Transitional Segment Research Articles

Novel Knotless Technique with Quill Suture in Laparoscopic Sacrocolpopexy

Study Objective: To demonstrate the recent developments of a knotless self retaining system in a suture intensive procedure. Methods: A retrospective case series of 51 consecutive women with six months follow up who underwent laparoscopic Sacrocolpopexy with novel, knotless Quill suture technique. This innovative tool allows rapid soft tissue approximation and eliminates the tedious, time consuming knot tying. This knotless surgical wound closure system has barbs on it's surface that are arrayed in opposing directions on either side of a transitional unbarbed segment. When the suture is advanced, the barbs penetrate into the surrounding tissue locking the suture in place, thus providing the security of an interrupted suture strand without the knot. If the suture breaks, remaining sutures passes hold the wound edges in approximation. Results: This technique provides equivalent results with standard laparoscopic technique, may substantially decrease the time required for surgical wound closure, thus reducing surgeon's time and operating room costs.

Constraints on the mantle temperature gradient along the Southeast Indian Ridge from crustal structure and isostasy: implications for the transition from an axial high to an axial valley

Axial and ridge flank depths on the Southeast Indian Ridge (SEIR) systematically increase for 2500 km from 90°E to 120°E approaching the Australian-Antarctic Discordance. The SEIR also experiences an abrupt change in ridge axis morphology near 103°30′E with axial highs found to the west and axial valleys to the east. Since the spreading rate is constant throughout this region, these variations have been ascribed to an along-axis gradient in mantle temperature. A seismic refraction experiment provides information on the crustal thickness and seismic velocity structure of two segments with differing axial morphology. Segment P2, centred near 102°E with an axial high has a mean crustal thickness of 5.9 ± 0.2 km, while the mean crustal thickness is 5.3 ± 0.3 km at Segment S1 with an axial valley and centred near 109°45′E. Isostatic compensation of the difference in crustal thickness and density structure between the two segments only accounts for 33 m of the 198 m difference in average ridge flank depth between the two segments. The remaining depth difference must result from a difference in mantle density. Melt production models imply a mantle temperature difference of 11–13.5 °C to produce the observed difference in crustal thickness. Isostatic compensation of the two segments requires that the resulting density difference must extend to about 300 km in the mantle. The transition in axial morphology along the SEIR is very abrupt occurring over a narrow zone within a single segment in which the transition is complete. If a linear mantle temperature gradient is assumed, the temperature difference across the transition segment is only 2.4 °C. The change in axial morphology is accompanied by abrupt changes in other parameters including abyssal hill height, magnetic anomaly amplitude, layer 2a thickness and the presence or absence of an axial magma lens. The abrupt, coincident change in a number of parameters with a very small change in mantle temperature strongly suggests a threshold change between two distinctly different modes of crustal accretion. The trigger for the transition appears to be whether a steady-state crustal magma lens can be maintained.

Using FlyAtlas to detect novel functions for well-known genes in Drosophila melanogaster

