bluuebunny/crossref_metadata_2025 huggingface dataset:
The Bilobed Flap: A New Application in the Reconstruction of Congenital Thumb Deviation
Authors: CERQUEIRO-MOSQUERA J. , FLEMING A. N. M.
Published: September 2002

Congenital radial angulation deformity of the thumb in Rubinstein-Taybi syndrome is generally corrected by a wedge osteotomy of the delta phalanx and a redistribution of the overlying skin using a Z-plasty or, rarely, skin grafting. We describe a new application of the bilobed flap in the reconstruction of the thumb and discuss its advantages over traditional methods in providing tension-free skin cover, excellent access to the delta phalanx and aesthetically acceptable scars.
Primary Vascularized Distal Radius Bone Graft for Nonunion of the Scaphoid
Authors: UERPAIROJKIT C. , LEECHAVENGVONGS S. , WITOONCHART K.
Published: September 2002

A vascularized bone graft from the dorsoradial aspect of the distal radius was used with internal fixation to treat nonunion of the scaphoid in ten patients who had not received any previous surgical treatment. Five cases were classified as Lichtman type I and five as type II. The average age was 30 years (range, 18–40 years). Associated avascular necrosis was observed in five cases. Post-operatively pain was relieved and union was achieved in all cases. The mean time to union was 6.5 weeks. Range of motion, grip strength and pinch strength were also restored satisfactorily. These results suggest that this vascularized bone graft should be used as the primary procedure in Lichtman type I and II of scaphoid nonunions, regardless of the presence of avascular necrosis of the proximal pole.
Recurrent Compressive Neuropathy of the Median Nerve at the Wrist: Treatment with Autogenous Saphenous Vein Wrapping
Authors: VARITIMIDIS S. E. , RIANO F. , VARDAKAS D. G. , SOTEREANOS D. G.
Published: September 2002

Recurrence of symptoms occurs in a significant number of patients after surgical decompression for carpal tunnel syndrome, and its management is both challenging and difficult. Fifteen patients with recurrent carpal tunnel syndrome were treated with a vein wrapping technique using the autologous saphenous vein. A total of 48 operations had been performed on these patients before wrapping the median nerve with a saphenous vein graft. At a mean follow-up of 43 months all patients reported significant pain relief and improvement in their sensory disturbances. Two-point discrimination and the findings of nerve conduction studies also improved.
Defatting of Skin Flaps Using Arthroscopic Instruments – an Effective Alternative
Authors: WU W. C. , CHAN W. F.
Published: September 2002

Defatting is often required when skin flaps are transferred to the hand. We present three patients with skin flaps which were defatted using an arthroscopic shaver and a standard suction device. There were no complications and all three patients were satisfied with their outcomes. This method provided an effective treatment for our patients and did not require the purchase of specialised equipment.
Reverse Posterior Interosseous Flap Based on an Exteriorized Pedicle to Cover Digital Skin Defects
Authors: BRUNELLI F. , GIELE H. , PERROTTA R.
Published: September 2002

The posterior interosseous arterial flap is limited by its short vascular pedicle and proximal axis of rotation to the coverage of defects on the dorsal aspect of the hand and the first web space. The authors present the results of three cases in which these limits were surpassed by extending the wrist and exteriorizing the vascular pedicle, thus causing it to bowstring across the angle created by the extended wrist. When flap inset is complete the vascular pedicle is excised under local anaesthesia. This technique is an amalgamation of an island flap and a traditional pedicle flap and, as such, it is a two-stage procedure.
Variations of the Posterior Interosseous Nerve
Authors: MISSANKOV A. A. , SEHGAL A. K. , MENNEN U.
Published: September 2002

The posterior interosseous nerves of 58 cadaver forearms of black South Africans were dissected to study their order of branching. In 43 specimens (74%), the most common order of branching was: extensor carpi radialis brevis; supinator; extensor digitorum; extensor carpi ulnaris; extensor digiti minimi; abductor pollicis longus; extensor pollicis brevis; extensor pollicis longus and extensor indicis. In 15 specimens (26%) different variations of the nerve were observed, some of which are reported for the first time. The knowledge of these variations could be useful during operations in the vicinity of the nerve, and when repairing a nerve injury or forecasting the location of a compressive lesion.
Continuous Postoperative Catheter Irrigation is not Necessary for the Treatment of Suppurative Flexor Tenosynovitis
Authors: LILLE S. , HAYAKAWA T. , NEUMEISTER M. W. , BROWN R. E. , ZOOK E. G. , MURRAY K.
Published: September 2002

The records of 75 patients admitted with pyogenic flexor tenosynovitis at two academic centers were reviewed. The functional outcomes of patients who received intraoperative irrigation only ( n=20) and those that had both intraoperative irrigation and continuous postoperative irrigation ( n=55) were compared. There were no statistically significant differences between the outcomes in the two groups.
Open Surgical Therapy for Carpal Tunnel Decompression in Long-Term Haemodialysis Patients
Authors: SHIOTA E. , TSUCHIYA K. , YAMAOKA K. , KAWANO O.
Published: September 2002

