Absence Of Instability Research Articles

Cervical Spinal Cord, Root, and Bony Spine Injuries

The aim of this study was to characterize cervical cord, root, and bony spine claims in the American Society of Anesthesiologists Closed Claims database to formulate hypotheses regarding mechanisms of injury. All general anesthesia claims (1970-2007) in the Closed Claims database were searched to identify cervical injuries. Three independent teams, each consisting of an anesthesiologist and neurosurgeon, used a standardized review form to extract data from claim summaries and judge probable contributors to injury. Cervical injury claims (n = 48; mean ± SD age 47 ± 15 yr; 73% male) comprised less than 1% of all general anesthesia claims. When compared with other general anesthesia claims (19%), cervical injury claims were more often permanent and disabling (69%; P < 0.001). In addition, cord injuries (n = 37) were more severe than root and/or bony spine injuries (n = 10; P < 0.001), typically resulting in quadriplegia. Although anatomic abnormalities (e.g., cervical stenosis) were often present, cord injuries usually occurred in the absence of traumatic injury (81%) or cervical spine instability (76%). Cord injury occurred with cervical spine (65%) and noncervical spine (35%) procedures. Twenty-four percent of cord injuries were associated with the sitting position. Probable contributors to cord injury included anatomic abnormalities (81%), direct surgical complications (24% [38%, cervical spine procedures]), preprocedural symptomatic cord injury (19%), intraoperative head/neck position (19%), and airway management (11%). Most cervical cord injuries occurred in the absence of traumatic injury, instability, and airway difficulties. Cervical spine procedures and/or sitting procedures appear to predominate. In the absence of instability, cervical spondylosis was the most common factor associated with cord injury.

Feeling the Elephant’s Weight: The Impact of Côte d’Ivoire’s Crisison WAEMU Trade

This paper analyzes the impact of political instability in Cote d’Ivoire on WAEMU trade over 1990-2007, applying panel econometric techniques to a gravity model of trade within WAEMU and between WAEMU and the rest of the world. The paper finds that intra-regional trade represents a small share of total WAEMU trade and that Cote d’Ivoire accounts for around half of that total, highlighting the importance of this country for the region. The political instability in Cote d’Ivoire has led to an increase in transaction costs, making it relatively more costly for member countries to trade with each other than with the rest of world. Instability has also resulted in a diversion of trade away from Cote d’Ivoire in favor of other countries equipped with ports and in a reduction of WAEMU overall potential trade. For Cote d’Ivoire alone, lost trade is estimated at around 40 percent of its potential trade with the WAEMU in the absence of instability. With a normalization in Cote d’Ivoire, enhanced security and further integration would be essential to achieve higher levels of trade and growth in the WAEMU region.

New low-frequency waves and negative mass instability in dusty plasmas

AbstractLow-frequency dusty plasma waves with frequencies much smaller than the frequency of charging collisions of plasma particles with dust particles are considered taking into account elastic and charging collisions of plasma particles with dust and neutrals. The usual dust sound waves with an upper frequency equal to the dust plasma frequency are found to be present only for wavelengths much smaller than the plasma particle effective mean free path due to the effective collision frequency. The effectice collision frequency is found to be inversely proportional to the square root of the product of the charging frequency and the frequency of particle momentum losses, involving processes due to elastic plasma particle–dust collisions and collisions with neutrals. It is shown that when the wavelength of the wave is much larger than the mean free path for effective collisions, the properties of the waves are different from those considered previously. A negative mass instability is found in this domain of frequencies when the effective mean free path of ions is larger than the effective mean free path of electrons. In the absence of neutrals, this appears to be possible only if the temperature of ions exceeds the electron temperature. This can occur in laboratory experiments and space plasmas but not in plasma-etching experiments. In the absence of instability, a new dust oscillation, a dust charging mode, is found, whose frequency is almost constant over a certain range of wave numbers. It is inversely proportional to the dust mass and charging frequency of the dust. A new dust electron sound wave is found for frequencies less than the frequency of the dust charging mode. The velocity of the dust electron sound wave is determined by the electron temperature but not the ion temperature, as for the usual dust sound waves, with the electron temperature substantially exceeding the ion temperature.

