A statistical correlation technique and a neural network for the motion correspondence problem

A statistical correlation technique (SCT) and two variants of a neural network are presented to solve the motion correspondence problem. Solutions of the motion correspondence problem aim to maintain the identities of individuated elements as they move. In a pre-processing stage, two snapshots of a moving scene are convoluted with two-dimensional Gabor functions, which yields orientations and spatial frequencies of the snapshots at every position. In this paper these properties are used to extract, respectively, the attributes orientation, size and position of line segments. The SCT uses cross-correlations to find the correct translation components, angle of rotation and scaling factor. These parameters are then used in combination with the positions of the line segments to calculate the centre of motion. When all of these parameters are known, the new positions of the line segments from the first snapshot can be calculated and compared to the features in the second snapshot. This yields the solution of the motion correspondence problem. Since the SCT is an indirect way of solving the problem, the principles of the technique are implemented in interactive activation and competition neural networks. With boundary problems and noise these networks perform better than the SCT. They also have the advantage that at every stage of the calculations the best candidates for corresponding pairs of line segments are known.     

The vector of jaw muscle force as determined by computer-generated three dimensional simulation: a test of Greaves' model

We present results from a detailed three-dimensional finite element analysis of the cranium and mandible of the Australian dingo (Canis lupus dingo) during a range of feeding activities and compare results with predictions based on two-dimensional methodology [Greaves, W.S., 2000. Location of the vector of jaw muscle force in mammals. Journal of Morphology 243, 293-299]. Greaves showed that the resultant muscle vector intersects the mandible line slightly posterior to the lower third molar (m3). Our work demonstrates that this is qualitatively correct, although the actual point is closer to the jaw joint. We show that it is theoretically possible for the biting side of the mandible to dislocate during unilateral biting; however, the bite point needs to be posterior to m3. Simulations show that reduced muscle activation on the non-biting side can considerably diminish the likelihood of dislocation with only a minor decrease in bite force during unilateral biting. By modulating muscle recruitment the animal may be able to maximise bite force whilst minimising the risk of dislocation.     

A New Surgical Technique for Polysyndactyly of the Toes without Skin Graft

Reconstruction for polysyndactyly of the toes aims at cosmetic improvement. A previous method that uses a skin graft has inherent disadvantages of mismatched pigmentation between the graft and the surrounding skin and scar formation at the donor site. The authors' new improved surgical technique for the treatment of polysyndactyly of the toes does not require a skin graft and therefore avoids these problems. The authors designed a subcutaneous flap from the distal portion of a rectangular flap of skin from the dorsal side of the interdigital webbing and moved the former flap to the sidewall of the base of a toe. Both flaps are the same size; therefore, an interdigital space had to be of sufficient size to accommodate both of them. To ensure an adequate blood supply to the flap, careful handling of the subcutaneous flap is essential for success. This procedure can apply to polysyndactyly of the fourth, fifth, and sixth toes when the fourth and fifth toes adhere over the distal side of the distal interphalangeal joint and when the skin on the dorsal side of the fifth toe, regarded as the excessive one, is at lease twice the size of the dorsal rectangular flap. Ten patients with polysyndactyly of the toe were treated with this method. Aesthetically good results were obtained.     

Isolation of point mutations that affect the folding of the H chain of human ferritin in E.coli.

We have approached the problem of folding and assembly of the heavy (H) chain of human ferritin by isolating point mutations that affect this process. Apoferritin is an ideal model system to approach the problem of protein folding and assembly into multimeric structures. We have developed a recombinant hybrid molecule that allows us to select for ferritin mutants in which the folding-assembly process is altered or completely impaired. The selection procedure is based on a recombinant protein which consists of a fusion between the H chain of human ferritin and the alpha-peptide of beta-galactosidase. In the wild type situation, the alpha-peptide domain is segregated inside the apoferritin shell upon assembly and is unable to interact with the substrate and perform its enzymic function. We show that by selecting for mutations that restore beta-galactosidase activity we are able to identify ferritin mutations that affect the folding-assembly process. The selective procedure was applied to the analysis of the amino acid side chains that are important for the attainment of the correct conformation of the carboxy-terminal E helix in the 4-fold axis.     