This retrospective study assessed the treatment of 91 cases of carpal tunnel syndrome in long-term haemodialysis patients. One group of patients underwent an enlargement reconstruction of the flexor retinaculum with synovectomy and the other group was treated with a conventional carpal tunnel release. There were no major changes or differences between the outcomes of the two groups. However, there was an earlier functional recovery of grip strength and a lower recurrence rate in the enlargement plasty with synovectomy group.
Penetrating Injury to the Terminal Branches of the Posterior Interosseous Nerve with Nerve Grafting
Authors: LEECHAVENGVONGS S. , WITOONCHART K. , UERPAIROJKIT C.
Published: September 2002

We report two cases of penetrating injuries to the terminal branches of the posterior interosseous nerve in the forearm. Repair using nerve grafts in both cases were followed by complete recovery.
The Innervation of the Proximal Interphalangeal Joint and its Application in Neurectomy
Authors: BRAGA-SILVER J. , CALCAGNOTTO G.
Published: September 2002

In an anatomic study of 64 fingers, we demonstrated that the proximal interphalangeal joint is innervated by branches of the palmar digital nerves. The number of articular branches ranges from two to four and their origins from the digital nerve are between 2 and 8 mm from the proximal interphalangeal joint. In a clinical series of 24 neurectomies in 21 patients, there was a significant improvement in pain and range of motion in 22 fingers. We conclude that neurectomy is a therapeutic option in the treatment of osteoarthritis of the proximal, interphalangeal joint.
Surgical Treatment for Recurrent Dislocation of the Extensor Carpi Ulnaris Tendon
Authors: INOUE G. , TAMURA Y.
Published: September 2002

Twelve patients with recurrent dislocation of the extensor carpi ulnaris tendon were treated with repair or reconstruction of its tendon sheath, and each had a satisfactory result. We found three types of disruption of the fibro-osseous sheath. Type A: the fibro-osseous sheath ruptured ulnarly and the torn sheath lay superficial to the tendon ( n = 5). These were treated by reconstruction of the sheath using a piece of the extensor retinaculum. Type B: the fibro-osseous sheath ruptured radially and the torn sheath lay in the ulnar groove beneath the tendon ( n = 3). These were treated by direct suture of the sheath over the tendon. Type C: detachment of the periosteum from the ulnar side of the ulna in continuity with the fibro-osseous sheath formed a false pouch into which the tendon easily dislocated ( n = 4). These were treated by reattachment of the periosteum.
A Comparison of the Findings of Wrist Arthroscopy and Magnetic Resonance Imaging in the Investigation of Wrist Pain
Authors: MORLEY J. , BIDWELL J. , BRANSBY-ZACHARY M.
Published: September 2002

Between 1996 and 1999, 54 patients with wrist pain had magnetic resonance imaging performed using a 1.5 Tesla scanner without a wrist coil. Wrist arthroscopy was performed using a standard technique. The findings were then compared. Magnetic resonance imaging had a low sensitivity for the detection of triangular fibrocartilage complex injuries (0.44) and scapholunate ligament injuries (0.11) when wrist arthroscopy was used as the standard of reference.

We conclude that when a magnetoresonance technique that does not employ a dedicated wrist coil is used, a negative magnetic resonance imaging scan does not exclude these two significant injuries.
Surgical Correction of Supination Deformity in Children with Obstetric Brachial Plexus Palsy
Authors: BAHM J. , GILBERT A.
Published: September 2002

We present a series of 40 children who were operated on for supination contracture following severe obstetric brachial plexus palsy. Surgery was done at an average age of 7 years and the mean postoperative follow-up was 4 years. In the 23 cases treated by an open or closed radial osteotomy, the mean intraoperative derotation was 78°, the immediate postoperative position was 29° pronation and it stabilized at follow-up at 17° pronation. Biceps rerouting was performed in 17 cases without any recurrence of supination deformity and the final position was 22° pronation. Some active forearm rotation was obtained in a few cases. These surgical corrections are part of an overall treatment plan and allow the “begging hand” to be corrected to a more functional and less noticeable position.
Long-Term Results of Digital Arthrodesis with the Harrison–Nicolle Peg
Authors: SABBAGH W. , GROBBELAAR A. O. , CLARKE C. , SMITH P. J. , HARRISON D. H.
Published: September 2002

This study determined the long-term success of digital arthrodesis with the Harrison–Nicolle peg. We reviewed 90 digital joints in 60 patients fused with the peg between 1986 and 1998 at a mean follow-up of 6 (range 2–11) years. The prime indication for surgery was rheumatoid arthritis. The early complication rate was 8%. At 1 month 89% of joints were pain-free and stable. In the long-term follow up, 96% of the joints were pain-free and stable, with the original angle of fusion. 85% achieved bony fusion, with no clinical difference between bony and fibrous fusion. Overall there was a significantly higher complication rate in the distal interphalangeal joint. We conclude that, with the exception of the distal interphalangeal joint, the Harrison–Nicolle peg is extremely effective for digital arthrodesis in the rheumatoid patient.
Obstetrical Brachial Plexus Palsy. Prediction of Outcome in Upper Root Injuries
Authors: NEHME A. , KANY J. , SALES-DE-GAUZY J. , CHARLET J. P. , DAUTEL G. , CAHUZAC J. P.
Published: September 2002

