Abstract

Abstract

Object
The authors report the use and preliminary results of a novel hybrid dynamic stabilization and fusion construct for the surgical treatment of degenerative lumbar spine pathology.

Methods
The authors performed a retrospective chart review of all patients who underwent posterior lumbar instrumentation with the Dynesys-to-Optima (DTO) hybrid dynamic stabilization and fusion system. Preoperative symptoms, visual analog scale (VAS) pain scores, perioperative complications, and the need for subsequent revision surgery were recorded. Each patient was then contacted via telephone to determine current symptoms and VAS score. Follow-up was available for 22 of 24 patients, and the follow-up period ranged from 1 to 22 months. Clinical outcome was gauged by comparing VAS scores prior to surgery and at the time of telephone interview.

Results
A total of 24 consecutive patients underwent lumbar arthrodesis surgery in which the hybrid system was used for adjacent-level dynamic stabilization. The mean preoperative VAS score was 8.8, whereas the mean postoperative VAS score was 5.3. There were five perioperative complications that included 2 durotomies and 2 wound infections. In addition, 1 patient had a symptomatic medially placed pedicle screw that required revision. These complications were not thought to be specific to the DTO system itself. In 3 patients treatment failed, with treatment failure being defined as persistent preoperative symptoms requiring reoperation.

Conclusions
The DTO system represents a novel hybrid dynamic stabilization and fusion construct. The technique holds promise as an alternative to multilevel lumbar arthrodesis while potentially decreasing the risk of adjacent-segment disease following lumbar arthrodesis. The technology is still in its infancy and therefore follow-up, when available, remains short. The authors report their preliminary experience using a hybrid system in 24 patients, along with short-interval clinical and radiographic follow-up.

Object
Dynamic stabilization systems are used to stabilize degenerative lumbar spondylosis. Loosening of the pedicle screws in such nonfusion implants is predictable. This retrospective study evaluated the incidence of screw loosening and its effect on clinical outcomes.

Methods
Charts, radiographic films, and medical records of 71 consecutive patients who underwent decompression using Dynesys dynamic stabilization for 1- or 2-level lumbar spondylosis were reviewed. Radiographic films were evaluated and compared to detect screw loosening. A visual analog scale (VAS) for back pain and the Oswestry Disability Index (ODI) were used for measuring clinical outcome. Statistical analysis was conducted using the chisquare test and Student t-test.

Results
The 71 patients in the study sample had a mean age of 59.2 ± 11.65 years (range 23–80 years), with slight female predominance (39 women, 32 men). The mean follow-up duration was 16.6 months (range 8–29 months). There were loose screws in 14 of 71 patients (19.7%), for a rate of 4.6% per screw (17 of 368 screws). Most screw loosening occurred in patients = 55 years old (13 of 14 patients) although age and sex had no effect on screw loosening (p = 0.233 and 0.109, respectively). Both the loose screw and solid screw groups experienced significant improvement after the surgery in VAS and ODI scores. On the VAS, scores improved from 5.9 ± 2.99 to 2.1 ± 2.14 in the loose screw group (p = 0.003), and from 5.7 ± 3.45 to 2.9 ± 2.68 in the solid screw group (p < 0.001). For the ODI scale, scores improved from 43.5 ± 16.78% to 28.0 ± 18.18% (p = 0.006) in the loose screw group, and from 52.1 ± 20.92% to 24.6 ± 19.78% (p < 0.001) in the solid screw group. There were no significant differences between the 2 groups (p = 0.334 for VAS, p = 0.567 for ODI).

Conclusions
The preliminary study of this pedicle-based dynamic stabilization device for 1- and 2-level lumbar spondylosis shows radiographic evidence of screw loosening in 19.7% of patients and 4.6% of screws. Nonetheless, the loosening of screws has no adverse effect on clinical improvement.

