series of 1‐m and 2‐m laboratory flow cells. Our motivation was to examine air barriers as an alternative to hydraulic barriers to inhibit saline intrusion in coastal areas. Steady flow conditions were created in homogeneous and heterogeneous unconsolidated sand systems. Dry air was injected at progressively higher flow rates through a well in the center of each flow cell. Discharge and NaCl−tracer breakthrough data were measured at the outflow reservoir of each cell. In addition, a dye tracer was used to visualize the flow patterns. In all cases, air injection was found to produce stable, low‐conductivity barriers that reduced discharge by an order of magnitude or more. Effective hydraulic conductivity values determined from discharge and hydraulic head data showed exponential declines with increased air‐injection rates in all cases. Numerical simulation was used to quantify hydraulic conductivity and effective porosity values in the saturated and aerated regions created by air injection, and to study advective flow behavior. Pore‐filling cement formed in the air‐injection region and was analyzed to determine its composition, mass, and volume. Approximately 60% of the cement consisted of soluble minerals, and 40% was less soluble carbonates. Evaporation and increase in solution pH due to stripping of CO2 by the injected air were responsible for creating the cement. The cement occupied <10% of the pore space in the sand‐cement aggregate. Both the air and mineral pore‐fillings dissolved when air injection ceased, indicating that both barriers are temporary. These results serve as a preliminary proof of concept that air‐injection barriers might effectively inhibit undesired subsurface flow, such as saline intrusion or contaminated groundwater.
Self‐organizing fault systems and self‐organizing elastodynamic events on them: Geometry and the distribution of sizes of events
Authors: Shaw Bruce E.
Published: September 2004

We introduce a new model which both generates a self‐organizing complex segmented fault system which then accommodates finite strain, and generates sequences of elastodynamic events on that complex fault system. This opens up a new realm of study of populations of cascading elastodynamic ruptures on complex fault systems. We examine the distribution of sizes of events in the model, and its dependence on fault geometry. We see an evolution from a more Gutenberg‐Richter like distribution of events at smaller strains to a more characteristic like distribution at larger strains. We see relative insensitivity of the distribution of sizes of events to the friction used. Examining the distributions of sizes of events on fault segments of different lengths, we find support for a modified segmentation hypothesis whereby segments both break in power law small events and occasionally participate in cascading multisegment larger ruptures, but also predominantly break as a unit.
Midtropospheric CO2 concentration retrieval from AIRS observations in the tropics
Authors: Crevoisier C. , Heilliette S. , Chédin A. , Serrar S. , Armante R. , Scott N. A.
Published: September 2004

Midtropospheric carbon dioxide (CO2) concentration is retrieved in the tropics [20S:20N], over sea, at night, for the period April to October 2003 from the Atmospheric Infrared Sounder (AIRS) observations. The method relies on a non‐linear regression inference scheme using neural networks. A rough estimate of the mean precision of the method is about 2.5 ppmv (0.7%). The retrieved seasonal cycle and its latitudinal dependence agree well with aircraft CO2 in situ measurements made at the same altitude range. Maps produced on a monthly basis at a resolution of 15° × 15°, although not yet fully understood, show good agreement with known characteristics of CO2 distribution reflecting both atmospheric transport and surface fluxes (fossil fuel emissions, biomass burning, air‐surface gas exchanges).
The North‐Africa/Western Asia (NAWA) sea level pressure index: A Mediterranean signature of the Northern Annular Mode (NAM)
Authors: Tourre Yves M. , Paz Shlomit
Published: September 2004

Following work by Paz et al. [2003], the relationship between NAWA and the Eastern Mediterranean (EM) winter climate is explored further. It is found that NAWA can be viewed as the regional signature of the hemispheric northern annular mode (NAM), at all time scales. While in‐phase variability of winter NAM and NAWA increased after the so‐called climate shift of 1976–77, largest correlation between the two indices is found during January. This is also the month when largest correlations are to be found between NAM and the NAWA poles. Correlations between NAWA and NAM are larger than that between NAWA and the North Atlantic Oscillation (NAO). Further evidence of direct relationship between NAM, NAWA, winter air temperature and rainfall in the EM is given.
A nonparametric method for separating photosynthesis and respiration components in CO2 flux measurements
Authors: Yi Chuixiang , Li Runze , Bakwin Peter S. , Desai Ankur , Ricciuto Daniel M. , Burns Sean P. , Turnipseed Andrew A. , Wofsy Steven C. , Munger J. William , Wilson Kell , Monson Russell K.
Published: September 2004