Thirty obstetrical brachial plexus palsies involving the upper roots were retrospectively reviewed. There were 20 C5–C6 palsies and ten C5–C6–C7 palsies in which recovery of C7 occured by the end of the first month. Recovery of elbow flexion at 3 months, C7 involvement and high birthweight were the best early predictors of outcome, but all were unreliable when used separately. In combination, recovery of elbow flexion and birthweight predicted the final outcome reasonably satisfactorily, particularly when elbow flexion at 9 months, and not 3 months was considered (risk of error = 13%). Brachial plexus reconstruction may therefore be justified when there was initial C7 involvement associated with increased birthweight and poor elbow flexion at 6–9 months.
Treatment of Soft Tissue Injuries to the Dorsum of the Metacarpophalangeal Joint (Boxer’s Knuckle)
Authors: ARAI K. , TOH S. , NAKAHARA K. , NISHIKAWA S. , HARATA S.
Published: September 2002

We retrospectively reviewed the surgical treatment for 16 cases of traumatic soft tissue injury to the metacarpophalangeal joint (Boxer’s knuckle). A history of trauma was present in all cases and there was an associated extensor tendon dislocation in seven cases. Eight cases were initially treated conservatively, but their symptoms persisted. Intraoperative findings included rupture of the extensor hood or joint capsule in all cases. Surgical closure of the rupture of the joint capsule resulted in a successful outcome in all cases. We consider that conservative treatment of this injury may not be effective when the joint capsule of the metacarpophalangeal joint is ruptured. We recommend arthrography of the metacarpophalangeal joint to assist in the decision as to whether to proceed with surgical or conservative treatment.
Assessment of the Method and Timing of Repair of a Brachial Plexus Traction Injury in an Animal Model for Obstetric Brachial Plexus Palsy
Authors: FULLARTON A. C. , LENIHAN D. V. , MYLES L. M. , GLASBY M. A.
Published: September 2002

A Sunderland type IV traction injury to the C6 root of adult sheep or newborn lamb brachial plexus was used as a model for obstetric traction injury to the C5 root in humans. In one experimental cohort the injury was created and repaired using interfascicular nerve autografts or coaxially aligned freeze-thawed skeletal muscle autografts in a group of adult sheep and in a group of newborn lambs. In a second cohort a similar injury was created and repaired either immediately or after a delay of 30 days, using either interfascicular nerve autografts or coaxially aligned freeze-thawed skeletal muscle autografts in four groups of six newborn lambs. In all cases both functional and morphometric indices of nerve regeneration were poorer in the injured and repaired nerves than in normal nerves. In lambs the method of repair made no difference and no significant differences were found for any of the indices of nerve function or morphology. In sheep the use of muscle grafts was associated with a poorer outcome than the use of nerve autografts. Where a delay of 30 days had elapsed between injury and repair, the results using nerve autografts were not significantly different. Where freeze-thawed muscle autografts had been used, the maturation of the regenerated nerve fibres after delay was significantly poorer than after immediate repair. The electrophysiological variables CVmax and jitter, which may be applied clinically, were found to be good discriminators of recovery in all of the animals and in respect of all procedures.
Upper Extremity Infections Following Common Carp Fish (Cyprinus Carpio) Handling
Authors: CALIF E. , PICK N. , DREYFUSS U. , STAHL S.
Published: September 2002

Upper extremity infection caused by aquatic pathogens on fish is a well recognized clinical entity. We report five consecutive cases of upper extremity infections, ranging from a simple localized reaction to a life-threatening systemic illness, which developed after handling common carp fish ( Cyprinus carpio). In four cases, infection occurred following a penetrating injury by either the bones or the fin spines of the fish. Vibrio vulnificus was isolated from wound aspirates in four cases. Early broad-spectrum antibiotic therapy is mandatory. Deterioration in the clinical condition or a poor response to conservative treatment requires a meticulous surgical drainage and excision of both infected and necrotic tissues.
Juxta-Epiphyseal Fractures of the Base of the Proximal Phalanx of the Fingers in Children and Adolescents
Authors: AL-QATTAN M. M.
Published: September 2002

A series of 34 juxta-epiphyseal fractures of the base of the proximal phalanx of the fingers of children and adolescents are presented. The pattern of injury appeared identical in all these fractures, with a lateral angulation force separating a small triangular metaphyseal fragment from the base of the phalanx on the side of angulation and the fracture line then continuing through the metaphysis, 1–2mm distal to the growth plate. Fractures were classified into two types according to the degree of displacement. Type 1 fractures ( n=18) were mildly displaced and were all successfully treated with closed reduction and splinting. Type 2 fractures ( n=16) were severely displaced and problems with obtaining an adequate reduction and long-term residual deformities were encountered. One patient with a severely displaced fracture required open reduction and Kirschner-wire fixation because of flexor tendon entrapment at the fracture site. Another five cases required Kirschner-wire fixation after closed manipulation in order to maintain the reduction. The remaining 10 patients with Type 2 fractures were treated by closed reduction and splinting, and two patients healed with malunion causing a “pseudo-claw” deformity.
Nerve Conduction Studies for Carpal Tunnel Syndrome: Essential Prelude to Surgery or Unnecessary Luxury?
Authors: SMITH N.J.
Published: September 2002

Although carpal tunnel syndrome is a relatively trivial condition, controversy surrounds the use of nerve conduction studies, and whether they are essential to make the diagnosis, or as a prelude to surgery. This is partly due to the lack of a generally agreed definition of the condition, and failure to recognize that the patient’s first priority is rapid relief of symptoms. If nerve conduction studies do not contribute to achieving that aim it would be better not to do them. Supporters of routine preoperative nerve conduction studies ignore their shortcomings, which include lack of standardization, absence of population-based reference intervals, and lack of sensitivity and specificity. Only a controlled trial, in which patients are randomized to receive treatment either with or without nerve conduction studies, will determine whether they improve the outcome in patients with a firm clinical diagnosis of carpal tunnel syndrome.
Synovial Chondromatosis of the Metacarpophalangeal Joint
Authors: HETTIARATCHY S. P. , NANCHAHAL J.
Published: September 2002