Basilar invagination, Chiari malformation, syringomyelia: A review

Institute and personal experience (over 25 years) of basilar invagination was reviewed. The database of the department included 3300 patients with craniovertebral junction pathology from the year 1951 till date. Patients with basilar invagination were categorized into two groups based on the presence (Group A) or absence (Group B) of clinical and radiological evidence of instability of the craniovertebral junction. Standard radiological parameters described by Chamberlain were used to assess the instability of the craniovertebral junction. The pathogenesis and clinical features in patients with Group A basilar invagination appeared to be related to mechanical instability, whereas it appeared to be secondary to embryonic dysgenesis in patients with Group B basilar invagination. Treatment by facetal distraction and direct lateral mass fixation can result in restoration of craniovertebral and cervical alignment in patients with Group A basilar invagination. Such a treatment can circumvent the need for transoral or posterior fossa decompression surgery. Foramen magnum bone decompression appears to be a rational surgical treatment for patients having Group B basilar invagination. The division of patients with basilar invagination on the basis of presence or absence of instability provides insight into the pathogenesis of the anomaly and a basis for rational surgical treatment.

Posterior Interosseous Nerve Palsy and Proximal Radio-Ulnar Joint Locking after Radial Head and Neck Fracture: A Case Report

Radial head fractures are common injuries which can be managed conservatively in the absence of instability or mechanical block at the elbow. We report a case of radial head and neck fracture which uniquely incorporates two rare complications: posterior interosseous nerve (PIN) palsy, and locking of the proximal radio-ulnar joint. The causative mechanisms are described with review of the relevant literature.

Sternal Nonunion: A Review of Current Treatments and a New Method of Rigid Fixation

Sternal nonunion as the result of cardiac intervention or trauma remains a morbid condition with serious sequelae. Patients often report pain with breathing, coughing, and/or movement. The authors present 6 patients that were diagnosed with sterile sternal nonunion after cardiac procedure (4) or trauma (2). The cardiac patients presented 5, 7, 15, and 60 months after their cardiac procedure; the trauma patients presented 8 and 12 months after the accident. Diagnosis was made based on the clinical triad of sternal instability, pain, and absence of infection. Management with open reduction and internal rigid plate fixation with Sternalock plates (W. Lorenz Surgical, Inc., Jacksonville, FL) was performed on all 6 patients. There was no incidence of subsequent infection. Pain completely resolved in all patients. All wounds healed to completion, and bone healing was assessed clinically with the absence of instability and pain and follow-up chest radiographs.

Modeling of the Steady-State Response of Granular Soils

The paper presents a study of the static liquefaction of granular soils, particularly the existence and uniqueness of the so-called steady-state and the conditions leading to the steady-state. The study is carried out using a simple constitutive model for granular soils established using a few well-known relationships based on results of drained triaxial tests on sands and silts. The paper clarifies the necessary theoretical and experimental conditions in determining whether a soil has achieved the steady-state. The results of the analytical study strongly emphasize the importance of dilatancy and deformability on the steady-state response of granular soils. It is shown that, in the absence of instability, liquefaction should be treated simply as another aspect of the stress-strain response of granular soils, and liquefaction should be treated not just as a strength problem but also as a deformation problem.

Colorectal cancers with mononucleotide microsatellite instability can be identified using microfabricated chip technology

syndrome is the most prevalent form offamilial colorectal cancer. It is caused by a defectivepostreplication DNA mismatch repair system. As aconsequence, errors that occur during replication ofDNA cannot be repaired but instead accumulate atmicrosatellite sites. Microsatellites are very short nu-cleotide sequences (e.g., mono-, di-, tri-, tetranucleo-tides) that are repeated tens of times and in tens ofthousands of copies distributed throughout the humangenome. These repeating sequences are highly poly-morphic, although their repeat length is uniform in theDNA of all cells of an individual. The accumulation oferrors at microsatellites, termed microsatellite instability(MSI), can be visualized on an electrophoresis gel asband shifts in tumor DNA. These shifts, caused by thesomatic insertion or deletion of one or more copies ofthe repeat units, are characteristic of microsatellite in-stability and allow identification of cancers with MSI.This is important because family history criteria for theidentification of HNPCC family members can be am-biguous and the phenotyping of colorectal cancers forMSI status is therefore a useful adjunct. Furthermore,there are additional reasons for developing accuratemolecular assays for detecting the MSI phenotype: (i)approximately 15–20% of sporadic colorectal cancersalso display MSI [1], (ii) the MSI phenotype appears toconfer a survival benefit for patients who develop suchtumors [2], (iii) MSI status may be a favorable prog-nostic indicator in patients with colorectal cancer re-ceiving chemotherapy [3], and (iv) colorectal cancersappear to have pronounced lymphocytic infiltrates [4],raising the possibility that these tumors may excite anantigen-specific immune response [5]. Clearly, the accu-rate identification of such tumors is important to bothclinical and scientific interests in the tumor immunologyof colorectal cancer.Molecular MSI criteria have been defined [6] andinclude mononucleotide repeat (BAT26 and BAT40)and dinucleotide repeat (D2S123, D5S346, andD17S250) markers. Of these, BAT26, an intronic seg-ment of the hMSH2 gene, has emerged as a highlyspecific marker for MSI-high (MSI-H) [7–10]. Tumorsare classified as MSI-H when two or more of the fivemarkers show instability or as MSI-low (MSI-L) whenonly one marker shows instability. Microsatellite stable(MSS) is characterized by the absence of instability in allfive markers. Currently, colorectal cancers are not rou-tinely screened for MSI status although several molec-ular techniques offer accurate detection of MSI from invivo samples. Most rely on the detection of smallPCR-amplified DNA fragments (