Future climate change is expected to affect ecosystem‐atmosphere CO2 exchange, particularly through the influence of temperature. To date, however, few studies have shown that differences in the response of net ecosystem CO2 exchange (NEE) to temperature among ecosystems can be explained by differences in the photosynthetic and respiratory processes that compose NEE. Using a new nonparametric statistical model, we analyzed data from four forest ecosystems. We observed that differences among forests in their ability to assimilate CO2 as a function of temperature were attributable to consistent differences in the temperature dependence of photosynthesis and respiration. This observation provides empirical validation of efforts to develop models of NEE from the first‐principle relationships between photosynthetic and respiratory processes and climate. Our results also showed that models of seasonal dynamics in NEE that lack specific consideration of the temperature dependence of respiration and photosynthesis are likely to carry significant uncertainties.
Regulation of transcription bySaccharomyces cerevisiae14-3-3 proteins
Authors: BRUCKMANN Astrid , STEENSMA H. Yde , TEIXEIRA de MATTOS M. Joost , van HEUSDEN G. Paul H.
Published: September 2004

14-3-3 proteins form a family of highly conserved eukaryotic proteins involved in a wide variety of cellular processes, including signalling, apoptosis, cell-cycle control and transcriptional regulation. More than 150 binding partners have been found for these proteins. The yeast Saccharomyces cerevisiae has two genes encoding 14-3-3 proteins, BMH1 and BMH2. A bmh1 bmh2 double mutant is unviable in most laboratory strains. Previously, we constructed a temperature-sensitive bmh2 mutant and showed that mutations in RTG3 and SIN4, both encoding transcriptional regulators, can suppress the temperature-sensitive phenotype of this mutant, suggesting an inhibitory role of the 14-3-3 proteins in Rtg3-dependent transcription [van Heusden and Steensma (2001) Yeast 18, 1479–1491]. In the present paper, we report a genome-wide transcription analysis of a temperature-sensitive bmh2 mutant. Steady-state mRNA levels of 60 open reading frames were increased more than 2.0-fold in the bmh2 mutant, whereas those of 78 open reading frames were decreased more than 2.0-fold. In agreement with our genetic experiments, six genes known to be regulated by Rtg3 showed elevated mRNA levels in the mutant. In addition, several genes with other cellular functions, including those involved in gluconeogenesis, ergosterol biosynthesis and stress response, had altered mRNA levels in the mutant. Our data show that the yeast 14-3-3 proteins negatively regulate Rtg3-dependent transcription, stimulate the transcription of genes involved in ergosterol metabolism and in stress response and are involved in transcription regulation of multiple other genes.
Metabolic cleavage of cell-penetrating peptides in contact with epithelial models: human calcitonin (hCT)-derived peptides, Tat(47–57) and penetratin(43–58)
Authors: TRÉHIN Rachel , NIELSEN Hanne M. , JAHNKE Heinz-Georg , KRAUSS Ulrike , BECK-SICKINGER Annette G. , MERKLE Hans P.
Published: September 2004

We assessed the metabolic degradation kinetics and cleavage patterns of some selected CPP (cell-penetrating peptides) after incubation with confluent epithelial models. Synthesis of N-terminal CF [5(6)-carboxyfluorescein]-labelled CPP, namely hCT (human calcitonin)-derived sequences, Tat(47–57) and penetratin(43–58), was through Fmoc (fluoren-9-ylmethoxycarbonyl) chemistry. Metabolic degradation kinetics of the tested CPP in contact with three cell-cultured epithelial models, MDCK (Madin–Darby canine kidney), Calu-3 and TR146, was evaluated by reversed-phase HPLC. Identification of the resulting metabolites of CF-hCT(9–32) was through reversed-phase HPLC fractionation and peak allocation by MALDI–TOF-MS (matrix-assisted laser-desorption ionization–time-of-flight mass spectrometry) or direct MALDI–TOF-MS of incubates. Levels of proteolytic activity varied highly between the investigated epithelial models and the CPP. The Calu-3 model exhibited the highest proteolytic activity. The patterns of metabolic cleavage of hCT(9–32) were similar in all three models. Initial cleavage of this peptide occurred at the N-terminal domain, possibly by endopeptidase activity yielding both the N- and the C-terminal counterparts. Further metabolic degradation was by aminopeptidase, endopeptidase and/or carboxypeptidase activities. In conclusion, when in contact with epithelial models, the studied CPP were subject to efficient metabolism, a prerequisite of cargo release on the one hand, but with potential for premature cleavage and loss of the cargo as well on the other. The results, particularly on hCT(9–32), may be used as a template to suggest structural modifications towards improved CPP performance.