We describe a case of synovial chondromatosis in a metacarpophalangeal joint with invasion of local structures. The degree of local tissue involvement was not demonstrated on the preoperative MRI scans. This case highlights that synovial chondromatosis can be invasive and that even the best preoperative imaging may not demonstrate this.
Radiolunate Arthrodesis in the Rheumatoid Wrist: A Retrospective Clinical and Radiological Longterm Follow-Up
Authors: BORISCH N. , HAUSSMANN P.
Published: September 2002

A retrospective study was performed to investigate the clinical and radiological results of radiolunate arthrodesis in the rheumatoid wrist. Ninety-one wrists in 78 patients were assessed at a mean follow-up of 60 months. Most patients were pain-free and content with the overall result. In 68 wrists the carpus had been repositioned or maintained in neutral or slightly ulnar alignment and no further translation occurred. Midcarpal dislocation occured in ten and midcarpal rotation in 13 wrists. The midcarpal joint underwent further arthritic destruction in 34 wrists and secondary arthrosis in 32 wrists. In 25 wrists the midcarpal joint space remained unchanged. Radiolunate arthrodesis can successfully be performed in wrists even with advanced destruction. In cases with fixed carpal collapse, anatomical repositioning of the lunate and restoration of carpal height should not be attempted as this causes midcarpal dislocation or rotation or precipitates secondary arthrosis.
Spongy Hydroxyapatite in Hand Surgery – A Five Year Follow-Up
Authors: BAER W. , SCHALLER P. , CARL H. D.
Published: September 2002

Twenty-two patients were treated for enchondromas or cysts of the hand by curettage and complete filling of the defect with hydroxyapatite. Postoperatively no complications occurred and marginal osseous integration was radiologically complete after 6 to 8 weeks. Patients were re-examined after a minimum of 5 years after operation and the functional and aesthetic results were excellent in all patients. Radionuclide imaging showed identical bone activity to that in the contralateral healthy hand and there were no signs of inflammation.
Genetic Susceptibility in Dupuytren’s Disease: Lack of Association of a Novel Transforming Growth Factor β2 Polymorphism in Dupuytren’s Disease
Authors: BAYAT A. , ALANSAR A. , HAJEER A. H. , SHAH M. , WATSON J. S. , STANLEY J. K. , FERGUSON M. W. J. , OLLIER W. E. R.
Published: September 2002

The genes involved in the pathogenesis of Dupuytren’s disease have yet to be identified. In this study, we tested for an association between Dupuytren’s disease (DD) and a novel insertion polymorphism within the 5′-untranslated region (5′-UTR), of the TGFβ2 gene. DNA samples from 179 DD patients and 187 ethnically matched controls were examined. There was no statistically significant difference in TGFβ2 allele frequency distributions between cases and controls for the TGFβ2 polymorphism.
Percutaneous Cannulated Screw Fixation of Acute Scaphoid Waist Fracture
Authors: YIP H. S. F. , WU W. C. , CHANG R. Y. P. , SO T. Y. C.
Published: September 2002

This prospective study assessed the outcome of percutaneous cannulated screw fixation in 49 of 60 acute scaphoid fractures. The union rate was 100% (mean time for radiological union at 12 weeks). There were no early or mid-term complications and all achieved an excellent functional recovery.
Outcome after Corrective Osteotomy for Malunited Fractures of the Distal End of the Radius
Authors: PROMMERSBERGER K. J. , VAN SCHOONHOVEN J. , LANZ U. B.
Published: September 2002

This retrospective study evaluated the outcome of corrective osteotomy for malunited distal radial fractures and investigated the influence of the radiological result on the clinical outcome. Twenty-nine patients underwent corrective osteotomy for malunited, dorsally tilted fractures of the distal radius and 20 underwent corrective osteotomy for malunited, palmarly angulated distal radial fractures. All were surveyed at an average of 18 months after surgery and assessed for: pain; grip strength; range of motion; radial tilt; radial inclination; and ulnar variance. Postoperative radial tilt, radial inclination and ulnar variance were significantly improved by corrective osteotomy. Patients with no, or only minor residual deformity after corrective osteotomy had significantly better results than those with gross residual deformity.
Condylar Advancement Osteotomy for Correcting Condylar Malunion of the Finger
Authors: TEOH L. C. , YONG F. C. , CHONG K. C.
Published: September 2002

Unicondylar fractures of proximal and middle phalanges of the finger can unite with intra-articular malunion, which may result in joint pain, stiffness and deformity. There is currently no satisfactory technique of corrective osteotomy for these fractures. Extra-articular osteotomies often do not give good results and existing techniques of intra-articular osteotomy through the healed fracture site are technically difficult due to the small bone fragment, difficulty achieving stable fixation and the risk of avascular necrosis. We propose a different method of intra-articular correction with a longitudinal osteotomy and advancement of the malunited condyle. The “condylar advancement osteotomy” can overcome problems encountered with the other techniques. Excellent results were obtained in six patients.
Linear Relation between Cell Growth and Water Channels Conducted Lp in Nitellopsis
Authors: Zhu G. L. , Zhu M. J. , Ye Q. , Li S. , Zhu R. , Cao Y. , Chen J. , Wang X. C.
Published: September 2002