New low-frequency waves and negative mass instability in dusty plasmas

Low-frequency dusty plasma waves with frequencies much smaller than the frequency of charging collisions of plasma particles with dust particles are considered, taking into account elastic and charging collisions of plasma particles with dust and with neutrals. The usual dust sound waves with an upper frequency equal to the dust plasma frequency are found to be present only for wavelengths much smaller than the plasma particle effective mean free path due to the effective collision frequency. The effective collision frequency is found to be inversely proportional to the square root of the product of the charging frequency and the frequency of particle momentum losses, involving processes due to elastic plasma particle–dust collisions, and collisions with neutrals. It is shown that when the wavelength of the wave is much larger than the mean free path for effective collisions the properties of the waves are different from those previously considered. A negative mass instability is found in this domain of frequencies when the effective mean free path of ions is larger than the effective mean free path of electrons. In the absence of neutrals this appears to be possible only if the temperature of ions exceeds the electron temperature. This can occur in laboratory experiments and space plasmas but not in plasma-etching experiments. In the absence of instability a new dust oscillation, a dust charging mode, is found the frequency of which is almost constant over a certain range of wavenumbers. It is inversely proportional to the dust mass and charging frequency of the dust. A new dust electron sound wave is found for frequencies less than the frequency of the dust charging mode. The velocity of the dust electron sound wave is determined by the electron temperature but not the ion temperatures, as for the usual dust sound waves, with the electron temperature exceeding the ion temperature substantially.

Surgical treatment of lateral instability of the metacarpophalangeal joint of the first finger

Examination and treatment results of 27 patients with lateral instability of metacarpal-phalanx thumb joint were presented. The indication to operation and technique of surgical intervention in dependence on the terms from injury moment, presence or absence of instability, value of passive lateral deviation angle were detected. Surgical technique for the treatment of complete tears of collateral ligaments of metacarpal-phalanx thumb joint was petfected. In 22 patients follow up period ranged from 6 to 12 months. Excellent results were achieved in 13 (59%o), good in 7 (32%)), satisfactory in 2 (9%) patients.

Subduction along a Midocean Front and the Generation of Intrathermocline Eddies: A Theoretical Study*

Through an idealized model, the authors consider the dynamics of subduction along a midocean front and its linkage to the intrathermocline eddies (ITEs). The subduction is necessitated by advective–diffusive balance of potential vorticity (PV), with its flux mainly a function of the mixed layer depth over the normal range of the horizontal diffusivity. The mismatch of PV impedes the entry of the subducted water into the interior, resulting in an excess flux that peaks at some intermediate mixed layer depth. This mismatch also causes the generation of anticyclonic ITEs, whose radius contains no lower bound, and a maximum limited by the entrainment rate. Through entrainment cooling, ITEs may leave their imprints in the surface temperature, giving rise to a meandering appearance of the front, even in the absence of instability.

Uniform plasma model of shot noise in gyroklystrons

Theoretical estimates of electron cyclotron shot noise in gyroklystrons have recently been confirmed at low currents. However at high beam current, the noise temperature is always reduced. We examine the effect of transverse collective effects on the shot noise. There are two collective effects; shielding, which reduces the noise; and instability, which increases it. It is shown that the effect of transverse shielding is negligible unless the gyrotron beam is extremely cold. Regarding instability, if the bare shot noise amplitude is denoted /spl Xi/, then the shot noise, including the effect of instability, can be expressed as /spl Xi/(1+A exp /spl Gamma/), where /spl Gamma/ is the integrated growth. The effect of instability is then measured by two parameters, /spl Gamma/ and A. For a cold gyrotron beam, A is about 0.3, meaning about 10 dB of power growth is needed for the instability to manifest itself. Thermal effects both reduce A and /spl Gamma/. For realistic gyrotron beams, about 20-25 dB of power e folds would be necessary for instability to manifest itself. To summarize, the theory developed explains the absence of instability in the measurements, but indicates that phenomena other than transverse shielding are responsible for the noise reduction.