The aim of this study was to evaluate retrospectively 48 medium to toy breed dogs with developmental medial patellar luxation submitted to corrective surgical procedures. In the grade 1 limbs, 46.7% were treated by lateral retinacular overlap and 53.3% by lateral retinacular overlap and deepening of the femoral groove with no complications. In the grade 2 limbs (n=35) were used the techniques of deepening of the femoral groove and lateral retinacular overlap (100% of the cases), medial desmotomy (28.6%), fabello-patellar sutures (2.8%) with 14.3% of reluxation. The last evaluation varied from 3 to 9 months, and clinical signs of lameness were still observed in 20% of the limbs. In all grade 3 cases (n=11) were performed deepening of the femoral groove, lateral retinacular overlap, partial quadriceps released, medial desmotomy and lateral transposition of the tibial tuberosiy that was fixated with Kirschner wire or screw. Reluxation occurred in 27.3% of the limbs that were reoperated. In this group 72.7% of the limbs had absence of lameness. In the grade 4 limbs (n=10) were used the same techniques of grade 3, but it was also necessary the femoral corrective osteotomy in 4 limbs. Reluxation was observed in 30% of the limbs that were reoperated. Although 60% of the limbs showed a positive evolution of the locomotion after 5.2 months of evaluation, in general the dogs showed a posture with the hind limbs in a semi-flexed position, due to the inability to fully extend the stifle. In conclusion, the surgical procedures used allowed an improvement of the locomotion, but except to grade 1, the patellar reluxation may occur in the other degrees suggesting the necessity of other protocols.

In Latin America, the most accepted disposal systems for Municipal Solid Waste (MSW) are landfills, which nowadays have low rates of stabilization. The objective of this study was to develop design criteria for sanitary landfills which lead to a reduction in the stabilization times of MSW, based on experiment results obtain from a pre-pilot scale operation of two sanitary landfills (0.5 Ton), one with recirculation of leachates treated in an anaerobic digester and the other with recirculation of untreated leachates. This was complemented by another pilot scale sanitary landfill (1440 Ton) with recirculation of leaches treated in an anaerobic filter, and additionally by a computer simulation of leachate generation through the water balance of a theoretical cell of MSW (850 Ton), in which the initial humidity of the MSW and the type of final cover were evaluated. The results obtained on the pre-pilot scale indicate that recirculation of anaerobically treated leachates, when compared to the recirculation of untreated leachates, increased the rate of MSW stabilization, projecting a stabilization time reduction of 72%. In the pilot sanitary landfill an increase in the settling rate of around 200% was observed when operating with the recirculation of anaerobically treated leachates as opposed to operation without recirculation. The water balance carried out on the theoretical cell of MSW demonstrated the importance to leachate generation of both the initial landfill water saturation and the type of final barrier. From these results it may be stated that it is important for landfill design to maintain waste humidity close to its field capacity along with an adequate leachate application rate.

The interplay between entropy and robustness of gene network is a core mechanism
of systems biology. The entropy is a measure of randomness or disorder of a
physical system due to random parameter fluctuation and environmental noises in
gene regulatory networks. The robustness of a gene regulatory network, which can
be measured as the ability to tolerate the random parameter fluctuation and to
attenuate the effect of environmental noise, will be discussed from the robust
H_∞ stabilization and filtering perspective. In this review, we will
also discuss their balancing roles in evolution and potential applications in
systems and synthetic biology.

Abstract

 We report on
the epitaxial stabilization of tetragonal DO₂₂-type
Mn_3-?Ga (? = 0 to 2) films on GaSb(001) using molecular beam epitaxy
technique and the structural and magnetic properties as a function of Mn
concentration. The growth orientation of Mn-Ga(114)//GaSb(001) make the easy
magnetocrystalline direction located in the film plane in our experiment, which
is different from the ordinarily observed perpendicular-magnetic-anisotropy of
Mn_3-?Ga films. The increase in coercivity with the increase in
temperature for the MnGa film is possibly due to the increase in anisotropy
energy. With decreasing Mn concentration, MnGa exhibits the enhanced anisotropy
energy with respect to Mn₃Ga. The enhanced average saturation
magnetization per Mn atom with decreasing Mn content was also observed,
indicating a ferrimagnetic ordering with partially compensating moments of the
two crystallographically different Mn sites in DO₂₂
structure.

The paper deals with a specific kind of discrete-time recurrent neural network designed with dynamic neuron models. Dynamics are reproduced within each single neuron, hence the network considered is a locally recurrent globally feedforward. A crucial problem with neural networks of the dynamic type is stability as well as stabilization in learning problems. The paper formulates local stability conditions for the analysed class of neural networks using Lyapunov's first method. Moreover, a stabilization problem is defined and solved as a constrained optimization task. In order to tackle this problem, a gradient projection method is adopted. The efficiency and usefulness of the proposed approach are justified by using a number of experiments