Abstract: The effect of Lp on growth of internodes of Nitellopsis obtusa (Desv. In Lois) J. Gr. was studied, with treatments of HgCl2 and antibodies against aquaporins (anti‐RD28) on the plasmalemma, using laser scanning confocal microscopy, and simultaneous monitoring of cell growth, turgor, Em and Lp using a turgor/membrane potential probe (T‐EP probe). Laser scanning confocal immunofluorescent microscopy indicated the immunoreaction of anti‐RD28 on the plasma membrane. Experiments showed that, following treatment with 25 μM HgCl2, cell growth was entirely and Lp largely inhibited, and no growth recovery was seen even when Lp was completely reversed by replacement of HgCl2 with β‐mercaptoethanol (ME). Anti‐RD28 inhibited both Lp and growth of internodes of N. obtusa by about 80 %, and the possible influences on cell growth of changes in turgor, respiration and pH in cell walls, being excluded during treatment. It was confirmed experimentally that enlargement growth of internodes of N. obtusa was linearly related to cell Lp.
Protein crystallization induced by polyethylene glycol: A model study using apoferritin
Authors: Tanaka Shinpei , Ataka Mitsuo
Published: September 2002

The phase behavior of apoferritin solutions induced by the addition of polyethylene glycol (PEG) was studied. The interaction between apoferritin molecules was determined by dynamic light scattering. The comparison of the experiments with the theoretical calculations showed that the addition of NaCl to the protein solution only screened the electrostatic repulsion and did not induce attraction. By the addition of PEG, on the other hand, significant attraction was induced and three types of precipitation (crystals, liquid domains, and random aggregates) appeared depending on the concentration of PEG and on its molecular weight. The strength of the attraction could be explained by the depletion mechanism, although there was slight discrepancy between the simple theory and the experiments. Superiority of PEG is thus demonstrated since the depletion mechanism does not depend on specific nature of proteins. From the phase diagram, we suggest that the control of the concentration and molecular weight of PEG are both needed for protein crystallization.
A unified treatment of quartic invariants at fixed and arbitrary energy
Authors: Karlovini Max , Pucacco Giuseppe , Rosquist Kjell , Samuelsson Lars
Published: September 2002

Two-dimensional Hamiltonian systems admitting second invariants which are quartic in the momenta are investigated using the Jacobi geometrization of the dynamics. This approach allows for a unified treatment of invariants at both arbitrary and fixed energy. In the differential geometric picture, the quartic invariant corresponds to the existence of a fourth rank Killing tensor. Expressing the Jacobi metric in terms of a Kähler potential, the integrability condition for the existence of the Killing tensor at fixed energy is a nonlinear equation involving the Kähler potential. At arbitrary energy, further conditions must be imposed which lead to an overdetermined system with isolated solutions. We obtain several new integrable and superintegrable systems in addition to all previously known examples.
Commensurate harmonic oscillators: Classical symmetries
Authors: Amiet Jean-Pierre , Weigert Stefan
Published: September 2002

The symmetry properties of a classical N-dimensional harmonic oscillator with rational frequency ratios are studied from a global point of view. A commensurate oscillator possesses the same number of globally defined constants of motion as an isotropic oscillator. In both cases invariant phase-space functions form the algebra su(N) with respect to the Poisson bracket. In the isotropic case, the phase-space flows generated by the invariants can be integrated globally to a set of finite transformations isomorphic to the group SU(N). For a commensurate oscillator, however, the group SU(N) of symmetry transformations is found to exist only on a reduced phase space, due to unavoidable singularities of the flow in the full phase space. It is therefore crucial to distinguish carefully between local and global definitions of symmetry transformations in phase space. This result solves the longstanding problem of which symmetry to associate with a commensurate harmonic oscillator.
Improved electron ionization ion source for the detection of supersonic molecular beams
Authors: Amirav Aviv , Fialkov Alexander , Gordin Alexander
Published: September 2002

An improved electron ionization (EI) ion source is described, based on the modification of a Brink-type EI ion source through the addition of a second cage with a fine mesh outside the ion chamber. The added outer cage shields the inner ion cage (ionization zone) against the penetration of the filament and electron repeller potentials, and thus results in the provision of ions with narrower ion energy distribution, hence improved ion-beam quality. The closer to zero electrical field inside the ion cage enables improved filtration (rejection) of ions that are produced from vacuum background compounds, based on difference in ion energies of beam and background species. The improved background ion filtration and ion-beam quality resulted in 2.6 times higher mass spectrometric ion signal, combined with 6.4 times better signal to noise ratio, in comparison with the same ion source having a single cage. The dual cage ion source further provides a smaller or no reduction of the electron emission current upon lowering the electron energy for achieving softer EI and/or electron attachment ionization. It also improves the long-term mass spectral and signal reproducibility and enables fast, automated change of the electron energy. Consequently, the dual cage EI ion source is especially effective for use with gas chromatography mass spectrometry with supersonic molecular beams (SMB), liquid chromatography mass spectrometry with SMB, ion guns with SMB, and any other experimental systems with SMB or nonthermal molecular beams.
Third-generation conical spot profile analyzing low-energy electron diffraction
Authors: Zahl P. , Horn-von Hoegen M.
Published: September 2002