Phase 2 prolongation, in the absence of instability and triangulation, antagonizes class III proarrhythmia.

To evaluate whether prolongation of the plateau of the action potential duration, in the absence of instability and triangulation, can reverse the proarrhythmia elicited by a class III antiarrhythmic agent. The effects of almokalant, erythromycin and their combination, on cardiac electrophysiological parameters (action potential duration (APD), instability, triangulation and ectopics) were evaluated in isolated hearts from female albino rabbits. In this study, proarrhythmia was estimated quantitatively by number of ectopic beats. Erythromycin lengthened the APD primarily by a prolongation of the plateau, while having only minor effects upon phase 3 repolarization. The prolongation did not induce much instability, triangulation or reverse use dependence and, as expected, erythromycin did not induce significant proarrhythmia. Almokalant also lengthened APD, but it did not lengthen the plateau; instead, it prolonged phase 3 repolarization. The prolongation markedly triangulated the action potential, elicited much instability and marked reverse use dependence. This combination of effects induced very marked proarrhythmia. When almokalant and erythromycin were combined, their effects upon APD appeared additive: both the plateau and the repolarization phase were prolonged. However, the larger prolongation of APD did not lead to more proarrhythmia; this suggests that a prolongation of APD is not proarrhythmic per se. On the contrary, proarrhythmia as a function of APD prolongation was reduced in the presence of erythromycin (P<0.05). Instability plus triangulation consistently lead to serious proarrhythmia especially when combined with reverse use dependence, but prolongation of APD in itself is not necessarily proarrhythmic. In fact, APD prolongation in the absence of instability and triangulation can be antiarrhythmic.

Dust cyclotron instability in presence of dust charge fluctuations

Electrostatic ion cyclotron instability has been studied in presence of dust charge fluctuation. A comparative study has been done between instability in absence of dust charge fluctuation and in presence of that. It is observed that the critical velocity of electrons for the onset of instability increases due to dust charge fluctuations.

Stability of stratified flow of large depth over finite-amplitude topography

The flow of a Boussinesq density-stratified fluid of large depth past the algebraic mountain (Witch of Agnesi) is studied in the hydrostatic limit using the asymptotic theory of Kantzios & Akylas (1993). The upstream conditions are those of constant velocity and Brunt-Vaisala frequency. On the further assumptions that the flow is steady and there is no permanent alteration of the upstream flow conditions (no upstream influence), Long's model (Long 1953) predicts a critical amplitude of the mountain (e = 0.85) above which local density inversions occur, leading to convective overturning. Linear stability analysis demonstrates that Long's steady flow is in fact unstable to infinitesimal modulations at topography amplitudes below this critical value, 0.65 ≤ e < 0.85. This instability grows at the expense of the mean flow and may be attributed to a discrete spectrum of modes that become trapped over the mountain in the streamwise direction. The transient problem is also solved numerically, mimicking impulsive startup conditions. In the absence of instability, Long's steady flow is reached. For topography amplitudes in the unstable range 0.65 ≤ e < 0.85, however, the flow fluctuates about Long's steady state over a long timescale ; there is no significant upstream influence and no evidence of transient wave breaking is found for e ≤ 0.75.

Financial deregulation, demand for narrow money and monetary policy in Australia

This paper examines the long-run relationship between narrow money and output, interest rate, and price level in Australia for the period 1970–1993 with quarterly seasonally adjusted data using the concept of cointegration. The results suggest the presence of a long-run demand function, the absence of instability in the relationship in the face of deregulation/innovation in the Australia's financial system around 1980. The results also indicate the rejection of price homogeneity in the demand equation vindicating this specification in terms of nominal money balances. The underlying latent relationship is further promoted by a high speed of short-run adjustment evidenced from an analysis of short-run dynamics. All the estimated elasticities proved significant and were correctly signed.