Drosophila melanogaster has been an important model organism for over a century, cumulating in a vast array of mutant and transgenic stocks, the publication of the genome, its subsequent annotation and more recently the production of the online gene expression database, FlyAtlas. Much of what we know about developmental biology was pioneered in Drosophila and it is possibly the most well studied and understood model organism, in terms of development, genetics and physiology. The so-called ‘omics’ era of biology has resulted in a relatively data poor discipline quickly becoming a data rich one. Therefore the need for a good model organism, which offers the balance between genetic power and relevance has never been more important, as scientists begin to evaluate and analysis this data. We will argue that Drosophila melanogaster offers the best opportunity to study the relevance of omics data. FlyAtlas is an online resource, which allows scientists to look at tissue specific gene expression in the fruit fly Drosophila melanogaster. Unexpected expression patterns of previously characterised genes may hint at novel functions, thus helping to close the phenotype gap. To test this hypothesis we looked at the neuronal gene Fasciclin 2 (fas2), which has been exhaustively characterised (over 500 papers), with neural functions ranging from axonal growth in development to synapse stabilization in the adult. Surprisingly FlyAtlas showed fas2 is predominately expressed in the Malpighian tubule (a renal, rather than neural, tissue), hinting at a previously unreported function in this tissue. Results suggest fas2 may play an important role in apical microvilli development and stability in the principal cells of the tubules. We have also shown that Fas2 may be involved in actin localisation. Fas2 shows dynamic localisation in response to cAMP and over expression of the protein results in a significant increase in secretion when tubules are stimulated with cAMP. We also present evidence that Fas2 co-localises with F-Actin bundles in response to cAMP, hinting at a role for the actin cytoskeleton in secretion. Proteomics experiments carried out in order to determine Fas2’s, interacting partners proved problematic. For this reason 2D Blue Native PAGE and sucrose gradient techniques were optimised in order to facilitate this problem. 4 Unfortunately we were unable to isolate Fas2, however we have shown that BN-PAGE offers a robust protocol for the isolation of protein/protein complexes. We can also conclude from these experiments that 2D BN-PAGE offers an ideal comparative data source for transcriptomics data such as FlyAtlas. The second gene tested in this study is the sex determination transcription factor Doublesex (dsx). Dsx has been extensively studied in its role in differentiation of both the soma and to some extent the nervous system in males and females. FlyAtlas results indicate that it is also expressed in the Malpighian tubules, again hinting at previously unknown function in this tissue. Further to this the male and female transcripts of dsx are expressed in a sex specific manner. Our results confirm these observations and dsx was localised to the principal cells of the main and lower segments of the tubules. Male tubules however do not express dsx in the transitional segment whereas females do, suggesting that perhaps this segment of the tubule constitutes a previously unknown sex specific function. We have determined that Tra RNAi is effective at knocking down the female transcript in female tubules, allowing for the study of masculinised tubules in an otherwise female fly. Experiments concluded that although males and females show differential survival in response to bacterial infection, this is not controlled by dsx expression in the tubules. Preliminary results also suggest that two genes CG8719 and YP3 are differentially expressed in male and female tubules and offer ideal candidates to study dsx role in sexually dimorphic gene expression in the tubules. In conclusion this study verifies the use of FlyAtlas to determine novel functions for well-known genes in D.melanogaster. In turn this indicates the importance of omics data, as a staring point for further functional analysis of both genes and proteins.

Mucosal nerve deficiency in chronic childhood constipation: a postmigration defect?

Purpose Idiopathic chronic childhood constipation (ICCC) includes children who are severely constipated and who are resistant to behavioral or medical treatments. These children are distinguished from those with Hirschsprung's disease (HSCR) by the presence of enteric ganglia in rectal biopsy specimens. We investigated potential autonomic dysfunction by examining nerves in rectal mucosa. Methods Immunostaining, confocal microscopy, and nerve analysis were performed on formalin-fixed and on Zamboni-fixed rectal biopsy specimens from children who were severely constipated. A computer-assisted neuron tracing technique was used to determine mucosal nerve density in Zamboni-fixed biopsy sections. Results Nerves in Zamboni-fixed biopsy specimens were better stained than in formalin-fixed biopsy specimens. Regardless of fixation method, a deficiency of mucosal nerves was observed in ICCC when compared to children who are not constipated. Analysis of autotraced mucosal nerves confirmed the deficiency in ICCC biopsy specimens. Mucosal nerves were also severely deficient in patients with HSCR, even in transitional segments that contained ganglia. Conclusions Most patients with ICCC had decreased innervation of the rectal mucosa. Because mucosal nerves are critical for the peristaltic reflex, water secretion, and absorption, their deficiency can be related to patient constipation. Mucosal nerve density provides a pathologic basis for diagnosis of dysfunction in children who do not have HSCR but are chronically constipated. The study validates the neuron tracing method for objective evaluation of mucosal innervation.