Secondary correction of the unilateral cleft lip nose using a conchal composite graft

The secondary deformity of the unilateral cleft lip nose has many components. One is the dorsal dislocation of the lateral crus of the alar cartilage. We used a conchal composite graft positioned between the piriform aperture and the lateral crus and the upper lateral cartilage to correct this dislocation in nine patients. We believe that this graft is effective because it elevates the lateral crus of the alar cartilage off the depressed piriform aperture. This technique is very simple to perform, and it is easy to achieve nasal symmetry. Our results have been quite satisfactory, with no recurrence of dorsal dislocation. The donor site was covered by a subcutaneous pedicled flap from the cephaloauricular sulcus, leaving an inconspicuous deformity.     

Reconstruction of the maxilla with a double musculoperiosteal flap in connection with a composite calvarial bone graft

A new technique is shown for a one-stage reconstruction of the mucosa of the floors of the nose and maxillary sinus, the bone structures of the maxilla and the hard palate, as well as the mucosal layers of the hard and soft palates and vestibulum. To accomplish this coverage, a vascularized calvarial bone graft with temporal muscle from one side is combined with a vascularized temporal muscle flap from the other side to achieve a three-layer "sandwich" plasty. The advantage of this procedure is reconstruction of the complete maxillary defect with the possibility of denture rehabilitation and the avoidance of oronasal fenestration. Besides the possible complication of insufficient vascularization of the bone and muscle grafts, the donor defect in the calvarial bone and the missing muscle for mastication are to be considered.     

Individual variability of the projection line of the common carotid artery

The investigation has been performed on 87 corpses of persons of both sex, that died after 60 years of age from the pathology not connected with any diseases in the neck organs. Individual variability in the common carotid artery projection line has been revealed; it conforms, to a certain extent, with the value of the neck index. When the neck is short and thick, the artery position corresponds to the line that runs across the following points: the superior--0.5 cm forward from the mandibular angle, the inferior--0.5 cm medially from the sternoclavicular joint. When the neck index is within the limits 1.71-1.88, it is expedient to draw the classical projection line. When the neck index is within the limits 1.57-1.69, it is possible to determine the projection zone as an elongated rectangle. At the bottom of every side the border of this zone is a straight line drawn between the sternoclavicular joint and the point situating 0.6 cm laterally from the joint, and at the top--the line connecting the top of the mastoid process with the point 1.0 cm behind the mandibular angle.     

An O(n log n)-time algorithm for the restriction scaffold assignment problem.

The restriction scaffold assignment problem takes as input two finite point sets S and T (with S containing more points than T ) and establishes a correspondence between points in S and points in T , such that each point in S maps to exactly one point in T and each point in T maps to at least one point in S. An algorithm is presented that finds a minimum-cost solution for this problem in O(n log n) time, provided that the points in S and T are restricted to lie on a line and the cost function delta is the L(1) metric. This algorithm runs in linear time, if S and T are presorted. This improves the previously best-known O(n (2))-time algorithm for this problem.     

Lengthening of the postoperative short nose: combined use of a gull-wing concha composite graft and a rib costochondral dorsal onlay graft

Several causes of short nose are known: congenital anomaly, developmental problem, trauma, and various types of rhinoplasty-the postoperative short nose being one of the most difficult problems to correct in plastic surgery. Contracted skin envelope, tissue deficiency of cartilage and mucosal lining, and poor circulation make postoperative short nose difficult to lengthen and susceptible to recurrence. Thus, for effective lengthening and long-term maintenance of it, specific grafts should be used to supplement the missing lining and cartilage and a mechanical support also is needed to withstand the skin contraction. The nose consists of three structural layers: the outer skin envelope, middle osteocartilaginous framework, and inner mucosal lining. Many methods have been proposed to correct short nose deformity. Those procedures lengthen the nose slightly, but none of them take into account the unique characteristics of postoperative causes and the structural concept of the nose. The procedures have resulted in only limited success. On the basis of the above clinical findings and the structural concept, we developed a surgical technique to correct postoperative short nose according to the structural layers. Our method consists of three main surgical maneuvers: (1) a gull-wing concha chondrocutaneous composite graft to supplement the deficient middle and inner layers, (2) a rib costochondral onlay graft on the dorsum to reinforce the framework, and (3) wide dissection of the outer skin envelope to cover the lengthened framework without tension. We prefer a closed surgical approach rather than an open approach to avoid too much tension on the columellar incision site and to allay patients' fear of an additional scar. From 1988 to 1998, we performed our lengthening technique on six female patients. All six patients demonstrated a significant lengthening and improved appearance postoperatively. After the lengthening procedure, the average nasolabial angle improved from 116 degrees to 104 degrees. The mean follow-up period was 8.7 months, with a range of 3 to 17 months. Sometimes, epidermal sloughing in the vertical strut of the gull-wing     