Scintigraphy in the Evaluation of Osteoarthritis of the Canine Stifle Joint

SummaryThe aim of this study was to investigate the role of scintigraphy in the evaluation of osteoarthritis of the canine stifle joint. Forty dogs with osteoarthritis of the stifle joint were examined scintigraphically using 99mTechnetium hydroxymethylene diphosphonate (99mTc-HMDP). Early (perfusion) and late (bone) scans of both stifle joints from each dog were obtained. Preliminary review of scans suggested three grades of early phase isotope retention (0, 1, 2) and two abnormal patterns of late phase retention (“generalised” and “marginal”). The reproducibility of these gradings/groupings was tested using unweighted kappa (ĸ) tests and found to be good (ĸ = 0.58) to excellent (ĸ = 0.93). Of 73 early phase scans, 35 (48%) showed some abnormality as did 61 (85%) of 72 late phase scans. Where both early and late phase scans were available (n = 65), 58 (89%) were considered abnormal. Results of scans were compared to clinical, radiographic and surgical observations. Scintigraphy was associated with clinical and radiographic data (ρ &lt;0.05) but also appears to provide additional information. The marginal pattern was associated with bodyweight (ρ = 0.018), instability (odds ratio [OR] = 8.82), osteophytosis (OR = 18.64) and intra-articular mineralisation (OR = 31.09). Although not reaching statistical significance, the marginal pattern tended to be associated with articular cartilage fibrillation as observed at arthrotomy. The generalised pattern was seen in the absence of instability, effusion and osteophytosis. Scintigraphy appears to be a useful method for staging osteoarthritis of the canine stifle joint, as well as providing a means to study disease mechanisms.Osteoarthritic canine stifle joints were examined scinti-graphically (early and late phase scans), clinically, radio-graphically and visually at surgery. Abnormal scan grades and patterns were defined, and the reproducibility of these gradings/groupings was tested and found to be good to excellent. Scintigraphic findings were associated with other disease measures but it appears that scintigraphy supplies additional information. Scintigraphy provides a useful method with which to investigate osteoarthritis of the canine stifle joint.

Dynamic Instability Criterion for Circular String Loops

Dynamic perturbation equations are derived for a generic stationary state of an elastic string model-of the kind ppropriate for representing a superconducting cosmic string - in a flat background. In the case of a circular equilibrium state of closed string loop it is shown that the fundamental axisymmetric ( n = 0) and lowest order ( n = 1) nonaxisymmetric perturbation modes can never be unstable. However, stability for modes of higher order ( n ≥ 2) is found to be nontrivially dependent on the values of the characteristic propagation velocity, c say, of longitudinal perturbations and of the corresponding extrinsic perturbation velocity, v say. For each mode number the criterion for instability is the existence of nonreal roots for a certain cubic eigenvalue equation for the corresponding mode frequency. A very simple sufficient but not necessary condition for reality of all the roots and therefore absence of instability is that the characteristic velocity ratio, c/ v be greater than or equal to unity. Closer examination of the low velocity (experimentally accessible) nonrelativistic regime shows that in that limit the criterion for instability is just that the dimensionless characteristic ratio c/ v be less than a critical value χ c whose numerical value is approximately 1 2 . In the relativistic regime that is relevant to superconducting cosmic strings the situation is rather delicate, calling for more detailed investigation that is postponed for future work.

The role of trochanteric wire revision after total hip replacement.

Fifty-nine cases of trochanteric wire revision following hip arthroplasty with trochanteric osteotomy and reattachment were identified and their outcome was studied. Two were infected and were excluded. Five were revised for instability: four became stable while one continued to have persistent dislocation. Fifty-two were revised for pain, 36 by removal of the trochanteric wire and 16 by reattachment of the greater trochanter. Successful relief of pain was obtained in less than half the cases. There was no difference in the incidence of back pain, wiring technique, trochanteric advancement, previous surgery to the same hip, trochanteric size or the pattern of wire breakage in the successfully treated group and the unsuccessful group. Neither was the removal of intact wire from a united trochanter any more certain of relieving pain than removal of broken wire from an un-united trochanter. Six patients later required revision for loosening or infection. These results indicate the need for full radiological and haematological investigation before exploration of the greater trochanter. At exploration for pain the wires should simply be removed as we could show no successful union after late reattachment of the trochanter in the absence of instability.

Lateral and Anterior Instability in Acute Ankle Distortion

In a prospective consecutive investigation radiologic tests for lateral and anterior instability in acute ankle distortion were found to be reliable indications of lateral ligament ruptures. Arthrography of the ankle joint was used as reference. Absence of instability, however, gives little information as to the ligamental status. The size of this group constitutes a clinical problem. Better results are achieved by combining lateral and anterior instability tests. If only one test is used, the anterior instability test should be preferred. The results of the two tests bare no relation to the degree of ligament ruptures found at operation.