China: Innovative Use of Materials for Highway Construction

Ever since the Open Door Policy was set forth, China has been developing rapidly and infrastructure construction has been booming and leaping forward with the economy. The highway network is developing at an unprecedented speed and turns out to be successful and fruitful, reaching almost all cities throughout the country in a decade. The freeway length increases by several thousand kilometers annually. By the end of 2007, the freeways nested inside the entire roadway system of 3.57 million km had reached the length of 53,600 km. The fast development of the highway network improves mobility throughout China, while effectively supporting the economic development in both cities and countryside. Highway development relies heavily on current advanced technologies and applied science, and the innovation and renovation of construction techniques accelerate highway construction in China. In recent years, many important innovations and technical breakthroughs with renovations have occurred in various aspects of highway construction in China. The Global Positioning System GPS , remote sensing RS , and computer-aided design CAD have been integrated for road surveying; in particular, this integrated system is used for scenic design of mountain roads and ramp design of mountain highways. In addition, a single radio station is incorporated into a network-based GPS with a multipleantenna sensing technique. Recently, new techniques have been applied to construct a subgrade/subbase on deserts, freeze-susceptible soils, yellow soils, expansive soils, and soils with substrata rich in calcite and/or dolomite. Mixtures of large-size crushed stones and soils have been used to construct roadway bases. Moreover, new methods are being innovated for stabilizing roadway cut slopes, mitigating embankment settlement and deformation, designing roadway drainage systems, and constructing transition segments connecting highways to bridges. Asphalt paving technologies have been renovated by using modified bituminous binders with polymers, rubber powders, and rubber particles. Also being put into practices are new pavement maintenance strategies, pavement distress survey and assessment using advanced technologies, accelerating bridge deck construction, fire-resistant materials for pavements through tunnels, ultrathin asphalt pavement construction, emulsified asphalt binders for interface coating, and lean concrete treatment to subgrade. These construction technologies incorporated with current environmental protection and safety improvement plans in the road network throughout China will greatly enhance the performance of the entire roadway system.

Segmented Transition Pathway Of The Receiver Domain Of Nitrogen Regulatory Protein C

The receiver domain of nitrogen regulatory protein C (NtrC) has two distinct conformations. The largest differences between the two conformations occur in the alpha4-helix. In addition to rigid body translocation and rotation, the alpha4-helix gains half a turn at one end and loses half a turn at the other end when the protein transforms from one conformation to another. The transition pathway between the two conformations is explored by the targeted molecular dynamics (TMD) algorithm in explicit solvent. It is segmented with four consecutive and distinct transition stages. Each transition stage has its own characteristic motion. We propose the reaction coordinates for each transition stage. By projecting the quasi-harmonic principal components along the first stage of the transition, we show that the dynamics of the nano-second time scale overlaps well with the beginning segment of the whole transition. The TMD pathway suggests that several transient hydrogen bonds help stabilize the intermediate structure and facilitate the transition.

Estimation of Place of Articulation During Stop Closures of Vowel–Consonant–Vowel Utterances

Production of vowel-oral stop consonant-vowel utterances involves movement of articulators from the articulatory position of the initial vowel towards that of the oral stop closure, and then to that of the final vowel. As the closure segments have zero or low signal energy, linear predictive coding (LPC)-based estimation of vocal tract shape fails during stop closure. This paper reports a technique for estimation of place of articulation during stop closures by performing bivariate polynomial modeling on vocal tract area values during transition segments preceding and following the closure. The technique with second-degree polynomial modeling was found to be suitable for estimating the place of maximum constriction during stop closure segments of vowel-consonant-vowel utterances with bilabial, alveolar, and velar stops. The estimated places compared well with the actual constriction locations observed from the articulatory data. The technique may be useful for improving effectiveness of speech-training aids for production of stop consonants by providing visual feedback of the estimated place of articulation.