A newly designed conical spot profile analyzing low-energy electron diffraction (LEED) allows optimized access to the sample up to an angle of 45° with respect to the surface plane. This allows in vivo LEED measurements during deposition or adsorption. The electron optics of the electrostatic deflection unit and the newly designed entrance lens were simulated and optimized using an electron-beam ray-tracing algorithm. Different sample distances can be accommodated by adjusting the deflection voltage between the front and rear section. A new “real-image” SPA-LEED operation mode is presented allowing simple control of the instrument and accurate electron-beam positioning on the sample.
Permanent magnet Penning trap for heavy ion storage
Authors: Suess L. , Finch C. D. , Parthasarathy R. , Hill S. B. , Dunning F. B.
Published: September 2002

The construction and operation of a Penning ion trap is described in which the trapping field is provided by a cladded NdFeB permanent magnet. Studies with atomic ions show that the trap can provide stable ion confinement for extended periods (≳100 ms) making it suitable for use in a wide variety of applications. Use of the trap to measure the lifetime of excited SF6−* and C7F14−* ions produced in Rydberg atom collisions is briefly discussed.
Effects of rare earth metal substituents on the piezoelectric and polarization properties of Pb(Zr,Ti)O3–Pb(Sb,Mn)O3 ceramics
Authors: Gao Yongkang , Uchino Kenji , Viehland Dwight
Published: September 2002

The piezoelectric properties of Pb(Zr,Ti)O3–Pb(Sb,Mn)O3 modified with the rare earth (RE) metal species Ce (1.03 Å), Eu (0.95 Å) and Yb (0.85 Å) have been investigated. For all rare earth substituents investigated in this system, regardless of the species ionic radii, the piezoelectric properties were observed to have combinatory hard and soft characteristics. Under high drive levels, the mechanical quality factor and the vibrational velocity were both significantly improved by RE substitution, resulting in a significant increase in ultrasonic power. Systematic polarization–electric field measurements revealed significant relaxational polarization similar to a soft piezoelectric, in addition to an internal field similar to a hard piezoelectric. A possible explanation for the combinatory “hardening” and “softening” effects is the coexistence of randomly quenched and mobile defects.
Stimulated Raman back-scattering from a mm-scale inhomogeneous plasma irradiated with ultra-intense laser pulse
Authors: Miyakoshi T. , Jovanović M. S. , Kitagawa Y. , Kodama R. , Mima K. , Offenberger A. A. , Tanaka K. A. , Yamanaka T.
Published: September 2002

Stimulated Raman scattering (SRS) from a mm-scale inhomogeneous plasma irradiated with an ultra-intense laser pulse was studied. Experimental results show that backward SRS spectral intensities increase with scattered light wavelength up to 1.3 λ0 and saturate at longer wavelength, where λ0 is the wavelength of the ultra-intense laser. Nonlinear phase mismatch was found to cause the saturation from a fully relativistic nonlinear 1D fluid simulation due to the relativistic mass increase of electron. The total amount of SRS was measured to be less than 3% of the incident laser energy.
Assessment of simple exchange-correlation energy functionals of the one-particle density matrix
Authors: Staroverov Viktor N. , Scuseria Gustavo E.
Published: September 2002

An improved density matrix functional (DMF) combining the properties of the “corrected Hartree” (CH) and “corrected Hartree–Fock” (CHF) approximations is proposed. Functionals of the CH/CHF type and the closely related natural orbital functional of Goedecker and Umrigar (GU) are tested in fully variational finite basis set calculations of light atoms, the lowest energy singlet methylene, and, for the first time, potential energy curves of diatomic molecules. Although CH/CHF-style DMFs may give reasonable energies for atoms and molecules near equilibrium geometries, they predict unrealistically shallow minima in the potential energy curves for diatomic molecules with more than two electrons. The calculated CH and CHF molecular dissociation curves exhibit the same patterns of over- and under-correlations as the corresponding correlation energy plots for the homogeneous electron gas undergoing a transition from high to low densities. In contrast, the GU functional yields not only accurate atomic and molecular energies but also plausible dissociation curves. The reasons behind the observed performance are analyzed.
Comment on “Oscillating two-stream instability in ionospheric heating experiments” [Phys. Plasmas 9, 1456 (2002)]
Authors: Mamun A. A. , Shukla P. K.
Published: September 2002

It is noted that the coupled mode equations of Kuo [Phys. Plasmas 9, 1456 (2002)] can be extended for studying the oscillating two-stream instability of high-frequency electrostatic (HFES) waves in the Earth’s ionosphere where Joule heating of electrons in the HFES wave fields play a significant role. Accordingly, a complete set of equations governing the nonlinear coupling between HFES waves and nonresonant density and temperature perturbations including the HFES ponderomotive force and thermal nonlinearity is presented.
Synchronization of two passively mode-locked, picosecond lasers within 20 fs for coherent anti-Stokes Raman scattering microscopy
Authors: Jones David J. , Potma Eric O. , Cheng Ji-xin , Burfeindt Berndt , Pang Yang , Ye Jun , Xie X. Sunney
Published: September 2002