The Turkish delight: a pliable graft for rhinoplasty

In nose surgery, carved or crushed cartilage used as a graft has some disadvantages, chiefly that it may be perceptible through the nasal skin after tissue resolution is complete. To overcome these problems and to obtain a smoother surface, the authors initiated the use of Surgicel-wrapped diced cartilage. This innovative technique has been used by the authors on 2365 patients over the past 10 years: in 165 patients with traumatic nasal deformity, in 350 patients with postrhinoplasty deformity, and in 1850 patients during primary rhinoplasty. The highlights of the surgical procedure include harvested cartilage (septal, alar, conchal, and sometimes costal) cut in pieces of 0.5 to 1 mm using a no. 11 blade. The fine-textured cartilage mass is then wrapped in one layer of Surgicel and moistened with an antibiotic (rifamycin). The graft is then molded into a cylindrical form and inserted under the dorsal nasal skin. In the lateral wall and tip of the nose, some overcorrection is performed depending on the type of deformity. When the mucosal stitching is complete, this graft can be externally molded, like plasticine, under the dorsal skin. In cases of mild-to-moderate nasal depression, septal and conchal cartilages are used in the same manner to augment the nasal dorsum with consistently effective and durable results. In cases with more severe defects of the nose, costal cartilage is necessary to correct both the length of the nose and the projection of the columella. In patients with recurrent deviation of the nasal bridge, this technique provided a simple solution to the problem. After overexcision of the dorsal part of deviated septal cartilage and insertion of Surgicel-wrapped diced cartilage, a straight nose was obtained in all patients with no recurrence (follow-up of 1 to 10 years). The technique also proved to be highly effective in primary rhinoplasties to camouflage bone irregularities after hump removal in patients with thin nasal skin and/or in cases when excessive hump removal was performed. As a complication, in six patients early postoperative swelling was more than usual. In 16 patients, overcorrection was persistent owing to fibrosis, and in 11 patients resorption was excessive beyond the expected amount. A histologic evaluation was possible in 16 patients, 3, 6, and 12 months postoperatively, by removing thin slices of excess cartilage from the dorsum of the nose during touch-up surgery. This graft showed a mosaic-type alignment of graft cartilage with fibrous tissue connection among the fragments. In conclusion, this type of graft is very easy to apply, because a plasticine-like material is obtained that can be molded with the fingers, giving a smooth surface with desirable form and long-lasting results in all cases. The favorable results obtained by this technique have led the authors to use Surgicel-wrapped diced cartilage routinely in all types of rhinoplasty.     

Asymmetric incision for open rhinoplasty in cleft lip nasal deformity.

One of the problems in the correction of the unilateral cleft lip nasal deformity is the alar web deformity on the mediosuperior side of the nostril. A number of methods for the correction of the alar web deformity have been introduced, but no single procedure has been identified as the standard. In this report, the incision line of the open rhinoplasty was modified and the alar web deformity was corrected by using an incision and closure. Open rhinoplasty with the asymmetric incision was performed on 18 patients with unilateral cleft lip nasal deformity. The incision line used in the normal side was the usual intranasal rim incision line and that used for the columella was the transcolumella incision line. For the cleft side, an intranasal rim incision line was plotted after the rim was lifted upward with forceps to achieve symmetry of the nasal tip. After removal of the forceps, the incision line of the cleft side was displaced outside the nostril. After such an incision, the alar cartilage mobilization and suspension were performed with or without the conchal cartilage graft. All patients used nasal retainers for 6 months after the procedures. So far, satisfactory results have been obtained with the modification of the incision line for open rhinoplasty. This method is unique in designing the incision line, and its procedure is rather simple. The postoperative follow-up period has been 12 to 26 months. A long-term follow-up is still needed, especially in growing children.     