Thoracolumbar Injury Classification and Scoring System

To The ediTor: The thoracolumbar junction is uniquely predisposed to injury as a result of the significant forces exerted over the relatively short spinal segment as the spine transitions from a kyphotic thoracic posture to a lumbar lordosis. In the transitional thoracolumbar segment (T10–L2) the body’s center of gravity moves from anterior to posterior relative to the anterior spinal column, with the load consequently shifting from the anterior column to the posterior elements. In this transitional region the thoracic ribcage no longer serves as a buttress, and the lumbar spine has not yet transitioned to its full lordosis, with a concomitant shift of the load to the more sagittally oriented facets.2 Historically there have been multiple descriptive and mechanistic classification systems for thoracolumbar injuries. These systems have evolved with an increased understanding of spinal biomechanics afforded by advances in clinical imaging. The goal of a classification system is to facilitate accurate description and communication of the salient features of an injury between investigators and clinicians; consequently, any classification system must be validated for interand intraobserver reproducibility. To be of clinical utility, the information conveyed in a classification system should aid the physician in guiding treatment. Due to the complexity of existing classification systems, concerns about interand intraobserver reproducibility, the lack of inclusion of neurological status, and the need for clinical guidelines, the Spine Trauma Study Group developed a classification system for thoracolumbar injuries that builds on concepts from prior systems with an aim to be more applicable to clinical decision making. The goal was to develop a system that is easy to use, easy to communicate, incorporates key decision making considerations, and facilitates clinical decision making. The Thoracolumbar Injury Classification and Severity Scale (TLICSS) assesses each injury according to its morphological characteristics, the integrity of the posterior ligamentous complex, and neurological status of the patient. The severity of the injury and consequent treatment recommendations are guided by assigning a point score to each of these features.4,5 Injuries are classified by morphological characteristics as compression fracture (1 point), burst fracture (2 points), translational or rotational injuries (3 points), or distraction injuries (4 points.) The posterior ligamentous complex is assessed on MR images or CT scans and classified as intact (0 points), suspected injury (2 points), or confirmed injury (3 points.) Neurological status is assessed as intact (0 points), nerve root injury (2 points), complete neurological injury (American Spinal Injury Association scale Grade A, 2 points), incomplete neurological injury (American Spinal Injury Association scale Grades B, C, and D) or cauda equina (3 points.) The scores in each category are summed to yield the overall severity score, ranging from 1 to 10. Injuries with a severity score of ≤ 3 are likely candidates for nonoperative treatment, while injuries with a severity score of ≥ 5 probably require surgical stabilization. Injuries with a severity score of 4 are indeterminate with regard to the need for surgical intervention, and treatment considerations are based on clinical qualifiers. Clinical qualifiers include extreme kyphosis, marked spinal collapse, lateral angulation, open fractures, soft tissue compromise, adjacent rib fractures, inability to brace, multisystem trauma, severe head injury, and sternum fracture. An earlier version of this classification system (Thoracolumbar Injury Severity Scale) also considered injury mechanism, but it was found that mechanism of injury had the greatest interobserver variability. Consequently, this factor was removed from the system and the focus was turned to the morphological characteristics of the injury.3 The 2 cases of a unilateral thoracolumbar facet dislocation presented by Reddy and colleagues are illustrative of the utility of the TLICSS system. The patient in Case 1 had a TLICSS score of 9: 3 (translational/rotational) + 3 (disrupted posterior ligamentous complex) + 3 (cord/ medullary conus injury, incomplete). The patient in Case 2 also has a TLICSS score of 9, but with additional clinical qualifiers. A severity score of 9 probably necessitates surgical intervention in the absence of precluding clinical qualifiers. As the authors noted, resection of the facet was necessary to achieve reduction in both cases, and it is important to emphasize this. Conceptually these fractures can be viewed as a failure of the posterior ligamentous complex, which allowed a flexion-distraction force to dislocate the facet with consequent spondylolisthesis. At presentation, the injury morphology was one of lateral spondylolisthesis resulting from lateral facet dislocation, and the posterior ligamentous instability is highlighted by the anterolisthesis in Case 2 when the patient was positioned prone on a Jackson table. See the corresponding article in this issue, pp 576–580.

Nature of heterointerfaces in GaAs/InAs and InAs/GaAs axial nanowire heterostructures

The structural and compositional characteristics of heterointerfaces of Au-catalyzed GaAs/InAs and InAs/GaAs axial nanowire heterostructures were comprehensively investigated by transmission electron microscopy. It has been found that the GaAs/InAs interface is not sharp and contains an InGaAs transition segment, and in contrast, the InAs/GaAs interface is atomically sharp. This difference in the nature of heterointerfaces can be attributed to the difference in the affinity of the group III elements with the catalyst material.