We report on the synchronization of two commercial picosecond Ti:sapphire lasers with unprecedented low temporal jitter between the pulse trains. Pulse jitter is reduced from a few picoseconds to 20 fs with a stability of several hours. The technology enabling the tight pulse synchronization is reviewed in this article. We demonstrate the usefulness of the synchronization scheme by applying the technique to coherent anti-Stokes Raman scattering (CARS) microscopy. It is shown that CARS images can be acquired with a significant improvement in signal-to-noise ratio. This level of performance brings the fluctuations of the CARS signal down to the fundamental photon shot-noise limit. We present detailed statistical analysis of the pulse jitter and CARS noise along with enhanced CARS vibrational images of polymer beads.
Excited-state diffusion-influenced reversible association–dissociation reaction: Brownian dynamics simulation in three dimensions
Authors: Oh Changryul , Kim Hyojoon , Shin Kook Joe
Published: September 2002

Excited-state diffusion-influenced reversible reaction, A*+B⇄C*, is investigated in three dimensions by suitably modifying the Brownian dynamics simulation algorithm of Edelstein and Agmon [J. Chem. Phys. 99, 5396 (1993)] which requires the exact Green functions of the geminate system. The proposed simulation algorithm is based on using the mixed look-up tables. For the excited bound state, the unimolecular decay is coupled to the reactive movement and its trajectory can be calculated with the aid of the excited-state look-up table. On the other hand, the unimolecular decay of the excited unbound state is assumed to be independent of the reactive movement and its trajectory is calculated with the ground-state look-up table. The optimum size of the time step is found by fitting simulations performed for the geminate case to the analytic result. The simulation results with varying concentration of B particles as well as the ratio of unimolecular decay constants are in excellent agreement with the kinetic theoretical predictions of Kwac et al. [J. Chem. Phys. 114, 3883 (2001)].
Stabilization of Tollmien–Schlichting waves by finite amplitude optimal streaks in the Blasius boundary layer
Authors: Cossu Carlo , Brandt Luca
Published: September 2002

In this Letter we show by numerical simulation that streamwise streaks of sufficiently large amplitude are able to stabilize Tollmien–Schlichting waves in zero pressure gradient boundary layers at least up to Re=1000. This stabilization is due to the spanwise averaged part of the nonlinear basic flow distortion induced by the streaks and occurs for streak amplitudes lower than the critical threshold beyond which secondary inflectional instability is observed. A new control strategy is implemented using optimal perturbations in order to generate the streaks.
Steady-state rimming flow of the generalized Newtonian fluid
Authors: Fomin S. , Watterson J. , Raghunathan S. , Harkin-Jones E.
Published: September 2002

Rimming flow of a liquid polymer on the inner surface of a horizontal rotating cylinder is investigated. Using a scale analysis, a theoretical description for steady-state non-Newtonian flow is obtained. Simple lubrication theory is applied since the Reynolds number is small and the liquid film thin. Since a steady-state viscometric flow is considered, the general constitutive law requires only a single function relating shear stress and shear rate that corresponds to a generalized Newtonian liquid. For this case the existence of a continuous steady-state solution is proved. The properties of the solution for the different flow regimes are discussed. Numerical results are carried out for the Carreau–Yasuda model, which exhibits the Newtonian behavior at low shear rates with transition to power-law shear thinning at moderate shear rates.
Combined molecular dynamics–direct simulation Monte Carlo computational study of laser ablation plume evolution
Authors: Zeifman Michael I. , Garrison Barbara J. , Zhigilei Leonid V.
Published: September 2002

A two-stage computational model of evolution of a plume generated by laser ablation of an organic solid is proposed and developed. The first stage of the laser ablation, which involves laser coupling to the target and ejection of molecules and clusters, is described by the molecular dynamics (MD) method. The second stage of a long-term expansion of the ejected plume is modeled by the direct simulation Monte Carlo (DSMC) method. The presence of clusters, which comprise a major part of the overall plume at laser fluences above the ablation threshold, presents the main computational challenge in the development of the combined model. An extremely low proportion of large-sized clusters hinders both the statistical estimation of their characteristics from the results of the MD model and the following representation of each cluster size as a separate species, as required in the conventional DSMC. A number of analytical models are proposed and verified for the statistical distributions of translational and internal energies of monomers and clusters as well as for the distribution of the cluster sizes, required for the information transfer from the MD to the DSMC parts of the model. The developed model is applied to simulate the expansion of the ablation plume ejected in the stress-confinement irradiation regime. The presence of the directly ejected clusters drastically changes the evolution of the plume as compared to the desorption regime. A one-dimensional self-similar flow in the direction normal to the ablated surface is developed within the entire plume at the MD stage. A self-similar two-dimensional flow of monomers forms in the major part of the plume by about 40 ns, while its counterpart for large clusters forms much later, leading to the plume sharpening effect. The expansion of the entire plume becomes self-similar by about 500 ns, when interparticle interactions vanish. The velocity distribution of particles cannot be characterized by a single translational temperature; rather, it is characterized by a spatially and direction dependent statistical scatter about the flow velocity. The cluster size dependence of the internal temperature is mainly defined by the size dependence of the unimolecular dissociation energy of a cluster.
A new sequential importance sampling method and its application to the two-dimensional hydrophobic–hydrophilic model
Authors: Zhang Junni L. , Liu Jun S.
Published: September 2002