The Topology of the Energy Landscapes of Macromolecules in the Torsion Angle Space and the Principle of the Minimum Energy Dissipation Rate in Conformational Relaxation

This article discusses some basic problems of structural biology and molecular dynamics simulation methods that need to be taken into account when considering, the protein folding problem, and prediction of 3D-structures for biopolymers. A multidimensional Fourier series expansions were formulated for the energy landscapes of the systems with conformational mobility, These energy landscape representations are correct from the viewpoint of the topology of the macromolecule configuration spaces. The problem of the single global minimum on the energy landscape for proteins is discussed and is formulated in tems of phase rules for the component of Fourier expansions. This rule is formally similar to the problem of diffraction on a multidimensional cubic lattice. The calibration of biopolymer force fields and their correspondence to topologically correct energy landscapes are discussed. Equations of motion were obtained in a matrix form for the relaxation of a representative point position on a multidimensional potential energy surface. The solutions of the equations for conformational relaxation were shown to obey the principle of the minimum energy dissipation rate at a given relaxation rate of potential energy (or folding rate).     

Non-destructive assessment of developing hydraulic connections in the graft union of tomato

Hydraulic architecture prescribes water flow in plants and is,therefore, fundamental to many areas of plant physiology. Itis usually analysed destructively, or on excised material. Amethod is explored here based on displacement transducers forthe continuous, nondestructive assessment of functional hydraulicconnections within the intact plant. The graft union was chosenas a test system. The technique involves repeated applicationof water at some point in the system, while simultaneously observingpatterns of swelling (increase in water status) at other points.Such patterns will reflect the hydraulic resistance of the interveningpathways. It is demonstrated that the major hydraulic connections withinthe graft union of tomato become functional over a period ofabout 48 h from the fifth day after grafting. This is consistentwith histological observations on the appearance of wound-xylembridges at this time. This approach could be useful for non-destructive monitoringof changes in hydraulic connections in various other intactsystems, for example, during abscission, drought-induced embolism,or attack by vascular-wilt pathogens. Key words: Hydraulic architecture, xylem, graft union, Lycopersicon esculentum L     

Alar rim deformities

Alar disharmony is one of the most common abnormalities observed after a rhinoplasty. This article describes three classes in addition to Gunter's classifications of alar/columella deformities, which include concave ala, convex ala caused by convex lateral crus, and convex ala caused by thick alar tissues. These deformities are best visualized from the basilar view. The different surgical techniques for correction of true alar abnormalities are presented. The alar convexity, when it is the result of a misshapen cartilage, is corrected using a lateral crura spanning suture, posterior transection of the lateral crura, or transdomal suture. A thick ala, resulting in convexity, can be thinned through either a direct incision on the ala or an incision in the alar base. A lateral crura strut, an onlay graft, or a rim graft eliminates the concavity. For a slight retraction, an alar rim cartilage graft is an optimal choice. For significant alar retractions, the author's preferred technique is an internal V-to-Y advancement, which is described in detail. An elliptical excision of the alar lining will effectively correct the hanging ala. These techniques have been used to correct alar disharmonies on 58 patients. One patient from the V-Y advancement group exhibited a small area of alar necrosis, and two early patients demonstrated an overcorrection; all were easily resolved with revision surgery. By carefully identifying nasal base and alar abnormalities, harmony can be established to correct an undesirable appearance.     

A simple technique for closure of a palatal fistula using a conchal cartilage graft.

A simple technique for closure of a palatal fistula using a conchal cartilage graft as a substitute for nasal lining flaps is reported. This graft simplifies the repair of the palatal fistula and protects the suture line of the oral covering flaps from recurrence.     