The Specific Amino Acid Sequence between Helices 7 and 8 Influences the Binding Specificity of Human Apolipoprotein A-I for High Density Lipoprotein (HDL) Subclasses: A POTENTIAL FOR HDL PREFERENTIAL GENERATION

Humans have two major high density lipoprotein (HDL) sub-fractions, HDL(2) and HDL(3), whereas mice have a monodisperse HDL profile. Epidemiological evidence has suggested that HDL(2) is more atheroprotective; however, currently there is no direct experimental evidence to support this postulate. The amino acid sequence of apoA-I is a primary determinant of HDL subclass formation. The majority of the alpha-helical repeats in human apoA-I are proline-punctuated. A notable exception is the boundary between helices 7 and 8, which is located in the transitional segment between the stable N-terminal domain and the C-terminal hydrophobic domain. In this study we ask whether the substitution of a proline-containing sequence (PCS) separating other helices in human apoA-I for the non-proline-containing sequence (NPCS) between helices 7 and 8 (residues 184-190) influences HDL subclass association. The human apoA-I mutant with PCS2 replacing NPCS preferentially bound to HDL(2). In contrast, the mutant where PCS3 replaced NPCS preferentially associated with HDL(3). Thus, the specific amino acid sequence between helices 7 and 8 influences HDL subclass association. The wild-type and mutant proteins exhibited similar physicochemical properties except that the two mutants displayed greater lipid-associated stability versus wild-type human apoA-I. These results focus new attention on the influence of the boundary between helices 7 and 8 on the properties of apoA-I. The expression of these mutants in mice may result in the preferential generation of HDL(2) or HDL(3) and allow us to examine experimentally the anti-atherogenicity of the HDL subclasses.

Interaction of a gas-droplet turbulent jet with a cocurrent high-velocity high-temperature gas flow

A mathematical model and a method for calculating a gas-droplet turbulent jet with allowance for velocity nonequilibrium and virtual mass of the condensed phase during turbulent fluctuations and also heat and mass transfer within the three-temperature scheme are developed. Methodical calculations are performed. The results of these calculations are in reasonable agreement with available experimental data. The structure of the gas-droplet jet in a cocurrent high-velocity high-temperature gas flow is studied by numerical methods. The ratio of intensities of heat and mass transfer between the phases and turbulent diffusion transfers of substances is found to be different at the initial, transitional, and basic segments of the jet. This difference is responsible for the nonmonotonic axial distribution of vapor density and the lines of the halved mass flow of the condensed phase.

Type IV collagen alpha chains of the basement membrane in the rat bronchioalveolar transitional segment

In the present study, we have analyzed the alpha(IV) chain distribution in the subepithelial basement membrane (BM) of the rat pulmonary airway from the bronchi to alveoli. We have furthermore analyzed the alpha(IV) chain distribution in the subepithelial BM of the bronchioalveolar duct junction (BADJ) using alpha(IV) chain specific monoclonal antibodies. Our results show that the BM of the bronchial and bronchiolar epithelium contains [alpha1(IV)]2alpha2(IV) and [alpha5(IV)]2alpha6(IV) molecules and confirmed that the alveolar BM consists of [alpha1(IV)]2alpha2(IV) and alpha3(IV) alpha4(IV)alpha5(IV) molecules. There are also small regions in BADJ consisting of only [alpha1(IV)]2alpha2(IV) molecules without alpha3(IV)alpha4(IV)alpha5(IV) and [alpha5(IV)]2alpha6(IV) molecules. Moreover, the bronchioalveolar stem cells (BASCs)-primordial cells for bronchiolar Clara cells and alveolar type II (AT2) cells - lie adjacent to such small regions. These findings suggest that [alpha1(IV)]2 alpha2(IV) may be important for the BASCs to self-renew or to self-maintain themselves and that microenvironments produced by alpha(IV) chains may be important for cell differentiation.

Transitions from Temporary to Permanent Work in Canada: Who Makes the Transition and Why?

The focus of this paper is on a microeconomic analysis of the annual transition rate from temporary to permanent work of individual workers in Canada for the period 1999–2004. Given that a large proportion of temporary employment is involuntary, an understanding of the factors associated with the transition to permanent work may inform public policy. Factors associated with the transition, namely, human capital, household structures and labour market segmentation are analyzed using data from the Statistics Canada’s Survey of Labour and Income Dynamics (SLID) for the period 1999–2004, limited to paid workers aged 20–64 years, excluding students. Among the key factors associated with the transitions are younger age and low unemployment rates. The analysis adds to the Canadian and international literature on transitions from temporary to permanent work.