The sequential importance sampling method and its various modifications have been developed intensively and used effectively in diverse research areas ranging from polymer simulation to signal processing and statistical inference. We propose a new variant of the method, sequential importance sampling with pilot-exploration resampling (SISPER), and demonstrate its successful application in folding polypeptide chains described by a two-dimensional hydrophobic-hydrophilic (HP) lattice model. We show by numerical results that SISPER outperformed several existing approaches, e.g., a genetic algorithm, the pruned-enriched Rosenbluth method, and the evolutionary Monte Carlo, in finding the ground folding states of 2D square-lattice HP sequences. In a few difficult cases, the new method can find the ground states without using any prior structural information on the chain. We also discuss the potential applications of SISPER in more general problems.
Experimental study of lower-hybrid drift turbulence in a reconnecting current sheet
Authors: Carter T. A. , Yamada M. , Ji H. , Kulsrud R. M. , Trintchouk F.
Published: September 2002

The role of turbulence in the process of magnetic reconnection has been the subject of a great deal of study and debate in the theoretical literature. At issue in this debate is whether turbulence is essential for fast magnetic reconnection to occur in collisionless current sheets. Some theories claim it is necessary in order to provide anomalous resistivity, while others present a laminar fast reconnection mechanism based on the Hall term in the generalized Ohm’s law. In this work, a thorough study of electrostatic potential fluctuations in the current sheet of the magnetic reconnection experiment (MRX) [Yamada et al., Phys. Plasmas 4, 1936 (1997)] was performed in order to ascertain the importance of turbulence in a laboratory reconnection experiment. Using amplified floating Langmuir probes, broadband fluctuations in the lower hybrid frequency range (fLH∼5–15 MHz) were measured which arise with the formation of the current sheet in MRX. The frequency spectrum, spatial amplitude profile, and spatial correlation characteristics of the measured turbulence were examined carefully, finding consistency with theories of the lower-hybrid drift instability (LHDI). The LHDI and its role in magnetic reconnection has been studied theoretically for decades, but this work represents the first detection and detailed study of the LHDI in a laboratory current sheet. The observation of the LHDI in MRX has provided the unique opportunity to uncover the role of this instability in collisionless reconnection. It was found that: (1) the LHDI fluctuations are confined to the low-beta edge of current sheets in MRX; (2) the LHDI amplitude does not correlate well in time or space with the reconnection electric field, which is directly related to the rate of reconnection; and (3) significant LHDI amplitude persists in high-collisionality current sheets where the reconnection rate is classical. These findings suggest that the measured LHDI fluctuations do not play an essential role in determining the reconnection rate in MRX.
High-pressure and thermal properties of γ-Mg2SiO4 from first-principles calculations
Authors: Piekarz P. , Jochym P. T. , Parlinski K. , Łażewski J.
Published: September 2002

First-principles density-functional approach was used to obtain the crystal parameters and phonon spectra of γ-Mg2SiO4 (spinel and ringwoodite) as functions of pressure. The Grüneisen parameters at the Γ point were obtained and compared with the experimental data. Using quasiharmonic approximation, the total free energy of the crystal was calculated as a function of volume for several temperatures, hence, the bulk modulus and thermal expansion were found as a function of temperature. A good agreement between calculated and experimental values was obtained in a wide temperature range.
The p–T dependency of the ice II crystal structure and the effect of helium inclusion
Authors: Lobban C. , Finney J. L. , Kuhs W. F.
Published: September 2002

No reliable structural data have been reported on ice II under pressure, earlier work in the literature relating either to samples recovered to ambient pressure or the helium hydrate that is formed when helium is used as the pressurizing medium. We report structural refinements of helium-free ice II at three points in the phase’s region of stability. The structural differences from the helium-affected structure are significant, and can be related to the mainly repulsive interaction between the helium and both the oxygen and hydrogen atoms of the ice framework. These repulsions explain, among other changes, the different behaviors of the a (expansion) and c (contraction) lattice parameters, and the change in compressibility on the inclusion of helium.
Formation dynamics of layer-by-layer self-assembled films probed by second harmonic generation
Authors: Breit M. , Gao M. , von Plessen G. , Lemmer U. , Feldmann J. , Cundiff S. T.
Published: September 2002

We investigate the formation dynamics of self-assembled polyelectrolyte multilayers on glass substrates by in situ and ex situ second harmonic generation (SHG) measurements and atomic force microscopy (AFM). The time dependence of the SHG signal during the adsorption process is attributed to a time dependent surface potential of the polyelectrolyte film. The dynamics can be quantitatively understood using a random sequential adsorption (RSA) model for the buildup of a film consisting of polyelectrolyte disks with polydisperse sizes. Differences between wet and dry films are also investigated.
An effective potential function with enhanced charge-transfer-type interaction for hydrogen-bonding liquids
Authors: Honda Kazuhiko
Published: September 2002

The potential energy function (PEF) has been derived to perform the liquid simulations using the Monte Carlo method for three hydrogen-bonding systems, water, hydrogen fluoride, and ammonia. The PEF is a pair potential function of the overlap integrals between molecules and of the Coulomb interactions between atomic fractional charges. The parameters of the PEF are easily determined in order to reproduce the ab initio pair interaction energies. The lack of many-body interactions, however, prevents the reproduction of the liquid structures. The PEF consists of some physically meaningful terms, and using the characteristics of the function, it is found that the enhancement of a component in the PEF reasonably succeeds in producing the liquid structures. The general procedure for obtaining an effective pair potential function for the hydrogen-bonding systems is reported by a simple modification to the PEF.