Fluid-structure interaction of deformable aortic prostheses with a bileaflet mechanical valve

Two different aortic prostheses can be used for performing the Bentall procedure: a standard straight graft and the Valsalva graft that better reproduces the aortic root anatomy. The aim of the present work is to study the effect of the graft geometry on the blood flow when a bileaflet mechanical heart valve is used, as well as to evaluate the stress concentration near the suture line where the coronary arteries are connected to graft. An accurate three-dimensional numerical method is proposed, based on the immersed boundary technique. The method accounts for the interactions between the flow and the motion of the rigid leaflets and of the deformable aortic root, under physiological pulsatile conditions. The results show that the graft geometry only slightly influences the leaflets dynamics, while using the Valsalva graft the stress level near the coronary-root anastomoses is about half that obtained using the standard straight graft.     

Dupuytren's Contracture of the Fingers—A Simplified Approach to Surgical Treatment

Hematoma formation, delay in healing, pain, stiffened finger joints are complications that sometimes follow classical surgical approaches to Dupuytren''s contracture. A new surgical approach to the disease that can correct the contractures without the attendant morbidity is urgently needed. By treating Dupuytren''s as any other scar contracture (division of the contracting soft tissue at its point of maximal tension and interposing normal free full-thickness skin) postoperative morbidity can be greatly decreased. Full return of function was achieved within 21 days following operation in 85 percent of the cases in which finger contractures were present before operation. Contracture release of 100 joints was done by this means, with loss of only one graft and without recurrence of the disease. This technique offers simple surgical control of progressive and recurrent Dupuytren''s contracture of the fingers with minimal postoperative morbidity.     

A simple method for the simulation of steady-state diffusion through membranes: pressure-tuned,boundary-driven molecular dynamics

We present a novel molecular dynamics-based simulation technique for investigating gas transport through membranes. In our simulations, the main control parameters are the partial pressure for the components on the input side of the membrane and the total pressure on the output side. The essential point of our scheme is that this pressure control should be realised by adjusting the particle numbers in the input and output side control cells indirectly. Although this perturbation is applied sufficiently far from the membrane, the bulk-phase properties are well controlled in a simulation cell of common size. Numerical results are given for silicalite-1 membrane with permeating CH₄, CO₂, H₂ and N₂ gases as well as with binary mixtures of CO₂ with the other three components. To describe interactions between particles, we used the simple shifted and cut Lennard–Jones potential with parameters available in the literature. It is expected that the proposed technique can be applied to several other types of membranes and transported fluids in order to support the development of a deeper understanding of separation processes.     

Cytochrome P-450scc-substrate interactions. Role of the 3 beta- and side chain hydroxyls in binding to oxidized and reduced forms of the enzyme

The steroid binding specificity of cytochrome P-450scc has been investigated for different oxidation/reduction and ligand-binding states of the enzyme (oxidized, reduced, oxygen-bound, and carbon monoxide-bound forms). The oxygen of the 3 beta-hydroxyl of cholesterol is important for the initial enzyme-substrate interaction. Significant binding requires the correct stereochemistry and appears to be controlled by the electron density on the 3 beta-oxygen. Interactions at this position (located at least 13 A from the heme iron) can modulate the heme midpoint potential. The binding site in this region contains a cleft which can accommodate up to two carbons joined in an ether linkage to the 3 beta-oxygen. The steroid intermediates of side chain cleavage (22R-hydroxycholesterol and 20 alpha,22R-dihydroxycholesterol) bind more tightly to the ferric enzyme than does cholesterol and utilize specific interactions of these side chain hydroxyls with a grouping(s) on the polypeptide chain (i.e. not with the heme iron). The interaction requires the correct stereochemistry; a 22S-hydroxyl cannot be readily accommodated in the binding site. The specificity of the interaction for hydroxyls at the 22R- versus the 20 alpha-position is altered upon reduction of the enzyme, indicating a reduction-induced conformational change in the active site. The specific interference of binding of 22R-hydroxy steroids by heme-bound carbon monoxide (but not oxygen), together with the known bond angles and distances for Fe-C-O and Fe-O-O, allows localization of the 22R-hydroxyl group on a line perpendicular to the heme plane, between 2 and 3 A from the iron.     

Comment on Cowling's "Spatial methods for line transect surveys"

We consider the problem of estimating the parameters of a two-dimensional Neyman-Scott process, from data collected through a line transect survey. Cowling (1998, Biometrics 54, 828-839) suggested an estimation method based on a one-dimensional K-function along the transect line. However, her expression for the theoretical K-function is wrong. In this article, we correct her K-function.