Microphysics of Raindrop Size Spectra: Tropical Continental and Maritime Storms

Abstract This work uses raindrop size spectra measured at the surface in tropical continental storms to determine the associated parameters of the best-fit gamma distributions. The physical processes responsible for those parameters and their relations to the measurable radar reflectivity Z and differential reflectivity ZDR are then explored. So too are their relations to quantitative measurements of rain. Comparison is then made with corresponding features previously reported in tropical maritime regimes. The storms observed in Brazil and Arecibo, Puerto Rico, have been divided into convective (C), transition (T), and stratiform (S) segments. The raindrop size distribution (DSD) parameters are clearly defined on a gamma parameter diagram (GPD) that shows 1) how median volume drop size D0 increases from S to T to C segments of the rain while 2) the range of the spectrum breadth parameter μ increases, and the range of the slope parameter Λ decreases in the same sequence of S to C. Drop growth occurs predominantly below the 0°C level by collision, coalescence, and breakup in the C rains. The median volume diameter D0 grows as more of the water is concentrated near that size and so the DSD narrows; that is, both μ and Λ increase. In both maritime and continental storms the DSD in the convective portion of the storm approaches equilibrium. The coefficient A in the Z = ARb relation increases with D0 while the exponent b approaches unity. The D0 and A pair increase with, and appear to be determined largely by, the updraft strength, thus providing a possible means of determining the appropriate algorithms for rainfall measurement. Although the small drop number samples measured by the surface disdrometer relative to the large volumes sampled by a radar tend to truncate the DSD at both small and large drop sizes, narrow distributions with μ = 5 to 12 cannot be attributed to such an effect. Such narrow DSDs accord with common experience of monodispersed large drops at the beginning of a convective storm. There is also remarkable agreement of the surface-based observations of ZDR–Z–D0 with the time–space variations from C to T to S rain types observed by radar in England and elsewhere. Because the C region of a storm often accounts for a major share of the rain accumulation despite its shorter duration, it is particularly important to measure that region more accurately. There are distinctive clusters of the generalized number parameter NW versus D0 between maritime and continental storms. Methods for remote sensing and parameterization must partition the rainstorms into convective, transition, and stratiform segments.

Does Abnormal Expression of Acetylcholine Receptors in Hirschsprung's Disease Induce Acetylcholine Esterase Positive Nerve Fibres?

Alpha bungarotoxin (alpha-BTX) is a neurotoxin isolated from the venom of Bungarus multicinctus that binds specifically to the beta-subunits of nicotinic acetylcholine receptors (nAChR) on myotube membranes. The purpose of the present study was to investigate the distribution of alpha-BTX-sensitive nAChR in Hirschsprung's disease (HD) to understand the histopathological features of HD, especially the increase in acetylcholine esterase (AChE) positive nerve fibres. Confocal microscopy was used to study the expression of FITC (fluorescein isothiocyanate)-alpha-BTX, anti-synaptophysin (A-SY) antibody, and anti-neurofilament (A-NF) antibody to determine the distribution of nAChR and ganglion cell and nerve fibres in colon specimens from five cases of HD and three normal controls. Quantitative assessment of the immunoreactivity of colonic muscle and colonic mucosal epithelium from an aganglionic segment of HD bowel demonstrated markedly increased nAChR compared with colonic muscle and colonic mucosal epithelium from a ganglionic segment of HD bowel and normal bowel (p < 0.0001, respectively), both of which have only a few positive nAChR. In colonic muscle from aganglionic and transitional segments of HD, there were many nAChR around hypertrophic nerve trunks identified by A-NF and A-SY staining. We suggest that abnormal expression of nAChR in HD might be implicated in causing gastrointestinal dysmotility because of their localization around hypertrophic nerve trunks.

Pan-S replication patterns and chromosomal domains defined by genome-tiling arrays of ENCODE genomic areas

In eukaryotes, accurate control of replication time is required for the efficient completion of S phase and maintenance of genome stability. We present a high-resolution genome-tiling array-based profile of replication timing for approximately 1% of the human genome studied by The ENCODE Project Consortium. Twenty percent of the investigated segments replicate asynchronously (pan-S). These areas are rich in genes and CpG islands, features they share with early-replicating loci. Interphase FISH showed that pan-S replication is a consequence of interallelic variation in replication time and is not an artifact derived from a specific cell cycle synchronization method or from aneuploidy. The interallelic variation in replication time is likely due to interallelic variation in chromatin environment, because while the early- or late-replicating areas were exclusively enriched in activating or repressing histone modifications, respectively, the pan-S areas had both types of histone modification. The replication profile of the chromosomes identified contiguous chromosomal segments of hundreds of kilobases separated by smaller segments where the replication time underwent an acute transition. Close examination of one such segment demonstrated that the delay of replication time was accompanied by a decrease in level of gene expression and appearance of repressive chromatin marks, suggesting that the transition segments are boundary elements separating chromosomal domains with different chromatin environments.

Pocketing toolpath optimization for sharp corners

Abstract In pocket milling, there may be residual material left at sharp corners when stepover is inappropriately large in contour-parallel tool paths. According to this problem, the paper proposes an improved NC toolpath generation strategy in order to optimize NC machining processes for pocket milling. By inserting two types of biarc transition segments in contour-parallel toolpaths, the new method can remove the residual material completely without cutter compensation, produce second order continuous toolpath, and allow the stepover to be as wide as possible to reduce the machining time. A machining experiment has been implemented to validate the efficiency of the method.

Duhamel operation vs neonatal transanal endorectal pull-through procedure for Hirschsprung disease: which are the changes for pathologists?

Background The aim of this study was to evaluate whether performing definitive surgery for Hirschsprung disease (HD) in neonatal period with a transanal endorectal pull-through (TEPT) procedure had modified our diagnostic relevance, particularly during intraoperative frozen sections (IOFS), compared to classic Duhamel (DH) surgery performed in older children. Methods We collected pathologic data for 47 children who underwent surgery for neonatal nontotal HD over a 5-year period. Results Twenty-nine patients underwent TEPT and 18 the DH operation. Mean age at operation was 19 days for TEPT and 4 months for DH operation. The mean number of IOFS was 2.6 for TEPT and 2.4 for DH operation. Gross examination could be fully completed in all TEPT cases, but was incomplete in 5 DH cases. The average total lengths of bowel, and aganglionic, transitional, and ganglionic segments were 12.3, 7.3, 3, and 2 cm for TEPT, and 17.6, 9.3, 3.5, and 4.8 cm for DH operation, respectively. Discordance between IOFS and paraffin-section analysis occurred in 5 cases (3 TEPT and 2 DH operation). Conclusion When TEPT was used, the gross examination and sampling was more accurate, leading to a clearer pathology report. The TEPT procedure facilitates the work of the pathologist without modifying the results of IOFS, if some precautions are taken.

Solution−Liquid−Solid (SLS) Growth of ZnSe−ZnTe Quantum Wires having Axial Heterojunctions

Heterostructured ZnSe-ZnTe quantum wires are grown by the solution-liquid-solid (SLS) mechanism. The nature of the axial or radial heterostructure obtained is strongly influenced by the growth sequence and related synthetic conditions. Compositionally graded ZnSe(x)Te(1-x) wires, ZnSe-ZnTe axial heterostructures containing a ZnSe(x)Te(1-x) transitional segment, ZnSe-ZnTe wires with sharp axial heterojunctions, and radial core-shell ZnSe-ZnTe quantum wires have been selectively prepared. The axial and radial quantum-wire heterostructures are characterized microscopically and spectroscopically.

Multicomponent AM–FM Representations: An Asymptotically Exact Approach

This paper presents, on the basis of a rigorous mathematical formulation, a multicomponent sinusoidal model that allows an asymptotically exact reconstruction of nonstationary speech signals, regardless of their duration and without any limitation in the modeling of voiced, unvoiced, and transitional segments. The proposed approach is based on the application of the Hilbert transform to obtain an amplitude signal from which an AM component is extracted by filtering, so that the residue can then be iteratively processed in the same way. This technique permits a multicomponent AM-FM model to be derived in which the number of components (iterations) may be arbitrarily chosen. Additionally, the instantaneous frequencies of these components can be calculated with a given accuracy by segmentation of the phase signals. The validity of the proposed approach has been proven by some applications to both synthetic signals and natural speech. Several comparisons show how this approach almost always has a higher performance than that obtained by current best practices, and does not need the complex filter optimizations required by other techniques